konoma 0.18.0

//! Application state: the `App` struct and its methods — mode (Tree/Preview), the tree,
//! tabs, and the current preview target. Git view methods live in the `git_view` submodule.

use std::collections::BTreeSet;
use std::path::{Path, PathBuf};
use std::sync::Arc;

use anyhow::Result;
use ratatui::layout::Rect;
use ratatui::text::{Line, Span};
use ratatui_image::errors::Errors;
use ratatui_image::picker::Picker;
use ratatui_image::protocol::Protocol;
use ratatui_image::thread::{ResizeRequest, ResizeResponse, ThreadProtocol};
use ratatui_image::{FilterType, Resize};
use tokio::sync::mpsc::UnboundedSender;

use crate::config::Config;
use crate::i18n::tr;
use crate::preview::PreviewKind;

mod bookmark_actions;
mod file_actions;
mod git_view;
mod md_tasks;
mod paste_jump;
mod session_actions;

#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub enum Mode {
    #[default]
    Tree,
    Preview,
}

/// Display mode (outer): what is currently shown full-screen. The **outer chip** in the status bar (colors assigned by `ui`).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum DisplayMode {
    Tree,
    Preview,
    Image,
    /// CSV/TSV table preview (aligned grid + cell cursor).
    Table,
}

/// Internal mode (inner): what is currently being operated. Shows the **inner chip** only while active and switches the footer keys too.
/// Priority: dialog > each footer mode (filter/search/sort/bookmarks) > visual.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum InternalMode {
    Visual,
    /// Windowed-preview line selection (`v` in a code/text preview).
    PreviewVisual,
    Filter,
    /// Changed-files-only tree view (`C`; Agent Watch).
    ChangedFilter,
    Search,
    Sort,
    Mark,
    Bookmarks,
    Tabs,
    Outline,
    Info,
    Create,
    Rename,
    BatchRename,
    RenamePreview,
    DeleteConfirm,
    DropConfirm,
    QuitConfirm,
    BookmarkConfirm,
    GitChanges,
    GitDiff,
    Commit,
    GitLog,
    GitDetail,
    GitBranch,
    GitGraph,
    GitGraphPicker,
}

/// Preview paging key style. Specified via the `ui.keys` setting (default vim).
/// Diffs use only the page/half-page keys. j/k line movement, arrows, and PageUp/Down are common to both styles.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum KeyScheme {
    /// vim style: Ctrl-f/Ctrl-b=page, Ctrl-d/Ctrl-u=half.
    Vim,
    /// less style: Space/b=page, d/u=half.
    Less,
}

impl KeyScheme {
    pub fn parse(s: &str) -> Self {
        match s {
            "less" => Self::Less,
            _ => Self::Vim,
        }
    }
}

/// diff layout (config `git.diff`; cycle at runtime with `s`). Auto picks vertical/horizontal automatically from the terminal width.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum DiffLayout {
    /// Vertical (unified).
    Unified,
    /// Side-by-side.
    Split,
    /// Horizontal if wide, vertical if narrow.
    Auto,
}

impl DiffLayout {
    /// Parse a config value. "split"/"horizontal"/"side-by-side"=horizontal / "auto"=auto / otherwise=vertical.
    pub fn parse(s: &str) -> Self {
        let n: String = s
            .chars()
            .filter(|c| !matches!(c, ' ' | '-' | '_'))
            .flat_map(|c| c.to_lowercase())
            .collect();
        match n.as_str() {
            "split" | "horizontal" | "sidebyside" | "side" => Self::Split,
            "auto" => Self::Auto,
            _ => Self::Unified, // "unified" / "vertical" / 不明
        }
    }
    /// Resolve whether to lay out side-by-side at the actual display width `width`. Auto decides by a threshold.
    pub fn is_split(self, width: u16) -> bool {
        match self {
            DiffLayout::Unified => false,
            DiffLayout::Split => true,
            DiffLayout::Auto => width >= DIFF_AUTO_MIN_WIDTH,
        }
    }
    /// Cycle to the next layout (vertical→horizontal→Auto→vertical). For `s`.
    #[cfg_attr(not(feature = "git"), allow(dead_code))]
    pub fn next(self) -> Self {
        match self {
            DiffLayout::Unified => DiffLayout::Split,
            DiffLayout::Split => DiffLayout::Auto,
            DiffLayout::Auto => DiffLayout::Unified,
        }
    }
}

/// Minimum inner width for side-by-side under Auto (below this, vertical). A guideline so two-column code is not cramped.
const DIFF_AUTO_MIN_WIDTH: u16 = 90;

/// Layout of the status chrome (config `ui.statusbar`).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum StatusbarLayout {
    /// Context (mode/path/zoom) on top (right of the tab row), key hints at the bottom (default).
    Split,
    /// Combine both context and key hints into a single bottom line.
    Bottom,
}

impl StatusbarLayout {
    pub fn parse(s: &str) -> Self {
        match s {
            "bottom" => Self::Bottom,
            _ => Self::Split,
        }
    }
}

/// Path display style. Used for the title (tree/preview). Cycle with the `p` key.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum PathStyle {
    /// Relative to the launch directory name (e.g. konoma/src/main.rs). Default.
    Relative,
    /// Relative to HOME (e.g. ~/work/konoma).
    Home,
    /// Full path (e.g. /Users/me/work/konoma).
    Full,
}

impl PathStyle {
    pub fn parse(s: &str) -> Self {
        match s {
            "home" => Self::Home,
            "full" => Self::Full,
            _ => Self::Relative,
        }
    }
    pub fn next(self) -> Self {
        match self {
            Self::Relative => Self::Home,
            Self::Home => Self::Full,
            Self::Full => Self::Relative,
        }
    }
}

/// A single entry shown in the tree.
#[derive(Debug, Clone)]
pub struct Entry {
    pub path: PathBuf,
    pub is_dir: bool,
    pub depth: usize,
    pub expanded: bool,
}

/// Tree sort key (FR / M7 auxiliary). Switch via the footer menu (`s`).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum SortKey {
    Name,
    Size,
    Modified,
    Ext,
}

/// Sort settings. `reverse`=flip ascending/descending, `dirs_first`=group directories at the top.
/// Default is "name, ascending, directories first" (matches the previous behavior). Global (not per-tab).
#[derive(Clone, Copy)]
pub struct Sort {
    pub key: SortKey,
    pub reverse: bool,
    pub dirs_first: bool,
}

impl Default for Sort {
    fn default() -> Self {
        Self {
            key: SortKey::Name,
            reverse: false,
            dirs_first: true,
        }
    }
}

impl SortKey {
    /// Parse a config string (case-insensitive). Unknown/empty falls back to Name.
    pub fn parse(s: &str) -> Self {
        match s.trim().to_lowercase().as_str() {
            "size" => SortKey::Size,
            "modified" | "mtime" | "mod" => SortKey::Modified,
            "ext" | "extension" | "type" => SortKey::Ext,
            _ => SortKey::Name,
        }
    }
}

impl Sort {
    /// Build the startup sort order from the `[ui.sort]` config.
    pub fn from_config(c: &crate::config::SortConfig) -> Self {
        Self {
            key: SortKey::parse(&c.key),
            reverse: c.reverse,
            dirs_first: c.dirs_first,
        }
    }
}

/// Destructive/creation operations confirmed through a modal dialog (M7 Phase B, safety first).
// git 専用バリアント(GitDiscard/GitDeleteBranch)は非 git ビルドでは構築経路が無い(その構築元は
// git ディスパッチ専用)。バリアント自体は match の網羅性のため残し、非 git のみ dead_code を許す。
#[cfg_attr(not(feature = "git"), allow(dead_code))]
#[derive(Clone)]
enum PendingOp {
    /// Create with the entered name. A trailing `/` means a folder. `dir` is the destination (based on the cursor).
    Create { dir: PathBuf },
    /// Rename the target to the entered name within the same parent.
    Rename { target: PathBuf },
    /// Send the target to the trash (recoverable).
    Delete { targets: Vec<PathBuf> },
    /// Template-input stage of batch rename (`targets`=targets in display order). On confirm, builds a plan and moves to preview.
    BatchRenameInput { targets: Vec<PathBuf> },
    /// Preview→apply stage of batch rename (`plan`=(old, new) pairs).
    BatchRenameApply { plan: Vec<(PathBuf, PathBuf)> },
    /// In the Git view, `x`=discard a file's changes (via a confirmation dialog). On confirm, git::discard.
    GitDiscard { path: PathBuf },
    /// In the Git view, `c`=enter a commit message. On confirm, git::commit (uses the staged index).
    GitCommit,
    /// In the branch list, `n`=enter a new branch name. On confirm, git::create_branch (create and switch).
    GitCreateBranch,
    /// In the branch list, `d`=delete confirmation. `y`=safe (-d) / `!`=force (-D).
    GitDeleteBranch { name: String },
    /// A transfer received via file drag & drop (through a terminal paste). `c`=copy / `m`=move / Esc=cancel.
    /// `sources`=the dropped existing paths, `dir`=the drop destination (directory based on the cursor).
    DropTransfer { sources: Vec<PathBuf>, dir: PathBuf },
    /// Quit the whole app. A confirmation is requested before exiting (see `ui.confirm_quit`).
    Quit,
    /// Overwrite an existing bookmark under `key` with `target` (confirmation via `ui.confirm_bookmark_overwrite`).
    BookmarkOverwrite { key: char, target: PathBuf },
}

/// A confirmation (yes/no) or text-input modal. On confirm, calls fileops according to `op`.
struct Dialog {
    op: PendingOp,
    kind: DialogKind,
}

/// Dialog kind. Confirm=y/n for a destructive op (delete) / Input=name entry for create/rename.
/// `allow_permanent`=whether the delete confirmation also offers `!`=permanent delete (unrecoverable) (true=delete confirmation only).
enum DialogKind {
    Confirm {
        message: String,
        allow_permanent: bool,
    },
    Input {
        title: String,
        buffer: String,
        /// Insertion position (**character** index within buffer, 0..=char count). Move with ←→/Home/End.
        cursor: usize,
    },
    /// Confirmation preview for batch rename. `lines`=the "old → new" list, `scroll`=the top visible line.
    Preview {
        title: String,
        lines: Vec<String>,
        scroll: usize,
    },
}

/// File clipboard operation kind. Copy=duplicate / Cut=move (consumed on paste).
#[derive(Clone, Copy, PartialEq, Eq)]
enum ClipOp {
    Copy,
    Cut,
}

/// Copy/cut targets pushed with `Y`/`X`. Apply them with `P` to the cursor-based directory.
#[derive(Clone)]
struct Clipboard {
    op: ClipOp,
    paths: Vec<PathBuf>,
}

/// Snapshot of one tab's tree context (FR-5).
/// The active tab's working state lives in App's fields as the source of truth, and is saved/loaded here on switch.
/// It keeps not just the tree but also the **mode/preview state per tab**, restoring them on switch instead of dropping to Tree.
/// The heavy image state (protocol/source image) is not carried over and is reloaded on restore (zoom/center are kept).
/// `Default` exists only as the placeholder `load_active` leaves in the slot after moving the
/// snapshot out — the active slot is never read (tab_label/tab_root use the live App fields)
/// and the next save_active overwrites it.
#[derive(Clone, Default)]
struct TabState {
    root: PathBuf,
    open_dir: PathBuf,
    entries: Vec<Entry>,
    selected: usize,
    show_hidden: bool,
    tree_viewport: u16,
    mode: Mode,
    preview_path: Option<PathBuf>,
    preview_kind: Option<PreviewKind>,
    preview_scroll: u16,
    preview_hscroll: u16,
    preview_viewport: u16,
    preview_byte_top: u64,
    preview_top_line: usize,
    image_zoom: f64,
    image_center: (f64, f64),
    // PDF の現在ページ/総ページ数もタブごとに保持(別タブから戻ったとき同じページを再描画する)。
    pdf_page: u32,
    pdf_pages: Option<u32>,
    // CSV/TSV テーブルのセルカーソル/スクロールもタブごとに保持(テーブル本体は復元時に再パース)。
    table_cur_row: usize,
    table_cur_col: usize,
    table_top_row: usize,
    table_left_col: usize,
    // windowed(Code/Text)プレビューの 2D キャレット位置(別タブから戻っても同じ行/列に戻る)。選択(anchor)は持ち越さない。
    preview_cursor_line: usize,
    preview_cursor_col: usize,
    // Markdown/Mermaid の raw ソース表示(`R`)状態もタブごとに保持する。
    md_raw: bool,
    // Markdown プレビューの Tab フォーカスと、インライン図のその場ズーム/全画面復帰情報も
    // タブごとに保持する。タブ非依存のままだと、両タブが md プレビュー中の切替(enter_preview を
    // 経ない唯一の経路)で前タブのフォーカス/ズームが別文書へ漏れ、hjkl が見えない図のパンに
    // 化ける(image_zoom が TabState 保存されるのと同じ扱いに揃える)。
    focused_item: Option<usize>,
    fence_zoom: f64,
    fence_center: (f64, f64),
    fence_return: Option<(u16, Option<usize>)>,
    // git オーバーレイもタブごとに保持する(別タブでドキュメントを見て戻っても git モードのまま)。
    git_view: bool,
    git_view_sel: usize,
    git_view_entries: Vec<crate::git::ChangeEntry>,
    came_from_git_view: bool,
    git_log: Option<Vec<crate::git::CommitInfo>>,
    git_log_sel: usize,
    git_detail: Option<Vec<crate::git::DiffLine>>,
    git_detail_meta: Option<crate::git::CommitMeta>,
    git_detail_title: Option<String>,
    git_detail_scroll: u16,
    git_detail_hscroll: u16,
    git_detail_viewport: u16,
    git_detail_total: usize,
    git_branches: Option<Vec<crate::git::BranchInfo>>,
    git_branch_sel: usize,
    git_branch_filter: String,
    git_branch_filtering: bool,
    git_graph: Option<Vec<crate::git::GraphRow>>,
    git_graph_sel: usize,
    // グラフ本体(git_graph)を保存する以上、それを装飾する派生状態(基準ピン・凡例・表示ブランチ・
    // 優先順)も同じタブに保存しないと、別タブで基準/表示を変えて戻ったとき凡例や `base:` タイトルが
    // 他タブのまま残る(load_active はグラフを再構築しない)。git_detail_meta/title を git_detail と
    // 一緒に保存するのと同じ扱い。ピッカー(モーダル)の一時状態は保存せず復元時にリセットする。
    git_graph_base: Option<String>,
    git_graph_base_label: Option<String>,
    git_graph_visible: std::collections::HashSet<String>,
    git_graph_legend: Vec<crate::git::LegendEntry>,
    git_graph_hidden: usize,
    git_graph_order: Vec<String>,
    // --- タブ毎の選択 / 絞り込み / プレビュー検索 (#2/#6: タブ跨ぎのデータ損失 footgun 対策) ---
    // これらが TabState に無いと、タブAで選択 → 別タブ/別 dir で D/X/Y/P したとき、
    // 見えていない旧選択のファイルが操作対象になる(マーカー不可視で気付けない)。
    // クリップボード(Y/X/P の paths バッファ)は app 全体共有のままで、ここには入れない(ユーザ確定事項)。
    selection: BTreeSet<PathBuf>,
    visual_anchor: Option<usize>,
    tree_filter: Option<String>,
    filter_input: Option<String>,
    filter_pool: Vec<Entry>,
    changed_filter: bool,
    preview_search: Option<String>,
    search_input: Option<String>,
    search_matches: Vec<(u64, usize, usize)>,
    search_idx: usize,
}

/// The media payload loaded on a separate thread (sent back to the UI thread).
pub enum MediaPayload {
    /// A still image (single-frame GIF / video thumb / PDF page) → goes to image_src.
    Static(image::DynamicImage),
    /// All GIF frames (composited RGBA + delay) → goes to gif_frames.
    Gif(Vec<(image::DynamicImage, std::time::Duration)>),
    /// A raster of a vector source (SVG file / mermaid diagram). The SVG is retained so zooming
    /// re-rasterizes at the needed density (sharp zoom) instead of blowing up pixels.
    Vector {
        img: image::DynamicImage,
        svg: std::sync::Arc<Vec<u8>>,
    },
}

/// Result of media loading from another thread. Matched by generation via `gen`; results made stale by navigation are discarded.
pub struct MediaResult {
    gen: u64,
    /// None = decode/rasterize failure (the render side shows a fallback).
    payload: Option<MediaPayload>,
}

/// The geometry a kitty image targets: `(crop rect (x,y,w,h) in source px, display cols, rows)`.
type KittyGeom = ((u32, u32, u32, u32), u16, u16);

/// Result of an async kitty image build (resize + `o=z` compress) from a worker thread. Matched by
/// `gen` (latest-wins): a build superseded by a newer zoom/pan is discarded. None = build failed.
pub struct KittyResult {
    gen: u64,
    image: Option<crate::preview::kitty::KittyImage>,
}

/// Heavy media loading to run on a separate thread (pure work that does not reference App).
enum MediaJob {
    /// Rasterize an SVG (path, max-edge px). Vector-backed: keeps the source for sharp zoom.
    Svg(PathBuf, u32),
    /// Expand all GIF frames. Falls back to still-image decode for single-frame/non-animated GIFs.
    Gif(PathBuf),
    /// Extract one representative frame from a video (delegated to ffmpegthumbnailer/ffmpeg). Thumbnail only; no playback.
    Video(PathBuf),
    /// Rasterize page N (1-based) of a PDF (delegated to pdftocairo/pdftoppm/qlmanage/sips). Loaded one page at a time.
    Pdf(PathBuf, u32),
    /// Render a standalone mermaid file to SVG (pure Rust) and rasterize it (max-edge px, theme).
    /// None (unsupported diagram / parse failure) → the caller's text-diagram fallback shows.
    Mermaid(PathBuf, u32, String),
    /// Render mermaid source text (a ```mermaid fence opened full-screen) and rasterize it.
    MermaidSrc(String, u32, String),
    /// Re-rasterize the retained SVG source at a new max-edge px (sharp zoom). The path is only
    /// the base for relative resources inside the SVG (mermaid output has none).
    SvgReraster(std::sync::Arc<Vec<u8>>, PathBuf, u32),
}

impl MediaJob {
    /// Load the actual data (called on a separate thread or via the synchronous fallback). None on failure.
    fn run(self) -> Option<MediaPayload> {
        match self {
            MediaJob::Svg(p, max_px) => {
                let data = std::fs::read(&p).ok()?;
                let img = crate::preview::svg::rasterize_bytes(&data, &p, max_px)?;
                Some(MediaPayload::Vector {
                    img,
                    svg: std::sync::Arc::new(data),
                })
            }
            MediaJob::Gif(p) => match crate::preview::image::decode_gif(&p) {
                Some(frames) => Some(MediaPayload::Gif(frames)),
                // 単一フレーム/アニメでない GIF → 静止画として表示。
                None => crate::preview::image::decode_static(&p).map(MediaPayload::Static),
            },
            MediaJob::Video(p) => crate::preview::video::thumbnail(&p).map(MediaPayload::Static),
            MediaJob::Pdf(p, page) => {
                crate::preview::pdf::render_page(&p, page).map(MediaPayload::Static)
            }
            MediaJob::Mermaid(p, max_px, theme) => {
                let code = std::fs::read_to_string(&p).ok()?;
                MediaJob::MermaidSrc(code, max_px, theme).run()
            }
            MediaJob::MermaidSrc(code, max_px, theme) => {
                let svg = crate::preview::markdown::mermaid_to_svg(&code, &theme)?;
                let data = svg.into_bytes();
                let img =
                    crate::preview::svg::rasterize_bytes(&data, Path::new("mermaid.svg"), max_px)?;
                Some(MediaPayload::Vector {
                    img,
                    svg: std::sync::Arc::new(data),
                })
            }
            MediaJob::SvgReraster(svg, p, max_px) => {
                let img = crate::preview::svg::rasterize_bytes(&svg, &p, max_px)?;
                Some(MediaPayload::Vector { img, svg })
            }
        }
    }
}

/// Result of the **heavy ignored set (`git::ignored`)** computed on a separate thread. Staleness is judged by `gen`, and
/// only the latest generation is applied (results from after moving to another repo while computing are discarded). `workdir` is the
/// repo workdir being computed; on apply it is put into `git_ignored_for` to serve as the Phase G cache key.
pub struct IgnoredResult {
    gen: u64,
    workdir: PathBuf,
    set: std::collections::HashSet<PathBuf>,
}

pub struct App {
    pub mode: Mode,
    pub root: PathBuf,
    /// The directory opened at startup. The base for relative-path display (kept separately because root moves up with h).
    pub open_dir: PathBuf,
    /// The directory opened at startup (immutable). The reset target for `A` ResetAnchor. Kept separately because open_dir moves with `a`.
    launch_dir: PathBuf,
    pub path_style: PathStyle,
    pub key_scheme: KeyScheme,
    pub lang: crate::i18n::Lang,
    pub cfg: Config,

    /// The tree flattened into display order. For M0 it is fine to simply rebuild it every time.
    pub entries: Vec<Entry>,
    pub selected: usize,
    pub show_hidden: bool,
    /// Tree sort settings (FR / M7 auxiliary). Global (not per-tab). Changed via the `s` menu.
    pub sort: Sort,
    /// Whether the `s` sort-selection menu is showing (while true, main intercepts keys).
    sort_menu: bool,
    /// Bookmarks (M7 auxiliary). Lowercase a-z=local (per launch dir) / uppercase A-Z=global.
    pub bookmarks: crate::bookmarks::Bookmarks,
    /// Tab-session persistence (`[ui] restore_tabs`). Attached by main like the loader senders;
    /// `None` (tests) = tab operations never write session files.
    session_store: Option<crate::session::SessionStore>,
    /// True only while `restore_session` is rebuilding the saved tabs. Suppresses the per-op
    /// `save_session` calls that `tab_new`/`tab_goto` would otherwise fire, so a crash mid-restore
    /// cannot overwrite the on-disk session with a partial set; one complete write happens at the end.
    session_restoring: bool,
    /// State of waiting for a letter after `m`/`'` (Set=register / Jump=jump).
    /// Waiting for the letter key after `m` (bookmark set). (`'` opens the list directly.)
    mark_set_pending: bool,
    /// Whether the bookmark-list overlay is showing.
    bookmark_list: bool,
    /// Selection position in the list (a flat index over local on top and global below, concatenated).
    bookmark_list_sel: usize,
    /// Confirmation/input dialog (create `a` / rename `R` / delete `D`). While showing, main intercepts keys.
    dialog: Option<Dialog>,
    /// Multi-selection (M7 Phase B). The set of **absolute paths** selected via `V`/visual. The target of batch delete, etc.
    /// Held by path (not by index), so the selection is preserved across tree rebuilds and filtering.
    selection: BTreeSet<PathBuf>,
    /// Anchor of visual (range) selection mode (entries index). Visual mode is active while it is Some.
    /// Range = anchor to cursor. On confirm, it is taken into `selection`.
    visual_anchor: Option<usize>,
    /// File clipboard (M7 Phase B). Push with `Y`=copy/`X`=cut, apply with `P`=paste.
    clipboard: Option<Clipboard>,
    /// Height (in rows) of the tree display area at the last render. Used as the page size for paging.
    pub tree_viewport: u16,

    /// Tree filter (`/`). Some=filter is active (the query). entries holds the result of narrowing filter_pool.
    tree_filter: Option<String>,
    /// Editing buffer for the filter query. Some=input mode (intercepts keys).
    filter_input: Option<String>,
    /// All entries to filter from (recursively collected under root). Built once when `/` starts.
    filter_pool: Vec<Entry>,
    /// Changed-files-only tree filter (`C`). While true, entries is a flat list of the files with a git
    /// status under root (the review companion for AI-made changes; broot's `:gs` equivalent). Per tab.
    changed_filter: bool,
    /// Follow mode (`F`, global): while true, an external file change (e.g. an AI agent writing) jumps the
    /// tree selection to that file and opens its preview. Any other keypress turns it off (Zed-style).
    follow_mode: bool,
    /// Files changed during the current follow session (since `F` was last turned ON; first-change order,
    /// deduped). Powers the session-scoped `n`/`N` review in follow-opened diffs — "what just changed",
    /// not the whole dirty worktree. Kept after follow turns off (review continues); reset by the next ON.
    follow_session: Vec<PathBuf>,
    /// Whether the current GitDiff preview was opened by follow mode. While true, `n`/`N` and the title's
    /// position indicator use `follow_session` instead of the full git change set.
    diff_follow_scope: bool,

    /// The target, kind, and scroll position (vertical/horizontal) while in Preview mode.
    /// Horizontal scroll is used to view long lines when not wrapping (ui.wrap=false).
    /// To avoid scrolling past the end, the actual clamp is done at render time (when content and screen size are known).
    pub preview_path: Option<PathBuf>,
    pub preview_kind: Option<PreviewKind>,
    pub preview_scroll: u16,
    pub preview_hscroll: u16,
    /// Height (in rows) of the text display area at the last render. Used as the page size for paging.
    pub preview_viewport: u16,
    /// Total wrapped display rows of the current decorated Markdown at the last render (what
    /// `preview_scroll` is clamped against). Set by the preview renderer; used with `MdCache::src_lines`
    /// to map the scroll position back to an approximate source line when opening the editor (`e`).
    pub md_view_rows: usize,

    /// less-style windowed reading for Code/Text (does not read the whole file). Always Some during a Code/Text preview.
    /// While Some, scrolling uses preview_byte_top (the line-head byte) instead of preview_scroll.
    preview_win: Option<crate::preview::window::FileWindow>,
    /// Byte offset of the top line of the window (the scroll position when windowed).
    preview_byte_top: u64,
    /// Absolute line number of the top of the window (0-based). For the line-number gutter. Changes with scrolling, and
    /// is corrected from the total line count when reaching the end.
    preview_top_line: usize,
    /// Cache of the total line count (computed once with count_lines when line numbers are ON).
    preview_total_lines: Option<usize>,
    /// Cache of the highlighted window (avoids re-highlighting on every render).
    win_cache: Option<WinCache>,

    /// Whether the current Code preview is a "heavy first time" (waiting for grammar compilation of a cold language).
    /// While true, the render shows a loading display (indicator) or plain text (progressive).
    /// Judged with `code::is_ext_warm` at preview start; if already warm, false from the start (immediate coloring).
    hl_pending: bool,
    /// Whether a background-thread warm is in progress (prevents double-launch). Common to indicator/progressive.
    hl_warming: bool,
    /// Frame index of the central spinner (advanced by the run loop while waiting on the indicator = animation).
    spinner_frame: usize,

    /// The file requested for external-editor launch via `e`, plus the 1-based line to open at (matching
    /// the on-screen preview position; None = open at the top). The run loop takes it, suspends the TUI, and
    /// launches (because entering/leaving the terminal must happen on the render thread, here we only raise the "request").
    pending_edit: Option<(PathBuf, Option<usize>)>,

    /// Flag requesting launch of an external git tool (lazygit, etc.) via `O`. The run loop takes it, suspends the TUI, and launches.
    pending_git_tool: bool,

    /// Cache of decorated preview content (Markdown/Mermaid).
    /// Avoids re-parsing (pulldown-cmark/syntect/mermaid layout) on every scroll.
    /// It depends on width (to fit mermaid to the display width), so the key is (path, width).
    md_cache: Option<MdCache>,

    /// `R`: show a Markdown/Mermaid preview as its raw source (windowed, like a code file) instead of the
    /// decorated render. Raw mode makes lines/columns match the file, so the 2D caret selection/copy works.
    md_raw: bool,

    /// Cache of raw diff lines for the GitDiff preview (per path). Avoids recomputing `git diff` every frame.
    diff_cache: Option<DiffCache>,
    gutter_cache: Option<GutterCache>,

    /// Interactive items in the Markdown preview (links + task checkboxes, collected on each render).
    /// Focus with Tab/⇧Tab; Enter opens a link / toggles a checkbox, Space toggles a checkbox.
    md_items: Vec<MdItem>,
    /// Index of the focused item (within md_items). None=nothing selected.
    focused_item: Option<usize>,
    /// Per-`<details>`-block open override (ordinal → open), set by `Space`/`Enter` on the summary.
    /// Absent = the default (from the `open` attribute + `ui.md_details`). Reset on file/tab change.
    details_open: std::collections::HashMap<usize, bool>,

    /// In-preview search (`/`, less style). Some=search is active (the query). Highlights matches and moves with n/N.
    /// Supported in Code/Text (windowed) and table previews — see `search_target`.
    preview_search: Option<String>,
    /// Editing buffer for the search query. Some=input mode (intercepts keys, runs on Enter).
    search_input: Option<String>,
    /// For each occurrence: (line-head byte offset, 0-based line number, byte column within the line). The result of `find_all_matches`.
    /// Multiple occurrences on one line become separate elements (so `n`/`N` move per occurrence).
    /// **Table previews reuse this slot as `(0, data row, column)`** — cell coordinates in reading order.
    search_matches: Vec<(u64, usize, usize)>,
    /// The matching table cells as a set, for O(1) lookup while rendering (mirrors `search_matches`).
    /// Kept separate so a large result set does not turn cell drawing into a linear scan.
    table_search_hits: std::collections::HashSet<(usize, usize)>,
    /// Index of the current match (within search_matches).
    search_idx: usize,

    /// Image backend (M2). None if the terminal is unsupported or uninitialized, in which case images fall back to text.
    /// For rendering, ui::preview passes `image` by &mut to StatefulImage. Resize/encode is
    /// offloaded to a separate thread via `img_tx`, and the result is applied in apply_image_resize.
    picker: Option<Picker>,
    img_tx: Option<UnboundedSender<ResizeRequest>>,
    pub image: Option<ThreadProtocol>,
    /// On a kitty-graphics terminal, still images take konoma's own transmit path instead of
    /// ratatui-image's `image`/`ThreadProtocol`: the pixels are **zlib-compressed** (`o=z`), which
    /// shrinks the terminal transfer 2×–50× (the real latency; see docs/PERF-IMAGE-TRANSFER-2026-07).
    /// `use_kitty` is set from the picker's protocol type; on other terminals (sixel/iterm2/
    /// halfblocks) `kitty_image` stays None and the `image` path is used unchanged.
    use_kitty: bool,
    kitty_is_tmux: bool,
    /// The prepared compressed image for the current crop (None until built / on non-kitty terminals).
    kitty_image: Option<crate::preview::kitty::KittyImage>,
    /// Offloads the kitty resize+compress (~30–50 ms) to a worker thread so rapid zoom/pan does not
    /// hitch the UI. The **first** build after opening a file stays synchronous (so the image appears
    /// without a blank frame); subsequent rebuilds (zoom/pan/resize) go async and the previous image
    /// keeps showing until the new one arrives. None in tests → everything runs synchronously.
    kitty_tx: Option<std::sync::mpsc::Sender<KittyResult>>,
    /// Latest-wins generation for async kitty builds: only the newest spawn's result is applied.
    kitty_gen: u64,
    /// The (crop, cols, rows) the current kitty image (or in-flight build) targets. Prevents
    /// re-spawning the same build every frame while the geometry is unchanged.
    kitty_want: Option<KittyGeom>,
    /// The geometry the **currently shown** kitty image was actually built for. A build is in flight
    /// exactly when this differs from `kitty_want` (covers pan, where the cell size is unchanged).
    kitty_shown: Option<KittyGeom>,
    /// The source image (decoded). Zoom/pan crops this at render time and rebuilds the protocol
    /// (because ratatui-image has no offset pan). Held in an `Arc` so the async kitty-build worker
    /// can share it without copying the (potentially large) pixels.
    image_src: Option<std::sync::Arc<image::DynamicImage>>,
    /// Zoom factor. 1.0=the whole image fits, >1.0 zooms in (overflowing the viewport clips and enables pan).
    pub image_zoom: f64,
    /// Display center (image-normalized coordinates [0,1]). Moved by pan. Default is the center.
    image_center: (f64, f64),
    /// The most recently built crop rectangle (source-image px: x,y,w,h). The protocol is rebuilt only when it changes.
    image_crop: Option<(u32, u32, u32, u32)>,
    /// The most recent visible fraction (0..1, w/h). Less than 1 = the image overflows the viewport and is clipped = pan is possible.
    image_vis_frac: (f64, f64),
    /// SVG source of the current image preview when it is vector-backed (SVG file / mermaid diagram).
    /// Zooming past the raster's density re-rasterizes this at the needed scale on a worker thread
    /// ("sharp zoom"); raster images leave it None (pixel zoom only).
    vector_svg: Option<std::sync::Arc<Vec<u8>>>,
    /// Logical (layout) pixel size of a vector-backed image = the dimensions of its **first** raster.
    /// `image_layout` sizes/zooms against this identity, so swapping in a sharper raster changes only
    /// pixel density, never the on-screen geometry (HiDPI-style backing store).
    image_logical: Option<(u32, u32)>,
    /// A full-screen sharp-zoom re-raster is in flight (at most one — key-repeat `+` must not spawn
    /// the same job a dozen times; the inline-fence analog is `MdImgEntry::reraster_inflight`).
    /// Cleared when a media result arrives (`apply_media`) and by `clear_image` (generation bump).
    vector_reraster_inflight: bool,
    /// Where to return when closing a full-screen mermaid-fence view (`q`): the Markdown preview's
    /// scroll offset and Tab-focus index at the moment the fence was opened.
    fence_return: Option<(u16, Option<usize>)>,
    /// Signature of the inline-image overlay drawn last frame (urls + screen rects). When it
    /// changes (scroll/focus moved a diagram, or the document was left), the run loop clears the
    /// terminal once to sweep orphaned kitty unicode-placeholder rows (they are printed into the
    /// terminal grid and a blank-over-blank diff never repaints them).
    md_overlay_last: Option<u64>,
    /// Overlay signature seen during the current frame (None until the overlay draws).
    md_overlay_seen: Option<u64>,
    /// The overlay moved/vanished since the previous frame → the run loop full-redraws once.
    md_overlay_moved: bool,
    /// In-place zoom of the **focused** inline mermaid diagram (`+`/`-` while focused; 1.0 = fit).
    /// The reserved cell area never changes — the zoom crops within it (embedded-map feel).
    fence_zoom: f64,
    /// Pan center of the in-place zoom (image-normalized [0,1]; hjkl while zoomed).
    fence_center: (f64, f64),

    /// PDF: current page (1-based). Each page is rasterized on demand (one at a time) into image_src.
    pdf_page: u32,
    /// PDF: total page count from poppler `pdfinfo`. None = unknown (no poppler) → page navigation disabled.
    pdf_pages: Option<u32>,
    /// mtime of the previewed media file at load time. Media (image/svg/gif/video/pdf) is reloaded on an
    /// FS event only when this changes (avoids re-decoding / re-running external tools on unrelated edits).
    preview_media_mtime: Option<std::time::SystemTime>,

    /// Parsed CSV/TSV table (Some while a table preview is active and parsing succeeded).
    /// None while not a table, or when parsing failed (then the preview degrades to raw text).
    table_data: Option<crate::preview::table::TableData>,
    /// Cell cursor: 0-based data-row index (header is a fixed non-selectable row above).
    table_cur_row: usize,
    /// Cell cursor: 0-based column index.
    table_cur_col: usize,
    /// First visible data row (vertical scroll). Adjusted at render time to keep the cursor visible.
    table_top_row: usize,
    /// First visible column (horizontal scroll). Adjusted at render time to keep the cursor visible.
    table_left_col: usize,
    /// Visible data-row count at the last render (the page size for PageUp/Down). Set by the renderer.
    table_viewport_rows: u16,

    /// Line cursor for windowed (Code/Text) previews: absolute 0-based logical line under the cursor.
    /// The current line is highlighted; `j`/`k` move it (the window follows). Only meaningful while windowed.
    preview_cursor_line: usize,
    /// Column cursor: 0-based char index within the logical line (`h`/`l` move it). The render clamps it to the
    /// line's length and writes the clamp back. Used for the block caret and charwise (`v`) selection.
    preview_cursor_col: usize,
    /// Visual-selection anchor `(line, col)`. Some = selecting. Charwise (`v`) uses both; linewise (`V`) uses the line.
    preview_visual_anchor: Option<(usize, usize)>,
    /// Whether the active selection is linewise (`V`, whole lines) rather than charwise (`v`, exact character range).
    preview_visual_linewise: bool,

    /// GIF animation (M6). All frames (composited RGBA) + each display duration. Empty means no animation (still image).
    /// A separate path from the still-image asynchronous ThreadProtocol: to avoid the "render an unencoded
    /// new protocol → nothing shows" churn in an animation whose frame changes each time, the current frame is **synchronously encoded**
    /// and atomically swapped into `gif_protocol` (see below). Zoom/pan share image_zoom/image_center.
    gif_frames: Vec<(image::DynamicImage, std::time::Duration)>,
    /// Index of the currently displayed GIF frame.
    gif_idx: usize,
    /// The time the current frame began showing (the start point for the next-frame deadline). None=before the first tick.
    gif_shown_at: Option<std::time::Instant>,
    /// The render protocol (kitty, etc.) of the current frame synchronously encoded to the display size. Drawn with the Image widget.
    gif_protocol: Option<Protocol>,
    /// The (frame index, crop rectangle) gif_protocol was built from. Re-encoded only when it changes (avoids wasteful re-encode).
    gif_proto_key: Option<(usize, (u32, u32, u32, u32))>,

    /// Sending end that offloads heavy media loading (SVG rasterize / GIF full-frame decode) to a separate thread.
    /// The result is received by main's poll loop and applied in apply_media. None=synchronous fallback (tests, etc.).
    media_tx: Option<std::sync::mpsc::Sender<MediaResult>>,
    /// Decoded/encoded cache for inline Markdown images, keyed by resolved absolute path.
    md_image_cache: std::collections::HashMap<PathBuf, MdImgEntry>,
    /// Render cache for the tree's detail columns (`ui.details`): path → formatted cells.
    /// Filled lazily for visible rows (render pre-pass) and dropped on every tree rebuild, so the
    /// per-row stat (and the `items` column's read_dir) runs once per tree generation instead of
    /// on every keypress.
    detail_cells_cache: std::collections::HashMap<PathBuf, Vec<String>>,
    /// Sender that offloads inline-image decoding to a background thread.
    md_img_tx: Option<std::sync::mpsc::Sender<MdImageResult>>,
    /// Remote inline-image URLs whose background download is in flight (deduplicates fetches).
    md_remote_inflight: std::collections::HashSet<String>,
    /// Remote inline-image URLs whose download failed — do not retry; they show a text placeholder.
    md_remote_failed: std::collections::HashSet<String>,
    /// Sender that reports the completion of a background remote-image download to the run loop.
    md_remote_tx: Option<std::sync::mpsc::Sender<RemoteFetch>>,
    /// Sender that offloads inline-image encoding (resize + protocol) to the encode worker thread.
    md_enc_tx: Option<std::sync::mpsc::Sender<MdEncodeRequest>>,
    /// Media-load generation. Incremented in enter_preview/clear to make old thread results stale.
    media_gen: u64,
    /// Whether waiting on another thread's media load (used by the render side to show "Loading…").
    media_loading: bool,

    /// Run2 keymap (Surface × key → Action). Built from the config at startup.
    pub keymaps: crate::keymap::KeyMap,
    /// which-key leader-pending state (`Space`=file management / `y`=path copy). After the press, a
    /// which-key menu is shown in the footer and the next keystroke confirms/cancels (a generalization of the old two-key pending_chord).
    pub pending_leader: Option<crate::keymap::LeaderId>,

    /// A transient message (copy result, etc.). Cleared on the next key input. Shown in the status line.
    pub flash: Option<String>,

    /// Visibility state and scroll position of the `?` help (full key list) overlay.
    pub show_help: bool,
    pub help_scroll: u16,
    /// Visibility state of the `i` file-info popup.
    pub show_info: bool,

    /// Tabs (FR-5). Each tab is a tree context. The active tab's working state is held in the fields above as the source of truth.
    tabs: Vec<TabState>,
    active_tab: usize,
    /// Tab-list overlay (`T`). App-global (not per-tab).
    tab_list: bool,
    tab_list_sel: usize,
    /// Heading-outline overlay (`o` in a Markdown preview): jump to any heading.
    outline_open: bool,
    outline_sel: usize,

    /// git status (FR-7). Absolute path → kind. Cached per root and re-fetched when root changes.
    git_status: std::collections::HashMap<PathBuf, crate::git::FileStatus>,
    /// The set of top-level gitignore-excluded entries (`git::ignored`). Used to decide which tree entries are dimmed.
    /// Since it is a heavy computation, it is cached **per repo (workdir)** (`git_ignored_for`), so moving root to a
    /// subdirectory within the same repository does not rebuild it.
    git_ignored: std::collections::HashSet<PathBuf>,
    /// The root at which `git_status`/`git_branch` were computed. If it differs from the current root, a re-fetch is *considered* (but see `git_status_workdir`).
    git_status_for: Option<PathBuf>,
    /// The **repo workdir** `git_status`/`git_branch` cover. `git status` is run from the workdir, so its
    /// result is identical anywhere within the same repo — moving root with `l`/`h` reuses it instead of
    /// re-running a full worktree scan (slow on large repos). Same idea as `git_ignored_for` for the ignore set.
    git_status_workdir: Option<PathBuf>,
    /// The cached `git_status` may be stale (a file changed, a commit/checkout happened, ignore rules
    /// changed): force a recompute on the next `refresh_git_if_needed` even if the workdir is unchanged.
    git_status_dirty: bool,
    /// The **repo workdir** at which `git_ignored` (heavy) was computed. If it is the same, root moves within the same repository
    /// do not rebuild it (avoids the 410ms recomputation when descending into a subdirectory with `l`).
    git_ignored_for: Option<PathBuf>,
    /// The workdir for which `ignored` is being computed on a separate thread (a guard against duplicate dispatch). None=not computing.
    git_ignored_pending: Option<PathBuf>,
    /// Generation of the `ignored` computation. Incremented by +1 on dispatch; a result is applied only if it matches this generation
    /// (discards stale results from after moving to another repo while computing).
    git_ignored_gen: u64,
    /// Flag to **rebuild even for the same repo** because the ignore rules (`.gitignore`/`.git/info/exclude`) changed.
    /// Comes from FS events. Set when a recompute is wanted even if workdir is the same (the old set is kept until the result is applied).
    git_ignored_dirty: bool,
    /// Sender that returns results to the worker computing `ignored` in the background. If not attached (tests, etc.), a synchronous fallback is used.
    ignored_tx: Option<std::sync::mpsc::Sender<IgnoredResult>>,
    /// git diff layout (vertical/horizontal/Auto). Initialized from the `git.diff` setting and cycled with `s`. Used by both the GitDiff preview
    /// and the commit/working-tree detail.
    diff_layout: DiffLayout,
    /// Title override for the detail (git_detail). Used when opening all working-tree changes from the git view, etc.
    git_detail_title: Option<String>,
    /// The current branch name (fetched at the same time as git status). None if not a repo.
    git_branch: Option<String>,

    /// Whether the Git view (the changes hub) is showing. While true, content shows the change list instead of the tree, and
    /// main intercepts keys. When the feature is disabled or it is not a repo, open_git_view does not set it, so it is always false.
    git_view: bool,
    /// Cursor position in the Git view (index within git_view_entries).
    git_view_sel: usize,
    /// The list of changed files shown in the Git view (rebuilt after open/refresh/write).
    git_view_entries: Vec<crate::git::ChangeEntry>,
    /// Whether the GitDiff preview was entered from the Git view. If true, Esc/q returns to the Git view.
    came_from_git_view: bool,

    /// Some if showing the git log (linear, newest first). Shows a full-screen list in content, and main intercepts keys.
    /// When the feature is disabled, it is not a repo, or there are no commits, open_git_log does not set it, so it stays None.
    git_log: Option<Vec<crate::git::CommitInfo>>,
    /// Cursor position in the git log (index within git_log).
    git_log_sel: usize,
    /// Some if showing the commit detail (the DiffLine list from commit_diff). A full screen overlaid on the log.
    git_detail: Option<Vec<crate::git::DiffLine>>,
    /// The **full message, etc. shown at the top** of the commit detail (on Enter from log/graph). None for worktree diffs.
    git_detail_meta: Option<crate::git::CommitMeta>,
    /// Vertical scroll amount of the commit detail.
    git_detail_scroll: u16,
    /// Horizontal scroll amount of the commit detail (for long diff lines).
    git_detail_hscroll: u16,
    /// Number of visible rows when rendering the detail (for clamping g/G and scrolling; updated by the render side).
    git_detail_viewport: u16,
    /// Total line count when rendering the detail (the commit-message header + diff; for clamping the scroll limit; updated by the render side).
    git_detail_total: usize,
    /// Some if showing the branch list (`b`). Shows a full-screen list in content and main intercepts keys.
    git_branches: Option<Vec<crate::git::BranchInfo>>,
    /// Cursor position in the branch list (index within the **filtered** display list).
    git_branch_sel: usize,
    /// Branch filter query (`/`). Empty means all entries.
    git_branch_filter: String,
    /// Whether the branch filter is being typed (while true, main picks up keys as characters).
    git_branch_filtering: bool,
    /// Some if showing the commit graph (`G`, SourceTree/Git Graph style). Shown full-screen in content.
    git_graph: Option<Vec<crate::git::GraphRow>>,
    /// Cursor position in the graph (index within git_graph; sits on a commit row).
    git_graph_sel: usize,
    /// Phase 2: the base branch tip OID for the graph (if Some, pinned in a straight line on lane0). `s`=set / `x`=clear.
    git_graph_base: Option<String>,
    /// Display label for the base (for the title `base: …`; a branch name or a short hash).
    git_graph_base_label: Option<String>,
    /// The **set of local branch names shown** in the graph (for the cap/toggle when there are many branches).
    /// At startup, auto-selected up to `ui.graph_max_branches` by HEAD + base + recency. If it equals the total branch count, `--all`.
    git_graph_visible: std::collections::HashSet<String>,
    /// Legend (branch ⇄ lane color). Computed and cached on graph rebuild.
    git_graph_legend: Vec<crate::git::LegendEntry>,
    /// The number of local branches **hidden by the cap/toggle** (for the legend's `(+K hidden)`).
    git_graph_hidden: usize,
    /// Whether the branch-visibility panel (`b`) is open.
    git_graph_picker: bool,
    /// Cursor position in the panel (row = branch).
    git_graph_picker_sel: usize,
    /// Tentative selection while editing the panel (committed to `git_graph_visible` with Enter / discarded with q).
    git_graph_picker_set: std::collections::HashSet<String>,
    /// The graph's **priority order (display order of all local branches)**. Initialized by `[ui.graph_base_branches]`→HEAD→recency, and
    /// reordered for the current session only with the panel's `J`/`K`. Used for the order of the legend/panel/cap selection/base derivation.
    git_graph_order: Vec<String>,
    /// Whether `J`/`K` reordering was done in the panel (so the base is re-derived to the top branch on Enter confirm).
    git_graph_reordered: bool,
}

/// Path-copy kind (FR-6). Chosen by the key after `c`.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum CopyKind {
    /// File name only (`cn`).
    Name,
    /// Full path (`cp`).
    Full,
    /// Path relative to where it was opened (`cr`).
    Relative,
    /// Full path of the parent directory (`cd`).
    Parent,
    /// `@relative/path` reference for AI agents (`y@`). Claude Code reads `@path` as file context, so
    /// the path is strictly relative to `open_dir` (the launch/anchor dir where the agent usually runs),
    /// **without** the leading directory name that `Relative` prepends for display.
    AtRef,
}

/// Commit-info copy kind (chosen after `y` in git log/graph/detail).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[cfg_attr(not(feature = "git"), allow(dead_code))]
pub enum GitCopyKind {
    /// Short hash (7 digits).
    ShortHash,
    /// Full hash (40 digits).
    FullHash,
    /// Subject (the first line of the message).
    Subject,
    /// Full message (subject + body, multi-line).
    Message,
    /// Author name.
    Author,
    /// Date.
    Date,
}

/// What the in-preview search (`/`) searches, which decides how matches are found and how `n`/`N`
/// move. Each preview kind addresses positions differently, so the search plumbing routes on this
/// instead of testing preview fields in several places.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum SearchTarget {
    /// Code/Text and raw (`R`) Markdown: byte offsets into the file, moved via the read window.
    Windowed,
    /// CSV/TSV: (data row, column) cell coordinates, moved via the cell cursor.
    Table,
    /// Decorated Markdown/Mermaid: indices into the **decorated** lines, moved by scrolling.
    Markdown,
    /// Media and diffs — no search model (`/` flashes a hint).
    Unsupported,
}

/// CSV/TSV table copy kind (chosen after `y` in the table preview).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum TableCopyKind {
    /// The current cell's value.
    Cell,
    /// The current row's cells joined by the delimiter (`,` / tab).
    Row,
    /// The current column's header plus every cell value, one per line.
    Column,
}

/// Cache of decorated preview content. The key is (path, display width).
/// Everything derivable once per (path, width) lives here so a frame only clones the visible
/// slice (`md_slice`) instead of re-cloning / re-flowing the whole document on every keypress.
struct MdCache {
    path: PathBuf,
    width: u16,
    /// Decorated lines with links already collapsed (label-only; URLs recovered into `items`) —
    /// exactly what the renderer draws, minus the per-frame focus inversion.
    lines: Vec<Line<'static>>,
    /// Tab-cycle items (links / task checkboxes / code-block headers) in document order,
    /// built once from `lines`. Mirrored into `App::md_items` when the cache is (re)built.
    items: Vec<MdItem>,
    /// Block-level inline images reserved within `lines` (Markdown only; empty otherwise).
    images: Vec<crate::preview::markdown::ImagePlacement>,
    /// Number of source lines in the file. Used with the on-screen wrapped-row count to map the scroll
    /// position back to an approximate source line, so `e` opens the editor near the top of the view.
    src_lines: usize,
    /// Widest line in display cells (horizontal-scroll clamp for wrap=off).
    max_line_cols: usize,
    /// wrap=on: visual (post-wrap) start row of each line via ratatui's own per-line reflow;
    /// `len = lines.len() + 1`, last element = total display rows. Empty when wrap=off or width=0.
    row_prefix: Vec<usize>,
    /// Effective mermaid target rows the cache was built with (fit-to-view). A viewport change
    /// only invalidates documents that actually contain fence diagrams.
    fence_rows: u16,
    /// In-page anchor map (GitHub slug → decorated logical-line index) for `[x](#slug)` jumps.
    anchors: Vec<(String, usize)>,
    /// Effective open/closed state of each `<details>` block (document order) as rendered — the base
    /// a `Space`/`Enter` toggle flips.
    details_states: Vec<bool>,
}

/// Cache of raw diff lines for the GitDiff preview. `file_diff` (the git call) does not depend on display width
/// (side-by-side/coloring is done separately at render time), so the key is the path only. This avoids re-invoking git on every
/// scroll/horizontal scroll/resize (aligned with log/graph: load once on open).
/// Since the diff changes when the working tree changes, it is invalidated by `refresh()` (FS events / manual refresh).
struct DiffCache {
    path: PathBuf,
    lines: Vec<crate::git::DiffLine>,
}

/// Cache of the editor-style git gutter marks (per new-file line) for the currently-previewed code/text
/// file. Keyed by path; a working-tree change (`refresh`) drops it so external edits re-derive. Avoids
/// re-invoking `file_diff` (a git call) on every scroll/keypress while previewing.
struct GutterCache {
    path: PathBuf,
    marks: std::collections::HashMap<u32, GutterMark>,
}

/// One interactive item within a rendered Markdown preview: a link or a task-list checkbox.
/// `line`=index of the decorated line (for scrolling). Both are collected straight from the render
/// result (links = underlined blue spans + collapsed targets, checkboxes = `task_marker_style` spans),
/// so no source re-parsing is needed.
#[derive(Clone)]
struct MdItem {
    line: usize,
    kind: MdItemKind,
}

#[derive(Clone)]
enum MdItemKind {
    /// A link; `target`=URL/relative path.
    Link { target: String },
    /// A task checkbox; `state`=its current state char (` `/`x`/custom) as shown.
    Task { state: char },
    /// A fenced code block (its header line is the focus target; `Enter` copies its raw source).
    CodeBlock,
    /// An inline mermaid diagram (image mode); `ordinal`=fence index in document order.
    /// `Enter` opens it full screen with zoom/pan.
    MermaidFence { ordinal: usize },
    /// A `<details>` summary line; `ordinal`=details-block index in document order.
    /// `Enter`/`Space` toggle it collapsed ⇄ expanded.
    Details { ordinal: usize },
}

/// Cache of highlighted lines for windowed reading.
/// The key is (path, top byte, height). Rebuilt only when scroll/vertical resize changes it.
/// (Line content does not depend on display width, so width is not part of the key.)
struct WinCache {
    path: PathBuf,
    byte_top: u64,
    height: u16,
    /// Whether `lines` carry syntax colors. Plain text is cached too (same key space); the flag
    /// keeps a colored window from being mistaken for a plain one when the highlight state flips.
    styled: bool,
    lines: Vec<Line<'static>>,
}

/// A decoded inline Markdown image plus its background-encoded render protocol(s).
#[derive(Default)]
struct MdImgEntry {
    /// The decoded source image (None while the background decode is in flight). Shared with the encode
    /// worker via `Arc` (cheap clone) so cropping/encoding happens off the UI thread.
    decoded: Option<Arc<image::DynamicImage>>,
    /// The graphics protocol for the fully-visible image, encoded for `proto_size`.
    protocol: Option<Protocol>,
    /// The (cols, rows) `protocol` was encoded for.
    proto_size: Option<(u16, u16)>,
    /// The graphics protocol for a partially-scrolled image: only the visible vertical band, cropped and
    /// encoded so the image renders clipped instead of being hidden. Re-encoded when the band changes.
    clip_protocol: Option<Protocol>,
    /// The (cols, full_rows, row_off, vis_rows) band `clip_protocol` was encoded for.
    clip_key: Option<(u16, u16, u16, u16)>,
    /// An encode request is in flight on the worker thread (at most one per image, so scrolling does not
    /// queue a backlog — when it returns, the next render requests the then-current band).
    enc_inflight: bool,
    /// Decode or encode failed — do not retry; the placeholder/text fallback stays visible.
    failed: bool,
    /// In-place zoom protocol for a **focused inline mermaid diagram** (`+`/`-` while focused):
    /// a crop of the source encoded into the same (cols, rows) cell area (the layout never moves).
    zoom_protocol: Option<Protocol>,
    /// The (cols, rows, crop px rect) `zoom_protocol` was encoded for.
    zoom_key: Option<(u16, u16, PxRect)>,
    /// SVG source of a rendered mermaid fence — kept so in-place zoom can re-rasterize at a higher
    /// density (sharp zoom, same mechanism as the full-screen vector zoom).
    svg: Option<std::sync::Arc<Vec<u8>>>,
    /// Layout size = the **first** raster's dimensions. The markdown layout (cells) is computed from
    /// this, so a sharper re-raster never changes the reserved area (the user-visible size is fixed).
    layout_px: Option<(u32, u32)>,
    /// A sharpening re-raster is in flight (at most one per diagram).
    reraster_inflight: bool,
}

/// Outcome of a fence-sharpen check (the sync variant lets tests re-run with the new raster).
#[derive(PartialEq)]
enum FenceSharpen {
    NotNeeded,
    Spawned,
    AppliedSync,
}

/// Which protocol a background encode produces (so the result is stored in the right slot).
#[derive(Clone, Copy, PartialEq, Debug)]
enum MdEncodeKey {
    /// The whole image at (cols, rows) cells.
    Full { cols: u16, rows: u16 },
    /// A cropped vertical band, keyed by (cols, full_rows, row_off, vis_rows).
    Clip {
        cols: u16,
        full_rows: u16,
        row_off: u16,
        vis_rows: u16,
    },
    /// An in-place zoom crop of a focused inline mermaid diagram, encoded into the same
    /// (cols, rows) area. Keyed by the pixel crop so pan/zoom/re-raster all re-encode naturally.
    Zoom { cols: u16, rows: u16, crop: PxRect },
}

/// A request to encode an inline image (or a cropped band of it) off the UI thread (principle #4).
pub struct MdEncodeRequest {
    path: PathBuf,
    key: MdEncodeKey,
    image: Arc<image::DynamicImage>,
    /// Pixel band to crop before encoding; None encodes the whole image.
    crop: Option<PxRect>,
    cols: u16,
    rows: u16,
}

/// Result of a background inline-image encode, delivered to the run loop.
pub struct MdEncodeResult {
    path: PathBuf,
    key: MdEncodeKey,
    /// None = the encode failed. The worker **always** sends a result: swallowing failures left
    /// `enc_inflight` latched on, freezing all re-encodes of that image and keeping
    /// `md_images_loading()` true forever (busy spinner + 16ms polling — idle CPU 0% broken).
    protocol: Option<Protocol>,
}

/// Background worker that encodes inline-image protocols (the whole image or a cropped band) with a
/// cloned Picker, so the UI thread never blocks on the resize/encode (principle #4). Exits when the
/// request sender is dropped (App teardown).
pub fn md_encode_worker(
    picker: Picker,
    rx: std::sync::mpsc::Receiver<MdEncodeRequest>,
    tx: std::sync::mpsc::Sender<MdEncodeResult>,
) {
    while let Ok(req) = rx.recv() {
        let (path, key) = (req.path.clone(), req.key);
        let picker = &picker; // 借用: move クロージャがループ跨ぎで picker を消費しないように
                              // リクエスト処理全体を panic 捕捉で包む: 1件の new_protocol/crop が panic しても
                              // ワーカースレッドを殺さない(殺すと以後の全エンコードが止まり enc_inflight が恒久 latch)。
        let protocol = crate::preview::markdown::catch_silent(move || {
            let img = match req.crop {
                Some((x, y, w, h)) => req.image.crop_imm(x, y, w, h),
                None => (*req.image).clone(),
            };
            let size = ratatui::layout::Size::new(req.cols, req.rows);
            // フェンス図(ベクタ由来)は予約グリッドまで**拡大も**する(Scale): ラスタが小さくても
            // 左上詰めの余白バンドを作らず領域を満たす=シャープさは密度追従の再ラスタが担う。
            // 写真は従来どおり Fit(自然サイズ超に拡大しない=ぼやけさせない)。
            let resize =
                if crate::preview::markdown::is_mermaid_fence_url(&req.path.to_string_lossy()) {
                    Resize::Scale(Some(FilterType::Lanczos3))
                } else {
                    Resize::Fit(Some(FilterType::Lanczos3))
                };
            // 失敗(Err)でも必ず結果を送り返す: 握り潰すと enc_inflight が立ちっぱなしになる。
            picker.new_protocol(img, size, resize).ok()
        })
        .flatten();
        if tx
            .send(MdEncodeResult {
                path,
                key,
                protocol,
            })
            .is_err()
        {
            break;
        }
    }
}

/// Result of a background inline-image decode, delivered to the run loop.
pub struct MdImageResult {
    path: PathBuf,
    image: Result<image::DynamicImage, String>,
    /// SVG source alongside a rendered mermaid fence (kept for in-place sharp zoom). None otherwise.
    svg: Option<std::sync::Arc<Vec<u8>>>,
    /// True when this is a sharpening re-raster of an already-shown diagram: only the pixels are
    /// replaced — the layout size and the decoration cache stay untouched.
    reraster: bool,
}

/// Result of a background remote-image download (curl → local cache file), delivered to the run loop.
/// It carries no bytes: on success the file is already in the cache, so the run loop just invalidates
/// the decoration cache to re-lay the image out; on failure the URL is remembered so it is not retried.
pub struct RemoteFetch {
    url: String,
    ok: bool,
}

impl App {
    pub fn new(root: PathBuf, cfg: Config) -> Result<Self> {
        let path_style = PathStyle::parse(&cfg.ui.path_style);
        let key_scheme = KeyScheme::parse(&cfg.ui.keys);
        let lang = crate::i18n::Lang::resolve(&cfg.ui.lang);
        let sort = Sort::from_config(&cfg.ui.sort);
        // diff の並び初期値 (設定 git.diff)。実行時 `s` で 縦→横→Auto を巡回。
        let diff_layout = DiffLayout::parse(&cfg.git.diff);
        // Run2 キーマップ: 既定 + 設定 (`[keys.<surface>]` + 旧 copy_* alias) をマージし衝突を検証する。
        // page/half プロファイルは ui.keys (vim/less) に従う。Stage 2 は構築のみ (ディスパッチ未接続)。
        let keymaps = crate::keymap::KeyMap::from_config(
            crate::keymap::scheme_from_str(&cfg.ui.keys),
            &cfg.keys.to_keymap_config(),
        );
        let mut app = Self {
            mode: Mode::Tree,
            root: root.clone(),
            open_dir: root.clone(),
            launch_dir: root.clone(),
            path_style,
            key_scheme,
            lang,
            cfg,
            entries: Vec::new(),
            selected: 0,
            show_hidden: false,
            sort,
            sort_menu: false,
            bookmarks: crate::bookmarks::Bookmarks::load(&root),
            session_store: None,
            session_restoring: false,
            mark_set_pending: false,
            bookmark_list: false,
            bookmark_list_sel: 0,
            dialog: None,
            selection: BTreeSet::new(),
            visual_anchor: None,
            clipboard: None,
            tree_viewport: 0,
            tree_filter: None,
            filter_input: None,
            filter_pool: Vec::new(),
            changed_filter: false,
            follow_mode: false,
            follow_session: Vec::new(),
            diff_follow_scope: false,
            preview_path: None,
            preview_kind: None,
            preview_scroll: 0,
            md_view_rows: 0,
            preview_hscroll: 0,
            preview_viewport: 0,
            preview_win: None,
            preview_byte_top: 0,
            preview_top_line: 0,
            preview_total_lines: None,
            win_cache: None,
            hl_pending: false,
            hl_warming: false,
            spinner_frame: 0,
            pending_edit: None,
            pending_git_tool: false,
            md_cache: None,
            md_raw: false,
            diff_cache: None,
            gutter_cache: None,
            md_items: Vec::new(),
            focused_item: None,
            details_open: std::collections::HashMap::new(),
            preview_search: None,
            search_input: None,
            search_matches: Vec::new(),
            table_search_hits: std::collections::HashSet::new(),
            search_idx: 0,
            picker: None,
            img_tx: None,
            image: None,
            use_kitty: false,
            kitty_is_tmux: false,
            kitty_image: None,
            kitty_tx: None,
            kitty_gen: 0,
            kitty_want: None,
            kitty_shown: None,
            image_src: None,
            image_zoom: 1.0,
            image_center: (0.5, 0.5),
            image_crop: None,
            image_vis_frac: (1.0, 1.0),
            vector_svg: None,
            image_logical: None,
            vector_reraster_inflight: false,
            fence_return: None,
            fence_zoom: 1.0,
            fence_center: (0.5, 0.5),
            md_overlay_last: None,
            md_overlay_seen: None,
            md_overlay_moved: false,
            pdf_page: 1,
            pdf_pages: None,
            preview_media_mtime: None,
            table_data: None,
            table_cur_row: 0,
            table_cur_col: 0,
            table_top_row: 0,
            table_left_col: 0,
            table_viewport_rows: 0,
            preview_cursor_line: 0,
            preview_cursor_col: 0,
            preview_visual_anchor: None,
            preview_visual_linewise: false,
            gif_frames: Vec::new(),
            gif_idx: 0,
            gif_shown_at: None,
            gif_protocol: None,
            gif_proto_key: None,
            media_tx: None,
            md_image_cache: std::collections::HashMap::new(),
            detail_cells_cache: std::collections::HashMap::new(),
            md_img_tx: None,
            md_remote_inflight: std::collections::HashSet::new(),
            md_remote_failed: std::collections::HashSet::new(),
            md_remote_tx: None,
            md_enc_tx: None,
            media_gen: 0,
            media_loading: false,
            keymaps,
            pending_leader: None,
            flash: None,
            show_help: false,
            show_info: false,
            help_scroll: 0,
            tabs: Vec::new(),
            active_tab: 0,
            tab_list: false,
            tab_list_sel: 0,
            outline_open: false,
            outline_sel: 0,
            git_status: std::collections::HashMap::new(),
            git_ignored: std::collections::HashSet::new(),
            git_status_for: None,
            git_status_workdir: None,
            git_status_dirty: false,
            git_ignored_for: None,
            git_ignored_pending: None,
            git_ignored_gen: 0,
            git_ignored_dirty: false,
            ignored_tx: None,
            diff_layout,
            git_detail_title: None,
            git_branch: None,
            git_view: false,
            git_view_sel: 0,
            git_view_entries: Vec::new(),
            came_from_git_view: false,
            git_log: None,
            git_log_sel: 0,
            git_detail: None,
            git_detail_meta: None,
            git_detail_scroll: 0,
            git_detail_hscroll: 0,
            git_detail_viewport: 0,
            git_detail_total: 0,
            git_branches: None,
            git_branch_sel: 0,
            git_branch_filter: String::new(),
            git_branch_filtering: false,
            git_graph: None,
            git_graph_sel: 0,
            git_graph_base: None,
            git_graph_base_label: None,
            git_graph_visible: std::collections::HashSet::new(),
            git_graph_legend: Vec::new(),
            git_graph_hidden: 0,
            git_graph_picker: false,
            git_graph_picker_sel: 0,
            git_graph_picker_set: std::collections::HashSet::new(),
            git_graph_order: Vec::new(),
            git_graph_reordered: false,
        };
        app.rebuild_tree()?;
        // 最初のタブとして現在の状態を登録する。
        app.tabs.push(app.snapshot_tab());
        Ok(app)
    }

    /// Attach the per-project session store (`[ui] restore_tabs`). Called by main only, like the
    /// loader senders — tests that need persistence attach a temp-based store explicitly, so plain
    /// `App::new` (unit/e2e tests) never touches the real `~/.config`.
    pub fn attach_session_store(&mut self, store: crate::session::SessionStore) {
        self.session_store = Some(store);
    }

    /// Summarize startup keymap conflicts / ignored settings into one line (for the startup flash; i18n).
    /// Conflicts have already safely fallen back to defaults (#17/FR-8). None if there is nothing.
    pub fn keymap_report(&self) -> Option<String> {
        let nc = self.keymaps.conflicts.len();
        let nw = self.keymaps.warnings.len();
        if nc == 0 && nw == 0 {
            return None;
        }
        let mut parts: Vec<String> = Vec::new();
        if nc > 0 {
            parts.push(match self.lang {
                crate::i18n::Lang::Jp => format!("キー衝突{nc}件(既定で継続)"),
                crate::i18n::Lang::En => format!("{nc} key conflict(s) (using defaults)"),
            });
        }
        if nw > 0 {
            parts.push(match self.lang {
                crate::i18n::Lang::Jp => format!("無効な設定{nw}件を無視"),
                crate::i18n::Lang::En => format!("{nw} invalid key setting(s) ignored"),
            });
        }
        let head = tr(self.lang, crate::i18n::Msg::Keymap);
        Some(format!("{head}: {}", parts.join(" / ")))
    }

    /// Starting from directly under root, recursively expand the expanded directories and flatten them.
    /// A naive implementation for M0. Support for large directories will later be replaced with lazy loading.
    pub fn rebuild_tree(&mut self) -> Result<()> {
        let mut out = Vec::new();
        // HashSet: build_dir checks membership once per child (a Vec scan is E×N comparisons).
        let expanded_dirs: std::collections::HashSet<PathBuf> = self
            .entries
            .iter()
            .filter(|e| e.is_dir && e.expanded)
            .map(|e| e.path.clone())
            .collect();

        build_dir(
            &self.root,
            0,
            &expanded_dirs,
            self.show_hidden,
            self.sort,
            &mut out,
        )?;
        self.entries = out;
        if self.selected >= self.entries.len() {
            self.selected = self.entries.len().saturating_sub(1);
        }
        // entries を作り直したら visual_anchor(entries 添字)は stale。必ず無効化する。
        self.visual_anchor = None;
        // 詳細セルのキャッシュも世代交代(fs が変わった可能性がある節目=ここで必ず破棄)。
        self.detail_cells_cache.clear();
        Ok(())
    }

    /// Fill the detail-column cell cache for the given visible rows (tree render pre-pass).
    /// A path already cached is skipped; the whole cache is dropped by `rebuild_tree` (the choke
    /// point every fs change goes through), so cells are computed once per tree generation.
    pub fn ensure_detail_cells(&mut self, rows: &[(PathBuf, bool)], cols: &[String]) {
        for (path, is_dir) in rows {
            if self.detail_cells_cache.contains_key(path) {
                continue;
            }
            let meta = crate::fileops::quick_meta(path).unwrap_or(crate::fileops::RowMeta {
                is_dir: *is_dir,
                is_symlink: false,
                size: 0,
                mtime: None,
                mode: 0,
            });
            let cells: Vec<String> = cols
                .iter()
                .map(|id| crate::fileops::detail_cell(id, path, &meta).unwrap_or_default())
                .collect();
            self.detail_cells_cache.insert(path.clone(), cells);
        }
    }

    /// Cached detail cells for one row (filled by `ensure_detail_cells`).
    pub fn detail_cells_get(&self, path: &Path) -> Option<&Vec<String>> {
        self.detail_cells_cache.get(path)
    }

    /// Calls `rebuild_tree`, and on failure does not swallow it but reports via flash. Returns `true` on success.
    /// Used on paths that cannot bail out with `?` (bookmark jump, clearing the filter, rebuilding after a git discard).
    /// The return value lets the caller decide whether to show a subsequent success flash (=false means don't).
    fn rebuild_tree_notify(&mut self) -> bool {
        if let Err(e) = self.rebuild_tree() {
            self.flash = Some(format!(
                "{}{e}",
                crate::i18n::tr(self.lang, crate::i18n::Msg::OperationFailed)
            ));
            false
        } else {
            true
        }
    }

    // --- ソート (FR・M7 補助) -------------------------------------------------
    /// Whether the `s` sort-selection menu is showing.
    pub fn is_sort_menu(&self) -> bool {
        self.sort_menu
    }
    /// Open the sort menu with `s`. main routes the next key here.
    pub fn open_sort_menu(&mut self) {
        self.sort_menu = true;
    }
    /// Close the sort menu (Esc or an out-of-scope key).
    pub fn close_sort_menu(&mut self) {
        self.sort_menu = false;
    }
    /// Key handling for the sort menu. n/s/m/e=select the key (closes after selecting), r=flip asc/desc, .=directories first
    /// (toggles keep it open). Out-of-scope keys close it. If the order changes, rebuild (while filtering, applied after clearing).
    pub fn sort_menu_key(&mut self, c: char) -> Result<()> {
        let keep_open = match c {
            'n' => {
                self.sort.key = SortKey::Name;
                false
            }
            's' => {
                self.sort.key = SortKey::Size;
                false
            }
            'm' => {
                self.sort.key = SortKey::Modified;
                false
            }
            'e' => {
                self.sort.key = SortKey::Ext;
                false
            }
            'r' => {
                self.sort.reverse = !self.sort.reverse;
                true
            }
            '.' => {
                self.sort.dirs_first = !self.sort.dirs_first;
                true
            }
            _ => {
                self.sort_menu = false;
                return Ok(());
            }
        };
        // 絞り込み中は結果順を変えない(クリア後にツリー再構築で反映)。
        if self.tree_filter.is_none() {
            self.rebuild_tree()?;
        }
        self.sort_menu = keep_open;
        Ok(())
    }
    /// Current sort display for the top context bar (e.g. `sort: mod ↑`).
    pub fn sort_label(&self) -> String {
        let k = match self.sort.key {
            SortKey::Name => "name",
            SortKey::Size => "size",
            SortKey::Modified => "mod",
            SortKey::Ext => "ext",
        };
        let arrow = if self.sort.reverse { "↓" } else { "↑" };
        format!("sort: {k} {arrow}")
    }

    // --- モード表示 (2軸: 表示モード × 内部モード) ----------------------------
    /// Display mode (for the outer chip). Preview becomes Image if it is an image.
    pub fn display_mode(&self) -> DisplayMode {
        match self.mode {
            Mode::Tree => DisplayMode::Tree,
            Mode::Preview => {
                if self.is_image_preview() {
                    DisplayMode::Image
                } else if self.is_table_preview() {
                    DisplayMode::Table
                } else {
                    DisplayMode::Preview
                }
            }
        }
    }
    /// Internal mode (for the inner chip and footer switching). None if nothing is being operated.
    /// Priority: dialog > filter/search/sort/mark/bookmarks > visual.
    pub fn internal_mode(&self) -> Option<InternalMode> {
        if let Some(d) = &self.dialog {
            return Some(match &d.kind {
                // アプリ終了確認は非破壊。削除/ドロップとは別チップ/フッターにする。
                DialogKind::Confirm { .. } if self.confirm_is_quit() => InternalMode::QuitConfirm,
                // ブックマーク上書き確認も非破壊=別チップ/フッター。
                DialogKind::Confirm { .. } if self.confirm_is_bookmark() => {
                    InternalMode::BookmarkConfirm
                }
                // D&D 転送は破壊的でないので削除確認とは別チップ/フッターにする。
                DialogKind::Confirm { .. } if self.confirm_is_drop() => InternalMode::DropConfirm,
                DialogKind::Confirm { .. } => InternalMode::DeleteConfirm,
                DialogKind::Preview { .. } => InternalMode::RenamePreview,
                DialogKind::Input { .. } => match &d.op {
                    PendingOp::Create { .. } => InternalMode::Create,
                    PendingOp::BatchRenameInput { .. } => InternalMode::BatchRename,
                    PendingOp::GitCommit => InternalMode::Commit,
                    PendingOp::GitCreateBranch => InternalMode::GitBranch,
                    _ => InternalMode::Rename,
                },
            });
        }
        // コミット詳細は log の上に被さるので先に判定する。
        if self.is_git_detail() {
            return Some(InternalMode::GitDetail);
        }
        if self.is_git_log() {
            return Some(InternalMode::GitLog);
        }
        // パネルはグラフの上に被さる(is_git_graph も true なので先に判定)。
        if self.is_git_graph_picker() {
            return Some(InternalMode::GitGraphPicker);
        }
        if self.is_git_graph() {
            return Some(InternalMode::GitGraph);
        }
        if self.is_git_branches() {
            return Some(InternalMode::GitBranch);
        }
        if self.is_git_view() {
            return Some(InternalMode::GitChanges);
        }
        if self.is_git_diff_preview() {
            return Some(InternalMode::GitDiff);
        }
        if self.is_filtering() {
            return Some(InternalMode::Filter);
        }
        if self.is_searching() {
            return Some(InternalMode::Search);
        }
        if self.is_sort_menu() {
            return Some(InternalMode::Sort);
        }
        if self.is_marking() {
            return Some(InternalMode::Mark);
        }
        if self.is_bookmark_list() {
            return Some(InternalMode::Bookmarks);
        }
        if self.is_tab_list() {
            return Some(InternalMode::Tabs);
        }
        if self.is_outline() {
            return Some(InternalMode::Outline);
        }
        if self.is_info() {
            return Some(InternalMode::Info);
        }
        if self.is_visual() {
            return Some(InternalMode::Visual);
        }
        if self.is_preview_visual() {
            return Some(InternalMode::PreviewVisual);
        }
        if self.changed_filter && matches!(self.mode, Mode::Tree) {
            return Some(InternalMode::ChangedFilter);
        }
        None
    }

    /// The **frontmost surface** that currently receives keys (the single source of truth for Run2 keymap dispatch).
    /// Strictly follows the same priority as internal_mode, while also including the base full screens (Tree/Preview) and overlays (§4).
    /// Off the render path; references only existing bool predicates (same cost as now).
    pub fn surface(&self) -> crate::keymap::Surface {
        use crate::keymap::Surface as S;
        // ダイアログ最優先 (種別で細分: 入力 / 削除確認 / ドロップ確認 / リネームプレビュー)。
        if self.is_dialog() {
            if self.dialog_is_preview() {
                return S::DialogRenamePreview;
            }
            if self.dialog_is_confirm() {
                if self.confirm_is_quit() {
                    return S::DialogConfirmQuit;
                }
                if self.confirm_is_bookmark() {
                    return S::DialogConfirmBookmark;
                }
                if self.confirm_is_drop() {
                    return S::DialogConfirmDrop;
                }
                return S::DialogConfirmDelete;
            }
            return S::DialogInput;
        }
        // ヘルプ (全要素の上)。
        if self.show_help {
            return S::Help;
        }
        // Git オーバーレイ (詳細 > log > graph > branches > 変更ハブ > diff)。feature 無効時は到達しない。
        #[cfg(feature = "git")]
        {
            if self.is_git_detail() {
                return S::GitDetail;
            }
            if self.is_git_log() {
                return S::GitLog;
            }
            // パネルはグラフの上に被さる(is_git_graph も true なので先に判定)。
            if self.is_git_graph_picker() {
                return S::GitGraphPicker;
            }
            if self.is_git_graph() {
                return S::GitGraph;
            }
            if self.is_git_branches() {
                return if self.git_branch_filtering() {
                    S::BranchFilter
                } else {
                    S::GitBranches
                };
            }
            if self.is_git_view() {
                return S::GitChanges;
            }
            if self.is_git_diff_preview() {
                return S::PreviewGitDiff;
            }
        }
        // 入力系 / メニュー / 一覧 / 情報 / ビジュアル。
        if self.is_filtering() {
            return S::Filter;
        }
        if self.is_searching() {
            return S::Search;
        }
        if self.is_sort_menu() {
            return S::Sort;
        }
        if self.is_marking() {
            return S::Mark;
        }
        if self.is_bookmark_list() {
            return S::Bookmarks;
        }
        if self.is_tab_list() {
            return S::Tabs;
        }
        if self.is_outline() {
            return S::Outline;
        }
        if self.is_info() {
            return S::Info;
        }
        if self.is_visual() {
            return S::Visual;
        }
        // 基本全画面 (Preview は画像/テキストで分岐)。
        match self.mode {
            Mode::Preview => {
                if self.is_image_preview() {
                    S::PreviewImage
                } else if self.is_table_preview() {
                    S::PreviewTable
                } else if self.is_preview_visual() {
                    S::PreviewTextVisual
                } else {
                    S::PreviewText
                }
            }
            Mode::Tree => S::Tree,
        }
    }

    // --- コピー/カット&ペースト (M7 Phase B・既定キー Y/X/P・keymap で変更可) ---
    /// Label for the context display: "copy 3" / "cut 3". None if the clipboard is empty.
    pub fn clipboard_label(&self) -> Option<String> {
        self.clipboard.as_ref().map(|c| {
            let verb = match c.op {
                ClipOp::Copy => crate::i18n::tr(self.lang, crate::i18n::Msg::CopyHint),
                ClipOp::Cut => crate::i18n::tr(self.lang, crate::i18n::Msg::CutHint),
            };
            format!("{verb} {}", c.paths.len())
        })
    }
    /// `Y`=copy: push the selection (or the cursor if none) to the clipboard (for duplication). The selection is cleared.
    pub fn copy_selection(&mut self) {
        let targets = self.op_targets();
        if targets.is_empty() {
            self.flash = Some(crate::i18n::tr(self.lang, crate::i18n::Msg::NoTarget).into());
            return;
        }
        let n = targets.len();
        self.clipboard = Some(Clipboard {
            op: ClipOp::Copy,
            paths: targets,
        });
        self.clear_selection();
        self.flash = Some(format!(
            "{} ({n})",
            crate::i18n::tr(self.lang, crate::i18n::Msg::Copied)
        ));
    }
    /// `X`=cut: push the selection (or the cursor if none) to the clipboard (for moving). The selection is cleared.
    pub fn cut_selection(&mut self) {
        let targets = self.op_targets();
        if targets.is_empty() {
            self.flash = Some(crate::i18n::tr(self.lang, crate::i18n::Msg::NoTarget).into());
            return;
        }
        let n = targets.len();
        self.clipboard = Some(Clipboard {
            op: ClipOp::Cut,
            paths: targets,
        });
        self.clear_selection();
        self.flash = Some(format!(
            "{} ({n})",
            crate::i18n::tr(self.lang, crate::i18n::Msg::CutDone)
        ));
    }
    /// `P`=paste: apply to the cursor-based directory. Copy duplicates, cut moves (consumed). **Never overwrites.**
    pub fn paste(&mut self) -> Result<()> {
        let Some(clip) = self.clipboard.clone() else {
            self.flash = Some(crate::i18n::tr(self.lang, crate::i18n::Msg::ClipboardEmpty).into());
            return Ok(());
        };
        let dir = self.op_base_dir();
        let (mut ok, mut last, mut err) = (0usize, None, None);
        for src in &clip.paths {
            // 自分自身(やその中)への貼り付けは無限コピーになるので弾く。
            if dir.starts_with(src) {
                err = Some(
                    crate::i18n::tr(self.lang, crate::i18n::Msg::CannotPasteIntoSelf).to_string(),
                );
                continue;
            }
            let res = match clip.op {
                ClipOp::Copy => crate::fileops::copy_into(&dir, src),
                ClipOp::Cut => crate::fileops::move_into(&dir, src),
            };
            match res {
                Ok(p) => {
                    ok += 1;
                    last = Some(p);
                }
                Err(e) => err = Some(e.to_string()),
            }
        }
        if matches!(clip.op, ClipOp::Cut) {
            self.clipboard = None; // カットは消費(元が移動済み)
        }
        self.refresh()?;
        if let Some(p) = &last {
            self.reveal_and_select(p)?;
        }
        self.flash = Some(match err {
            Some(e) => format!(
                "{} {ok} / {}: {e}",
                crate::i18n::tr(self.lang, crate::i18n::Msg::Pasted),
                crate::i18n::tr(self.lang, crate::i18n::Msg::Failed),
            ),
            None => format!(
                "{} ({ok})",
                crate::i18n::tr(self.lang, crate::i18n::Msg::Pasted)
            ),
        });
        Ok(())
    }

    /// `Space→D`=duplicate: copy each target **in place** (into its own parent directory) with a
    /// collision-free name (`note copy.md`, then `note copy 2.md`). Operates on the selection, or the
    /// cursor entry when none. Directories are duplicated recursively (as a sibling `dir copy`), and
    /// symlinks are copied as links — both via `copy_into`. Never overwrites. The last new item is
    /// revealed and selected so the result is visible.
    pub fn duplicate_selection(&mut self) -> Result<()> {
        let targets = self.op_targets();
        if targets.is_empty() {
            self.flash = Some(crate::i18n::tr(self.lang, crate::i18n::Msg::NoTarget).into());
            return Ok(());
        }
        let (mut ok, mut last, mut err) = (0usize, None, None);
        for src in &targets {
            // 親ディレクトリ = 複製先(その場に複製)。ルート等で親が無ければ失敗扱い(クラッシュしない)。
            let Some(dir) = src.parent() else {
                err =
                    Some(crate::i18n::tr(self.lang, crate::i18n::Msg::OperationFailed).to_string());
                continue;
            };
            match crate::fileops::copy_into(dir, src) {
                Ok(p) => {
                    ok += 1;
                    last = Some(p);
                }
                Err(e) => err = Some(e.to_string()),
            }
        }
        self.clear_selection();
        self.refresh()?;
        if let Some(p) = &last {
            self.reveal_and_select(p)?;
        }
        self.flash = Some(match err {
            Some(e) => format!(
                "{} {ok} / {}: {e}",
                crate::i18n::tr(self.lang, crate::i18n::Msg::Duplicated),
                crate::i18n::tr(self.lang, crate::i18n::Msg::Failed)
            ),
            None => format!(
                "{} ({ok})",
                crate::i18n::tr(self.lang, crate::i18n::Msg::Duplicated)
            ),
        });
        Ok(())
    }

    /// The selection listed in the **current sort order (tree display order)**. Used as the numbering order for sequential rename.
    /// Selections not present in entries (collapsed, etc.) are appended at the end in path order.
    fn selection_in_display_order(&self) -> Vec<PathBuf> {
        let mut v: Vec<PathBuf> = self
            .entries
            .iter()
            .filter(|e| self.selection.contains(&e.path))
            .map(|e| e.path.clone())
            .collect();
        for p in &self.selection {
            if !v.contains(p) {
                v.push(p.clone());
            }
        }
        v
    }
    /// Heading for the batch-rename input dialog (the count + a placeholder legend).
    fn batch_rename_title(&self, count: usize) -> String {
        format!(
            "{} {} {}  {{n}} {{n:0W}} {{name}} {{ext}}",
            crate::i18n::tr(self.lang, crate::i18n::Msg::BatchRename),
            count,
            crate::i18n::tr(self.lang, crate::i18n::Msg::Items),
        )
    }
    /// `R` (with a selection)=batch rename. Opens template input that numbers the selection sequentially in display order.
    pub fn start_batch_rename(&mut self) {
        let targets = self.selection_in_display_order();
        if targets.is_empty() {
            self.flash = Some(crate::i18n::tr(self.lang, crate::i18n::Msg::NoTarget).into());
            return;
        }
        let title = self.batch_rename_title(targets.len());
        self.dialog = Some(Dialog {
            op: PendingOp::BatchRenameInput { targets },
            kind: DialogKind::Input {
                title,
                buffer: String::new(),
                cursor: 0,
            },
        });
    }

    /// `a`=create. Opens an input dialog to create with the entered name in the cursor-based directory (a trailing `/` makes a folder).
    pub fn start_create(&mut self) {
        let dir = self.op_base_dir();
        let where_ = self.format_path(&dir);
        self.dialog = Some(Dialog {
            op: PendingOp::Create { dir },
            kind: DialogKind::Input {
                title: format!(
                    "{} in {where_}  ({})",
                    crate::i18n::tr(self.lang, crate::i18n::Msg::Create),
                    crate::i18n::tr(self.lang, crate::i18n::Msg::TrailingSlashFolder),
                ),
                buffer: String::new(),
                cursor: 0,
            },
        });
    }

    /// `R`=rename. An input dialog to change the cursor's file/directory name (prefilled with the current name).
    pub fn start_rename(&mut self) {
        let Some(target) = self.entries.get(self.selected).map(|e| e.path.clone()) else {
            self.flash = Some(crate::i18n::tr(self.lang, crate::i18n::Msg::NoTarget).into());
            return;
        };
        let name = target
            .file_name()
            .and_then(|n| n.to_str())
            .unwrap_or("")
            .to_string();
        let cursor = name.chars().count(); // 末尾にカーソルを置く。
        self.dialog = Some(Dialog {
            op: PendingOp::Rename { target },
            kind: DialogKind::Input {
                title: crate::i18n::tr(self.lang, crate::i18n::Msg::Rename).into(),
                buffer: name,
                cursor,
            },
        });
    }

    /// `D`=delete (with confirmation). Opens a confirmation dialog targeting **all selected items if there is a selection**, or the cursor item otherwise.
    /// `y`=send to trash (recoverable) / `!`=permanent delete (unrecoverable) / `n`,Esc=cancel.
    pub fn start_delete(&mut self) {
        let targets = self.op_targets();
        if targets.is_empty() {
            self.flash = Some(crate::i18n::tr(self.lang, crate::i18n::Msg::NoTarget).into());
            return;
        }
        // メッセージ: 1件は名前、複数件は「N 件 (先頭名 他)」。
        let label = if targets.len() == 1 {
            targets[0]
                .file_name()
                .and_then(|n| n.to_str())
                .unwrap_or("?")
                .to_string()
        } else {
            let first = targets[0]
                .file_name()
                .and_then(|n| n.to_str())
                .unwrap_or("?");
            format!(
                "{} {} ({first} {})",
                targets.len(),
                crate::i18n::tr(self.lang, crate::i18n::Msg::Items),
                crate::i18n::tr(self.lang, crate::i18n::Msg::Etc),
            )
        };
        self.dialog = Some(Dialog {
            op: PendingOp::Delete { targets },
            kind: DialogKind::Confirm {
                message: format!(
                    "{}: {label}",
                    crate::i18n::tr(self.lang, crate::i18n::Msg::DeleteTarget),
                ),
                allow_permanent: true,
            },
        });
    }

    /// A mutable reference to the (buffer, cursor) being edited. None if not an input dialog.
    fn dialog_input_mut(&mut self) -> Option<(&mut String, &mut usize)> {
        match self.dialog.as_mut() {
            Some(Dialog {
                kind: DialogKind::Input { buffer, cursor, .. },
                ..
            }) => Some((buffer, cursor)),
            _ => None,
        }
    }

    /// Insert one character at the cursor position in the input dialog and advance the cursor by one.
    pub fn dialog_input_push(&mut self, c: char) {
        if let Some((buffer, cursor)) = self.dialog_input_mut() {
            let at = char_byte(buffer, *cursor);
            buffer.insert(at, c);
            *cursor += 1;
        }
    }
    /// Delete the character just before the cursor (Backspace).
    pub fn dialog_input_backspace(&mut self) {
        if let Some((buffer, cursor)) = self.dialog_input_mut() {
            if *cursor > 0 {
                let start = char_byte(buffer, *cursor - 1);
                let end = char_byte(buffer, *cursor);
                buffer.replace_range(start..end, "");
                *cursor -= 1;
            }
        }
    }
    /// Delete the character at the cursor position (Delete). The cursor does not move.
    pub fn dialog_input_delete(&mut self) {
        if let Some((buffer, cursor)) = self.dialog_input_mut() {
            let count = buffer.chars().count();
            if *cursor < count {
                let start = char_byte(buffer, *cursor);
                let end = char_byte(buffer, *cursor + 1);
                buffer.replace_range(start..end, "");
            }
        }
    }
    /// Move the cursor left (←).
    pub fn dialog_cursor_left(&mut self) {
        if let Some((_, cursor)) = self.dialog_input_mut() {
            *cursor = cursor.saturating_sub(1);
        }
    }
    /// Move the cursor right (→). Clamped at the end.
    pub fn dialog_cursor_right(&mut self) {
        if let Some((buffer, cursor)) = self.dialog_input_mut() {
            *cursor = (*cursor + 1).min(buffer.chars().count());
        }
    }
    /// Move the cursor to the start (Home).
    pub fn dialog_cursor_home(&mut self) {
        if let Some((_, cursor)) = self.dialog_input_mut() {
            *cursor = 0;
        }
    }
    /// Move the cursor to the end (End).
    pub fn dialog_cursor_end(&mut self) {
        if let Some((buffer, cursor)) = self.dialog_input_mut() {
            *cursor = buffer.chars().count();
        }
    }
    /// Cancel the dialog (Esc / confirm n).
    pub fn dialog_cancel(&mut self) {
        self.dialog = None;
    }

    /// Handle a quit request (`q` at the top level / `Q` from anywhere). If `ui.confirm_quit` is on,
    /// open a yes/no confirmation dialog and return `true` (the caller must NOT quit yet). Otherwise
    /// return `false` (the caller quits immediately).
    pub fn request_quit(&mut self) -> bool {
        if !self.cfg.ui.confirm_quit {
            return false;
        }
        self.dialog = Some(Dialog {
            op: PendingOp::Quit,
            kind: DialogKind::Confirm {
                message: crate::i18n::tr(self.lang, crate::i18n::Msg::QuitConfirm).into(),
                allow_permanent: false,
            },
        });
        true
    }

    /// Confirm the text-input dialog (Enter). Performs create/rename.
    pub fn dialog_submit(&mut self) -> Result<()> {
        let Some(dialog) = self.dialog.take() else {
            return Ok(());
        };
        let DialogKind::Input { buffer, .. } = dialog.kind else {
            return Ok(()); // 確認ダイアログはここへ来ない
        };
        // コミットは名前と扱いが違う(末尾 / を剥がさない・独自の空チェック)ので先に分岐。
        if matches!(dialog.op, PendingOp::GitCommit) {
            let message = buffer.trim();
            if message.is_empty() {
                self.flash =
                    Some(crate::i18n::tr(self.lang, crate::i18n::Msg::MessageEmpty).into());
                return Ok(());
            }
            match crate::git::commit(&self.root, message) {
                Ok(()) => {
                    // ステージ済み index でコミット成功 → git データ再取得＋ビュー更新。
                    self.refresh()?;
                    if self.is_git_view() {
                        self.git_view_reload();
                    }
                    self.flash =
                        Some(crate::i18n::tr(self.lang, crate::i18n::Msg::Committed).into());
                }
                Err(e) => {
                    // 失敗(stderr)を表示し、同じメッセージで入力ダイアログを再オープン(やり直せる)。
                    self.flash = Some(format!("{e}"));
                    let cursor = message.chars().count();
                    self.dialog = Some(Dialog {
                        op: PendingOp::GitCommit,
                        kind: DialogKind::Input {
                            title: crate::i18n::tr(self.lang, crate::i18n::Msg::CommitMessage)
                                .into(),
                            buffer: message.to_string(),
                            cursor,
                        },
                    });
                }
            }
            return Ok(());
        }
        // 新規ブランチ作成(コミット同様、名前を素直に trim して扱う)。
        if matches!(dialog.op, PendingOp::GitCreateBranch) {
            let bname = buffer.trim();
            if bname.is_empty() {
                self.flash = Some(crate::i18n::tr(self.lang, crate::i18n::Msg::NameEmpty).into());
                return Ok(());
            }
            match crate::git::create_branch(&self.root, bname) {
                Ok(()) => {
                    self.refresh()?;
                    self.refresh_git_if_needed(); // ブランチ名/状態のキャッシュを即更新
                    self.close_git_branches(); // 作成＆切替済み → 一覧を閉じて Git ビューへ
                    self.flash = Some(format!(
                        "{}: {bname}",
                        crate::i18n::tr(self.lang, crate::i18n::Msg::CreatedBranch)
                    ));
                }
                Err(e) => {
                    self.flash = Some(format!("{e}"));
                    let cursor = bname.chars().count();
                    self.dialog = Some(Dialog {
                        op: PendingOp::GitCreateBranch,
                        kind: DialogKind::Input {
                            title: crate::i18n::tr(self.lang, crate::i18n::Msg::NewBranch).into(),
                            buffer: bname.to_string(),
                            cursor,
                        },
                    });
                }
            }
            return Ok(());
        }
        let name = buffer.trim().trim_end_matches('/').trim();
        let want_folder = buffer.trim_end().ends_with('/');
        if name.is_empty() {
            self.flash = Some(crate::i18n::tr(self.lang, crate::i18n::Msg::NameEmpty).into());
            return Ok(());
        }
        match dialog.op {
            PendingOp::Create { dir } => {
                let created = if want_folder {
                    crate::fileops::create_dir(&dir, name)
                } else {
                    crate::fileops::create_file(&dir, name)
                };
                match created {
                    Ok(path) => {
                        self.refresh()?;
                        self.reveal_and_select(&path)?;
                        self.flash = Some(format!(
                            "{}: {}",
                            crate::i18n::tr(self.lang, crate::i18n::Msg::Created),
                            self.format_path(&path)
                        ));
                    }
                    Err(e) => {
                        self.flash = Some(format!(
                            "{}: {e}",
                            crate::i18n::tr(self.lang, crate::i18n::Msg::Failed)
                        ))
                    }
                }
            }
            PendingOp::Rename { target } => match crate::fileops::rename(&target, name) {
                Ok(path) => {
                    self.refresh()?;
                    self.reveal_and_select(&path)?;
                    self.flash = Some(format!(
                        "{}: {}",
                        crate::i18n::tr(self.lang, crate::i18n::Msg::Renamed),
                        self.format_path(&path)
                    ));
                }
                Err(e) => {
                    self.flash = Some(format!(
                        "{}: {e}",
                        crate::i18n::tr(self.lang, crate::i18n::Msg::Failed)
                    ))
                }
            },
            PendingOp::BatchRenameInput { targets } => {
                match build_rename_plan(&targets, name) {
                    Ok(plan) => {
                        // プレビュー(旧 → 新)へ遷移。適用は dialog_preview_apply。
                        let lines: Vec<String> = plan
                            .iter()
                            .map(|(s, d)| {
                                format!(
                                    "{}  →  {}",
                                    s.file_name().and_then(|n| n.to_str()).unwrap_or("?"),
                                    d.file_name().and_then(|n| n.to_str()).unwrap_or("?"),
                                )
                            })
                            .collect();
                        let title = format!(
                            "{} {} {}",
                            crate::i18n::tr(self.lang, crate::i18n::Msg::Rename),
                            plan.len(),
                            crate::i18n::tr(self.lang, crate::i18n::Msg::Items),
                        );
                        self.dialog = Some(Dialog {
                            op: PendingOp::BatchRenameApply { plan },
                            kind: DialogKind::Preview {
                                title,
                                lines,
                                scroll: 0,
                            },
                        });
                    }
                    Err(e) => {
                        // 入力をやり直せるよう、同じテンプレで入力ダイアログを再オープン。
                        self.flash = Some(format!(
                            "{}: {e}",
                            crate::i18n::tr(self.lang, crate::i18n::Msg::Failed)
                        ));
                        let cursor = name.chars().count();
                        let title = self.batch_rename_title(targets.len());
                        self.dialog = Some(Dialog {
                            op: PendingOp::BatchRenameInput { targets },
                            kind: DialogKind::Input {
                                title,
                                buffer: name.to_string(),
                                cursor,
                            },
                        });
                    }
                }
            }
            // 削除/Git 破棄は確認ダイアログ側 / 一括リネーム適用はプレビュー側。
            // GitCommit は上で早期 return 済みなので到達しない。
            PendingOp::Delete { .. }
            | PendingOp::BatchRenameApply { .. }
            | PendingOp::GitDiscard { .. }
            | PendingOp::GitCommit
            | PendingOp::GitCreateBranch
            | PendingOp::GitDeleteBranch { .. }
            | PendingOp::DropTransfer { .. }
            | PendingOp::BookmarkOverwrite { .. }
            | PendingOp::Quit => {}
        }
        Ok(())
    }

    /// In the preview, `y`=apply the batch rename. Two-phase rename → reload → clear selection.
    pub fn dialog_preview_apply(&mut self) -> Result<()> {
        let Some(dialog) = self.dialog.take() else {
            return Ok(());
        };
        if let PendingOp::BatchRenameApply { plan } = dialog.op {
            match crate::fileops::batch_rename(&plan) {
                Ok(()) => {
                    self.refresh()?;
                    self.clear_selection();
                    self.flash = Some(format!(
                        "{} ({})",
                        crate::i18n::tr(self.lang, crate::i18n::Msg::Renamed),
                        plan.len()
                    ));
                }
                Err(e) => {
                    self.flash = Some(format!(
                        "{}: {e}",
                        crate::i18n::tr(self.lang, crate::i18n::Msg::Failed)
                    ))
                }
            }
        }
        Ok(())
    }

    /// Response to a confirmation dialog. yes=execute (delete → trash, recoverable) / no=cancel.
    pub fn dialog_confirm(&mut self, yes: bool) -> Result<()> {
        let Some(dialog) = self.dialog.take() else {
            return Ok(());
        };
        if !yes {
            self.flash = Some(crate::i18n::tr(self.lang, crate::i18n::Msg::Canceled).into());
            return Ok(());
        }
        match dialog.op {
            PendingOp::Delete { targets } => match crate::fileops::move_to_trash(&targets) {
                Ok(()) => {
                    self.refresh()?;
                    self.clear_selection();
                    self.flash = Some(format!(
                        "{} ({})",
                        crate::i18n::tr(self.lang, crate::i18n::Msg::MovedToTrash),
                        targets.len()
                    ));
                }
                Err(e) => {
                    self.flash = Some(format!(
                        "{}: {e}",
                        crate::i18n::tr(self.lang, crate::i18n::Msg::Failed)
                    ))
                }
            },
            // Git ビューの破棄: git::discard → 一覧/ツリーの git status を取り直す。
            // GitDiff プレビューからの破棄(came_from_git_view)なら Git ビューを開き直して戻す。
            PendingOp::GitDiscard { path } => match crate::git::discard(&self.root, &path) {
                Ok(()) => {
                    let from_diff = self.is_git_diff_preview();
                    if from_diff {
                        // プレビューを畳んで Git ビューへ復帰。
                        self.came_from_git_view = false;
                        self.back_to_tree();
                        self.open_git_view();
                    }
                    self.git_view_reload();
                    // 破棄自体は成功。ツリー再構築が失敗した時はその旨を通知し、
                    // 成功 flash で上書きしない(誤って「成功」と見せない)。
                    if self.rebuild_tree_notify() {
                        self.flash = Some(format!(
                            "{}: {}",
                            crate::i18n::tr(self.lang, crate::i18n::Msg::Discarded),
                            self.format_path(&path)
                        ));
                    }
                }
                Err(e) => {
                    self.flash = Some(format!(
                        "{}: {e}",
                        crate::i18n::tr(self.lang, crate::i18n::Msg::Failed)
                    ))
                }
            },
            // ブランチ削除(安全): git branch -d。失敗(未マージ等)は git の stderr を flash。
            PendingOp::GitDeleteBranch { name } => self.git_delete_branch(&name, false),
            // ブックマーク上書きの確定: 実際に登録する(mark_input と同じ経路)。
            PendingOp::BookmarkOverwrite { key, target } => self.perform_mark_set(key, target),
            _ => {}
        }
        Ok(())
    }

    /// In a confirmation dialog, `!`=**permanent delete / force** (delete=without going through the trash / branch=`-D` force).
    pub fn dialog_delete_permanent(&mut self) -> Result<()> {
        let Some(dialog) = self.dialog.take() else {
            return Ok(());
        };
        // ブランチの強制削除 (`-D`)。
        if let PendingOp::GitDeleteBranch { name } = &dialog.op {
            self.git_delete_branch(&name.clone(), true);
            return Ok(());
        }
        if let PendingOp::Delete { targets } = dialog.op {
            match crate::fileops::delete_permanently(&targets) {
                Ok(()) => {
                    self.refresh()?;
                    self.clear_selection();
                    self.flash = Some(format!(
                        "{} ({})",
                        crate::i18n::tr(self.lang, crate::i18n::Msg::DeletedPermanently),
                        targets.len()
                    ));
                }
                Err(e) => {
                    self.flash = Some(format!(
                        "{}: {e}",
                        crate::i18n::tr(self.lang, crate::i18n::Msg::Failed)
                    ))
                }
            }
        }
        Ok(())
    }

    pub fn tree_next(&mut self) {
        if self.selected + 1 < self.entries.len() {
            self.selected += 1;
        }
    }

    pub fn tree_prev(&mut self) {
        self.selected = self.selected.saturating_sub(1);
    }

    /// To the top of the tree.
    pub fn tree_first(&mut self) {
        self.selected = 0;
    }

    /// To the bottom of the tree.
    pub fn tree_last(&mut self) {
        self.selected = self.entries.len().saturating_sub(1);
    }

    /// Page the tree by one (dir: +1=next / -1=previous). Overlaps one row to keep context.
    pub fn tree_page(&mut self, dir: i32) {
        let page = self.tree_viewport.saturating_sub(1).max(1) as i32;
        self.tree_move(dir * page);
    }

    /// Half-page the tree (vim: Ctrl-d/Ctrl-u, less: d/u).
    pub fn tree_half_page(&mut self, dir: i32) {
        let half = (self.tree_viewport / 2).max(1) as i32;
        self.tree_move(dir * half);
    }

    /// Move the selection by delta rows and clamp it to [0, end].
    fn tree_move(&mut self, delta: i32) {
        self.selected = clamp_cursor(self.selected, delta, self.entries.len());
    }

    /// If a directory, toggle expansion; if a file, transition to Preview.
    /// While filtering (a flat result list), expand-toggle is meaningless, so behave the same as `tree_descend`.
    pub fn tree_activate(&mut self) -> Result<()> {
        if self.tree_filter.is_some() || self.changed_filter {
            return self.tree_descend();
        }
        let Some(entry) = self.entries.get(self.selected).cloned() else {
            return Ok(());
        };
        if entry.is_dir {
            // expanded をトグルして再構築
            if let Some(e) = self.entries.get_mut(self.selected) {
                e.expanded = !e.expanded;
            }
            self.rebuild_tree()?;
        } else {
            self.enter_preview(&entry.path);
        }
        Ok(())
    }

    /// Before switching root, discard state that points to items of the old root.
    /// `selection` is held by path, so under a different root it stays invisible yet becomes a target for mis-operations (a footgun), and
    /// `visual_anchor` is an entries index, so it goes stale under a different root. The filter and preview search are also
    /// for the old root, so they are cleared together (rebuild_tree also invalidates visual_anchor, but we do it explicitly).
    fn clear_for_root_change(&mut self) {
        self.selection.clear();
        self.visual_anchor = None;
        self.clear_filter_state();
        self.search_clear();
    }

    /// Move to the parent directory (raise the root). For `h`. While filtering, first clear the filter (the normal tree of the current root).
    pub fn tree_leave(&mut self) -> Result<()> {
        if self.tree_filter.is_some() {
            self.filter_clear();
            return Ok(());
        }
        if self.changed_filter {
            self.toggle_changed_filter(); // OFF に戻す(通常ツリーへ)
            return Ok(());
        }
        if let Some(parent) = self.root.parent().map(Path::to_path_buf) {
            self.clear_for_root_change();
            self.root = parent;
            self.entries.clear();
            self.selected = 0;
            self.rebuild_tree()?;
        }
        Ok(())
    }

    /// Descend into the selected directory (make that directory the new root). For `l`.
    /// Symmetric to `h` (to the parent). If a file, transition to Preview.
    /// Works on filter results too: directory → move there and clear the filter / file → preview.
    pub fn tree_descend(&mut self) -> Result<()> {
        let Some(entry) = self.entries.get(self.selected).cloned() else {
            return Ok(());
        };
        let was_filtering = self.tree_filter.is_some();
        if entry.is_dir {
            // root を変えるので旧 root の選択/ビジュアル/絞り込み/検索を破棄する(持ち越さない)。
            self.clear_for_root_change();
            self.root = entry.path;
            self.entries.clear();
            self.selected = 0;
            self.rebuild_tree()?;
        } else {
            // ファイルは絞り込みを保ったままプレビュー(戻ると結果一覧に復帰)。
            let _ = was_filtering;
            self.enter_preview(&entry.path);
        }
        Ok(())
    }

    pub fn toggle_hidden(&mut self) -> Result<()> {
        self.show_hidden = !self.show_hidden;
        self.rebuild_tree()
    }

    // --- フォローモード (`F`) — Agent Watch ② -------------------------------------
    /// `F`: toggle follow mode (auto-jump to externally changed files; the "watch the AI work" view).
    /// Turning it ON starts a fresh follow session (the "what changed while following" list for `n`/`N`).
    pub fn toggle_follow(&mut self) {
        self.follow_mode = !self.follow_mode;
        if self.follow_mode {
            self.follow_session.clear();
        }
        let msg = if self.follow_mode {
            crate::i18n::Msg::FollowOn
        } else {
            crate::i18n::Msg::FollowOff
        };
        self.flash = Some(tr(self.lang, msg).into());
    }

    /// Whether follow mode is on (chip display / the run loop's jump gate).
    pub fn follow_enabled(&self) -> bool {
        self.follow_mode
    }

    /// The user took over the keyboard (pressed any key not bound to `F`): stop following (Zed-style —
    /// following is a hands-off state; re-enable with one `F`). Flash so the state change is visible.
    pub fn follow_break(&mut self) {
        if self.follow_mode {
            self.follow_mode = false;
            self.flash = Some(tr(self.lang, crate::i18n::Msg::FollowOff).into());
        }
    }

    /// Follow-mode jump: reveal `path` in the tree and open its preview. Gated to meaningful targets:
    /// under root, an existing visible file, not gitignored, not already being previewed (the preview
    /// auto-reload handles content changes of the current file). No-op outside Tree/Preview surfaces
    /// (dialogs and git views are never hijacked — normally unreachable anyway since any key breaks follow).
    pub fn follow_jump(&mut self, path: &Path) {
        use crate::keymap::Surface;
        if !self.follow_mode {
            return;
        }
        // フォロー自身が開いた diff ビュー(PreviewGitDiff)からも次のファイルへ追従を続ける。
        // それ以外の git ビュー/ダイアログ等は乗っ取らない(通常はキー押下で follow が切れるので届かない)。
        let surface_ok = matches!(
            self.surface(),
            Surface::Tree | Surface::PreviewText | Surface::PreviewImage | Surface::PreviewTable
        );
        #[cfg(feature = "git")]
        let surface_ok = surface_ok || matches!(self.surface(), Surface::PreviewGitDiff);
        if !surface_ok {
            return;
        }
        if self.preview_path.as_deref() == Some(path) {
            return;
        }
        if !self.follow_target_ok(path) {
            return;
        }
        // 追尾がビューを動かす瞬間に古い flash(「follow: on」等)を消す=フッターを
        // その面の操作ヒントに明け渡す(flash は本来キー入力で消えるが、追尾はキー無しで進むため)。
        self.flash = None;
        if self.changed_filter {
            // 変更一覧を最新化してから対象を選択(一覧に居るはず=変更イベント由来)。
            self.reapply_changed_filter();
            if let Some(i) = self.entries.iter().position(|e| e.path == path) {
                self.selected = i;
            }
        } else if !matches!(self.reveal_path_deep(path), Ok(true)) {
            return;
        }
        // 既定(`ui.follow_view="diff"`)は**全画面 diff** で開く=何から何に変わったかがハンク単位で
        // 見える(hunk/livediff/diffpane と同じ提示)。diff を出せない未追跡(全行新規)・リポジトリ外や、
        // バイナリのメディア系はファイルプレビュー(+最初の変更ハンクへスクロール)へフォールバック。
        if self.cfg.ui.follow_view != "file" && !self.follow_is_media(path) {
            let diff = crate::git::file_diff(&self.root, path);
            if !diff.is_empty() {
                self.open_git_diff(path);
                // いま取った diff をキャッシュに載せ、描画での再取得(git 再実行)を省く。
                self.diff_cache = Some(DiffCache {
                    path: path.to_path_buf(),
                    lines: diff,
                });
                // フォロー由来の diff: n/N と位置表示は「このセッションで変わったファイル」を回遊。
                self.diff_follow_scope = true;
                return;
            }
        }
        self.enter_preview(path);
        self.follow_scroll_to_first_change();
    }

    /// Whether `path` is a valid follow target: under root, an existing file, not gitignored, and not
    /// inside a hidden (dot) directory unless hidden files are shown. Shared by the jump and the
    /// session-list recording so both see the same set.
    fn follow_target_ok(&self, path: &Path) -> bool {
        if !path.starts_with(&self.root) || !path.is_file() || self.is_ignored(path) {
            return false;
        }
        if !self.show_hidden {
            // 隠し(ドット)ディレクトリ/ファイル配下はツリーに出せないので追わない(show_hidden で解禁)。
            let hidden = path
                .strip_prefix(&self.root)
                .map(|r| {
                    r.components().any(|c| {
                        c.as_os_str()
                            .to_str()
                            .map(|s| s.starts_with('.'))
                            .unwrap_or(false)
                    })
                })
                .unwrap_or(true);
            if hidden {
                return false;
            }
        }
        true
    }

    /// Record one changed file into the current follow session (called from the run loop's event drain
    /// while follow is ON). Returns whether the path is a valid follow target (the caller uses this to
    /// decide whether it may become the pending jump target). First-change order, deduped.
    pub fn follow_note_change(&mut self, path: &Path) -> bool {
        if !self.follow_mode || !self.follow_target_ok(path) {
            return false;
        }
        if !self.follow_session.iter().any(|p| p == path) {
            self.follow_session.push(path.to_path_buf());
        }
        true
    }

    /// Whether `path` previews as media (image/SVG/video/PDF) — its git diff would be a useless
    /// "binary files differ" line, so follow shows the content preview instead.
    fn follow_is_media(&self, path: &Path) -> bool {
        matches!(
            self.cfg.resolve_preview(path),
            PreviewKind::Image(_)
                | PreviewKind::Svg(_)
                | PreviewKind::Video(_)
                | PreviewKind::Pdf(_)
        )
    }

    /// After a follow jump, scroll the (windowed) preview to the **first changed hunk** instead of the
    /// file top — an edit deep in a large file would otherwise be off-screen and invisible, which defeats
    /// "watch the agent work" (Zed follows the edit position; diffpane scrolls to the latest change).
    /// A few context lines are kept above, and the caret lands on the changed line (ready for `v`/`Y`).
    /// No-ops for non-windowed previews, untracked files (all-new → top is right), and outside a repo.
    fn follow_scroll_to_first_change(&mut self) {
        if !self.is_windowed() {
            return;
        }
        let Some(path) = self.preview_path.clone() else {
            return;
        };
        // ガター設定 OFF でも変更行は取得する(ON なら同じ計算が gutter_cache に載り描画でも再利用)。
        let marks = if self.cfg.ui.git_gutter {
            self.git_gutter_marks()
        } else {
            gutter_marks(&crate::git::file_diff(&self.root, &path))
        };
        let Some(first) = marks.keys().min().copied() else {
            return;
        };
        let line0 = (first as usize).saturating_sub(1); // marks は 1-based
        let top = line0.saturating_sub(3); // 上に文脈を数行残す
        let Some(win) = self.preview_win.as_mut() else {
            return;
        };
        if let Ok((off, _)) = win.advance(0, top) {
            self.preview_byte_top = off;
            self.preview_top_line = top;
            self.preview_cursor_line = line0;
        }
    }

    fn enter_preview(&mut self, path: &Path) {
        // 同一ファイルへの再入(全画面フェンスからの `q` 復帰)か。この場合はインライン画像
        // キャッシュを温存する: キーはフェンス=内容ハッシュ/画像=パスなので stale にならず、
        // 捨てると全フェンスが Loading からやり直し=縮退レイアウトの 1 描画で復元スクロール/
        // フォーカスがクランプされ「元の位置に戻る」約束が破れていた。
        let same_file = self.preview_path.as_deref() == Some(path);
        self.preview_path = Some(path.to_path_buf());
        // 設定駆動でプレビュー種別を解決。未対応は CanNotPreview。
        let kind = self.cfg.resolve_preview(path);
        self.preview_scroll = 0;
        self.preview_hscroll = 0;
        self.preview_byte_top = 0;
        self.preview_top_line = 0;
        // 画像状態は毎回リセット。SVG/GIF は別スレッドで読み込み開始(UI を塞がない)。
        self.clear_image();
        // PDF はページ数を先に求める(pdfinfo・~数 ms)。None なら単ページ扱い=ページ移動なし。
        if matches!(kind, PreviewKind::Pdf(_)) {
            self.pdf_pages = crate::preview::pdf::page_count(path);
        }
        self.start_media_load(&kind, path);
        self.preview_kind = Some(kind);
        self.fence_return = None; // 通常のプレビュー遷移でフェンス復帰情報は用済み
        self.fence_zoom = 1.0;
        self.fence_center = (0.5, 0.5);
        self.md_raw = false; // 新規ファイルは装飾表示から(Markdown/Mermaid)。`R` で raw へ。
        self.md_cache = None; // 別ファイルに切替: 装飾キャッシュを無効化
        self.md_items.clear();
        if !same_file {
            self.md_image_cache.clear(); // 別ファイル: インライン画像キャッシュも破棄
        }
        self.focused_item = None;
        self.outline_open = false; // 新規プレビューでアウトラインオーバーレイは閉じる
        self.details_open.clear(); // <details> の開閉状態は文書ごと=別ファイルでリセット
        self.preview_search = None;
        self.search_input = None;
        self.search_matches.clear();
        self.table_search_hits.clear();
        self.search_idx = 0;
        self.setup_windowed(); // 大きい Code/Text なら less 風ウィンドウ読みに切替
                               // windowed プレビューの 2D キャレット/選択を先頭へリセット。
        self.preview_cursor_line = 0;
        self.preview_cursor_col = 0;
        self.preview_visual_anchor = None;
        self.preview_visual_linewise = false;
        // CSV/TSV はテーブルへパース。カーソル/スクロールを先頭へ戻してから読み込む。
        self.table_cur_row = 0;
        self.table_cur_col = 0;
        self.table_top_row = 0;
        self.table_left_col = 0;
        self.load_table();
        self.mode = Mode::Preview;
    }

    /// Code/Text previews use less-style windowed reading **regardless of size**.
    /// This avoids whole-file highlighting (1.3s/debug for 1600 lines) and reads/colors only the visible window (tens of lines), so
    /// opening is instant even for small files and behavior is symmetric with huge files. Images/md/mermaid are excluded
    /// (md/mermaid need their whole structure understood and are usually small).
    fn setup_windowed(&mut self) {
        self.preview_win = None;
        self.win_cache = None;
        self.preview_total_lines = None;
        // 重いハイライト待ち状態を判定: Code かつ ハイライト有効 かつ 文法が未コンパイル(cold)なら
        // 初回だけローディング表示/段階表示が要る。温まっていれば最初から即時着色。
        self.hl_pending = self.cfg.ui.syntax_highlight
            && matches!(self.preview_kind, Some(PreviewKind::Code(_)))
            && !crate::preview::code::is_ext_warm(self.current_preview_ext());
        self.hl_warming = false;
        // Code/Text は常に windowed。Markdown/Mermaid は raw 表示(`R`)のときだけ windowed 化＝
        // 素のソースを行/桁一致で読み、2D キャレット選択をそのまま乗せる。
        let windowed_kind = matches!(
            self.preview_kind,
            Some(PreviewKind::Code(_)) | Some(PreviewKind::Text(_))
        ) || self.is_raw_source();
        if !windowed_kind {
            return;
        }
        let Some(path) = self.preview_path.clone() else {
            return;
        };
        if let Ok(w) = crate::preview::window::FileWindow::open(&path) {
            self.preview_win = Some(w);
        }
    }

    /// Extension of the current preview target file (empty string if none). Used for the highlight-warm check, etc.
    pub fn current_preview_ext(&self) -> &str {
        self.preview_path
            .as_deref()
            .and_then(|p| p.extension())
            .and_then(|e| e.to_str())
            .unwrap_or("")
    }

    /// Whether waiting on heavy code highlighting (whether the render shows a loading/progressive display).
    pub fn is_highlight_pending(&self) -> bool {
        self.hl_pending
    }

    /// Whether the loading display is the "central spinner" style (false=progressive=immediate plain text).
    pub fn loading_is_indicator(&self) -> bool {
        self.cfg.ui.preview_loading != "progressive"
    }

    /// Clear the loading state on warm completion (swap in the colored version). Common to indicator/progressive.
    pub fn clear_highlight_pending(&mut self) {
        self.hl_pending = false;
        self.hl_warming = false;
    }

    /// If the background warm has not started yet, return the launch target (the caller runs `code::warm_file` on a separate thread).
    /// Both indicator and progressive **compile on a background thread** so the UI is not stalled (the spinner keeps spinning).
    /// Launch only when the return value is Some((ext, path)) (= prevents double-launch).
    pub fn take_warm_job(&mut self) -> Option<(String, PathBuf)> {
        if self.hl_pending && !self.hl_warming {
            if let Some(path) = self.preview_path.clone() {
                self.hl_warming = true;
                return Some((self.current_preview_ext().to_string(), path));
            }
        }
        None
    }

    /// Background jobs currently in flight, as i18n labels (drives the top-right busy indicator).
    /// **Derived** from the existing per-job state (no separate begin/end pairing that could leak
    /// a stuck spinner): git-ignored scan / media decode / syntax-highlight warm-up / inline images.
    pub fn busy_jobs(&self) -> Vec<crate::i18n::Msg> {
        let mut v = Vec::new();
        if self.git_ignored_pending.is_some() {
            v.push(crate::i18n::Msg::BusyGitScan);
        }
        if self.media_loading {
            v.push(crate::i18n::Msg::BusyMedia);
        }
        if self.hl_pending || self.hl_warming {
            v.push(crate::i18n::Msg::BusyHighlight);
        }
        if self.md_images_loading() {
            v.push(crate::i18n::Msg::BusyImages);
        }
        v
    }

    /// Whether the top-right busy indicator should be shown/animated right now
    /// (config on + at least one background job in flight). The run loop only schedules
    /// animation ticks while this is true, so idle CPU stays at zero.
    pub fn busy_indicator_active(&self) -> bool {
        self.cfg.ui.busy_indicator && !self.busy_jobs().is_empty()
    }

    /// Advance the spinner by one frame (the run loop calls this periodically while waiting = keeps it spinning).
    pub fn tick_spinner(&mut self) {
        self.spinner_frame = self.spinner_frame.wrapping_add(1);
    }

    /// The current spinner glyph (no emoji; the classic braille-pattern spinner = single-width and color-free in the terminal).
    pub fn spinner_glyph(&self) -> &'static str {
        const FRAMES: [&str; 10] = ["⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏"];
        FRAMES[self.spinner_frame % FRAMES.len()]
    }

    /// `e`: decide the target to open in the external editor and raise the request. Tree=the selected file / Preview=the file being shown.
    /// For a directory or no target, notify via flash and do nothing (only files can be edited).
    /// In Preview the editor is asked to open at the on-screen position (see `preview_edit_line`).
    pub fn request_edit(&mut self) {
        let target = match self.mode {
            Mode::Tree => match self.entries.get(self.selected) {
                Some(e) if e.is_dir => {
                    self.flash = Some(tr(self.lang, crate::i18n::Msg::CannotEditDirectory).into());
                    return;
                }
                Some(e) => Some(e.path.clone()),
                None => None,
            },
            Mode::Preview => self.preview_path.clone(),
        };
        match target {
            Some(p) => self.pending_edit = Some((p, self.preview_edit_line())),
            None => self.flash = Some(tr(self.lang, crate::i18n::Msg::NoFileToEdit).into()),
        }
    }

    /// The 1-based file line to open the external editor at, matching the on-screen position.
    /// - Windowed preview (plain text / code / raw-Markdown via `R`): the exact caret line.
    /// - Rendered Markdown: an **approximate** source line for the top of the current view. Reflow means
    ///   there is no exact scroll-row → source-line mapping, so the top-of-view fraction through the wrapped
    ///   output (`preview_scroll / md_view_rows`) is mapped to that fraction of the source. This lands the
    ///   editor near where you were reading rather than at the top (block-structured docs land on the
    ///   section being read; see `preview_edit_line` verification).
    /// - Otherwise (tree edits, Mermaid, images): None (open at the top).
    fn preview_edit_line(&self) -> Option<usize> {
        if self.mode != Mode::Preview {
            return None;
        }
        if self.is_windowed() {
            return Some(self.preview_cursor_line + 1);
        }
        // Rendered Markdown: reflow means there is no exact scroll-row → source-line mapping. Anchor on a
        // logical line (a Tab-focused item if one is visible, else the top of the view), estimate its
        // source line proportionally, then refine by content (see md_content_anchor_line).
        if matches!(self.preview_kind, Some(PreviewKind::Markdown(_))) {
            if let Some(c) = &self.md_cache {
                let same = self.preview_path.as_ref().is_some_and(|p| *p == c.path);
                if same && c.src_lines > 0 && self.md_view_rows > 0 {
                    // Prefer the on-screen Tab focus (the visible "cursor"); otherwise the top of view.
                    let (logical, row) = match self.md_focused_visible_line() {
                        Some(hit) => hit,
                        None => (
                            self.md_top_logical_line().unwrap_or(0),
                            self.preview_scroll as usize,
                        ),
                    };
                    let est = (row * c.src_lines / self.md_view_rows).min(c.src_lines - 1);
                    return Some(self.md_content_anchor_line(logical, est).unwrap_or(est) + 1);
                }
            }
        }
        None
    }

    /// The (decorated logical line, top display row) of the Tab-focused Markdown item, but only when it
    /// is currently on screen — so `e` opens where the visible cursor is. None if nothing is focused or
    /// the focus has been scrolled out of view (then `e` falls back to the top of the view).
    fn md_focused_visible_line(&self) -> Option<(usize, usize)> {
        let item = self.focused_item.and_then(|i| self.md_items.get(i))?;
        let (row, h) = self.md_visual_span(item.line);
        let scroll = self.preview_scroll as usize;
        let vh = self.preview_viewport.max(1) as usize;
        (row < scroll + vh && row + h > scroll).then_some((item.line, row))
    }

    /// The 0-based decorated (logical) line at the top of the current Markdown view, resolving wrapping
    /// so it matches what the renderer draws (`preview_scroll` is in post-wrap display rows).
    fn md_top_logical_line(&self) -> Option<usize> {
        let c = self.md_cache.as_ref()?;
        if c.lines.is_empty() {
            return None;
        }
        let scroll = self.preview_scroll as usize;
        if !self.cfg.ui.wrap || c.width == 0 || c.row_prefix.len() != c.lines.len() + 1 {
            return Some(scroll.min(c.lines.len() - 1));
        }
        // prefix は各行の開始表示行(単調増加)。scroll を含む行 = pp(p <= scroll) - 1。
        let i = c
            .row_prefix
            .partition_point(|&p| p <= scroll)
            .saturating_sub(1);
        Some(i.min(c.lines.len() - 1))
    }

    /// Refine the proportional editor-open estimate for rendered Markdown by content: take the longest
    /// visible span of decorated logical line `logical` (a single span carries no Markdown markers, so its
    /// text is a verbatim substring of the source) and find the source line containing it, closest to
    /// `est`. Returns a 0-based source line, or None to fall back to `est`. Re-reads the file so it
    /// matches what the editor will open (an agent may have edited it since the preview was built).
    fn md_content_anchor_line(&self, logical: usize, est: usize) -> Option<usize> {
        use ratatui::style::Modifier;
        let c = self.md_cache.as_ref()?;
        let line = c.lines.get(logical)?;
        // Longest non-hidden, non-blank span (hidden spans carry link/URL targets, not on-screen text).
        let key = line
            .spans
            .iter()
            .filter(|s| !s.style.add_modifier.contains(Modifier::HIDDEN))
            .map(|s| s.content.trim())
            .filter(|t| !t.is_empty())
            .max_by_key(|t| t.chars().count())?;
        if key.chars().count() < 4 {
            return None;
        }
        let content = crate::preview::text::load(c.path.as_path()).ok()?;
        let mut best: Option<usize> = None;
        let mut best_d = usize::MAX;
        for (i, sl) in content.lines.iter().enumerate() {
            if sl.contains(key) {
                let d = i.abs_diff(est);
                if d < best_d {
                    best_d = d;
                    best = Some(i);
                }
            }
        }
        best
    }

    /// Taken by the run loop: if set, return the editor-launch target path (+ line) and clear it.
    pub fn take_pending_edit(&mut self) -> Option<(PathBuf, Option<usize>)> {
        self.pending_edit.take()
    }

    /// `O`: request launching an external git tool (lazygit, etc.) (the run loop picks it up, suspends, then launches).
    #[cfg_attr(not(feature = "git"), allow(dead_code))]
    pub fn launch_git_tool(&mut self) {
        self.pending_git_tool = true;
    }

    /// Taken by the run loop: if a git-tool launch request is set, return true and clear it.
    pub fn take_launch_git_tool(&mut self) -> bool {
        std::mem::take(&mut self.pending_git_tool)
    }

    /// Reopen the preview after the external editor exits (reflect the edited content). Caches are also discarded.
    /// Even if the editor replaces the file (temp→rename), the FileWindow is reopened so the latest is read.
    pub fn reload_preview(&mut self) {
        self.md_cache = None;
        self.win_cache = None;
        if matches!(self.mode, Mode::Preview) {
            self.setup_windowed();
            self.reload_media_if_changed();
            // CSV/TSV は外部編集で内容が変わり得る。再パースしてカーソルを範囲内へクランプ(位置は保つ)。
            if matches!(self.preview_kind, Some(PreviewKind::Table { .. })) {
                self.load_table();
                self.clamp_table_cursor();
            }
        }
    }

    /// On an FS-driven reload, re-load media (image/svg/gif/video/pdf) **only when the previewed file
    /// actually changed** (mtime guard). Without this, an image preview stays stale after an external
    /// edit: text/markdown follows via the md_cache clear, but images go through a separate path and were
    /// missed — so when a file is edited externally (e.g. an editor on the right), the konoma preview on the left did not refresh.
    /// The mtime guard avoids re-decoding / re-running external tools (pdftocairo/ffmpeg) on unrelated FS
    /// events. Zoom / pan / page are preserved across the reload.
    fn reload_media_if_changed(&mut self) {
        let is_media = match &self.preview_kind {
            Some(kind) => self.kind_loads_media(kind),
            None => false,
        };
        if !is_media {
            return;
        }
        let Some(path) = self.preview_path.clone() else {
            return;
        };
        let Some(kind) = self.preview_kind.clone() else {
            return;
        };
        if file_mtime(&path) == self.preview_media_mtime {
            return; // 対象ファイルは未変更 → 無駄な再デコード/外部ツール実行を避ける
        }
        // 表示状態(ズーム/中心/ページ)を保持して再ロード。
        let (zoom, center, page) = (self.image_zoom, self.image_center, self.pdf_page);
        self.clear_image(); // ズーム/中心/ページ/メディア世代をリセット
        if matches!(kind, PreviewKind::Pdf(_)) {
            self.pdf_pages = crate::preview::pdf::page_count(&path);
            self.pdf_page = page.clamp(1, self.pdf_pages.unwrap_or(1).max(1));
        }
        self.start_media_load(&kind, &path); // preview_media_mtime も更新される
        self.image_zoom = zoom;
        self.image_center = center;
    }

    /// The directory to watch **in addition** to the tree root so external (agent) edits to the
    /// currently shown file are still detected. Returns the shown file's parent directory **only when
    /// that file lives outside the watched root**: a global-bookmark target, or the repo-wide git view
    /// when the root is a repo subdirectory. Files under the root are already covered by the recursive
    /// root watch (so this returns `None` for them, and whenever no file is shown / not in Preview).
    ///
    /// This closes the gap where the FSEvents watcher only covers `app.root`: an out-of-root preview
    /// or diff never received change events, so an AI/external edit left it stale (the user's own `e`
    /// edit still reloaded via the editor-return path — hence "my edits show, the AI's don't").
    /// Consumed by the run loop in `main.rs`, which adds a non-recursive watch on this directory.
    pub fn out_of_root_watch_dir(&self) -> Option<PathBuf> {
        if !matches!(self.mode, Mode::Preview) {
            return None;
        }
        let p = self.preview_path.as_ref()?;
        if p.starts_with(&self.root) {
            return None; // already covered by the recursive root watch
        }
        p.parent().map(|d| d.to_path_buf())
    }

    /// The repo's `.git` directory to watch **non-recursively** when the tree root is a *subdirectory*
    /// of the repo (so the parent `.git` sits above `root` and is not covered by the recursive root
    /// watch). Without this, an external git op that touches only `.git` (a commit of already-staged
    /// files, an external checkout) fires no event under the subdir, so the cached `git status` /
    /// branch would linger stale — the per-workdir status cache no longer re-verifies on `h`/`l`.
    /// `.git/index` and `.git/HEAD` are direct children, so a non-recursive watch catches the signals
    /// that change status/branch. Returns None when root *is* the repo root (`.git` already watched)
    /// or outside any repo. konoma's own reads are lock-free (`--no-optional-locks`), so this does not
    /// create a self-feedback loop.
    pub fn git_dir_watch(&self) -> Option<PathBuf> {
        let wd = crate::git::workdir(&self.root)?;
        if self.root == wd {
            return None; // root is the repo root → `.git` is already under the recursive watch
        }
        let git = wd.join(".git");
        git.is_dir().then_some(git)
    }

    /// Whether in windowed (large file) mode. Used for the render and scroll branching.
    pub fn is_windowed(&self) -> bool {
        self.preview_win.is_some()
    }

    /// Index of the focused Markdown item (link/checkbox), if any. Read-only query used by the
    /// E2E simulation tests to assert Tab/⇧Tab focus movement.
    #[cfg(test)]
    pub fn focused_item(&self) -> Option<usize> {
        self.focused_item
    }

    /// The link targets in the current Markdown preview's `md_items`, in document order (E2E: assert
    /// exactly which URLs became focusable links — e.g. that a URL inside code did NOT).
    #[cfg(test)]
    pub fn md_link_targets(&self) -> Vec<String> {
        self.md_items
            .iter()
            .filter_map(|it| match &it.kind {
                MdItemKind::Link { target } => Some(target.clone()),
                _ => None,
            })
            .collect()
    }

    /// Whether the current preview is a Markdown/Mermaid file shown as its raw source (`R` toggled on).
    /// Such a preview is windowed like a code file, so the 2D caret selection/copy applies.
    pub fn is_raw_source(&self) -> bool {
        self.md_raw
            && matches!(
                self.preview_kind,
                Some(PreviewKind::Markdown(_)) | Some(PreviewKind::Mermaid(_))
            )
    }

    /// Whether the current preview is Markdown/Mermaid (has a decorated render, so `R` can toggle raw source).
    pub fn is_decorated_kind(&self) -> bool {
        matches!(
            self.preview_kind,
            Some(PreviewKind::Markdown(_)) | Some(PreviewKind::Mermaid(_))
        )
    }

    /// Whether raw source view is currently on (for the footer/title indicator).
    pub fn is_md_raw(&self) -> bool {
        self.md_raw
    }

    /// `R`: toggle a Markdown/Mermaid preview between its decorated render and raw source. No-op for other kinds.
    /// Rebuilds the windowed reader and resets the caret/scroll/selection so the new view starts at the top.
    pub fn toggle_md_raw(&mut self) {
        if !self.is_decorated_kind() {
            return;
        }
        self.md_raw = !self.md_raw;
        // 表示切替＝先頭から。窓読み(raw)/装飾(rendered)を張り直す。
        self.preview_byte_top = 0;
        self.preview_top_line = 0;
        self.preview_scroll = 0;
        self.preview_hscroll = 0;
        self.preview_cursor_line = 0;
        self.preview_cursor_col = 0;
        self.preview_visual_anchor = None;
        self.preview_visual_linewise = false;
        self.md_cache = None;
        self.setup_windowed();
    }

    // ---- windowed プレビューの 2D キャレット / ビジュアル選択コピー -----------

    /// Whether a visual selection is active in a windowed preview (routes the PreviewTextVisual surface).
    pub fn is_preview_visual(&self) -> bool {
        self.is_windowed() && self.preview_visual_anchor.is_some()
    }

    /// Whether the active preview selection is linewise (`V`) rather than charwise (`v`). For the status chip/footer.
    pub fn preview_visual_linewise(&self) -> bool {
        self.preview_visual_linewise
    }

    /// The active selection for the render/copy: charwise (`v`) or linewise (`V`), normalized so start ≤ end.
    pub fn preview_selection(&self) -> PreviewSelection {
        let Some((al, ac)) = self.preview_visual_anchor else {
            return PreviewSelection::None;
        };
        let (cl, cc) = (self.preview_cursor_line, self.preview_cursor_col);
        if self.preview_visual_linewise {
            PreviewSelection::Line {
                lo: al.min(cl),
                hi: al.max(cl),
            }
        } else {
            // charwise: order by (line, col)
            let (start, end) = if (al, ac) <= (cl, cc) {
                ((al, ac), (cl, cc))
            } else {
                ((cl, cc), (al, ac))
            };
            PreviewSelection::Char { start, end }
        }
    }

    /// `v` (charwise) / `V` (linewise): start a visual selection at the current 2D caret (windowed previews only).
    pub fn preview_enter_visual(&mut self, linewise: bool) {
        if self.is_windowed() {
            self.preview_visual_anchor = Some((self.preview_cursor_line, self.preview_cursor_col));
            self.preview_visual_linewise = linewise;
        }
    }

    /// Exit visual selection without copying (`v`/`V` again / Esc / q).
    pub fn preview_exit_visual(&mut self) {
        self.preview_visual_anchor = None;
    }

    /// The selected text read from the real file: whole logical lines (linewise) or an exact character range
    /// (charwise, end-inclusive). Uses the file's unwrapped/logical lines so a paste keeps the original layout.
    /// Empty when there is no path or the range is out of bounds.
    fn preview_selection_text(&self) -> String {
        let Some(path) = self.preview_path.as_ref() else {
            return String::new();
        };
        let bytes = match std::fs::read(path) {
            Ok(b) => b,
            Err(_) => return String::new(),
        };
        let s = String::from_utf8_lossy(&bytes);
        let lines: Vec<&str> = s.lines().collect();
        if lines.is_empty() {
            return String::new();
        }
        let last = lines.len() - 1;
        match self.preview_selection() {
            PreviewSelection::Line { lo, hi } => {
                let end = hi.min(last);
                if lo > end {
                    String::new()
                } else {
                    lines[lo..=end].join("\n")
                }
            }
            PreviewSelection::None => {
                // not selecting → the current logical line
                let l = self.preview_cursor_line.min(last);
                lines[l].to_string()
            }
            PreviewSelection::Char { start, end } => selection_char_text(&lines, start, end),
        }
    }

    /// `y`: copy the current selection (or the current line if not selecting) to the clipboard, then exit visual.
    pub fn preview_copy_selection(&mut self) {
        let text = self.preview_selection_text();
        self.preview_visual_anchor = None;
        if text.is_empty() {
            self.flash = Some(tr(self.lang, crate::i18n::Msg::NoCopyTarget).into());
            return;
        }
        self.set_clipboard_flash(&text);
    }

    /// The `@path#L12-34` reference text (Claude Code's file+line context syntax) for the current
    /// selection — or the caret line when not selecting. Line numbers are 1-based and inclusive; a single
    /// line is `#L12`. In non-windowed previews (no caret) it degrades to `@path`. None without a target.
    fn preview_selection_ref_text(&self) -> Option<String> {
        let path = self.preview_path.as_ref()?;
        let base = at_ref_text(&self.open_dir, path);
        if !self.is_windowed() {
            return Some(base);
        }
        let (lo, hi) = match self.preview_selection() {
            PreviewSelection::Line { lo, hi } => (lo, hi),
            PreviewSelection::Char { start, end } => (start.0, end.0),
            PreviewSelection::None => (self.preview_cursor_line, self.preview_cursor_line),
        };
        Some(if lo == hi {
            format!("{base}#L{}", lo + 1)
        } else {
            format!("{base}#L{}-{}", lo + 1, hi + 1)
        })
    }

    /// `Y`: copy the `@path#L…` reference of the selection/caret to the clipboard, then exit visual
    /// (paste it to Claude Code to point the conversation at this exact spot).
    pub fn preview_copy_selection_ref(&mut self) {
        let Some(text) = self.preview_selection_ref_text() else {
            self.flash = Some(tr(self.lang, crate::i18n::Msg::NoCopyTarget).into());
            return;
        };
        self.preview_visual_anchor = None;
        self.set_clipboard_flash(&text);
    }

    /// `h`/`l`: move the column caret by `dir` chars (windowed previews). The render clamps it to the line length
    /// and writes the clamp back, so overshoot is corrected on the next frame. Falls back to hscroll otherwise.
    pub fn preview_col_move(&mut self, dir: i32) {
        if self.is_windowed() {
            let next = (self.preview_cursor_col as i64 + dir as i64).max(0) as usize;
            self.preview_cursor_col = next;
        } else {
            self.preview_hscroll(dir * 2);
        }
    }

    /// `0`: move the caret to the first column (windowed), else scroll home.
    pub fn preview_col_home(&mut self) {
        if self.is_windowed() {
            self.preview_cursor_col = 0;
        } else {
            self.preview_hscroll_home();
        }
    }

    /// `$`: move the caret to the last column (windowed). The render clamps the sentinel to the line length.
    pub fn preview_col_end(&mut self) {
        if self.is_windowed() {
            self.preview_cursor_col = usize::MAX;
        } else {
            self.preview_hscroll_end();
        }
    }

    /// Page the preview to the next/previous **file** in tree display order (`dir`=+1/-1, wraps
    /// at the ends). Directories are skipped; the tree cursor follows the shown file, so leaving
    /// the preview lands where you are. The anchor is the previewed file's tree position, falling
    /// back to the cursor when the previewed file is not in the tree (e.g. a global-bookmark
    /// target outside the root). With no other file to go to, this is a no-op.
    pub fn preview_jump_file(&mut self, dir: i32) {
        if self.mode != Mode::Preview || self.entries.is_empty() {
            return;
        }
        let anchor = self
            .preview_path
            .as_ref()
            .and_then(|p| self.entries.iter().position(|e| e.path == *p))
            .unwrap_or_else(|| self.selected.min(self.entries.len() - 1));
        let n = self.entries.len() as i64;
        let mut i = anchor as i64;
        for _ in 0..n {
            i = (i + dir as i64).rem_euclid(n);
            if i as usize == anchor {
                break; // 一周した=他にファイルが無い
            }
            if !self.entries[i as usize].is_dir {
                self.selected = i as usize;
                let path = self.entries[i as usize].path.clone();
                self.enter_preview(&path);
                return;
            }
        }
    }

    pub fn back_to_tree(&mut self) {
        // 全画面フェンス表示からの `q` は「ツリーへ」ではなく「元の Markdown ビューへ」戻る
        // (git diff の came_from_git_view と同じ、来た場所へ帰る流儀)。スクロール/フォーカスも復元。
        if matches!(self.preview_kind, Some(PreviewKind::MermaidFence(_))) {
            if let Some(md) = self.preview_path.clone() {
                let ret = self.fence_return.take();
                self.enter_preview(&md);
                if let Some((scroll, focus)) = ret {
                    self.preview_scroll = scroll;
                    self.focused_item = focus;
                }
                return;
            }
        }
        self.mode = Mode::Tree;
        // Re-verify git status when the tree becomes visible again. FSEvents is inherently lossy
        // (bursts get coalesced, and an external commit can arrive as `.git/*.lock`-only churn), so
        // an external git op during Preview may have left `git_status` stale. Invalidating here makes
        // the next render's `refresh_git_if_needed` refetch the cheap statuses+branch (the heavy
        // `ignored` set is kept, since the repo is unchanged) — so returning to the tree always shows
        // fresh markers, instead of a stale change marker until you navigate across a directory (`h`/`l`).
        // Mark dirty too, so the per-workdir status cache (reused across `h`/`l` in the same repo) is
        // bypassed for this deliberate re-verify — otherwise the stale markers would linger.
        self.git_status_for = None;
        self.git_status_dirty = true;
        // Same seam re-verification for the detail columns: their cells are cached per tree
        // generation (Phase G) and a missed fs event would otherwise pin stale size/mtime until
        // the next rebuild. Dropping here keeps them as robust as the git markers.
        self.detail_cells_cache.clear();
        self.preview_path = None;
        self.preview_kind = None;
        self.clear_image(); // graphics 状態を解放
        self.md_cache = None;
        self.md_raw = false;
        self.preview_win = None;
        self.win_cache = None;
        self.preview_total_lines = None;
        self.hl_pending = false;
        self.hl_warming = false;
        self.preview_byte_top = 0;
        self.preview_top_line = 0;
        self.md_items.clear();
        self.focused_item = None;
        self.preview_search = None;
        self.search_input = None;
        self.search_matches.clear();
        self.table_search_hits.clear();
        self.search_idx = 0;
        self.came_from_git_view = false;
        self.table_data = None;
        self.table_cur_row = 0;
        self.table_cur_col = 0;
        self.table_top_row = 0;
        self.table_left_col = 0;
        self.preview_cursor_line = 0;
        self.preview_cursor_col = 0;
        self.preview_visual_anchor = None;
        self.preview_visual_linewise = false;
    }

    /// Whether this preview kind displays through the media (image) pipeline — and therefore needs
    /// a `start_media_load` whenever its display state was dropped (tab restore / fs reload).
    /// Mermaid kinds count only in image mode; in text mode they draw via the decorated path.
    fn kind_loads_media(&self, kind: &PreviewKind) -> bool {
        matches!(
            kind,
            PreviewKind::Image(_)
                | PreviewKind::Svg(_)
                | PreviewKind::Video(_)
                | PreviewKind::Pdf(_)
        ) || (matches!(kind, PreviewKind::Mermaid(_) | PreviewKind::MermaidFence(_))
            && self.mermaid_image_mode())
    }

    /// Release and reset the image display state (protocol, source image, zoom/pan).
    fn clear_image(&mut self) {
        self.image = None;
        self.kitty_image = None;
        // Discard any in-flight kitty build from the file we are leaving (gen bump) and clear the
        // wanted geometry so the next image triggers a fresh (synchronous first) build.
        self.kitty_gen = self.kitty_gen.wrapping_add(1);
        self.kitty_want = None;
        self.kitty_shown = None;
        self.image_src = None;
        self.image_zoom = 1.0;
        self.image_center = (0.5, 0.5);
        self.image_crop = None;
        self.image_vis_frac = (1.0, 1.0);
        self.vector_svg = None;
        self.image_logical = None;
        self.gif_frames = Vec::new();
        self.gif_idx = 0;
        self.gif_shown_at = None;
        self.gif_protocol = None;
        self.gif_proto_key = None;
        self.pdf_page = 1;
        self.pdf_pages = None;
        // 世代を進めて、別ファイルの読み込み中に届く前ファイルのメディア結果を陳腐化させる。
        self.media_gen = self.media_gen.wrapping_add(1);
        self.media_loading = false;
        self.vector_reraster_inflight = false;
        // 画像状態を捨てたら mtime の主張も捨てる(不変条件)。残すと「表示は無いのに mtime は
        // 最新」の地雷になり、reload_media_if_changed が未変更と誤判定して再ロードを塞ぐ
        // (タブ復帰で mermaid がテキスト図に劣化していた真因の一つ)。
        self.preview_media_mtime = None;
    }

    /// Build (or reuse) the decorated cache for a Markdown/Mermaid/code preview at display width
    /// `width`. On a miss (file/width change) this renders, collapses links, collects the Tab items,
    /// and precomputes the wrap layout (row prefix sums via ratatui's own per-line reflow) — all the
    /// per-document work, done once. Frames then only slice the visible range (`md_slice`).
    fn ensure_md_cache(&mut self, width: u16) {
        let Some(path) = self.preview_path.clone() else {
            return;
        };
        // fence 図の目標行数(fit-to-view)が変わったら、図を含む文書だけ作り直す(ビューポートの
        // 高さ変化で全 md を毎回リビルドしない)。
        let fence_rows = self.mermaid_fit_rows();
        if matches!(&self.md_cache, Some(c) if c.path == path && c.width == width
            && (c.fence_rows == fence_rows
                || !c.images.iter().any(|p| crate::preview::markdown::is_mermaid_fence_url(&p.url))))
        {
            return;
        }
        let (raw, images, remote, fences, math, src_lines) = self.build_decorated(&path, width);
        // Kick off background downloads for any remote images shown as "loading". Each completes
        // by invalidating md_cache (apply_remote_fetch) so this rebuilds with the cached file.
        for url in &remote {
            self.ensure_remote_md_fetch(url);
        }
        // Kick off background renders for any ```mermaid fences not yet in the diagram cache
        // (content-hash keyed). Completion invalidates md_cache (apply_md_image), so the loading
        // line re-lays out into the real inline diagram — the remote-image pattern exactly.
        // Synchronous completions (no loader tx = tests) land *before* we store the cache below,
        // so the just-built decoration is already stale — rebuild once with the results in.
        let mut resync = false;
        for code in &fences {
            if code.trim().is_empty() {
                continue; // 空フェンス(書きかけ)は図にならない=レンダを起動しない
            }
            resync |= self.ensure_mermaid_fence_render(code.clone());
        }
        // 数式も同型: latex+display キーで未着のものをレンダ起動(mermaid フェンスと同じ経路)。
        for (latex, display) in &math {
            if latex.trim().is_empty() {
                continue;
            }
            resync |= self.ensure_math_render(latex.clone(), *display);
        }
        // 現在の文書に**もう存在しない**フェンス/数式キーを回収する。キーは内容ハッシュなので、外部
        // 編集(agent-watch の反復編集)で内容が変わるたび新キーが生まれ、旧キーの decoded
        // ラスタ/protocol/SVG は誰も参照しないままファイル切替まで単調成長していた。
        {
            let mut live: std::collections::HashSet<PathBuf> = fences
                .iter()
                .map(|c| PathBuf::from(crate::preview::markdown::mermaid_fence_url(c)))
                .collect();
            live.extend(
                math.iter()
                    .map(|(l, d)| PathBuf::from(crate::preview::markdown::math_url(l, *d))),
            );
            self.md_image_cache.retain(|k, _| {
                let s = k.to_string_lossy();
                !(crate::preview::markdown::is_mermaid_fence_url(&s)
                    || crate::preview::markdown::is_math_url(&s))
                    || live.contains(k)
            });
        }
        let (raw, images, remote, src_lines) = if resync {
            let (raw, images, remote, _fences, _math, src_lines) =
                self.build_decorated(&path, width);
            (raw, images, remote, src_lines)
        } else {
            (raw, images, remote, src_lines)
        };
        let _ = &remote;
        let (lines, targets) = self.postprocess_md(raw);
        // 描画済み mermaid placement のソース序数(文書順)を番兵の照合用に渡す。
        let fence_ords: Vec<usize> = images.iter().filter_map(|p| p.fence_ord).collect();
        let items = build_md_items(&lines, &targets, &fence_ords);
        let anchors = compute_md_anchors(&lines);
        let max_line_cols = lines.iter().map(|l| l.width()).max().unwrap_or(0);
        let row_prefix = if self.cfg.ui.wrap && width > 0 {
            use ratatui::text::Text;
            use ratatui::widgets::{Paragraph, Wrap};
            let mut pre = Vec::with_capacity(lines.len() + 1);
            let mut acc = 0usize;
            pre.push(0);
            for line in &lines {
                acc += Paragraph::new(Text::from(vec![line.clone()]))
                    .wrap(Wrap { trim: false })
                    .line_count(width)
                    .max(1);
                pre.push(acc);
            }
            pre
        } else {
            Vec::new()
        };
        // Mirror the items into the live field (the same refresh decorate_md_items used to do per
        // frame — items only change when the cache is rebuilt) and keep the focus index in range.
        self.md_items = items.clone();
        match self.focused_item {
            Some(_) if self.md_items.is_empty() => self.focused_item = None,
            Some(f) if f >= self.md_items.len() => {
                self.focused_item = Some(self.md_items.len() - 1)
            }
            _ => {}
        }
        self.md_cache = Some(MdCache {
            path,
            width,
            lines,
            items,
            images,
            src_lines,
            max_line_cols,
            row_prefix,
            fence_rows,
            anchors,
            details_states: crate::preview::markdown::current_details_states(),
        });
    }

    /// The default open state of a `<details>` block from `ui.md_details` and its `open` attribute:
    /// `"open"`/`"closed"` force it; `"auto"` (or anything else) honors the attribute like GitHub.
    fn details_default_open(&self, open_attr: bool) -> bool {
        match self.cfg.ui.md_details.as_str() {
            "open" => true,
            "closed" => false,
            _ => open_attr,
        }
    }

    /// `Space`/`Enter` on a focused `<details>` summary: flip its open state and rebuild the cache.
    pub fn toggle_details(&mut self, ordinal: usize) {
        let cur = self
            .md_cache
            .as_ref()
            .and_then(|c| c.details_states.get(ordinal).copied())
            .unwrap_or(true);
        self.details_open.insert(ordinal, !cur);
        self.md_cache = None; // 再構築で開閉を反映
    }

    /// Scroll the current Markdown preview so the heading matching `slug` (a GitHub-style in-page
    /// anchor, minus the leading `#`) is at the top of the view. Returns false if there is no such
    /// heading (so the caller can flash). Keeps the decorated view (unlike a raw-source line jump).
    fn md_scroll_to_anchor(&mut self, slug: &str) -> bool {
        let target = slug.trim().to_lowercase();
        let Some(logical) = self.md_cache.as_ref().and_then(|c| {
            c.anchors
                .iter()
                .find(|(s, _)| *s == target)
                .map(|(_, i)| *i)
        }) else {
            return false;
        };
        let (row, _) = self.md_visual_span(logical);
        // The draw path clamps preview_scroll against the document height, so an anchor near the
        // end simply scrolls as far as it can.
        self.preview_scroll = row.min(u16::MAX as usize) as u16;
        true
    }

    /// Ensure the decorated cache for `width` and return (total display rows, widest line in cells).
    /// The total is wrap-aware via the cached prefix sums, so the scroll clamp matches what the
    /// renderer draws without re-laying-out the whole document every frame.
    pub fn md_layout(&mut self, width: u16) -> (usize, usize) {
        self.ensure_md_cache(width);
        let Some(c) = &self.md_cache else {
            return (0, 0);
        };
        let total = if self.cfg.ui.wrap {
            c.row_prefix.last().copied().unwrap_or(c.lines.len())
        } else {
            c.lines.len()
        };
        (total, c.max_line_cols)
    }

    /// The visible slice of the decorated lines for the (already clamped) display-row `scroll`,
    /// plus the residual scroll offset to pass to Paragraph (the first sliced line may start above
    /// the viewport when wrapped). Only on-screen lines are cloned and the focus inversion touches
    /// only the focused line — O(viewport) per frame instead of O(document).
    pub fn md_slice(&self, scroll: u16, height: u16) -> (Vec<Line<'static>>, u16) {
        let Some(c) = &self.md_cache else {
            return (Vec::new(), 0);
        };
        let s = scroll as usize;
        let h = height.max(1) as usize;
        let (lo, hi, local) = if self.cfg.ui.wrap && c.row_prefix.len() == c.lines.len() + 1 {
            // 可視表示行 [s, s+h) にかかる論理行区間。prefix は各行の開始表示行(単調増加)。
            let lo = c.row_prefix.partition_point(|&p| p <= s).saturating_sub(1);
            let hi = c
                .row_prefix
                .partition_point(|&p| p < s + h)
                .min(c.lines.len());
            (lo, hi.max(lo), (s - c.row_prefix[lo]) as u16)
        } else {
            let lo = s.min(c.lines.len());
            let hi = (s + h).min(c.lines.len());
            (lo, hi, 0)
        };
        let mut out: Vec<Line<'static>> = c.lines[lo..hi].to_vec();
        // 検索中は可視行の一致箇所を強調(現在の一致=オレンジ / 他=黄色)。窓読みと同じ見た目・
        // 同じ関数を使う。可視範囲だけに掛けるので文書サイズに依らず O(viewport)。
        if let Some(q) = self.preview_search.as_deref() {
            let cur = self.search_matches.get(self.search_idx).copied();
            for (i, line) in out.iter_mut().enumerate() {
                let li = lo + i;
                // この行に一致が無ければ触らない(clone/再構築を避ける)。
                if !self.search_matches.iter().any(|(_, l, _)| *l == li) {
                    continue;
                }
                // 現在の一致がこの行なら、行内での出現順位を渡してその 1 つだけオレンジに。
                let rank = cur.and_then(|(_, cl, _)| {
                    (cl == li).then(|| {
                        self.search_matches[..self.search_idx]
                            .iter()
                            .filter(|(_, l, _)| *l == li)
                            .count()
                    })
                });
                *line = highlight_query_in_line(std::mem::take(line), q, rank);
            }
        }
        // フォーカス中アイテムの行だけ反転する(画面外なら何もしない=見た目は全文反転と同一)。
        if let Some(f) = self.focused_item {
            if let Some(it) = c.items.get(f) {
                if it.line >= lo && it.line < hi {
                    // コードブロックのみ行全体反転(ヘッダ帯が既に全幅)。フェンス図は
                    // キャプション span だけ反転(行全体だと中央寄せのインデント空白まで
                    // 反転して巨大な白バーになる=Ghostty 実機で捕まった)。
                    let whole = matches!(it.kind, MdItemKind::CodeBlock);
                    // 同一行内でのマーカー序数 = 自分より前で同じ行に載っている item の数。
                    let first_on_line = c.items.partition_point(|x| x.line < it.line);
                    let ordinal = f - first_on_line;
                    out[it.line - lo] = invert_focused_line(&c.lines[it.line], ordinal, whole);
                }
            }
        }
        (out, local)
    }

    /// Test-only view of the cached decorated lines (link-collapsed form, the same lines the
    /// renderer slices from). Production rendering goes through `md_layout` + `md_slice`.
    /// NOTE: the return value is already collapsed — feeding it into `decorate_md_items` runs
    /// `collapse_links` a second time, which finds no "(URL)" spans and leaves every rebuilt
    /// link item with an empty target. Fine for render/inversion assertions; do NOT use that
    /// combination to test link activation (use the cache built by `md_layout` instead).
    #[cfg(test)]
    pub fn decorated_lines(&mut self, width: u16) -> Vec<Line<'static>> {
        self.ensure_md_cache(width);
        self.md_cache
            .as_ref()
            .map(|c| c.lines.clone())
            .unwrap_or_default()
    }

    /// Block-level inline images reserved in the current decorated Markdown (empty for other kinds
    /// or when there is no image backend). `decorated_lines` must be called first (it fills the cache).
    pub fn md_images(&self) -> Vec<crate::preview::markdown::ImagePlacement> {
        self.md_cache
            .as_ref()
            .map(|c| c.images.clone())
            .unwrap_or_default()
    }

    /// Read the file with a cap and generate decorated lines (plus inline-image placements and the list
    /// of remote image URLs to fetch) according to its kind. A read failure becomes a single safe line.
    /// Only Markdown yields image placements / remote URLs.
    #[allow(clippy::type_complexity)] // (lines, images, remote urls, mermaid fences, math exprs, src line count)
    fn build_decorated(
        &self,
        path: &Path,
        width: u16,
    ) -> (
        Vec<Line<'static>>,
        Vec<crate::preview::markdown::ImagePlacement>,
        Vec<String>,
        Vec<String>,
        Vec<(String, bool)>,
        usize,
    ) {
        let src = match crate::preview::text::load(path) {
            Ok(content) => {
                let mut s = content.lines.join("\n");
                if content.truncated {
                    s.push_str("\n\n— (省略: 表示上限に達しました) —");
                }
                s
            }
            Err(e) => {
                return (
                    vec![Line::from(format!("[can not preview: 読み込み失敗] {e}"))],
                    Vec::new(),
                    Vec::new(),
                    Vec::new(),
                    Vec::new(),
                    0,
                )
            }
        };
        // Source line count, used to map the scroll position back to an approximate source line.
        let src_lines = src.lines().count();
        match &self.preview_kind {
            Some(PreviewKind::Markdown(_)) => {
                let theme = &self.cfg.ui.theme;
                let code = crate::preview::markdown::CodeStyle {
                    bg: theme.code_bg(),
                    label_bg: theme.code_label_bg(),
                    label_right: theme.code_label_right(),
                    tab_width: self.cfg.ui.tab_width,
                    wrap: self.cfg.ui.wrap,
                };
                // Front matter: split the leading `---`…`---` off so the body renders normally; a dim
                // metadata block is prepended to the result below (and image line indices offset).
                let (fm_lines, src) = if self.cfg.ui.md_frontmatter {
                    match crate::preview::markdown::strip_front_matter(&src) {
                        (Some(fm), body) => (
                            crate::preview::markdown::render_front_matter(&fm, width),
                            body,
                        ),
                        (None, body) => (Vec::new(), body),
                    }
                } else {
                    (Vec::new(), src)
                };
                // Footnotes: rewrite `[^1]` refs to superscripts and pull `[^1]: …` defs into a
                // section at the end (fence-aware; no-op without definitions).
                let src = if self.cfg.ui.md_footnotes {
                    crate::preview::markdown::process_footnotes(&src)
                } else {
                    src
                };
                // Inline HTML (<kbd>/<del>/<sup>/<sub>/<br>) → Markdown/Unicode tui-markdown renders.
                let src = if self.cfg.ui.md_inline_html {
                    crate::preview::markdown::process_inline_html(&src)
                } else {
                    src
                };
                // <details> の各ブロックの実効開閉状態を計算し、renderer(thread-local)へ渡す＋
                // ensure_md_cache が MdCache に載せられるよう stash する(トグルの基準値)。
                let details_states: Vec<bool> =
                    crate::preview::markdown::collect_details_open(&src)
                        .iter()
                        .enumerate()
                        .map(|(ord, &attr)| {
                            self.details_open
                                .get(&ord)
                                .copied()
                                .unwrap_or_else(|| self.details_default_open(attr))
                        })
                        .collect();
                crate::preview::markdown::set_details_open(details_states);
                // Decide how to render each image URL. A local file or a cached remote fetch resolves to
                // a path → Inline (with its display size in cells). An uncached remote URL is Loading
                // (a fetch is kicked off separately, in `decorated_lines`) unless it has already failed.
                // Anything else (no backend / missing file / data: URL) degrades to text (principle #3).
                let font = self.picker.as_ref().map(|p| p.font_size());
                let base_dir = path.parent().map(|p| p.to_path_buf());
                let avail = width.saturating_sub(2);
                let slot_of = |url: &str| -> crate::preview::markdown::ImageSlot {
                    use crate::preview::markdown::ImageSlot;
                    let Some(font) = font else {
                        return ImageSlot::Unavailable;
                    };
                    if let Some(p) = resolve_md_image_path(url, base_dir.as_deref()) {
                        match md_image_dims(&p) {
                            Some((pw, ph)) => {
                                let (cols, rows) = md_image_cells(
                                    pw,
                                    ph,
                                    font.width,
                                    font.height,
                                    avail,
                                    MD_IMAGE_MAX_ROWS,
                                );
                                ImageSlot::Inline { cols, rows }
                            }
                            None => ImageSlot::Unavailable,
                        }
                    } else if crate::preview::markdown::is_remote_image_url(url)
                        && !self.md_remote_failed.contains(url)
                    {
                        ImageSlot::Loading
                    } else {
                        ImageSlot::Unavailable
                    }
                };
                // ```mermaid フェンス: 画像モードならレンダ済みキャッシュ(内容ハッシュキー)を参照。
                // 未着はローディング行、失敗/モードOFFはテキスト図(原則#3)。probe(空文字)は
                // 「抽出するか」の代表判定なので、モードだけで答える。
                let mermaid_on = self.mermaid_image_mode();
                let fence_target_rows = self.mermaid_fit_rows();
                let mermaid_slot = |code: &str| -> crate::preview::markdown::MermaidSlot {
                    use crate::preview::markdown::MermaidSlot;
                    if !mermaid_on {
                        return MermaidSlot::Text;
                    }
                    if code.is_empty() {
                        return MermaidSlot::Loading; // probe: 抽出ON
                    }
                    let Some(font) = font else {
                        return MermaidSlot::Text;
                    };
                    let key = PathBuf::from(crate::preview::markdown::mermaid_fence_url(code));
                    match self.md_image_cache.get(&key) {
                        Some(e) if e.failed => MermaidSlot::Text,
                        Some(e) => match e.decoded.as_ref() {
                            Some(img) => {
                                use image::GenericImageView;
                                // レイアウトは**初回ラスタの寸法**(layout_px)で固定: ズーム時の
                                // シャープ再ラスタで密度が上がっても予約セル数=表示サイズ不変。
                                let (pw, ph) = e.layout_px.unwrap_or_else(|| img.dimensions());
                                let (cols, rows) = mermaid_cells(
                                    pw,
                                    ph,
                                    font.width,
                                    font.height,
                                    avail,
                                    fence_target_rows,
                                );
                                MermaidSlot::Image { cols, rows }
                            }
                            None => MermaidSlot::Loading,
                        },
                        None => MermaidSlot::Loading,
                    }
                };
                // 数式($…$ / $$…$$): 画像モードならレンダ済みキャッシュ(latex+display ハッシュキー)を
                // 参照。未着はローディング、失敗/未対応/フォント無しは生 LaTeX テキストへ降格(原則#3)。
                // インライン式は自前の行に持ち上がる(mermaid フェンスと同型の合成キー画像)。
                let math_on = font.is_some() && self.math_image_mode();
                let math_slot =
                    |latex: &str, display: bool| -> crate::preview::markdown::MathSlot {
                        use crate::preview::markdown::MathSlot;
                        let Some(font) = font else {
                            return MathSlot::Raw;
                        };
                        let key = PathBuf::from(crate::preview::markdown::math_url(latex, display));
                        match self.md_image_cache.get(&key) {
                            Some(e) if e.failed => MathSlot::Raw,
                            Some(e) => match (e.decoded.as_ref(), e.layout_px) {
                                // layout_px は数式では SVG の**内在サイズ(単位)**を持つ(ラスタ px でなく)。
                                // em 高さ→行数、内在アスペクト→桁数を導き、テキストと釣り合うサイズに。
                                (Some(_), Some((uw, uh))) => {
                                    let (cols, rows) =
                                        math_cells(uw, uh, font.width, font.height, avail, display);
                                    MathSlot::Image { cols, rows }
                                }
                                _ => MathSlot::Loading,
                            },
                            None => MathSlot::Loading,
                        }
                    };
                let (mut lines, mut images) = crate::preview::markdown::render_markdown_with_images(
                    &src,
                    width,
                    code,
                    &theme.code_theme,
                    self.cfg.ui.icons,
                    &self.cfg.ui.md_task_state_chars(),
                    &slot_of,
                    &mermaid_slot,
                    tr(self.lang, crate::i18n::Msg::MermaidCaption),
                    self.cfg.ui.md_alerts,
                    &math_slot,
                    math_on,
                );
                let remote = if font.is_some() {
                    crate::preview::markdown::collect_remote_image_urls(&src)
                } else {
                    Vec::new()
                };
                let fences = if mermaid_on {
                    crate::preview::markdown::collect_mermaid_fences(&src)
                } else {
                    Vec::new()
                };
                let math = if math_on {
                    crate::preview::markdown::collect_math_exprs(&src)
                } else {
                    Vec::new()
                };
                // Prepend the front-matter metadata block, shifting image placements down past it.
                if !fm_lines.is_empty() {
                    for p in &mut images {
                        p.line += fm_lines.len();
                    }
                    let mut all = fm_lines;
                    all.extend(lines);
                    lines = all;
                }
                (lines, images, remote, fences, math, src_lines)
            }
            Some(PreviewKind::Mermaid(_)) => (
                crate::preview::markdown::render_mermaid_file(&src, width),
                Vec::new(),
                Vec::new(),
                Vec::new(),
                Vec::new(),
                src_lines,
            ),
            // 単体コードファイルは syntect でシンタックスハイライト。
            Some(PreviewKind::Code(_)) => (
                crate::preview::code::highlight(&src, path, &self.cfg.ui.theme.code_theme),
                Vec::new(),
                Vec::new(),
                Vec::new(),
                Vec::new(),
                src_lines,
            ),
            _ => (
                Vec::new(),
                Vec::new(),
                Vec::new(),
                Vec::new(),
                Vec::new(),
                src_lines,
            ),
        }
    }

    /// Attach the image backend (terminal Picker and the offload tx) at startup.
    pub fn attach_image_backend(&mut self, picker: Picker, tx: UnboundedSender<ResizeRequest>) {
        // Use konoma's own compressed transmit only on a kitty-graphics terminal; other protocols
        // (sixel/iterm2/halfblocks) keep the ratatui-image path. tmux is detected via $TMUX (the
        // picker's own is_tmux is private), matching how the escapes must be passthrough-wrapped.
        self.use_kitty = matches!(
            picker.protocol_type(),
            ratatui_image::picker::ProtocolType::Kitty
        );
        self.kitty_is_tmux = std::env::var_os("TMUX").is_some();
        self.picker = Some(picker);
        self.img_tx = Some(tx);
    }

    /// Attach the sending end that offloads heavy media loading (SVG/GIF) to a separate thread.
    pub fn attach_media_loader(&mut self, tx: std::sync::mpsc::Sender<MediaResult>) {
        self.media_tx = Some(tx);
    }

    /// Attach the sender that offloads the kitty resize+compress (zoom/pan) to a worker thread.
    /// Without it (tests), kitty builds run synchronously.
    pub fn attach_kitty_loader(&mut self, tx: std::sync::mpsc::Sender<KittyResult>) {
        self.kitty_tx = Some(tx);
    }

    /// Attach the sender that offloads inline Markdown image decoding to a background thread.
    pub fn attach_md_image_loader(&mut self, tx: std::sync::mpsc::Sender<MdImageResult>) {
        self.md_img_tx = Some(tx);
    }

    /// Attach the sender that offloads inline-image encoding (resize + protocol) to the encode worker.
    pub fn attach_md_encoder(&mut self, tx: std::sync::mpsc::Sender<MdEncodeRequest>) {
        self.md_enc_tx = Some(tx);
    }

    /// Apply a completed background decode of an inline Markdown image. Returns whether to redraw.
    pub fn apply_md_image(&mut self, res: MdImageResult) -> bool {
        // エントリはキック時(ensure_mermaid_fence_render / ensure_md_image)に必ず先置きされる。
        // 無い=陳腐化した結果(ファイル切替でキャッシュ破棄済み/prune 済み)なので、復活させずに
        // 捨てる(or_default だと旧図のラスタが再挿入されて次の enter_preview まで残留し、しかも
        // 下の md_cache 無効化が**無関係な現文書**を 1 回無駄に全再構築していた)。
        if !self.md_image_cache.contains_key(&res.path) {
            return false;
        }
        // フェンス図・数式(合成キー)は寸法がここで初めて決まる=ローディング行→実配置に組み直す
        // ため装飾キャッシュを無効化する(remote 画像の apply_remote_fetch と同じ流儀)。
        // **シャープ化の再ラスタは除く**: ピクセル密度の差し替えだけで、レイアウト(予約セル数)は
        // layout_px 固定なので装飾を組み直さない(=md 上の表示サイズは不変・ユーザー要件)。
        let url_str = res.path.to_string_lossy().to_string();
        let is_math = crate::preview::markdown::is_math_url(&url_str);
        if !res.reraster && (crate::preview::markdown::is_mermaid_fence_url(&url_str) || is_math) {
            self.md_cache = None;
        }
        let entry = self.md_image_cache.entry(res.path).or_default();
        if res.reraster {
            entry.reraster_inflight = false;
        }
        match res.image {
            Ok(img) => {
                use image::GenericImageView;
                if entry.layout_px.is_none() {
                    // 数式は SVG の**内在サイズ(単位)**を layout_px に載せる(ラスタ px でなく): em 高さから
                    // 行数、内在アスペクトから桁数を導いてテキストと釣り合うサイズにするため(math_cells)。
                    // 内在サイズが取れない時のみラスタ寸法へフォールバック。フェンス/通常画像は従来どおり。
                    entry.layout_px = if is_math {
                        res.svg
                            .as_deref()
                            .and_then(|d| crate::preview::svg::intrinsic_size_bytes(d))
                            .or_else(|| Some(img.dimensions()))
                    } else {
                        Some(img.dimensions())
                    };
                }
                entry.decoded = Some(Arc::new(img));
                entry.failed = false;
                if let Some(svg) = res.svg {
                    entry.svg = Some(svg);
                }
                if res.reraster {
                    // 高密度ラスタで再エンコードさせる: キーだけ無効化し、旧 protocol は
                    // 新しいエンコードが届くまでの表示用に残す(消すと一瞬空白になる)。
                    entry.proto_size = None;
                    entry.clip_key = None;
                    entry.zoom_key = None;
                }
            }
            // 再ラスタ失敗は現ラスタ据え置き(表示は生きたまま)。初回失敗のみテキスト降格。
            Err(_) if res.reraster => {}
            Err(_) => entry.failed = true,
        }
        true
    }

    /// Drive the **in-place zoom** of the focused inline mermaid diagram: clamp the pan center,
    /// kick a sharpening re-raster when the zoom outgrows the raster density (the layout size stays
    /// fixed via `layout_px`), and request an encode of the current crop into the same (cols, rows)
    /// cell area. All heavy work runs on worker threads; at most one of each is in flight.
    pub fn ensure_md_fence_zoom(&mut self, url: &str, cols: u16, rows: u16) {
        use image::GenericImageView;
        let key_path = PathBuf::from(url);
        let zoom = self.fence_zoom;
        let font = self.picker.as_ref().map(|p| p.font_size());
        let enc_tx = self.md_enc_tx.clone();
        let Some(entry) = self.md_image_cache.get_mut(&key_path) else {
            return;
        };
        let Some(img) = entry.decoded.clone() else {
            return;
        };
        let (sw, sh) = img.dimensions();
        // シャープ化: 表示に必要な密度(セル×フォントpx×ズーム)が現ラスタを超えたら、保持 SVG を
        // 高密度に再ラスタ(全画面のシャープズームと同じ・レイアウトは layout_px 固定で不変)。
        if let Some(f) = font {
            let disp = ((cols as f64 * f.width as f64).max(rows as f64 * f.height as f64) * zoom)
                .ceil() as u32;
            if self.fence_sharpen_if_needed(&key_path, disp) == FenceSharpen::AppliedSync {
                // 同期フォールバック(テスト): 新しいラスタで最初からやり直す。
                drop(img);
                return self.ensure_md_fence_zoom(url, cols, rows);
            }
        }
        // 現ラスタから可視窓を切り出す(比率ベース=再ラスタ後も同じ窓)。中心は端でクランプし書き戻す。
        let f = (1.0 / zoom.max(1.0)).clamp(0.0, 1.0);
        let (crop, center) = fence_crop((sw, sh), f, self.fence_center);
        self.fence_center = center;
        let Some(entry) = self.md_image_cache.get_mut(&key_path) else {
            return;
        };
        let zkey = (cols, rows, crop);
        if entry.zoom_key == Some(zkey) || entry.enc_inflight {
            return;
        }
        let Some(tx) = enc_tx else { return };
        entry.enc_inflight = true;
        let _ = tx.send(MdEncodeRequest {
            path: key_path,
            key: MdEncodeKey::Zoom { cols, rows, crop },
            image: img,
            crop: Some(crop),
            cols,
            rows,
        });
    }

    /// The protocol for the focused inline diagram's current zoom, if encoded for this (cols, rows).
    /// While a fresh crop is still encoding, the previous zoom crop (or the unzoomed full protocol)
    /// stays visible instead of blinking out.
    pub fn md_fence_zoom_proto(&self, url: &str, cols: u16, rows: u16) -> Option<&Protocol> {
        let entry = self.md_image_cache.get(&PathBuf::from(url))?;
        match entry.zoom_key {
            Some((c, r, _)) if (c, r) == (cols, rows) => {
                entry.zoom_protocol.as_ref().or(entry.protocol.as_ref())
            }
            _ => entry.protocol.as_ref(),
        }
    }

    /// Kick a sharpening re-raster of a fence diagram when `needed_px` exceeds the current raster
    /// density (shared by the unzoomed density follow-up and the in-place zoom). Returns what
    /// happened so the synchronous test fallback can re-run with the fresh raster.
    fn fence_sharpen_if_needed(&mut self, key_path: &PathBuf, needed_px: u32) -> FenceSharpen {
        use image::GenericImageView;
        let img_tx = self.md_img_tx.clone();
        let Some(entry) = self.md_image_cache.get_mut(key_path) else {
            return FenceSharpen::NotNeeded;
        };
        let (Some(img), Some(svg)) = (entry.decoded.as_ref(), entry.svg.clone()) else {
            return FenceSharpen::NotNeeded;
        };
        let (sw, sh) = img.dimensions();
        let cur = sw.max(sh);
        if needed_px <= cur + cur / 8 || cur >= 4096 || entry.reraster_inflight {
            return FenceSharpen::NotNeeded;
        }
        entry.reraster_inflight = true;
        let target = needed_px.min(4096);
        let kp = key_path.clone();
        let job = move || {
            let image =
                crate::preview::svg::rasterize_bytes(&svg, Path::new("mermaid.svg"), target)
                    .ok_or_else(|| "rasterize failed".to_string());
            MdImageResult {
                path: kp,
                image,
                svg: None,
                reraster: true,
            }
        };
        if let Some(tx) = img_tx {
            std::thread::spawn(move || {
                let _ = tx.send(job());
            });
            FenceSharpen::Spawned
        } else {
            let res = job();
            // 失敗は AppliedSync を名乗らない: 呼び元(ensure_md_fence_zoom)は AppliedSync で
            // 「新しいラスタでやり直す」再帰をするため、失敗が続くと堂々巡りになる。成功時の
            // 再帰は 1 回で必ず収束する(次パスは needed<=cur か 4096 上限で NotNeeded)。
            let ok = res.image.is_ok();
            self.apply_md_image(res);
            if ok {
                FenceSharpen::AppliedSync
            } else {
                FenceSharpen::NotNeeded
            }
        }
    }

    /// Keep an inline diagram's raster density up with its **display size** (called per visible
    /// mermaid placement). `mermaid_rows` can size diagrams beyond the base raster (svg_max_px),
    /// so without this a large setting would show upscaled-blurry pixels.
    pub fn ensure_md_fence_density(&mut self, url: &str, cols: u16, rows: u16) {
        let Some(f) = self.picker.as_ref().map(|p| p.font_size()) else {
            return;
        };
        let needed =
            ((cols as f64 * f.width as f64).max(rows as f64 * f.height as f64)).ceil() as u32;
        let _ = self.fence_sharpen_if_needed(&PathBuf::from(url), needed);
    }

    /// Frame bookkeeping for the inline-image overlay (called by `ui::render`): reset at frame
    /// start, recorded by the overlay, compared at frame end. A change after a drawn state marks
    /// the frame "moved" so the run loop clears the terminal once (placeholder-orphan sweep).
    pub fn begin_md_overlay_frame(&mut self) {
        self.md_overlay_seen = None;
    }

    /// Record the overlay signature for this frame (urls + screen rects of drawn inline images).
    pub fn note_md_overlay(&mut self, sig: u64) {
        self.md_overlay_seen = Some(sig);
    }

    /// Compare this frame's overlay against the previous frame; latch "moved" on any change away
    /// from a previously drawn state (position shift, or the images left the screen entirely).
    pub fn finish_md_overlay_frame(&mut self) {
        if self.md_overlay_last != self.md_overlay_seen {
            if self.md_overlay_last.is_some() {
                self.md_overlay_moved = true;
            }
            self.md_overlay_last = self.md_overlay_seen;
        }
    }

    /// Whether the run loop should full-clear once to sweep orphaned placeholder rows (resets).
    pub fn take_md_overlay_moved(&mut self) -> bool {
        std::mem::take(&mut self.md_overlay_moved)
    }

    /// Ensure a background mermaid render is in flight (or cached) for one ```mermaid fence.
    /// Keyed by content hash, so an edited fence renders fresh while unchanged fences reuse their
    /// raster. With no loader tx (tests), renders synchronously so behavior stays observable.
    /// Returns true when the render completed **synchronously** (no loader tx = tests): the caller
    /// must rebuild its just-built decoration, which still shows the loading line.
    fn ensure_mermaid_fence_render(&mut self, code: String) -> bool {
        let key = PathBuf::from(crate::preview::markdown::mermaid_fence_url(&code));
        if self.md_image_cache.contains_key(&key) {
            return false;
        }
        self.md_image_cache
            .insert(key.clone(), MdImgEntry::default());
        let max_px = self.mermaid_px();
        let theme = self.cfg.ui.mermaid_theme.clone();
        let render = move || -> (Result<image::DynamicImage, String>, Option<std::sync::Arc<Vec<u8>>>) {
            let Some(svg) = crate::preview::markdown::mermaid_to_svg(&code, &theme) else {
                return (Err("mermaid render failed".to_string()), None);
            };
            let data = std::sync::Arc::new(svg.into_bytes());
            let img =
                crate::preview::svg::rasterize_bytes(&data, Path::new("mermaid.svg"), max_px)
                    .ok_or_else(|| "rasterize failed".to_string());
            (img, Some(data))
        };
        if let Some(tx) = self.md_img_tx.clone() {
            std::thread::spawn(move || {
                // render()(rasterize_bytes=resvg)が panic してもスレッドを殺さず必ず結果を返す:
                // 返さないとエントリが decoded=None && !failed のまま固着し busy が恒久 true になる。
                let (image, svg) = crate::preview::markdown::catch_silent(render)
                    .unwrap_or_else(|| (Err("mermaid render panicked".to_string()), None));
                let _ = tx.send(MdImageResult {
                    path: key,
                    image,
                    svg,
                    reraster: false,
                });
            });
            false
        } else {
            let (image, svg) = render();
            self.apply_md_image(MdImageResult {
                path: key,
                image,
                svg,
                reraster: false,
            });
            true
        }
    }

    /// Ensure a background render is in flight (or cached) for one math expression, keyed by latex +
    /// display so an edited equation renders fresh while unchanged ones reuse their raster. Mirrors
    /// `ensure_mermaid_fence_render`; the SVG is kept so `apply_md_image` can record its intrinsic (em)
    /// size for layout. Returns true on a synchronous completion (no loader tx = tests).
    fn ensure_math_render(&mut self, latex: String, display: bool) -> bool {
        let key = PathBuf::from(crate::preview::markdown::math_url(&latex, display));
        if self.md_image_cache.contains_key(&key) {
            return false;
        }
        self.md_image_cache
            .insert(key.clone(), MdImgEntry::default());
        let max_px = self.math_px();
        // グリフ色(サニタイズ済み)を worker へ move。RaTeX の既定は純黒=ダーク端末で不可視のため、
        // 端末背景に映える色で塗る(config `[ui] math_color`・既定は明るいグレー)。
        let color = self.cfg.ui.math_color().to_string();
        let render =
            move || -> (Result<image::DynamicImage, String>, Option<std::sync::Arc<Vec<u8>>>) {
                let Some(svg) = crate::preview::math::latex_to_svg(&latex, display, &color) else {
                    return (Err("math render failed".to_string()), None);
                };
                let data = std::sync::Arc::new(svg.into_bytes());
                let img = crate::preview::svg::rasterize_bytes(&data, Path::new("math.svg"), max_px)
                    .ok_or_else(|| "rasterize failed".to_string());
                (img, Some(data))
            };
        if let Some(tx) = self.md_img_tx.clone() {
            std::thread::spawn(move || {
                let (image, svg) = crate::preview::markdown::catch_silent(render)
                    .unwrap_or_else(|| (Err("math render panicked".to_string()), None));
                let _ = tx.send(MdImageResult {
                    path: key,
                    image,
                    svg,
                    reraster: false,
                });
            });
            false
        } else {
            let (image, svg) = render();
            self.apply_md_image(MdImageResult {
                path: key,
                image,
                svg,
                reraster: false,
            });
            true
        }
    }

    /// Apply a completed background encode: store the protocol in its full or clip slot. Returns redraw.
    /// A failed encode (`protocol: None`) records the attempted key **without** touching the stored
    /// protocols — the last good state stays visible and the same request is not retried every frame.
    /// Only when nothing was ever encodable (no full protocol at all) does the entry degrade to the
    /// text fallback (principle #3).
    pub fn apply_md_encode(&mut self, res: MdEncodeResult) -> bool {
        let Some(entry) = self.md_image_cache.get_mut(&res.path) else {
            return false;
        };
        entry.enc_inflight = false;
        let mut degrade = false;
        match (res.key, res.protocol) {
            (MdEncodeKey::Full { cols, rows }, Some(p)) => {
                entry.protocol = Some(p);
                entry.proto_size = Some((cols, rows));
            }
            (MdEncodeKey::Full { cols, rows }, None) => {
                entry.proto_size = Some((cols, rows));
                if entry.protocol.is_none() {
                    entry.failed = true;
                    degrade = true;
                }
            }
            (
                MdEncodeKey::Clip {
                    cols,
                    full_rows,
                    row_off,
                    vis_rows,
                },
                p,
            ) => {
                if let Some(p) = p {
                    entry.clip_protocol = Some(p);
                }
                entry.clip_key = Some((cols, full_rows, row_off, vis_rows));
            }
            (MdEncodeKey::Zoom { cols, rows, crop }, p) => {
                if let Some(p) = p {
                    entry.zoom_protocol = Some(p);
                }
                entry.zoom_key = Some((cols, rows, crop));
            }
        }
        if degrade {
            // 新規に failed へ降格した画像はテキスト行へ再レイアウト(見えない空白のまま残さない)。
            self.md_cache = None;
        }
        true
    }

    /// Attach the sender that reports background remote-image download completions to the run loop.
    pub fn attach_remote_md_loader(&mut self, tx: std::sync::mpsc::Sender<RemoteFetch>) {
        self.md_remote_tx = Some(tx);
    }

    /// Apply a completed remote-image download. On success the file is now cached, so drop the
    /// decoration cache to re-lay the image out inline; on failure remember the URL so it is not
    /// retried and shows a text placeholder instead. Returns whether to redraw.
    pub fn apply_remote_fetch(&mut self, res: RemoteFetch) -> bool {
        self.md_remote_inflight.remove(&res.url);
        if !res.ok {
            self.md_remote_failed.insert(res.url);
        }
        // Re-decorate so a now-cached image is laid out (or a failed one degrades to text).
        self.md_cache = None;
        true
    }

    /// Ensure a background download is in flight for the remote image `url` (deduplicated). Skips URLs
    /// that are already cached, already downloading, or known to have failed. The download runs off the
    /// UI thread (principle #4) via `curl`; on completion it reports through `md_remote_tx`.
    fn ensure_remote_md_fetch(&mut self, url: &str) {
        if !crate::preview::markdown::is_remote_image_url(url) {
            return;
        }
        // Already downloaded (cache file exists), already failed, or already downloading → nothing to do.
        if resolve_md_image_path(url, None).is_some()
            || self.md_remote_failed.contains(url)
            || self.md_remote_inflight.contains(url)
        {
            return;
        }
        let (Some(tx), Some(dest)) = (self.md_remote_tx.clone(), md_remote_cache_path(url)) else {
            return;
        };
        self.md_remote_inflight.insert(url.to_string());
        let u = url.to_string();
        std::thread::spawn(move || {
            // ダウンロードが panic しても md_remote_inflight を残さない(残すと busy 固着):
            // panic は取得失敗(ok=false)として必ず報告する。
            let ok = crate::preview::markdown::catch_silent(|| fetch_remote_image(&u, &dest))
                .unwrap_or(false);
            let _ = tx.send(RemoteFetch { url: u, ok });
        });
    }

    /// Ensure the inline image for `url` is decoding in the background and that the protocol for the
    /// currently-visible portion (whole image, or a cropped band when partially scrolled) is encoding on
    /// the worker thread. Called from the renderer for each visible inline image. Both decoding and
    /// encoding are off-thread (principle #4) so this never blocks the UI; the protocol appears a frame
    /// or two later. At most one encode is in flight per image, so scrolling never queues a backlog.
    pub fn ensure_md_image(
        &mut self,
        url: &str,
        cols: u16,
        full_rows: u16,
        row_off: u16,
        vis_rows: u16,
    ) {
        // 合成キー(フェンス図・数式)はそのままキャッシュキー(デコードは ensure_mermaid_fence_render /
        // ensure_math_render 済み)。実ファイル画像だけディスク解決する。数式 `math://` を実ファイル扱い
        // すると resolve が None を返し、エンコードを一度も要求せず予約行が空白のまま残っていた。
        let path = if crate::preview::markdown::is_synthetic_md_url(url) {
            PathBuf::from(url)
        } else {
            let base = self
                .preview_path
                .as_ref()
                .and_then(|p| p.parent())
                .map(|p| p.to_path_buf());
            let Some(p) = resolve_md_image_path(url, base.as_deref()) else {
                return;
            };
            p
        };
        // Kick off a one-time background decode.
        if !self.md_image_cache.contains_key(&path) {
            // 合成キー(フェンス図・数式)はここでは作れない(元の code/latex が要る)。配置が在る以上
            // キャッシュ済みのはずで、来ない前提の防御(次の再装飾で ensure_mermaid_fence_render /
            // ensure_math_render が作り直す)。`math://` を実ファイルとしてデコードさせない。
            if crate::preview::markdown::is_synthetic_md_url(url) {
                return;
            }
            self.md_image_cache
                .insert(path.clone(), MdImgEntry::default());
            if let Some(tx) = self.md_img_tx.clone() {
                let p = path.clone();
                let svg_max_px = self.cfg.ui.svg_max_px;
                std::thread::spawn(move || {
                    // Sniff the format from content (remote-cache files have no extension); rasterize SVG.
                    // panic(病的画像/SVG)も捕捉して必ず結果を返す(返さないと busy 固着)。
                    let image =
                        crate::preview::markdown::catch_silent(|| md_decode_image(&p, svg_max_px))
                            .flatten()
                            .ok_or_else(|| "decode failed".to_string());
                    let _ = tx.send(MdImageResult {
                        path: p,
                        image,
                        svg: None,
                        reraster: false,
                    });
                });
            }
            return;
        }
        let Some(enc_tx) = self.md_enc_tx.clone() else {
            return;
        };
        let Some(entry) = self.md_image_cache.get_mut(&path) else {
            return;
        };
        // Wait if it failed, is still decoding, or already has an encode in flight (one at a time).
        if entry.failed || entry.enc_inflight {
            return;
        }
        let Some(img) = entry.decoded.clone() else {
            return;
        };
        // Fully visible: request an encode of the whole image at (cols, full_rows) unless already cached.
        if row_off == 0 && vis_rows >= full_rows {
            if entry.proto_size == Some((cols, full_rows)) {
                return;
            }
            entry.enc_inflight = true;
            let _ = enc_tx.send(MdEncodeRequest {
                path,
                key: MdEncodeKey::Full {
                    cols,
                    rows: full_rows,
                },
                image: img,
                crop: None,
                cols,
                rows: full_rows,
            });
            return;
        }
        // Partially scrolled: request an encode of just the visible pixel band at (cols, vis_rows), so the
        // image renders clipped to the viewport rather than being hidden.
        if entry.clip_key == Some((cols, full_rows, row_off, vis_rows)) {
            return;
        }
        let (dw, dh) = (img.width(), img.height());
        let (y0, h) = md_band_pixels(full_rows, row_off, vis_rows, dh);
        entry.enc_inflight = true;
        let _ = enc_tx.send(MdEncodeRequest {
            path,
            key: MdEncodeKey::Clip {
                cols,
                full_rows,
                row_off,
                vis_rows,
            },
            image: img,
            crop: Some((0, y0, dw, h)),
            cols,
            rows: vis_rows,
        });
    }

    /// The render protocol to draw for the visible portion of inline image `url`. Prefers the protocol
    /// that exactly matches the current position (full image when fully visible, or the band matching
    /// `(cols, full_rows, row_off, vis_rows)`); while a newly-scrolled band is still encoding it returns
    /// the last encoded protocol so the image stays on screen (and snaps to the exact band on arrival)
    /// rather than blinking out. None only until the very first protocol for this image is ready.
    pub fn md_image_proto(
        &self,
        url: &str,
        cols: u16,
        full_rows: u16,
        row_off: u16,
        vis_rows: u16,
    ) -> Option<&Protocol> {
        let path = if crate::preview::markdown::is_synthetic_md_url(url) {
            PathBuf::from(url)
        } else {
            let base = self
                .preview_path
                .as_ref()
                .and_then(|p| p.parent())
                .map(|p| p.to_path_buf());
            resolve_md_image_path(url, base.as_deref())?
        };
        let entry = self.md_image_cache.get(&path)?;
        // Exact match for the current position.
        if row_off == 0 && vis_rows >= full_rows {
            if entry.proto_size == Some((cols, full_rows)) {
                return entry.protocol.as_ref();
            }
        } else if entry.clip_key == Some((cols, full_rows, row_off, vis_rows)) {
            // クリップのエンコードに失敗していた場合(clip_protocol 無しでキーだけ記録)は
            // 全体 protocol へ降格(空白のまま残さない)。
            return entry.clip_protocol.as_ref().or(entry.protocol.as_ref());
        }
        // Not yet encoded for this exact position: keep the last band (or the full image) visible.
        entry.clip_protocol.as_ref().or(entry.protocol.as_ref())
    }

    /// Whether any inline Markdown image is still loading — a remote download in flight, a decode not yet
    /// finished, or an encode in flight (used by the run loop to keep ticking so results are applied
    /// promptly and the image appears without waiting for the next key press).
    pub fn md_images_loading(&self) -> bool {
        !self.md_remote_inflight.is_empty()
            || self
                .md_image_cache
                .values()
                .any(|e| (e.decoded.is_none() && !e.failed) || e.enc_inflight)
    }

    /// Drop tx and the image state on exit (to terminate the worker thread).
    pub fn detach_image_backend(&mut self) {
        self.clear_image();
        self.img_tx = None;
    }

    /// Decode a still image and place it in image_src (the ThreadProtocol is built asynchronously at render time).
    /// Still images (PNG/JPG) decode fast, so this stays synchronous. On decode failure / no backend, image_src=None.
    fn load_image(&mut self, path: &Path) {
        if self.picker.is_none() || self.img_tx.is_none() {
            return; // バックエンド無し: 描画側がテキストにフォールバック
        }
        let Some(dyn_img) = crate::preview::image::decode_static(path) else {
            return;
        };
        self.set_static_image(dyn_img);
    }

    /// Common processing to set a still image (including SVG raster results / single-frame GIFs) as the display source.
    /// zoom/center are left untouched (enter_preview has the preceding clear_image set defaults, and tab restore has already
    /// overwritten them with the restored values; so that a late asynchronous result does not break the restored zoom/center).
    fn set_static_image(&mut self, img: image::DynamicImage) {
        self.image_src = Some(std::sync::Arc::new(img));
        self.image_crop = None; // 次の描画(prepare_image)でプロトコルを構築させる
                                // kitty 経路の「再ビルドせよ」合図。ズームでなく**ピクセルだけ差し替わる**(PDF ページ送り /
                                // 動画の再サムネ)経路は crop も表示セルも不変=`kitty_want` が変わらず、前ラスタが居残る。
                                // ここで want/shown を無効化し在り得る in-flight を陳腐化(gen bump)＝差し替えは必ず再ビルドされる。
                                // (SVG reraster は crop_rect 変化で別途再ビルドされ、fresh/reload は clear_image 経由で二重でも無害。)
        self.kitty_gen = self.kitty_gen.wrapping_add(1);
        self.kitty_want = None;
        self.kitty_shown = None;
    }

    /// Common processing to set all GIF frames into the display state (used from both the synchronous and asynchronous paths).
    /// zoom/center are left untouched for the same reason as set_static_image.
    fn set_gif_frames(&mut self, frames: Vec<(image::DynamicImage, std::time::Duration)>) {
        self.gif_frames = frames;
        self.gif_idx = 0;
        self.gif_shown_at = None; // 最初の tick で計時開始
        self.gif_protocol = None;
        self.gif_proto_key = None;
        self.image_crop = None;
    }

    /// Start loading image-type media according to the preview kind (from enter_preview / tab restore).
    /// Still images are synchronous, while **heavy SVG rasterization / GIF full-frame decode are offloaded to a separate thread**
    /// (to start display fast without blocking the UI thread). With no media_tx (tests, etc.), a synchronous fallback is used.
    fn start_media_load(&mut self, kind: &PreviewKind, path: &Path) {
        // メディア自動再読込の基準時刻を記録(reload_media_if_changed が mtime 比較に使う)。
        self.preview_media_mtime = file_mtime(path);
        match kind {
            PreviewKind::Image(_) if Self::looks_like_gif(path) => {
                self.spawn_or_sync_media(MediaJob::Gif(path.to_path_buf()))
            }
            // 静止画(PNG/JPG 等)はデコードが速いので同期のまま(エンコードは描画時に worker が非同期化)。
            PreviewKind::Image(_) => self.load_image(path),
            PreviewKind::Svg(_) => {
                self.spawn_or_sync_media(MediaJob::Svg(path.to_path_buf(), self.cfg.ui.svg_max_px))
            }
            PreviewKind::Video(_) => self.spawn_or_sync_media(MediaJob::Video(path.to_path_buf())),
            PreviewKind::Pdf(_) => {
                self.spawn_or_sync_media(MediaJob::Pdf(path.to_path_buf(), self.pdf_page))
            }
            // 単体 .mmd/.mermaid: 画像モードなら純 Rust で SVG 化→ラスタライズ(別スレッド)。
            // テキストモード/バックエンド無しは何もしない=装飾テキスト経路が描く(原則#3)。
            PreviewKind::Mermaid(_) if self.mermaid_image_mode() => {
                self.spawn_or_sync_media(MediaJob::Mermaid(
                    path.to_path_buf(),
                    self.mermaid_px(),
                    self.cfg.ui.mermaid_theme.clone(),
                ))
            }
            // 全画面フェンス表示: md からフェンス本文を序数で取り直す(count-guard=コードコピーと同型)。
            PreviewKind::MermaidFence(ord) => {
                if let Some(code) = self.mermaid_fence_code(path, *ord) {
                    self.spawn_or_sync_media(MediaJob::MermaidSrc(
                        code,
                        self.mermaid_px(),
                        self.cfg.ui.mermaid_theme.clone(),
                    ));
                }
            }
            _ => {}
        }
    }

    /// Whether mermaid renders as an image: config says so **and** the terminal has an image backend.
    /// Everything else (config `"text"`, no backend, render failure) degrades to the text diagram.
    pub fn mermaid_image_mode(&self) -> bool {
        self.cfg.ui.mermaid != "text" && self.picker.is_some()
    }

    /// Base raster target (max edge px) for mermaid diagrams — same knob as SVG previews.
    fn mermaid_px(&self) -> u32 {
        self.cfg.ui.svg_max_px
    }

    /// Whether math ($…$ / $$…$$) renders as an image (`[ui] math` != "text" and a graphics backend).
    /// Off → math stays as raw LaTeX inline (the delimiters are left in the text).
    pub fn math_image_mode(&self) -> bool {
        self.cfg.ui.math != "text" && self.picker.is_some()
    }

    /// Raster target (max edge px) for a math equation. Generous so the once-rendered raster stays
    /// crisp when the encode worker fits it into the (usually small) reserved cell area.
    fn math_px(&self) -> u32 {
        1024
    }

    /// Validated `[ui] mermaid_rows`: max rows of an inline diagram (0/invalid → default 24).
    fn mermaid_rows_cap(&self) -> u16 {
        match self.cfg.ui.mermaid_rows {
            0 => 24,
            v => v,
        }
    }

    /// Effective target rows for an inline diagram: the `mermaid_rows` cap, shrunk so the whole
    /// fence block (caption + diagram + bottom margin) fits the preview viewport — the initial
    /// view shows the entire diagram without scrolling (fit-to-view). Viewport 0 (no render yet /
    /// tests without a render pass) keeps the cap.
    fn mermaid_fit_rows(&self) -> u16 {
        let cap = self.mermaid_rows_cap();
        if self.preview_viewport == 0 {
            return cap;
        }
        cap.min(self.preview_viewport.saturating_sub(2)).max(4)
    }

    /// The Nth ```mermaid fence body of the Markdown file at `md`, re-extracted fresh so an external
    /// edit between focusing and opening can't render a stale diagram (None = gone/shifted).
    fn mermaid_fence_code(&self, md: &Path, ord: usize) -> Option<String> {
        let src = std::fs::read_to_string(md).ok()?;
        crate::preview::markdown::collect_mermaid_fences(&src)
            .into_iter()
            .nth(ord)
    }

    /// Run a media-load job on a separate thread (when media_tx is present). Otherwise run it synchronously.
    /// If there is no backend (picker), do nothing (the render side falls back).
    fn spawn_or_sync_media(&mut self, job: MediaJob) {
        if self.picker.is_none() {
            return; // 端末非対応: 描画側がテキスト/メッセージへフォールバック
        }
        let Some(tx) = self.media_tx.clone() else {
            // 同期フォールバック(テスト/チャネル未装着)。
            if let Some(payload) = job.run() {
                self.apply_payload(payload);
            }
            return;
        };
        self.media_gen = self.media_gen.wrapping_add(1);
        self.media_loading = true;
        let gen = self.media_gen;
        std::thread::spawn(move || {
            // job.run() が panic(resvg ラスタ/画像デコードの病的入力)してもスレッドを殺さず
            // 必ず結果を返す: 返さないと media_loading が次のプレビュー遷移まで true 固着し、
            // 「Loading…」表示のまま run ループが 16ms ポーリングを続ける(アイドル 0% が崩れる)。
            let payload = crate::preview::markdown::catch_silent(move || job.run()).flatten();
            let _ = tx.send(MediaResult { gen, payload });
        });
    }

    /// Apply a media-load result from another thread. Stale results (from after moving to another file) are discarded.
    /// Returns true if the state changes from applying / staleness judgment (the caller re-renders).
    pub fn apply_media(&mut self, result: MediaResult) -> bool {
        if result.gen != self.media_gen {
            return false; // 陳腐化: 既に別ファイルへ移っている
        }
        self.media_loading = false;
        // 現世代の結果が届いた=再ラスタの inflight は解消(失敗 None でも解除して詰まらせない)。
        self.vector_reraster_inflight = false;
        match result.payload {
            Some(payload) => {
                self.apply_payload(payload);
                true
            }
            None => true, // 失敗: loading を解除し描画側のフォールバック(生XML/メッセージ)へ
        }
    }

    fn apply_payload(&mut self, payload: MediaPayload) {
        match payload {
            MediaPayload::Static(img) => self.set_static_image(img),
            MediaPayload::Gif(frames) => self.set_gif_frames(frames),
            MediaPayload::Vector { img, svg } => {
                use image::GenericImageView;
                // 初回ラスタ到着=このサイズが論理(レイアウト)サイズ。以降のシャープ再ラスタは
                // ピクセル密度だけを差し替える(clear_image が logical を消す=別ファイルでリセット)。
                if self.image_logical.is_none() {
                    self.image_logical = Some(img.dimensions());
                }
                self.vector_svg = Some(svg);
                self.set_static_image(img);
                // ジョブ実行中にズームがさらに進んでいたら次の 1 本を出して収束させる
                // (足りていれば/上限 4096 なら NotNeeded 側で即 return)。
                self.maybe_sharpen_vector();
            }
        }
    }

    /// Whether waiting on another thread's media load (used by the render side to decide on the "Loading…" display).
    pub fn is_media_loading(&self) -> bool {
        self.media_loading
    }

    /// Decide whether it is a GIF by the leading bytes (looks at the magic, not the extension).
    fn looks_like_gif(path: &Path) -> bool {
        use std::io::Read;
        let Ok(mut f) = std::fs::File::open(path) else {
            return false;
        };
        let mut head = [0u8; 6];
        if f.read_exact(&mut head).is_err() {
            return false;
        }
        &head[..4] == b"GIF8" // GIF87a / GIF89a
    }

    /// Drive the GIF animation. If the current frame's display time has elapsed, advance to the next frame index.
    /// The actual re-encode is done by prepare_gif on the next render (detecting the gif_idx change).
    /// Returns true if advanced (the caller re-renders). Always false if not a GIF.
    pub fn advance_gif_if_due(&mut self) -> bool {
        if self.gif_frames.len() < 2 {
            return false;
        }
        let now = std::time::Instant::now();
        let Some(shown_at) = self.gif_shown_at else {
            // 最初の tick: 計時を開始するだけ(先頭フレームは表示済み)。
            self.gif_shown_at = Some(now);
            return false;
        };
        let delay = self.gif_frames[self.gif_idx].1;
        if now.duration_since(shown_at) < delay {
            return false;
        }
        self.gif_idx = (self.gif_idx + 1) % self.gif_frames.len();
        self.gif_shown_at = Some(now);
        true
    }

    /// Whether a GIF animation is active (used for branching in the render path and footer/zoom checks).
    pub fn is_gif_active(&self) -> bool {
        self.gif_frames.len() >= 2
    }

    /// The render protocol of the current GIF frame synchronously encoded to the display size (referenced by the render side).
    pub fn gif_protocol(&self) -> Option<&Protocol> {
        self.gif_protocol.as_ref()
    }

    /// Call just before rendering (for GIF). Compute the display rectangle target and crop from the current (gif_idx, zoom, center, inner), and
    /// if the frame/crop has changed, **synchronously encode** the current frame and swap it into gif_protocol.
    /// Being synchronous, "render an unencoded protocol → empty" does not happen, and the frame switches atomically (no churn).
    /// The return value is the render-target target. None when there is no backend / size 0.
    pub fn prepare_gif(&mut self, inner: Rect) -> Option<Rect> {
        let picker = self.picker.as_ref()?;
        let scale = self.cfg.ui.image_render_scale;
        let src = &self.gif_frames.get(self.gif_idx)?.0;
        let (target, crop_rect, center, frac) = image_layout(
            src,
            picker.font_size(),
            self.image_zoom,
            self.image_center,
            inner,
            scale,
            None, // GIF はラスタ実寸のまま(ベクタ由来でない)
        )?;
        let key = (self.gif_idx, crop_rect);
        // フレーム or crop(ズーム/パン/リサイズ)が変わったときだけ再エンコード。
        let built = if self.gif_proto_key != Some(key) {
            let (x0, y0, cw, ch) = crop_rect;
            let crop = src.crop_imm(x0, y0, cw, ch);
            let size = ratatui::layout::Size::new(target.width.max(1), target.height.max(1));
            // src/picker の借用はこの式で完結(結果は所有値)→以降 self を変更可。
            // GIF は UI スレッドで毎フレーム同期エンコードするため、軽量で滑らかな Triangle(bilinear) を使う
            // (最近傍 None だとアニメ各フレームがジャギる。最高品質の Lanczos3 は静止画側で使用)。
            Some(picker.new_protocol(crop, size, Resize::Scale(Some(FilterType::Triangle))))
        } else {
            None
        };
        if let Some(res) = built {
            match res {
                Ok(p) => {
                    self.gif_protocol = Some(p);
                    self.gif_proto_key = Some(key);
                }
                Err(_) => {
                    // エンコード失敗: 描画側はメッセージにフォールバック。次フレームで再試行。
                    self.gif_protocol = None;
                    self.gif_proto_key = None;
                }
            }
        }
        self.image_center = center;
        self.image_vis_frac = frac;
        self.image_crop = Some(crop_rect);
        Some(target)
    }

    /// Wait time until the next frame while a GIF is playing (for the poll timeout). None when not playing.
    /// Clamped to [10ms, 100ms] for smoothness (100ms is the same as the normal idle-tick upper bound).
    pub fn gif_poll_timeout(&self) -> Option<std::time::Duration> {
        use std::time::Duration;
        if self.gif_frames.len() < 2 {
            return None;
        }
        let remaining = match self.gif_shown_at {
            None => Duration::ZERO, // まだ計時前: すぐ次の tick を回して計時開始
            Some(t) => self.gif_frames[self.gif_idx]
                .1
                .checked_sub(t.elapsed())
                .unwrap_or(Duration::ZERO),
        };
        Some(remaining.clamp(Duration::from_millis(10), Duration::from_millis(100)))
    }

    // ---- CSV/TSV テーブルプレビュー ------------------------------------------

    /// Parse the current Table-kind preview into `table_data` (None on failure = raw-text fallback).
    /// Does not touch the cursor/scroll (callers reset or restore those as appropriate).
    fn load_table(&mut self) {
        self.table_data = None;
        if let Some(PreviewKind::Table { path, delimiter }) = self.preview_kind.clone() {
            if let Ok(t) = crate::preview::table::parse(&path, delimiter) {
                self.table_data = Some(t);
            }
        }
    }

    /// Clamp the cell cursor into the table's bounds (after a reload/restore that may have shrunk it).
    fn clamp_table_cursor(&mut self) {
        match &self.table_data {
            Some(t) if t.nrows() > 0 && t.ncols > 0 => {
                self.table_cur_row = self.table_cur_row.min(t.nrows() - 1);
                self.table_cur_col = self.table_cur_col.min(t.ncols - 1);
            }
            _ => {
                self.table_cur_row = 0;
                self.table_cur_col = 0;
            }
        }
    }

    /// Whether a CSV/TSV table preview is active **and parsed** (routes the PreviewTable surface / renderer).
    /// A Table kind whose parse failed returns false → the preview degrades to raw text.
    pub fn is_table_preview(&self) -> bool {
        matches!(self.preview_kind, Some(PreviewKind::Table { .. })) && self.table_data.is_some()
    }

    /// The field-separator byte of the active table (`,` by default).
    fn table_delimiter(&self) -> u8 {
        match self.preview_kind {
            Some(PreviewKind::Table { delimiter, .. }) => delimiter,
            _ => b',',
        }
    }

    /// The parsed table (for the renderer). None when not a table preview.
    pub fn table_data(&self) -> Option<&crate::preview::table::TableData> {
        self.table_data.as_ref()
    }

    /// The cell cursor as (data-row, column), both 0-based.
    pub fn table_cursor(&self) -> (usize, usize) {
        (self.table_cur_row, self.table_cur_col)
    }

    /// The current (top data row, left column) scroll offsets.
    pub fn table_scroll(&self) -> (usize, usize) {
        (self.table_top_row, self.table_left_col)
    }

    /// Renderer feedback: store the scroll offsets it settled on (to keep the cursor visible) plus the
    /// visible data-row count (used as the PageUp/Down step). Mirrors how `preview_scroll`/`preview_viewport`
    /// are clamped/recorded at render time.
    pub fn set_table_view(&mut self, top_row: usize, left_col: usize, viewport_rows: u16) {
        self.table_top_row = top_row;
        self.table_left_col = left_col;
        self.table_viewport_rows = viewport_rows;
    }

    /// Move the cell cursor by (drow, dcol), clamped to the table. The renderer scrolls to follow.
    pub fn table_cursor_move(&mut self, drow: i32, dcol: i32) {
        let Some(t) = &self.table_data else {
            return;
        };
        let (nr, nc) = (t.nrows(), t.ncols);
        if nr == 0 || nc == 0 {
            return;
        }
        let r = (self.table_cur_row as i64 + drow as i64).clamp(0, nr as i64 - 1);
        let c = (self.table_cur_col as i64 + dcol as i64).clamp(0, nc as i64 - 1);
        self.table_cur_row = r as usize;
        self.table_cur_col = c as usize;
    }

    /// Jump to the first (`bottom=false`) or last (`bottom=true`) data row.
    pub fn table_row_to(&mut self, bottom: bool) {
        let Some(t) = &self.table_data else {
            return;
        };
        self.table_cur_row = if bottom {
            t.nrows().saturating_sub(1)
        } else {
            0
        };
    }

    /// Jump to the first (`end=false`) or last (`end=true`) column.
    pub fn table_col_to(&mut self, end: bool) {
        let Some(t) = &self.table_data else {
            return;
        };
        self.table_cur_col = if end { t.ncols.saturating_sub(1) } else { 0 };
    }

    /// Move the cursor down/up by whole pages (`dir` = +1 / -1). The page size is the last render's visible rows.
    pub fn table_page(&mut self, dir: i32) {
        let page = self.table_viewport_rows.max(1) as i32;
        self.table_cursor_move(dir * page, 0);
    }

    /// Move the cursor down/up by half a page (`dir` = +1 / -1).
    pub fn table_half_page(&mut self, dir: i32) {
        let half = (self.table_viewport_rows / 2).max(1) as i32;
        self.table_cursor_move(dir * half, 0);
    }

    /// Build the text a table copy would place on the clipboard (None when there is no table).
    /// Cell = the current cell's value; Row = the current row's cells joined by the delimiter;
    /// Column = the column's header + every cell value, one per line.
    fn table_copy_text(&self, kind: TableCopyKind) -> Option<String> {
        let t = self.table_data.as_ref()?;
        let (r, c) = (self.table_cur_row, self.table_cur_col);
        let sep = (self.table_delimiter() as char).to_string();
        Some(match kind {
            TableCopyKind::Cell => {
                if t.nrows() == 0 {
                    t.header(c).to_string()
                } else {
                    t.cell(r, c).to_string()
                }
            }
            TableCopyKind::Row => {
                if t.nrows() == 0 {
                    t.headers.join(&sep)
                } else {
                    t.rows.get(r).map(|row| row.join(&sep)).unwrap_or_default()
                }
            }
            TableCopyKind::Column => {
                let mut vals = vec![t.header(c).to_string()];
                vals.extend(
                    t.rows
                        .iter()
                        .map(|row| row.get(c).cloned().unwrap_or_default()),
                );
                vals.join("\n")
            }
        })
    }

    /// Copy the current cell / row / column to the clipboard and flash the result.
    pub fn table_copy(&mut self, kind: TableCopyKind) {
        let Some(text) = self.table_copy_text(kind) else {
            self.flash = Some(tr(self.lang, crate::i18n::Msg::NoCopyTarget).into());
            return;
        };
        self.set_clipboard_flash(&text);
    }

    /// Whether the current preview is a (renderable) image. Used to route image-only keys (zoom/pan).
    /// Still images are judged by image_src, GIFs by gif_frames (image_src is not used). SVGs are already rasterized.
    pub fn is_image_preview(&self) -> bool {
        (self.image_src.is_some() || self.is_gif_active())
            && matches!(
                self.preview_kind,
                Some(
                    PreviewKind::Image(_)
                        | PreviewKind::Svg(_)
                        | PreviewKind::Video(_)
                        | PreviewKind::Pdf(_)
                        | PreviewKind::Mermaid(_)
                        | PreviewKind::MermaidFence(_)
                )
            )
    }

    /// Whether the current preview is a PDF (used to enable page-navigation keys / footer hints).
    pub fn is_pdf_preview(&self) -> bool {
        matches!(self.preview_kind, Some(PreviewKind::Pdf(_)))
    }

    /// (current, total) page for the PDF preview, or None when not a PDF or the page count is unknown
    /// (no poppler → single-page fallback, navigation disabled). Used for the footer/status indicator.
    pub fn pdf_page_indicator(&self) -> Option<(u32, u32)> {
        if !self.is_pdf_preview() {
            return None;
        }
        let total = self.pdf_pages?;
        Some((self.pdf_page.min(total), total))
    }

    /// Whether PDF page navigation is possible (a known multi-page PDF; requires poppler for both the
    /// count and per-page rendering, so this gates `J`/`K` from doing anything on single-page/no-poppler PDFs).
    pub fn pdf_can_navigate(&self) -> bool {
        matches!(self.pdf_pages, Some(n) if n > 1)
    }

    /// Go to the next PDF page (clamped to the last page). Re-rasterizes that page on demand (one at a time).
    pub fn pdf_next_page(&mut self) {
        self.pdf_goto(self.pdf_page.saturating_add(1));
    }

    /// Go to the previous PDF page (clamped to page 1).
    pub fn pdf_prev_page(&mut self) {
        self.pdf_goto(self.pdf_page.saturating_sub(1));
    }

    /// Jump to a 1-based page (clamped to [1, total]). No-op if not a navigable PDF or already there.
    /// Kicks off an off-thread rasterization of the new page and resets the view to fit (each page shows whole).
    fn pdf_goto(&mut self, page: u32) {
        if !self.pdf_can_navigate() {
            return;
        }
        let Some(total) = self.pdf_pages else { return };
        let page = page.clamp(1, total);
        if page == self.pdf_page {
            return;
        }
        self.pdf_page = page;
        // 新ページは全体が見えるよう fit に戻す(set_static_image は zoom/center を触らないので明示リセット)。
        self.image_zoom = 1.0;
        self.image_center = (0.5, 0.5);
        self.image_crop = None;
        if let Some(PreviewKind::Pdf(p)) = self.preview_kind.clone() {
            // 旧ページの画像は到着まで表示したまま(media_gen で陳腐化判定・スピナーが重畳)。
            self.spawn_or_sync_media(MediaJob::Pdf(p, self.pdf_page));
        }
    }

    /// Zoom (multiply the magnification by `factor`; clamped to 1.0–16.0). The actual crop is applied at render time.
    /// With no full-screen image showing, `+`/`-` instead zoom the **focused inline mermaid diagram**
    /// in place (the reserved area in the document never changes — the zoom crops within it).
    pub fn image_zoom_by(&mut self, factor: f64) {
        if self.image_src.is_none() && !self.is_gif_active() {
            if self.focused_mermaid_ordinal().is_some() {
                self.fence_zoom = (self.fence_zoom * factor).clamp(1.0, 16.0);
            }
            return;
        }
        self.image_zoom = (self.image_zoom * factor).clamp(1.0, 16.0);
        self.maybe_sharpen_vector();
    }

    /// Sharp zoom for vector-backed previews (SVG / mermaid): when the zoom outgrows the current
    /// raster's density, re-rasterize the retained SVG at the needed max-edge px on a worker thread
    /// and swap it in on arrival (latest-wins via media_gen). The pixel zoom shows instantly in the
    /// meantime, so this behaves like a map app: briefly soft, then crisp. The geometry never moves
    /// because `image_layout` works in the logical size (`image_logical`), not the raster size.
    /// Memory stays bounded by the rasterizer's HARD_MAX (4096px side ≈ 64 MiB RGBA).
    fn maybe_sharpen_vector(&mut self) {
        use image::GenericImageView;
        // 1 本だけ: キーリピートの `+` 連打(ジョブ完了前に必要密度が伸び続ける)で同じ再ラスタを
        // 多重 spawn しない(1 本 ~数百 ms・過渡 ~128MiB)。到着時(apply_media→apply_payload)に
        // もう一度この関数が走り、その時点の最新ズームへ収束する。
        if self.vector_reraster_inflight {
            return;
        }
        let (Some(svg), Some(src), Some((lw, lh))) =
            (&self.vector_svg, &self.image_src, self.image_logical)
        else {
            return;
        };
        let cur_side = src.dimensions().0.max(src.dimensions().1);
        let want = ((lw.max(lh) as f64) * self.image_zoom).ceil() as u32;
        // 現ラスタで足りている(+12% マージン)か、既に上限(4096)なら何もしない。
        if want <= cur_side + cur_side / 8 || cur_side >= 4096 {
            return;
        }
        let base = self.preview_path.clone().unwrap_or_default();
        // 同期フォールバック(media_tx 無し=テスト)は spawn しない=多重の余地が無いので立てない。
        if self.media_tx.is_some() {
            self.vector_reraster_inflight = true;
        }
        self.spawn_or_sync_media(MediaJob::SvgReraster(svg.clone(), base, want));
    }

    /// Reset to 1x (fit). Zoom=1 and recenter. Applies to the focused inline diagram when no
    /// full-screen image is showing (same dual role as `image_zoom_by`).
    pub fn image_zoom_reset(&mut self) {
        if self.image_src.is_none() && !self.is_gif_active() {
            if self.focused_mermaid_ordinal().is_some() {
                self.fence_zoom = 1.0;
                self.fence_center = (0.5, 0.5);
            }
            return;
        }
        self.image_zoom = 1.0;
        self.image_center = (0.5, 0.5);
    }

    /// Current in-place zoom of the focused inline diagram (renderer/footer cue).
    pub fn fence_zoom_level(&self) -> f64 {
        self.fence_zoom
    }

    /// Whether the focused inline diagram's reserved block is fully visible in the preview viewport
    /// (mirrors the renderer's in-place-zoom condition: `row_off == 0 && vis_rows >= rows`).
    /// Viewport 0 (no render pass yet — tests) counts as visible.
    fn focused_fence_fully_visible(&self) -> bool {
        let Some(ord) = self.focused_mermaid_ordinal() else {
            return false;
        };
        let Some((line, rows)) = self.mermaid_placement(ord) else {
            return false;
        };
        let vh = self.preview_viewport as usize;
        if vh == 0 {
            return true;
        }
        let (top, _) = self.md_visual_span(line);
        let scroll = self.preview_scroll as usize;
        top >= scroll && top + rows as usize <= scroll + vh
    }

    /// hjkl/arrows while an inline diagram is focused **and zoomed**: pan the diagram instead of
    /// scrolling the document; `0` fits (zoom reset — the image-view key). Returns true when
    /// consumed. At 1x nothing is consumed, so all keys scroll/navigate the document as usual.
    /// The diagram must also be on screen: after zooming and paging away (Ctrl-f/G), hjkl/j/k
    /// would otherwise pan an invisible diagram and the keys would appear dead.
    pub fn fence_pan_motion(&mut self, m: crate::keymap::Motion) -> bool {
        use crate::keymap::Motion as M;
        if self.fence_zoom <= 1.001 || !self.focused_fence_fully_visible() {
            return false;
        }
        // 0 = フィット(全画面画像と同じキー)。ズーム中のみ奪う(等倍では従来の行頭のまま)。
        if matches!(m, M::LineHome) {
            self.fence_zoom = 1.0;
            self.fence_center = (0.5, 0.5);
            return true;
        }
        let (dx, dy) = match m {
            M::Left => (-1.0, 0.0),
            M::Right => (1.0, 0.0),
            M::Up => (0.0, -1.0),
            M::Down => (0.0, 1.0),
            _ => return false,
        };
        // 1ステップ=可視窓の 1/4(全画面画像のパンと同じ感覚)。端のクランプは描画側の crop 計算。
        let f = 1.0 / self.fence_zoom;
        self.fence_center.0 = (self.fence_center.0 + dx * f * 0.25).clamp(0.0, 1.0);
        self.fence_center.1 = (self.fence_center.1 + dy * f * 0.25).clamp(0.0, 1.0);
        true
    }

    /// Pan. dx/dy are directions (-1/0/+1). Only clipped axes move the center, scaled by the visible fraction.
    /// Clamping is done at render time (prepare_image), looking at the visible fraction.
    pub fn image_pan(&mut self, dx: f64, dy: f64) {
        if self.image_src.is_none() && !self.is_gif_active() {
            return;
        }
        let (fw, fh) = self.image_vis_frac;
        // 1回で可視窓の約25%。見切れていない軸(frac>=1)は動かしても描画時にクランプされる。
        self.image_center.0 += dx * 0.25 * fw;
        self.image_center.1 += dy * 0.25 * fh;
    }

    /// Call just before rendering. From the current (zoom, center, display area inner), compute the image's display rectangle target
    /// (centered; z=1=fit, grows when zooming and clips once it exceeds the viewport) and the source-image crop of
    /// the visible portion; rebuild the protocol if the crop changed. The return value is the render-target target.
    /// Realizes "fit the render area to the image size (fit) → grow when zooming → clip + pan once exceeded".
    pub fn prepare_image(&mut self, inner: Rect) -> Option<Rect> {
        let src = self.image_src.as_ref()?;
        let picker = self.picker.as_ref()?;
        let scale = self.cfg.ui.image_render_scale;
        let (target, crop_rect, center, frac) = image_layout(
            src,
            picker.font_size(),
            self.image_zoom,
            self.image_center,
            inner,
            scale,
            self.image_logical,
        )?;
        let crop_changed = self.image_crop != Some(crop_rect);
        if self.use_kitty {
            // konoma-native compressed transmit. Request a rebuild only when the wanted geometry —
            // the crop (zoom/pan) or the display cell size (a terminal resize at fit) — changes;
            // otherwise the current/in-flight image already targets it, so a static image just
            // re-emits cheap placeholders every frame. The cell-size part matters because at fit zoom
            // a resize changes the area without the crop, and ratatui-image re-encodes on area change
            // internally, so konoma's path must too.
            let want = (crop_rect, target.width, target.height);
            if self.kitty_want != Some(want) {
                self.kitty_want = Some(want);
                self.request_kitty_build(crop_rect, target, picker.font_size());
            }
        } else {
            // ratatui-image path (sixel/iterm2/halfblocks, or kitty when disabled): rebuild the
            // ThreadProtocol only on crop change to avoid a per-frame re-encode.
            let new_tp = if crop_changed {
                let (x0, y0, cw, ch) = crop_rect;
                let crop = src.crop_imm(x0, y0, cw, ch);
                let proto = picker.new_resize_protocol(crop);
                Some(ThreadProtocol::new(
                    self.img_tx.as_ref()?.clone(),
                    Some(proto),
                ))
            } else {
                None
            };
            if let Some(tp) = new_tp {
                self.image = Some(tp);
            }
        }
        self.image_center = center;
        self.image_vis_frac = frac;
        self.image_crop = Some(crop_rect);
        Some(target)
    }

    /// Build the compressed kitty image for the given crop/target. The **first** build after opening
    /// a file (or after a failure left `kitty_image` None) runs synchronously so the image appears
    /// without a blank frame. Subsequent builds (zoom/pan/resize) run on a worker thread so rapid
    /// input does not hitch — the previous image keeps showing until the new one arrives (`apply_kitty`).
    /// With no `kitty_tx` (tests), everything runs synchronously.
    fn request_kitty_build(
        &mut self,
        crop_rect: (u32, u32, u32, u32),
        target: Rect,
        font: ratatui_image::FontSize,
    ) {
        let Some(src) = self.image_src.clone() else {
            return; // no source yet → render falls back
        };
        let (cols, rows) = (target.width, target.height);
        let is_tmux = self.kitty_is_tmux;
        // Every build bumps the generation so a stale async result is discarded by `apply_kitty`.
        self.kitty_gen = self.kitty_gen.wrapping_add(1);

        // Synchronous: the very first build (nothing to show yet) or when there is no worker channel.
        if self.kitty_image.is_none() || self.kitty_tx.is_none() {
            self.kitty_image = crate::preview::kitty::build_from_source(
                &src, crop_rect, cols, rows, font, is_tmux,
            );
            self.kitty_shown = self.kitty_want; // now showing the wanted geometry
            return;
        }

        // Async: keep the previous image visible; the newest spawn's result wins.
        let tx = self.kitty_tx.clone().unwrap();
        let gen = self.kitty_gen;
        std::thread::spawn(move || {
            // A pathological image must not kill the worker (else nothing is ever sent and the
            // previous image lingers); catch and report a failed build instead.
            let image = crate::preview::markdown::catch_silent(move || {
                crate::preview::kitty::build_from_source(&src, crop_rect, cols, rows, font, is_tmux)
            })
            .flatten();
            let _ = tx.send(KittyResult { gen, image });
        });
    }

    /// Apply a completed async kitty build. Stale results (superseded by a newer zoom/pan) and failed
    /// builds are dropped, keeping whatever image is currently shown rather than blanking it.
    pub fn apply_kitty(&mut self, result: KittyResult) -> bool {
        if result.gen != self.kitty_gen {
            return false; // superseded by a newer geometry
        }
        // Either way the newest generation has now settled — mark the wanted geometry as shown so
        // `kitty_build_pending()` clears. Otherwise a failed build (None) would leave it stuck true,
        // spinning the run loop at 16 ms forever (until the next geometry change). On failure the
        // previous image simply stays; on success we swap in the new one.
        self.kitty_shown = self.kitty_want;
        match result.image {
            Some(ki) => {
                self.kitty_image = Some(ki);
                true
            }
            None => false,
        }
    }

    /// Whether an async kitty build is in flight: the wanted geometry differs from what is shown.
    /// Covers pan (same cell size, different crop). The run loop polls faster while this is true so
    /// the result is picked up promptly.
    pub fn kitty_build_pending(&self) -> bool {
        self.use_kitty && self.kitty_want != self.kitty_shown
    }

    /// Whether still images are drawn via konoma's own compressed kitty transmit (kitty terminal).
    pub fn uses_kitty_image(&self) -> bool {
        self.use_kitty
    }

    /// The prepared compressed kitty image for the current crop, if built.
    pub fn kitty_image_ref(&self) -> Option<&crate::preview::kitty::KittyImage> {
        self.kitty_image.as_ref()
    }

    /// Page the text preview by one page (dir: +1=next page / -1=previous page).
    /// Overlaps one row to keep context. The upper bound is clamped at render time.
    pub fn preview_page(&mut self, dir: i32) {
        let page = self.preview_viewport.saturating_sub(1).max(1) as i32;
        self.preview_scroll(dir * page);
    }

    /// Half-page the text preview (vim: Ctrl-d/Ctrl-u, less: d/u).
    pub fn preview_half_page(&mut self, dir: i32) {
        let half = (self.preview_viewport / 2).max(1) as i32;
        self.preview_scroll(dir * half);
    }

    /// To the top of the preview.
    pub fn preview_to_top(&mut self) {
        if self.is_windowed() {
            self.preview_cursor_line = 0;
            self.preview_byte_top = 0;
            self.preview_top_line = 0;
        } else {
            self.preview_scroll = 0;
        }
    }

    /// To the bottom of the preview. The actual maximum is clamped at render time, when content and screen size are known.
    /// When windowed, moves to the line-head byte of the last page (found by a backward seek, without scanning the whole file).
    /// If line numbers are ON, the bottom line number is also corrected from the total line count.
    pub fn preview_to_bottom(&mut self) {
        if !self.is_windowed() {
            self.preview_scroll = u16::MAX;
            return;
        }
        let vh = self.preview_viewport.max(1) as usize;
        // 行カーソルの末尾クランプに総行数が要るので常に求める(キャッシュされる)。
        let total = self.win_total();
        let cur = self.preview_top_line;
        if let Some(b) = self
            .preview_win
            .as_mut()
            .map(|w| w.last_page_top(vh).unwrap_or(0))
        {
            self.preview_byte_top = b;
            self.preview_top_line = total.map(|t| t.saturating_sub(vh)).unwrap_or(cur);
        }
        if let Some(t) = total {
            self.preview_cursor_line = t.saturating_sub(1);
        }
    }

    /// Total line count (computed and cached only when line numbers are ON). Scans the whole file, so call it minimally.
    fn win_total(&mut self) -> Option<usize> {
        if let Some(t) = self.preview_total_lines {
            return Some(t);
        }
        let t = self.preview_win.as_mut()?.count_lines().ok()?;
        self.preview_total_lines = Some(t);
        Some(t)
    }

    /// Apply a re-encode result from the worker to the current image state. Returns true if applied.
    pub fn apply_image_resize(&mut self, resp: Result<ResizeResponse, Errors>) -> bool {
        let Ok(resp) = resp else {
            return false; // エンコード失敗は無視(クラッシュさせない)
        };
        match self.image.as_mut() {
            Some(state) => state.update_resized_protocol(resp),
            None => false,
        }
    }

    pub fn preview_scroll(&mut self, delta: i32) {
        if self.is_windowed() {
            // windowed(Code/Text)は行カーソルを動かし、窓を追従させる(常時カーソルモデル)。
            self.preview_cursor_move(delta);
            return;
        }
        let next = self.preview_scroll as i32 + delta;
        // 下限のみここで。上限 (末尾) は内容・画面サイズが判る描画時にクランプする。
        self.preview_scroll = next.max(0) as u16;
    }

    /// Move the windowed line cursor by `delta` (clamped to the file), then scroll the window to keep it visible.
    /// In visual mode the anchor stays fixed, so moving the cursor extends the selection.
    fn preview_cursor_move(&mut self, delta: i32) {
        let total = self.win_total().unwrap_or(usize::MAX);
        let maxl = total.saturating_sub(1) as i64;
        let next = (self.preview_cursor_line as i64 + delta as i64).clamp(0, maxl.max(0)) as usize;
        self.preview_cursor_line = next;
        self.follow_cursor();
    }

    /// Scroll the window (byte-based) just enough that the line cursor is on screen.
    fn follow_cursor(&mut self) {
        let vh = self.preview_viewport.max(1) as usize;
        let top = self.preview_top_line;
        let cur = self.preview_cursor_line;
        if cur < top {
            self.win_scroll_lines(-((top - cur) as i32));
        } else if cur >= top + vh {
            self.win_scroll_lines((cur + 1 - (top + vh)) as i32);
        }
    }

    /// Windowed scroll (delta lines). Computes the surrounding line-head bytes each time to move preview_byte_top, and
    /// updates preview_top_line (the line number) by the actual number of moved lines. Downward is clamped so as not to pass the last page.
    /// On end-clamp, the line number is corrected from the total line count when line numbers are ON.
    fn win_scroll_lines(&mut self, delta: i32) {
        let vh = self.preview_viewport.max(1) as usize;
        let top = self.preview_byte_top;
        let line = self.preview_top_line;
        // 行番号 ON、または(行カーソルのため)総行数が既にキャッシュされていれば末尾クランプに使う。
        let total = if self.cfg.ui.line_numbers || self.preview_total_lines.is_some() {
            self.win_total()
        } else {
            None
        };
        let result = self.preview_win.as_mut().map(|w| {
            if delta > 0 {
                let (adv, moved) = w.advance(top, delta as usize).unwrap_or((top, 0));
                let maxt = w.last_page_top(vh).unwrap_or(top);
                if adv >= maxt {
                    // 末尾ページ到達: 行番号は総行数から(無ければ素朴に加算)。
                    let bl = total.map(|t| t.saturating_sub(vh)).unwrap_or(line + moved);
                    (maxt, bl)
                } else {
                    (adv, line + moved)
                }
            } else if delta < 0 {
                let (ret, moved) = w.retreat(top, (-delta) as usize).unwrap_or((0, 0));
                (ret, line.saturating_sub(moved))
            } else {
                (top, line)
            }
        });
        if let Some((nt, nl)) = result {
            self.preview_byte_top = nt;
            self.preview_top_line = nl;
        }
    }

    /// For windowed display, read the current window (from the top byte for the height), highlight Code with syntect
    /// / leave Text plain, and return it as a list of ratatui Lines. Cached by (path, top byte, height),
    /// re-read only on scroll/resize. If the top exceeds the last page, it is clamped.
    pub fn windowed_lines(&mut self, height: u16, width: u16) -> Vec<Line<'static>> {
        let _ = width; // 行内容は幅に依存しない(折返しは描画側)。将来用に受けておく。
        let h = height.max(1) as usize;
        // リサイズ等で末尾を超えていたらクランプ(行番号も総行数から補正)。
        let top0 = self.preview_byte_top;
        let maxt = self
            .preview_win
            .as_mut()
            .and_then(|w| w.last_page_top(h).ok());
        if let Some(maxt) = maxt {
            if top0 > maxt {
                self.preview_byte_top = maxt;
                // 行番号ガター OFF でも検索の現在一致(橙)が abs=preview_top_line+i で
                // 参照するため、末尾ページへのクランプ時は line_numbers の有無に関わらず
                // 常に preview_top_line を総行数から補正する(#5)。
                if let Some(t) = self.win_total() {
                    self.preview_top_line = t.saturating_sub(h);
                }
            }
        }
        let top = self.preview_byte_top;
        let path = self.preview_path.clone().unwrap_or_default();
        // syntax を着けるか: ハイライト無効(off-switch) / progressive で待ち中(hl_pending)なら素。
        // Code は常に対象。Text は「拡張子/ファイル名から実在の文法が解決できる時だけ」対象にする＝
        // .bashrc/Makefile/Dockerfile 等の設定ファイルを着色しつつ、本当に素のテキストは無色のまま保つ。
        // progressive 待ち中だけは「差し替え前の素テキスト」なのでキャッシュしない(後で着色版に替わる)。
        let syntax_kind = match &self.preview_kind {
            Some(PreviewKind::Code(_)) => true,
            Some(PreviewKind::Text(p)) => crate::preview::code::has_named_syntax(p),
            // raw ソース表示(`R`)の Markdown/Mermaid はファイルの文法(.md→Markdown 等)で着色する。
            Some(PreviewKind::Markdown(p)) | Some(PreviewKind::Mermaid(p)) if self.md_raw => {
                crate::preview::code::has_named_syntax(p)
            }
            _ => false,
        };
        let want_syntax = self.cfg.ui.syntax_highlight
            && syntax_kind
            && (!self.hl_pending || self.loading_is_indicator());
        // progressive 待ち中の素テキストだけはキャッシュしない(後で着色版に差し替わるため)。
        // それ以外は素テキストでも (path, top, height) でキャッシュする=毎フレームのファイル
        // 読み直しをしない。`styled` をキーに含め、着色版と素版を取り違えない。
        let cacheable = want_syntax || !(self.cfg.ui.syntax_highlight && syntax_kind);
        let mut content: Vec<Line<'static>> = if cacheable {
            let hit = matches!(
                &self.win_cache,
                Some(c) if c.path == path && c.byte_top == top && c.height == height
                    && c.styled == want_syntax
            );
            if !hit {
                let raw = self
                    .preview_win
                    .as_mut()
                    .and_then(|w| w.read_lines(top, h).ok())
                    .unwrap_or_default();
                let lines = if want_syntax {
                    let src = raw.join("\n");
                    crate::preview::code::highlight(&src, &path, &self.cfg.ui.theme.code_theme)
                } else {
                    raw.into_iter().map(Line::from).collect()
                };
                self.win_cache = Some(WinCache {
                    path,
                    byte_top: top,
                    height,
                    styled: want_syntax,
                    lines,
                });
            }
            self.win_cache
                .as_ref()
                .map(|c| c.lines.clone())
                .unwrap_or_default()
        } else {
            // progressive 待ち中の素テキスト(キャッシュしない=着色完了で差し替わる)。
            let raw = self
                .preview_win
                .as_mut()
                .and_then(|w| w.read_lines(top, h).ok())
                .unwrap_or_default();
            raw.into_iter().map(Line::from).collect()
        };
        // タブを可視マーカー(→)＋タブストップ空白へ展開する(端末はタブを桁揃えしないため)。
        // 行番号ガター/検索強調の前に行う＝桁追跡が本文の先頭(0桁)基準になる。窓の可視行のみ=軽い。
        content = crate::preview::code::expand_tabs(content, self.cfg.ui.tab_width);
        // 検索中は一致箇所(クエリ)を強調する(ガターより先=本文だけ強調)。
        // 現在の出現(search_idx)1箇所だけオレンジ、他は黄色。表示行 i の絶対行 = preview_top_line + i。
        // その行が現在の出現の行なら、その列(col)の出現だけオレンジにする(同一行に複数あっても1つ)。
        if let Some(q) = self.preview_search.clone() {
            // 現在一致(search_idx)の行と、その「行内での出現順位」(0始まり)を求める。
            // タブ展開でバイト列がずれるため、列(バイト位置)ではなく出現順位で
            // 現在一致を同定する(#14)。同一行の一致は search_matches 内で連続・列昇順。
            let (cur_line, cur_rank) = match self.search_matches.get(self.search_idx).copied() {
                Some((_, line, _)) => {
                    let rank = self.search_matches[..self.search_idx]
                        .iter()
                        .filter(|(_, l, _)| *l == line)
                        .count();
                    (Some(line), Some(rank))
                }
                None => (None, None),
            };
            let top_line = self.preview_top_line;
            content = content
                .into_iter()
                .enumerate()
                .map(|(i, l)| {
                    let abs = top_line + i;
                    let rank = if cur_line == Some(abs) {
                        cur_rank
                    } else {
                        None
                    };
                    highlight_query_in_line(l, &q, rank)
                })
                .collect();
        }
        let top_line = self.preview_top_line;
        // 2D キャレット列を可視のカーソル行の実長さにクランプし、書き戻す(`l`/`$` の行き過ぎ補正)。
        // キャレット行はビューポート追従で常に可視なので、ここで content から実長を取得できる。
        if self.preview_cursor_line >= top_line
            && self.preview_cursor_line < top_line + content.len()
        {
            let ln = &content[self.preview_cursor_line - top_line];
            let len: usize = ln.spans.iter().map(|s| s.content.chars().count()).sum();
            // 読み取り専用キャレットは常に実在の文字の上に置く(空行は 0)。$ は最後の文字へ。
            self.preview_cursor_col = self.preview_cursor_col.min(len.saturating_sub(1));
        }
        // 行カーソル/選択範囲のハイライト(ガター前＝列インデックスが本文先頭 0 基準に揃う)。
        let content = apply_preview_caret(
            content,
            top_line,
            self.preview_cursor_line,
            self.preview_cursor_col,
            self.preview_selection(),
        );
        // 行番号ガター(設定 ON のときだけ)。先頭行番号 = preview_top_line。
        let content = if self.cfg.ui.line_numbers {
            with_line_numbers(content, top_line)
        } else {
            content
        };
        // git 変更ガター(設定 ON・変更のあるファイルのみ)。行番号の左に 1 セルのマーカーを前置する。
        let marks = self.git_gutter_marks();
        with_git_gutter(content, top_line, &marks)
    }

    /// Git gutter marks (per 1-based new-file line) for the current code/text preview, cached per path.
    /// Empty when the gutter is disabled, outside a repo, or the file is unchanged (→ no gutter column).
    /// Called from `windowed_lines`, which only runs for code/text previews, so no kind check is needed.
    fn git_gutter_marks(&mut self) -> std::collections::HashMap<u32, GutterMark> {
        if !self.cfg.ui.git_gutter {
            return std::collections::HashMap::new();
        }
        let Some(path) = self.preview_path.clone() else {
            return std::collections::HashMap::new();
        };
        let hit = matches!(&self.gutter_cache, Some(c) if c.path == path);
        if !hit {
            let diff = crate::git::file_diff(&self.root, &path);
            let marks = gutter_marks(&diff);
            self.gutter_cache = Some(GutterCache {
                path: path.clone(),
                marks,
            });
        }
        self.gutter_cache
            .as_ref()
            .map(|c| c.marks.clone())
            .unwrap_or_default()
    }

    /// Windowed scroll progress (0..=100 %). For the title display. None if not windowed.
    pub fn window_progress(&self) -> Option<u16> {
        let w = self.preview_win.as_ref()?;
        let len = w.len();
        if len == 0 {
            return Some(0);
        }
        Some((self.preview_byte_top.min(len) * 100 / len) as u16)
    }

    /// Whether in-preview search input mode is active (intercepting keys).
    pub fn is_searching(&self) -> bool {
        self.search_input.is_some()
    }

    /// The active search query (for highlighting).
    pub fn preview_search_query(&self) -> Option<&str> {
        self.preview_search.as_deref()
    }

    /// The search input being edited (for the footer prompt).
    pub fn search_input(&self) -> Option<&str> {
        self.search_input.as_deref()
    }

    /// Search status (current/total). Some((1-based, total)) when active and there are matches.
    pub fn search_status(&self) -> Option<(usize, usize)> {
        if self.preview_search.is_some() && !self.search_matches.is_empty() {
            Some((self.search_idx + 1, self.search_matches.len()))
        } else {
            None
        }
    }

    /// Which preview the in-preview search (`/`) runs against. Each target has its own way of
    /// locating matches and of moving to one, so `search_commit` / `jump_to_match` branch on this.
    fn search_target(&self) -> SearchTarget {
        if self.preview_win.is_some() {
            // Code/Text と `R` の生 Markdown（バイトオフセットで窓を動かす）。
            SearchTarget::Windowed
        } else if self.table_data.is_some() {
            SearchTarget::Table
        } else if self.md_cache.is_some() {
            // 装飾 Markdown / Mermaid。検索対象は**画面に出ている装飾行**であって
            // ソースではない(装飾は行を増減させるので、ソース行番号では位置を指せない)。
            SearchTarget::Markdown
        } else {
            SearchTarget::Unsupported
        }
    }

    /// Case-insensitive scan of the **decorated** Markdown lines — the same lines the renderer
    /// slices from — so a hit is always something visible on screen. Positions are
    /// `(0, logical line, byte column)`; `n`/`N` then scroll that line into view.
    ///
    /// Non-ASCII queries whose byte length changes under `to_lowercase` are skipped for that line,
    /// matching `highlight_query_in_line` so the highlight and the match list never disagree.
    fn md_search_scan(&mut self, q: &str) {
        self.search_matches.clear();
        let needle = q.to_lowercase();
        let Some(c) = self.md_cache.as_ref() else {
            return;
        };
        for (li, line) in c.lines.iter().enumerate() {
            let full: String = line.spans.iter().map(|s| s.content.as_ref()).collect();
            let lower = full.to_lowercase();
            if lower.len() != full.len() {
                continue;
            }
            let mut i = 0usize;
            while let Some(rel) = lower[i..].find(&needle) {
                let s = i + rel;
                self.search_matches.push((0, li, s));
                i = s + needle.len().max(1);
                if i >= lower.len() {
                    break;
                }
            }
        }
    }

    /// Scroll the decorated Markdown view to a search hit on logical line `line`.
    ///
    /// A hit that is already fully on screen does not move the view (searching for something you
    /// can see should not jolt the page). Otherwise the line is placed near the top with a few
    /// lines of context above — the same affordance as `follow_scroll_to_first_change`. Note this
    /// deliberately differs from `md_focus_move`'s minimal-scroll rule: with minimal scrolling the
    /// same hit lands at the top or the bottom depending on which way you arrived, so `n` `n` `n`
    /// wrapping back around would not return to the same view.
    fn md_scroll_line_into_view(&mut self, line: usize) {
        const CONTEXT_ROWS: usize = 3;
        let (top, height) = self.md_visual_span(line);
        let vh = self.preview_viewport.max(1) as usize;
        let scroll = self.preview_scroll as usize;
        let fully_visible = top >= scroll && top + height <= scroll + vh;
        if fully_visible {
            return;
        }
        self.preview_scroll = top.saturating_sub(CONTEXT_ROWS) as u16;
    }

    /// Start a search (`/`). Supported in Code/Text (windowed) and table previews. Enters input mode.
    pub fn start_search(&mut self) {
        if matches!(self.search_target(), SearchTarget::Unsupported) {
            self.flash = Some(tr(self.lang, crate::i18n::Msg::SearchCodeTextOnly).into());
            return;
        }
        self.search_input = Some(String::new());
    }

    /// Case-insensitive cell scan for a table preview, in reading order (row-major).
    /// Only data cells are searched: the cell cursor addresses data rows, so a header-only hit
    /// would have nowhere to jump to.
    fn table_search_scan(&mut self, q: &str) {
        self.table_search_hits.clear();
        self.search_matches.clear();
        let needle = q.to_lowercase();
        let Some(t) = self.table_data.as_ref() else {
            return;
        };
        for r in 0..t.nrows() {
            for c in 0..t.ncols {
                if t.cell(r, c).to_lowercase().contains(&needle) {
                    self.search_matches.push((0, r, c));
                    self.table_search_hits.insert((r, c));
                }
            }
        }
    }

    /// Whether this data cell matched the active search (renderer lookup — O(1) per cell).
    pub fn table_cell_is_hit(&self, row: usize, col: usize) -> bool {
        self.table_search_hits.contains(&(row, col))
    }

    pub fn search_input_push(&mut self, c: char) {
        if let Some(s) = self.search_input.as_mut() {
            s.push(c);
        }
    }

    pub fn search_input_backspace(&mut self) {
        if let Some(s) = self.search_input.as_mut() {
            s.pop();
        }
    }

    /// Confirm input (Enter): run the query (collect all matching lines) and jump to the first match at or after the current position.
    pub fn search_commit(&mut self) {
        let q = self.search_input.take().unwrap_or_default();
        if q.is_empty() {
            self.preview_search = None;
            self.search_matches.clear();
            self.table_search_hits.clear();
            return;
        }
        const CAP: usize = 5000;
        let target = self.search_target();
        match target {
            SearchTarget::Table => self.table_search_scan(&q),
            SearchTarget::Markdown => {
                self.table_search_hits.clear();
                self.md_search_scan(&q);
            }
            _ => {
                self.table_search_hits.clear();
                self.search_matches = self
                    .preview_win
                    .as_mut()
                    .and_then(|w| w.find_all_matches(&q, CAP).ok())
                    .unwrap_or_default();
            }
        }
        self.preview_search = Some(q);
        if self.search_matches.is_empty() {
            self.flash = Some(tr(self.lang, crate::i18n::Msg::NoMatch).into());
            return;
        }
        self.search_idx = match target {
            // 表: いま居るセル以降の最初の一致へ(読み順)。無ければ先頭へ巡回。
            SearchTarget::Table => {
                let (cr, cc) = (self.table_cur_row, self.table_cur_col);
                self.search_matches
                    .iter()
                    .position(|(_, r, c)| (*r, *c) >= (cr, cc))
                    .unwrap_or(0)
            }
            // 装飾 md: いま見えている先頭の論理行以降の最初の一致へ。無ければ先頭へ巡回。
            SearchTarget::Markdown => {
                let from = self.md_top_logical_line().unwrap_or(0);
                self.search_matches
                    .iter()
                    .position(|(_, line, _)| *line >= from)
                    .unwrap_or(0)
            }
            // 窓読み: 現在の表示位置(byte_top)以降の最初の出現へ。無ければ先頭へ巡回。
            _ => {
                let top = self.preview_byte_top;
                self.search_matches
                    .iter()
                    .position(|(off, _, _)| *off >= top)
                    .unwrap_or(0)
            }
        };
        self.jump_to_match();
    }

    /// `n`/`N`: to the next/previous match (cyclic).
    pub fn search_next(&mut self, dir: i32) {
        if self.search_matches.is_empty() {
            return;
        }
        let n = self.search_matches.len() as i32;
        self.search_idx = (self.search_idx as i32 + dir).rem_euclid(n) as usize;
        self.jump_to_match();
    }

    /// Clear the search (Esc).
    pub fn search_clear(&mut self) {
        self.preview_search = None;
        self.search_input = None;
        self.search_matches.clear();
        self.table_search_hits.clear();
        self.search_idx = 0;
    }

    /// Bring the line of the current occurrence to the top of the display (updates the line-head byte and line number). For moves within the same line,
    /// the top does not change, and only the highlight color (orange) moves to that occurrence (the column is referenced by the render side).
    fn jump_to_match(&mut self) {
        let Some(&(off, a, b)) = self.search_matches.get(self.search_idx) else {
            return;
        };
        match self.search_target() {
            // 表: (行, 列) はセル座標。カーソルを移すと描画側がスクロールして追従する。
            SearchTarget::Table => {
                self.table_cur_row = a;
                self.table_cur_col = b;
            }
            // 装飾 md: 一致した論理行を可視域へ(装飾表示のまま=raw に切替えない)。
            SearchTarget::Markdown => self.md_scroll_line_into_view(a),
            _ => {
                self.preview_byte_top = off;
                self.preview_top_line = a;
            }
        }
    }

    pub fn preview_hscroll(&mut self, delta: i32) {
        let next = self.preview_hscroll as i32 + delta;
        self.preview_hscroll = next.max(0) as u16;
    }
    /// Reset horizontal scroll to the line start (left edge) in one step. `0`. When wrapping, it is already 0, so no effect.
    pub fn preview_hscroll_home(&mut self) {
        self.preview_hscroll = 0;
    }
    /// Send horizontal scroll to the line end (right edge) in one step. `$`. The actual maximum is clamped to the longest line width at render time
    /// (here we set the upper bound, and the render side's `.min(max_h)` settles it at the correct right edge).
    pub fn preview_hscroll_end(&mut self) {
        self.preview_hscroll = u16::MAX;
    }

    /// Arrange the links in decorated Markdown lines to "show label only", build `md_items` (links +
    /// task checkboxes), and return the line list with the focused item rendered inverted (called just
    /// before rendering). Since tui-markdown outputs the "label (URL)" form, `collapse_links` folds the
    /// accompanying URL (the URL is the hidden destination) and styles the label as a link plus (when
    /// configured) an icon. Checkbox markers are recognized by their dedicated style (`is_task_span`).
    /// Test-only equivalent of the production path (`ensure_md_cache` + `md_slice`) over caller-
    /// supplied lines: collapse links, rebuild `md_items`, and invert the focused item. Shares
    /// `build_md_items` / `invert_focused_line` with the cache path so the two cannot drift.
    /// Post-process decorated Markdown lines just before caching/rendering: collapse the `label
    /// (URL)` links tui-markdown emits, then (when `ui.md_autolink`) auto-link bare URLs/emails, then
    /// (when `ui.md_emoji`) convert `:shortcode:` emoji. Shared by the cache build (`ensure_md_cache`)
    /// and the test-only decorate path so link/emoji collection cannot drift between them. Emoji runs
    /// last so width-affecting substitutions are reflected in the caller's reflow/`row_prefix`.
    fn postprocess_md(&self, lines: Vec<Line<'static>>) -> (Vec<Line<'static>>, Vec<String>) {
        let (lines, targets) = collapse_links(lines, self.cfg.ui.icons);
        let (lines, targets) = if self.cfg.ui.md_autolink {
            autolink_bare_urls(lines, targets)
        } else {
            (lines, targets)
        };
        let lines = if self.cfg.ui.md_emoji {
            substitute_emoji(lines)
        } else {
            lines
        };
        (lines, targets)
    }

    #[cfg(test)]
    pub fn decorate_md_items(&mut self, lines: Vec<Line<'static>>) -> Vec<Line<'static>> {
        let (lines, targets) = self.postprocess_md(lines);
        let items = build_md_items(&lines, &targets, &[]);
        // フォーカス添字を範囲内にクランプ。
        match self.focused_item {
            Some(_) if items.is_empty() => self.focused_item = None,
            Some(f) if f >= items.len() => self.focused_item = Some(items.len() - 1),
            _ => {}
        }
        self.md_items = items;

        let Some(target_idx) = self.focused_item else {
            return lines;
        };
        let (target_line, whole_line) = {
            let it = &self.md_items[target_idx];
            (it.line, matches!(it.kind, MdItemKind::CodeBlock))
        };
        let first_on_line = self.md_items.partition_point(|x| x.line < target_line);
        let ordinal = target_idx - first_on_line;
        lines
            .into_iter()
            .enumerate()
            .map(|(li, line)| {
                if li == target_line {
                    invert_focused_line(&line, ordinal, whole_line)
                } else {
                    line
                }
            })
            .collect()
    }

    /// Move the item focus of the Markdown preview (dir: +1=next / -1=previous, cyclic over links and
    /// checkboxes in document order). If the focused line is off-screen, scroll until it is visible.
    pub fn md_focus_move(&mut self, dir: i32) {
        if self.md_items.is_empty() {
            return;
        }
        let n = self.md_items.len() as i32;
        let next = match self.focused_item {
            Some(f) => (f as i32 + dir).rem_euclid(n),
            None if dir >= 0 => 0,
            None => n - 1,
        } as usize;
        if self.focused_item != Some(next) {
            // フォーカスが移ったらインライン図のズーム/パンは初期化(前の図の状態を持ち越さない)。
            self.fence_zoom = 1.0;
            self.fence_center = (0.5, 0.5);
        }
        self.focused_item = Some(next);
        // フォーカス行を表示範囲に収める。preview_scroll は**表示行(折返し後)**の座標系
        // (描画側が para.line_count でクランプしている)なので、アイテムの論理行も
        // 表示行へ変換してから比較する(論理行のままだと折返しで乖離し、画面外の
        // フォーカスに追従しない — 2026-07-08 ユーザー報告)。
        let line = self.md_items[next].line;
        let (top, mut height) = self.md_visual_span(line);
        // フェンス図: キャプションだけでなく**図ブロック全体**(キャプション+予約行+下マージン)を
        // 可視域へ入れる(図が下に見切れたまま「フォーカスしたのに見えない」を防ぐ=ユーザー要望)。
        if let MdItemKind::MermaidFence { ordinal } = self.md_items[next].kind {
            if let Some((pl, pr)) = self.mermaid_placement(ordinal) {
                let last = pl + pr as usize; // 下マージン行(placement.line + rows)
                let (bt, bh) = self.md_visual_span(last);
                height = (bt + bh).saturating_sub(top).max(height);
            }
        }
        let vh = self.preview_viewport.max(1) as usize;
        let scroll = self.preview_scroll as usize;
        if height >= vh || top < scroll {
            // ブロックが画面より大きい(先頭を出す) or 上に見切れている。
            self.preview_scroll = top as u16;
        } else if top + height > scroll + vh {
            self.preview_scroll = (top + height).saturating_sub(vh) as u16;
        }
    }

    /// (line, rows) of the inline mermaid placement whose **source ordinal** is `ordinal`
    /// (placements carry it in `fence_ord`; counting rendered placements would drift as soon as
    /// an earlier fence has no placement — loading or degraded to text).
    fn mermaid_placement(&self, ordinal: usize) -> Option<(usize, u16)> {
        let cache = self.md_cache.as_ref()?;
        cache
            .images
            .iter()
            .find(|p| p.fence_ord == Some(ordinal))
            .map(|p| (p.line, p.rows))
    }

    /// Ordinal of the focused inline mermaid diagram, if the focus is on one (border cue in the renderer).
    pub fn focused_mermaid_ordinal(&self) -> Option<usize> {
        let f = self.focused_item?;
        match self.md_items.get(f)?.kind {
            MdItemKind::MermaidFence { ordinal } => Some(ordinal),
            _ => None,
        }
    }

    /// Visual (post-wrap) row offset of decorated line `line` plus its own wrapped height.
    /// With wrap off this is just (line, 1). Reads the cached per-line reflow prefix sums
    /// (ratatui's own `line_count`, computed once at cache build), so the numbers match what
    /// the renderer draws exactly — and the lookup is O(1) instead of re-flowing the document.
    pub(crate) fn md_visual_span(&self, line: usize) -> (usize, usize) {
        if !self.cfg.ui.wrap {
            return (line, 1);
        }
        let Some(cache) = &self.md_cache else {
            return (line, 1);
        };
        if cache.width == 0
            || line >= cache.lines.len()
            || cache.row_prefix.len() != cache.lines.len() + 1
        {
            return (line, 1);
        }
        let top = cache.row_prefix[line];
        let height = (cache.row_prefix[line + 1] - top).max(1);
        (top, height)
    }

    /// Activate the focused item: a link opens (URLs externally, local paths within konoma),
    /// a task checkbox toggles.
    pub fn md_activate_focused(&mut self) -> Result<()> {
        let Some(f) = self.focused_item else {
            return Ok(());
        };
        match self.md_items.get(f) {
            Some(MdItem {
                kind: MdItemKind::Link { target },
                ..
            }) => {
                let target = target.clone();
                self.open_link_target(&target)
            }
            Some(MdItem {
                kind: MdItemKind::Task { .. },
                ..
            }) => {
                self.md_toggle_focused_task();
                Ok(())
            }
            // コードブロックは「開く/トグル」対象が無いので Enter では何もしない。
            // コピーは他のコピー操作と揃えて `y`(コピーリーダー)で行う(main.rs で先取り)。
            Some(MdItem {
                kind: MdItemKind::CodeBlock,
                ..
            }) => Ok(()),
            // インライン mermaid 図: 全画面(ズーム/パン付き)で開く。
            Some(MdItem {
                kind: MdItemKind::MermaidFence { ordinal },
                ..
            }) => {
                let ord = *ordinal;
                self.open_mermaid_fence(ord);
                Ok(())
            }
            // <details> の summary: 折りたたみをトグル。
            Some(MdItem {
                kind: MdItemKind::Details { ordinal },
                ..
            }) => {
                let ord = *ordinal;
                self.toggle_details(ord);
                Ok(())
            }
            None => Ok(()),
        }
    }

    /// Open the Nth ```mermaid fence of the current Markdown preview full screen (Enter on a
    /// Tab-focused inline diagram). The Markdown view's scroll/focus are stashed so `q` returns
    /// exactly where the reader was. Count-guarded re-extraction: if the file changed and the
    /// fence is gone, flash instead of rendering a stale diagram (principle #3).
    fn open_mermaid_fence(&mut self, ordinal: usize) {
        let Some(md) = self.preview_path.clone() else {
            return;
        };
        if self.mermaid_fence_code(&md, ordinal).is_none() {
            self.flash = Some(tr(self.lang, crate::i18n::Msg::DiagramOpenFailed).into());
            return;
        }
        self.fence_return = Some((self.preview_scroll, self.focused_item));
        self.clear_image();
        let kind = PreviewKind::MermaidFence(ordinal);
        self.start_media_load(&kind, &md);
        self.preview_kind = Some(kind);
    }

    /// Raw source of the focused code block, matched by ordinal against the on-screen headers. The
    /// block text is re-scanned from the file; `None` when the focused item is not a code block,
    /// there is no path, the read fails, or the counts disagree (file changed / pathological doc) —
    /// the caller then flashes instead of copying garbage (safe fallback, #3). Also used by tests
    /// to assert the copied value without a clipboard round-trip.
    fn focused_code_source(&self) -> Option<String> {
        let f = self.focused_item?;
        if !matches!(
            self.md_items.get(f),
            Some(MdItem {
                kind: MdItemKind::CodeBlock,
                ..
            })
        ) {
            return None;
        }
        // 文書内で何番目のコードブロックか(リンク/タスクを除いた序数)。
        let ordinal = self.md_items[..=f]
            .iter()
            .filter(|it| matches!(it.kind, MdItemKind::CodeBlock))
            .count()
            .saturating_sub(1);
        let total = self
            .md_items
            .iter()
            .filter(|it| matches!(it.kind, MdItemKind::CodeBlock))
            .count();
        let src = std::fs::read_to_string(self.preview_path.as_ref()?).ok()?;
        let blocks = crate::preview::markdown::code_block_source_locs(&src);
        // 画面上のヘッダ数とソースのブロック数が一致するときだけ信頼して写す。
        (blocks.len() == total)
            .then(|| blocks.get(ordinal).cloned())
            .flatten()
    }

    /// Copy the focused code block's raw source to the clipboard, or flash a safe notice when it
    /// cannot be resolved (`focused_code_source` = None). Triggered by the copy leader (`y`) in a
    /// Markdown preview when a code block is focused (pre-empted in `handle_key`).
    pub fn md_copy_focused_code(&mut self) {
        let Some(text) = self.focused_code_source() else {
            self.flash = Some(tr(self.lang, crate::i18n::Msg::CodeBlockCopyUnavailable).into());
            return;
        };
        match set_clipboard(&text) {
            Ok(()) => self.flash = Some(tr(self.lang, crate::i18n::Msg::CopiedCodeBlock).into()),
            Err(e) => {
                self.flash = Some(format!(
                    "{}{e}",
                    tr(self.lang, crate::i18n::Msg::CopyFailed)
                ))
            }
        }
    }

    /// Test-only: the exact text `Enter` would copy for the focused code block (no clipboard).
    #[cfg(test)]
    pub fn focused_code_text(&self) -> Option<String> {
        self.focused_code_source()
    }

    /// Whether the currently focused Markdown item is a code block (drives the footer hint:
    /// `Enter` copies the block).
    pub fn md_focused_code(&self) -> bool {
        !self.is_raw_source()
            && self
                .focused_item
                .and_then(|f| self.md_items.get(f))
                .is_some_and(|it| matches!(it.kind, MdItemKind::CodeBlock))
    }

    /// Whether the currently focused Markdown item is a task checkbox (drives the Space fixed key:
    /// only then does Space toggle instead of falling through to the keymap).
    pub fn md_focused_task(&self) -> bool {
        !self.is_raw_source()
            && self
                .focused_item
                .and_then(|f| self.md_items.get(f))
                .is_some_and(|it| matches!(it.kind, MdItemKind::Task { .. }))
    }

    /// The ordinal of the focused `<details>` summary, if one is focused (drives the Space fixed key
    /// and the footer hint). None when not focused on a details summary.
    pub fn md_focused_details(&self) -> Option<usize> {
        if self.is_raw_source() {
            return None;
        }
        match self.focused_item.and_then(|f| self.md_items.get(f)) {
            Some(MdItem {
                kind: MdItemKind::Details { ordinal },
                ..
            }) => Some(*ordinal),
            _ => None,
        }
    }

    /// Whether the rendered Markdown preview has any task checkboxes (drives the footer hint).
    pub fn md_has_tasks(&self) -> bool {
        self.md_items
            .iter()
            .any(|it| matches!(it.kind, MdItemKind::Task { .. }))
    }

    /// Open a link target. `scheme://`/`mailto:`, etc. are delegated externally; local paths open in konoma
    /// (file=preview / directory=make it the new root and Tree).
    fn open_link_target(&mut self, target: &str) -> Result<()> {
        let t = target.trim();
        if t.contains("://") || t.starts_with("mailto:") || t.starts_with("tel:") {
            return self.open_external(t);
        }
        if let Some(anchor) = t.strip_prefix('#') {
            if !self.md_scroll_to_anchor(anchor) {
                self.flash = Some(format!(
                    "{}{}",
                    tr(self.lang, crate::i18n::Msg::AnchorNotFound),
                    t
                ));
            }
            return Ok(());
        }
        let path_part = t.split('#').next().unwrap_or(t);
        let resolved = self.resolve_link_local(t);
        if resolved.is_dir() {
            self.back_to_tree();
            // root を変えるので旧 root の選択/ビジュアル/絞り込み/検索を破棄する(持ち越さない)。
            self.clear_for_root_change();
            self.root = resolved;
            self.open_dir = self.root.clone();
            self.entries.clear();
            self.selected = 0;
            self.rebuild_tree()?;
        } else if resolved.is_file() {
            self.enter_preview(&resolved);
        } else {
            self.flash = Some(format!(
                "{}{}",
                tr(self.lang, crate::i18n::Msg::NotFound),
                path_part
            ));
        }
        Ok(())
    }

    /// Resolve a local (non-URL, non-anchor) Markdown link target to an absolute path (existence not
    /// guaranteed), relative to the current preview file's directory. A `#anchor` suffix is dropped.
    fn resolve_link_local(&self, target: &str) -> PathBuf {
        let t = target.trim();
        let path_part = t.split('#').next().unwrap_or(t);
        let base = self
            .preview_path
            .as_ref()
            .and_then(|p| p.parent())
            .map(Path::to_path_buf)
            .unwrap_or_else(|| self.root.clone());
        let p = Path::new(path_part);
        let resolved = if p.is_absolute() {
            p.to_path_buf()
        } else {
            base.join(p)
        };
        std::fs::canonicalize(&resolved).unwrap_or(resolved)
    }

    /// `Ctrl-t`: open the focused Markdown link in a **new tab** (the current doc's tab stays intact).
    /// URLs still go to the browser (a tab makes no sense for them); a local file/dir opens in a fresh
    /// foreground tab via the shared paste-jump navigation (reveal + root-switch-if-outside + preview).
    /// No-op when the focused item is not a link (task/code) or nothing is focused.
    pub fn md_open_focused_link_new_tab(&mut self) -> Result<()> {
        let Some(f) = self.focused_item else {
            return Ok(());
        };
        let target = match self.md_items.get(f) {
            Some(MdItem {
                kind: MdItemKind::Link { target },
                ..
            }) => target.clone(),
            _ => return Ok(()),
        };
        let t = target.trim();
        // URL/mailto/tel はタブにできないので、Enter と同じく外部(ブラウザ等)で開く。
        if t.contains("://") || t.starts_with("mailto:") || t.starts_with("tel:") {
            return self.open_external(t);
        }
        if t.starts_with('#') {
            // A same-document anchor makes no sense in a new tab — scroll in place instead.
            return self.open_link_target(t);
        }
        // タブを作る前に、現在の md ファイルの位置基準でローカルパスを解決しておく。
        let resolved = self.resolve_link_local(t);
        if !resolved.exists() {
            self.flash = Some(format!(
                "{}{}",
                tr(self.lang, crate::i18n::Msg::NotFound),
                t.split('#').next().unwrap_or(t)
            ));
            return Ok(());
        }
        // 新規タブ(前面)を作り、その中でジャンプする。元のドキュメントのタブは save_active で保持済み。
        self.tab_new()?;
        self.paste_jump_to(&resolved, None);
        Ok(())
    }

    /// Open a URL/file with an external command (macOS `open`). The result is reported via flash.
    fn open_external(&mut self, url: &str) -> Result<()> {
        match std::process::Command::new("open").arg(url).spawn() {
            Ok(_) => self.flash = Some(format!("{}{url}", tr(self.lang, crate::i18n::Msg::Opened))),
            Err(e) => {
                self.flash = Some(format!(
                    "{}{e}",
                    tr(self.lang, crate::i18n::Msg::OpenFailed)
                ))
            }
        }
        Ok(())
    }

    pub fn cycle_path_style(&mut self) {
        self.path_style = self.path_style.next();
    }

    /// Toggle the `?` help. When opening, reset scroll to the top.
    pub fn toggle_help(&mut self) {
        self.show_help = !self.show_help;
        self.help_scroll = 0;
    }

    /// Toggle the `i` file-info popup. Does not open if there is no target.
    pub fn toggle_info(&mut self) {
        if self.show_info {
            self.show_info = false;
        } else if self.info_target().is_some() {
            self.show_info = true;
        } else {
            self.flash = Some(crate::i18n::tr(self.lang, crate::i18n::Msg::NoTarget).into());
        }
    }
    /// Whether the file-info popup is showing.
    pub fn is_info(&self) -> bool {
        self.show_info
    }
    /// The target path for the info display: Tree=the cursor item / Preview=the file being previewed.
    pub fn info_target(&self) -> Option<PathBuf> {
        match self.mode {
            Mode::Tree => self.entries.get(self.selected).map(|e| e.path.clone()),
            Mode::Preview => self.preview_path.clone(),
        }
    }

    /// Scroll within the help. The upper bound is clamped at render time (since content and screen size are then known).
    pub fn help_scroll_by(&mut self, delta: i32) {
        self.help_scroll = (self.help_scroll as i32 + delta).max(0) as u16;
    }

    /// The path to copy. In Preview it is the preview target; in Tree it is the entry selected in the tree.
    fn copy_target(&self) -> Option<PathBuf> {
        // Git 変更ハブ表示中は、ツリーの選択ではなく**変更ファイル**のパスをコピー対象にする。
        #[cfg(feature = "git")]
        if self.surface() == crate::keymap::Surface::GitChanges {
            return self.git_view_selected();
        }
        match self.mode {
            Mode::Preview => self.preview_path.clone(),
            Mode::Tree => self.entries.get(self.selected).map(|e| e.path.clone()),
        }
    }

    /// Copy the selected path to the clipboard according to the kind, and show the result in flash (FR-6).
    pub fn copy_path(&mut self, kind: CopyKind) {
        let Some(path) = self.copy_target() else {
            self.flash = Some(tr(self.lang, crate::i18n::Msg::NoCopyTarget).into());
            return;
        };
        let text = copy_text(&path, &self.open_dir, kind);
        match set_clipboard(&text) {
            Ok(()) => {
                self.flash = Some(format!(
                    "{}{text}",
                    tr(self.lang, crate::i18n::Msg::CopiedPrefix)
                ))
            }
            Err(e) => {
                self.flash = Some(format!(
                    "{}{e}",
                    tr(self.lang, crate::i18n::Msg::CopyFailed)
                ))
            }
        }
    }

    /// Test-only: the exact string `copy_path(kind)` would place on the clipboard for the current
    /// copy target (tree selection / preview path / git-changes selection). `None` when there is no
    /// target — the same gate as `copy_path`. Lets E2E assert copy values without the (headless-flaky)
    /// clipboard round-trip.
    #[cfg(test)]
    pub fn copy_string_for(&self, kind: CopyKind) -> Option<String> {
        let path = self.copy_target()?;
        Some(copy_text(&path, &self.open_dir, kind))
    }

    /// Test-only: the exact `@path#L..` string that `preview_copy_selection_ref` (`Y`) would copy.
    #[cfg(test)]
    pub fn selection_ref_string(&self) -> Option<String> {
        self.preview_selection_ref_text()
    }

    /// Get metadata for the selected commit in log/graph/detail. detail uses the already-loaded data, while log/graph
    /// fetch `commit_meta` from the selected commit id. None for non-commits (uncommitted rows, etc.) or out-of-scope surfaces.
    #[cfg(feature = "git")]
    fn current_commit_meta(&self) -> Option<crate::git::CommitMeta> {
        use crate::keymap::Surface;
        match self.surface() {
            Surface::GitDetail => self.git_detail_meta.clone(),
            Surface::GitLog => {
                let id = self.git_log_selected_id()?;
                crate::git::commit_meta(&self.root, &id)
            }
            Surface::GitGraph => {
                let id = self
                    .git_graph_selected_row()
                    .and_then(|r| r.commit.clone())?;
                crate::git::commit_meta(&self.root, &id)
            }
            _ => None,
        }
    }

    /// git log/graph/detail: copy the selected commit's info (short/full hash, subject, full message, author, date)
    /// to the clipboard. If there is no commit, notify via flash.
    #[cfg(feature = "git")]
    pub fn git_copy(&mut self, kind: GitCopyKind) {
        let Some(meta) = self.current_commit_meta() else {
            self.flash = Some(tr(self.lang, crate::i18n::Msg::NoCommitToCopy).into());
            return;
        };
        let text = match kind {
            GitCopyKind::ShortHash => meta.short,
            GitCopyKind::FullHash => meta.id,
            GitCopyKind::Subject => meta.message.lines().next().unwrap_or("").to_string(),
            GitCopyKind::Message => meta.message,
            GitCopyKind::Author => meta.author,
            GitCopyKind::Date => meta.date,
        };
        self.set_clipboard_flash(&text);
    }

    /// branches view: copy the selected branch name to the clipboard.
    #[cfg(feature = "git")]
    pub fn git_copy_branch_name(&mut self) {
        let Some(b) = self.git_branch_selected() else {
            self.flash = Some(tr(self.lang, crate::i18n::Msg::NoCopyTarget).into());
            return;
        };
        let name = b.name;
        self.set_clipboard_flash(&name);
    }

    /// Write to the clipboard and flash success/failure (common processing for copy operations). On success, shows a one-line preview
    /// (multi-line content such as a full message is rounded to the first line + `…` so the footer does not overflow).
    fn set_clipboard_flash(&mut self, text: &str) {
        match set_clipboard(text) {
            Ok(()) => {
                let first = text.lines().next().unwrap_or("");
                let mut preview: String = first.chars().take(60).collect();
                if first.chars().count() > 60 || text.lines().nth(1).is_some() {
                    preview.push('…');
                }
                self.flash = Some(format!(
                    "{}{preview}",
                    tr(self.lang, crate::i18n::Msg::CopiedPrefix)
                ));
            }
            Err(e) => {
                self.flash = Some(format!(
                    "{}{e}",
                    tr(self.lang, crate::i18n::Msg::CopyFailed)
                ))
            }
        }
    }

    // ---- タブ (FR-5) ----

    /// Snapshot the current tree working state.
    fn snapshot_tab(&self) -> TabState {
        TabState {
            root: self.root.clone(),
            open_dir: self.open_dir.clone(),
            entries: self.entries.clone(),
            selected: self.selected,
            show_hidden: self.show_hidden,
            tree_viewport: self.tree_viewport,
            mode: self.mode,
            preview_path: self.preview_path.clone(),
            preview_kind: self.preview_kind.clone(),
            preview_scroll: self.preview_scroll,
            preview_hscroll: self.preview_hscroll,
            preview_viewport: self.preview_viewport,
            preview_byte_top: self.preview_byte_top,
            preview_top_line: self.preview_top_line,
            image_zoom: self.image_zoom,
            image_center: self.image_center,
            pdf_page: self.pdf_page,
            pdf_pages: self.pdf_pages,
            table_cur_row: self.table_cur_row,
            table_cur_col: self.table_cur_col,
            table_top_row: self.table_top_row,
            table_left_col: self.table_left_col,
            preview_cursor_line: self.preview_cursor_line,
            preview_cursor_col: self.preview_cursor_col,
            md_raw: self.md_raw,
            focused_item: self.focused_item,
            fence_zoom: self.fence_zoom,
            fence_center: self.fence_center,
            fence_return: self.fence_return,
            git_view: self.git_view,
            git_view_sel: self.git_view_sel,
            git_view_entries: self.git_view_entries.clone(),
            came_from_git_view: self.came_from_git_view,
            git_log: self.git_log.clone(),
            git_log_sel: self.git_log_sel,
            git_detail: self.git_detail.clone(),
            git_detail_meta: self.git_detail_meta.clone(),
            git_detail_title: self.git_detail_title.clone(),
            git_detail_scroll: self.git_detail_scroll,
            git_detail_hscroll: self.git_detail_hscroll,
            git_detail_viewport: self.git_detail_viewport,
            git_detail_total: self.git_detail_total,
            git_branches: self.git_branches.clone(),
            git_branch_sel: self.git_branch_sel,
            git_branch_filter: self.git_branch_filter.clone(),
            git_branch_filtering: self.git_branch_filtering,
            git_graph: self.git_graph.clone(),
            git_graph_sel: self.git_graph_sel,
            git_graph_base: self.git_graph_base.clone(),
            git_graph_base_label: self.git_graph_base_label.clone(),
            git_graph_visible: self.git_graph_visible.clone(),
            git_graph_legend: self.git_graph_legend.clone(),
            git_graph_hidden: self.git_graph_hidden,
            git_graph_order: self.git_graph_order.clone(),
            // 選択 / 絞り込み / プレビュー検索もタブ毎に保存する(切替で旧タブへ持ち越さない)。
            selection: self.selection.clone(),
            visual_anchor: self.visual_anchor,
            tree_filter: self.tree_filter.clone(),
            filter_input: self.filter_input.clone(),
            filter_pool: self.filter_pool.clone(),
            changed_filter: self.changed_filter,
            preview_search: self.preview_search.clone(),
            search_input: self.search_input.clone(),
            search_matches: self.search_matches.clone(),
            search_idx: self.search_idx,
        }
    }

    /// Save the current working state to the active tab.
    fn save_active(&mut self) {
        let snap = self.snapshot_tab();
        self.tabs[self.active_tab] = snap;
    }

    /// Load the active tab's snapshot into the working fields.
    /// **Also restores that tab's mode/preview** (does not drop to Tree). Images are restored by reloading.
    /// The snapshot is **moved** out of the slot (no deep clone of entries/filter_pool/git vectors):
    /// while a tab is active its slot is never read (tab_label/tab_root use the live App fields)
    /// and every switch path calls save_active before the slot is needed again.
    fn load_active(&mut self) {
        let t = std::mem::take(&mut self.tabs[self.active_tab]);
        self.root = t.root;
        self.open_dir = t.open_dir;
        self.entries = t.entries;
        self.selected = t.selected;
        self.show_hidden = t.show_hidden;
        self.tree_viewport = t.tree_viewport;
        self.mode = t.mode;
        self.preview_path = t.preview_path;
        self.preview_kind = t.preview_kind;
        self.preview_scroll = t.preview_scroll;
        self.preview_hscroll = t.preview_hscroll;
        self.preview_viewport = t.preview_viewport;
        self.preview_byte_top = t.preview_byte_top;
        self.preview_top_line = t.preview_top_line;
        // git オーバーレイもそのタブの状態を復元する(タブごとに git モードを保持)。
        self.git_view = t.git_view;
        self.git_view_sel = t.git_view_sel;
        self.git_view_entries = t.git_view_entries;
        self.came_from_git_view = t.came_from_git_view;
        self.git_log = t.git_log;
        self.git_log_sel = t.git_log_sel;
        self.git_detail = t.git_detail;
        self.git_detail_meta = t.git_detail_meta;
        self.git_detail_title = t.git_detail_title;
        self.git_detail_scroll = t.git_detail_scroll;
        self.git_detail_hscroll = t.git_detail_hscroll;
        self.git_detail_viewport = t.git_detail_viewport;
        self.git_detail_total = t.git_detail_total;
        self.git_branches = t.git_branches;
        self.git_branch_sel = t.git_branch_sel;
        self.git_branch_filter = t.git_branch_filter;
        self.git_branch_filtering = t.git_branch_filtering;
        self.git_graph = t.git_graph;
        self.git_graph_sel = t.git_graph_sel;
        self.git_graph_base = t.git_graph_base;
        self.git_graph_base_label = t.git_graph_base_label;
        self.git_graph_visible = t.git_graph_visible;
        self.git_graph_legend = t.git_graph_legend;
        self.git_graph_hidden = t.git_graph_hidden;
        self.git_graph_order = t.git_graph_order;
        // グラフのブランチ可視ピッカー(モーダル)はタブ跨ぎで持ち越さない: 復元時は閉じておく。
        self.git_graph_picker = false;
        self.git_graph_picker_sel = 0;
        self.git_graph_picker_set.clear();
        self.git_graph_reordered = false;
        // 見出しアウトラインオーバーレイもタブ跨ぎで持ち越さない。
        self.outline_open = false;
        // <details> の開閉状態も文書ごと=タブ跨ぎで持ち越さない。
        self.details_open.clear();
        // 選択 / 絞り込み / プレビュー検索もそのタブの状態を復元する(entries も同時に復元するため
        // visual_anchor(entries 添字)は整合する)。load_active は rebuild_tree を呼ばない。
        self.selection = t.selection;
        self.visual_anchor = t.visual_anchor;
        self.tree_filter = t.tree_filter;
        self.filter_input = t.filter_input;
        self.filter_pool = t.filter_pool;
        self.changed_filter = t.changed_filter;
        self.preview_search = t.preview_search;
        self.search_input = t.search_input;
        self.search_matches = t.search_matches;
        self.search_idx = t.search_idx;
        // `table_search_hits` は `search_matches` から導出される描画用の集合。TabState には持たず
        // (二重管理を避ける)、復元した search_matches から作り直す。表以外は空にする — さもないと
        // 別タブの一致セル座標が居残り、表 renderer(`table_cell_is_hit` を無条件参照)が誤って強調する。
        self.table_search_hits = if matches!(self.preview_kind, Some(PreviewKind::Table { .. })) {
            self.search_matches
                .iter()
                .map(|&(_, r, c)| (r, c))
                .collect()
        } else {
            std::collections::HashSet::new()
        };
        // 装飾キャッシュは持ち越さない (decorated_lines が再生成)。
        self.md_cache = None;
        // 復元した diff プレビューはフォロー由来の印を持ち越さない(セッションはタブ横断の概念でない)。
        self.diff_follow_scope = false;
        // 画像は重い状態(protocol/元画像/GIFフレーム)を持ち越さず、画像系プレビューなら再読込で復元する。
        self.clear_image();
        if let (Some(kind), Some(path)) = (self.preview_kind.clone(), self.preview_path.clone()) {
            // Mermaid(.mmd 画像モード)/全画面フェンスも媒体復元の対象(kind_loads_media)。
            // 漏れると clear_image 後に誰も start_media_load を呼ばず、reload_media_if_changed も
            // mtime 一致で早期 return するため、タブ復帰でテキスト図/偽エラーに劣化していた。
            if self.kind_loads_media(&kind) {
                // SVG/動画サムネ/GIF は別スレッドで読み込み開始(set_* は zoom/center を触らない)。
                // 保存値を即セットしておけば、後から結果が届いても復元したズーム/中心が保たれる。
                // GIF は先頭フレームから再生。
                // PDF は保存ページを start_media_load の前に戻す(その世代でそのページをラスタライズする)。
                self.pdf_page = t.pdf_page.max(1);
                self.pdf_pages = t.pdf_pages;
                self.start_media_load(&kind, &path);
                self.image_zoom = t.image_zoom;
                self.image_center = t.image_center;
                self.image_crop = None;
            }
        }
        // raw ソース表示状態を復元してから windowed を張り直す(raw md は窓読みにするため順序が重要)。
        self.md_raw = t.md_raw;
        // Tab フォーカス/インライン図のズーム/全画面復帰情報はこのタブの保存値へ(前タブの値を
        // 別文書に適用しない)。md_items は次描画の ensure_md_cache がこのタブの文書で再構築し、
        // focused_item はその時に範囲へクランプされる(それまで旧文書の items を参照しないよう空に)。
        self.md_items.clear();
        self.focused_item = t.focused_item;
        self.fence_zoom = t.fence_zoom;
        self.fence_center = t.fence_center;
        self.fence_return = t.fence_return;
        // 大きい Code/Text(＋raw の Markdown/Mermaid)なら ウィンドウ読みリーダを張り直す(byte_top は上で復元済み)。
        self.setup_windowed();
        // windowed プレビューの 2D キャレットを復元(選択は持ち越さない)。範囲は次描画/移動でクランプされる。
        self.preview_cursor_line = t.preview_cursor_line;
        self.preview_cursor_col = t.preview_cursor_col;
        self.preview_visual_anchor = None;
        self.preview_visual_linewise = false;
        // CSV/TSV テーブルは本体を再パースし、保存済みカーソル/スクロールを復元してクランプする。
        self.load_table();
        self.table_cur_row = t.table_cur_row;
        self.table_cur_col = t.table_cur_col;
        self.table_top_row = t.table_top_row;
        self.table_left_col = t.table_left_col;
        self.clamp_table_cursor();

        // 切替でアクティブになったタブを**ディスクから再読み込み**する。ファイル監視はアクティブな
        // root しか見ていない(rewatch)ため、裏に居た間の外部変更(ファイルの作成/削除/リネーム・git
        // 状態・変更ガター/diff)がスナップショットのまま古い。fs イベント時と同じ refresh_fs 経路を
        // 通して、ツリー再構築・git status・diff/gutter キャッシュ・変更フィルタ・git ビュー・プレビュー
        // 再読込を一括で追従させる。`false`=重い ignore セット(gitignore)は作り直さずキャッシュ保持
        // (root が変われば次の描画の refresh_git_if_needed が workdir 単位キャッシュで面倒を見る＝
        // 巨大 repo の性能対策[[git-watch-feedback-loop-perf]]を壊さない)。プレビューの表示位置は
        // reload_preview が保持する(スクロール/ズーム/テーブルカーソル)。
        // タブは背面に居た間 fs 監視の対象外なので、そのタブの git status は外部変更を取りこぼして
        // いる可能性がある(同一 repo の別タブなら workdir 単位キャッシュで流用され陳腐化が居残る)。
        // 切替=再検証の節目として dirty を立て、次の描画の refresh_git_if_needed に取り直させる
        // (back_to_tree と同型。h/l 連打は dirty を立てないので最適化は保たれる)。
        self.git_status_dirty = true;
        let _ = self.refresh_fs(false);
    }

    pub fn tab_count(&self) -> usize {
        self.tabs.len()
    }

    pub fn active_tab_index(&self) -> usize {
        self.active_tab
    }

    /// Display name of tab `i`. While showing Tree, the **root directory name**; while showing Preview/image, etc.,
    /// the **preview target's file name**. The active tab references the latest working state (App fields),
    /// while inactive tabs reference the snapshot (`TabState`) (since saving happens only on switch).
    pub fn tab_label(&self, i: usize) -> String {
        // (mode, root, preview_path) をアクティブ/非アクティブで使い分ける。
        let (mode, root, preview) = if i == self.active_tab {
            (self.mode, self.root.as_path(), self.preview_path.as_deref())
        } else if let Some(t) = self.tabs.get(i) {
            (t.mode, t.root.as_path(), t.preview_path.as_deref())
        } else {
            return String::new();
        };
        let path = match mode {
            Mode::Preview => preview.unwrap_or(root), // 念のため preview 無しは root へ
            Mode::Tree => root,
        };
        path.file_name()
            .map(|n| n.to_string_lossy().into_owned())
            .unwrap_or_else(|| path.display().to_string())
    }

    /// New tab. Create another tree context starting from the current root and switch to it.
    /// The new tab starts in Tree (since it has no preview target). The source tab's preview is
    /// preserved by `save_active`, so it is not lost.
    pub fn tab_new(&mut self) -> Result<()> {
        self.save_active();
        // 見出しアウトラインオーバーレイは新タブへ持ち越さない(空タブ上の空オーバーレイを防ぐ)。
        self.outline_open = false;
        let root = self.root.clone();
        self.open_dir = root.clone();
        self.root = root;
        self.selected = 0;
        self.entries.clear();
        self.rebuild_tree()?;
        // snapshot 前に Tree へリセットする (snapshot がプレビュー状態も取り込むため順序が重要)。
        self.mode = Mode::Tree;
        self.clear_image();
        self.preview_path = None;
        self.preview_kind = None;
        self.preview_scroll = 0;
        self.preview_hscroll = 0;
        self.preview_byte_top = 0;
        self.preview_top_line = 0;
        self.preview_win = None;
        self.win_cache = None;
        self.preview_total_lines = None;
        self.md_cache = None;
        // 新規タブは md フォーカス/インライン図ズームも素の状態から(TabState 複製対象)。
        self.md_items.clear();
        self.focused_item = None;
        self.fence_zoom = 1.0;
        self.fence_center = (0.5, 0.5);
        self.fence_return = None;
        // 新規タブは git オーバーレイ無しの素の Tree から始める(現タブの git 状態は save_active で保持済み)。
        self.git_view = false;
        self.git_view_sel = 0;
        self.git_view_entries.clear();
        self.came_from_git_view = false;
        self.git_log = None;
        self.git_log_sel = 0;
        self.git_detail = None;
        self.git_detail_meta = None;
        self.git_detail_title = None;
        self.git_detail_scroll = 0;
        self.git_detail_hscroll = 0;
        self.git_detail_viewport = 0;
        self.git_detail_total = 0;
        self.git_branches = None;
        self.git_branch_sel = 0;
        self.git_branch_filter.clear();
        self.git_branch_filtering = false;
        self.git_graph = None;
        self.git_graph_sel = 0;
        // 新規タブはグラフの装飾状態(基準/凡例/表示ブランチ/優先順)とピッカーも素から始める
        // (現タブのこれらは直前の save_active で TabState に保持済み)。次に開くとき再導出される。
        self.git_graph_base = None;
        self.git_graph_base_label = None;
        self.git_graph_visible.clear();
        self.git_graph_legend.clear();
        self.git_graph_hidden = 0;
        self.git_graph_order.clear();
        self.git_graph_picker = false;
        self.git_graph_picker_sel = 0;
        self.git_graph_picker_set.clear();
        self.git_graph_reordered = false;
        // 新規タブは選択 / 絞り込み / プレビュー検索を空から始める
        // (現タブのこれらは直前の save_active で TabState に保持済み)。
        self.selection.clear();
        self.visual_anchor = None;
        self.clear_filter_state();
        self.search_clear();
        self.tabs.push(self.snapshot_tab());
        self.active_tab = self.tabs.len() - 1;
        // タブ集合が変わる節目でセッションを保存する(異常終了でも直近のタブ構成が残る)。
        self.save_session();
        Ok(())
    }

    /// `Ctrl-t` in the tree: open the entry under the cursor in a new (foreground) tab, leaving the
    /// current tab untouched. A file opens as a preview; a directory becomes the new tab's root
    /// (mirroring `l`). No-op when the tree is empty.
    pub fn tab_new_from_selection(&mut self) -> Result<()> {
        let Some(entry) = self.entries.get(self.selected).cloned() else {
            return Ok(());
        };
        self.tab_new()?; // fresh Tree tab at the current root, now active
        if entry.is_dir {
            // Descend into the folder in the new tab (same as `l`); root changes, so drop stale state.
            self.clear_for_root_change();
            self.root = entry.path;
            self.entries.clear();
            self.selected = 0;
            self.rebuild_tree()?;
        } else {
            // Reveal the file (so returning with `q` lands on it), then preview it.
            let _ = self.reveal_path_deep(&entry.path);
            self.enter_preview(&entry.path);
        }
        self.save_session();
        Ok(())
    }

    /// Close the active tab. The last one is not closed.
    pub fn tab_close(&mut self) {
        if self.tabs.len() <= 1 {
            self.flash = Some(tr(self.lang, crate::i18n::Msg::CantCloseLastTab).into());
            return;
        }
        self.tabs.remove(self.active_tab);
        if self.active_tab >= self.tabs.len() {
            self.active_tab = self.tabs.len() - 1;
        }
        self.load_active();
        self.save_session();
    }

    /// Move tabs relatively (dir: +1=next / -1=previous). Wraps at the ends.
    pub fn tab_cycle(&mut self, dir: i32) {
        self.tab_list = false; // 一覧から [/] で切替えた場合も一覧は用済み
        if self.tabs.len() <= 1 {
            return;
        }
        self.save_active();
        let n = self.tabs.len() as i32;
        self.active_tab = (self.active_tab as i32 + dir).rem_euclid(n) as usize;
        self.load_active();
        self.save_session();
    }

    /// Select a tab by number (0-based). Out-of-range or the same tab is ignored.
    pub fn tab_goto(&mut self, i: usize) {
        self.tab_list = false; // 一覧(1-9/Enter)からの切替で一覧を閉じる
        if i >= self.tabs.len() || i == self.active_tab {
            return;
        }
        self.save_active();
        self.active_tab = i;
        self.load_active();
        self.save_session();
    }

    // --- 見出しアウトラインオーバーレイ (`o` in a Markdown preview) --------
    pub fn is_outline(&self) -> bool {
        self.outline_open
    }

    /// Heading outline of the current Markdown preview: `(level, text, decorated-line-index)` in
    /// document order. Built from the decorated cache, so it reflects exactly what is on screen
    /// (front matter stripped, footnotes/inline-HTML processed). Empty for non-Markdown previews.
    pub(crate) fn md_outline(&self) -> Vec<(u8, String, usize)> {
        let Some(c) = &self.md_cache else {
            return Vec::new();
        };
        c.anchors
            .iter()
            .filter_map(|(_slug, line)| {
                let l = c.lines.get(*line)?;
                let text = crate::preview::markdown::heading_text(l)?;
                let level = crate::preview::markdown::heading_level_hint(l, c.lines.get(*line + 1));
                Some((level, text, *line))
            })
            .collect()
    }

    /// `o`: open/close the heading outline. Opening selects the heading of the current section
    /// (the last one at or above the viewport top). Flashes and stays closed if there are no
    /// headings (e.g. a non-Markdown preview or a document without any).
    pub fn toggle_outline(&mut self) {
        if self.outline_open {
            self.outline_open = false;
            return;
        }
        let items = self.md_outline();
        if items.is_empty() {
            self.flash = Some(tr(self.lang, crate::i18n::Msg::OutlineEmpty).into());
            return;
        }
        // Select the current section: the last heading at or above the top of the view.
        let top = self.md_top_logical_line().unwrap_or(0);
        self.outline_sel = items
            .iter()
            .rposition(|(_, _, line)| *line <= top)
            .unwrap_or(0);
        self.outline_open = true;
    }

    pub fn outline_sel(&self) -> usize {
        self.outline_sel
    }

    pub fn outline_move(&mut self, delta: i32) {
        let n = self.md_outline().len();
        if n == 0 {
            return;
        }
        self.outline_sel = (self.outline_sel as i32 + delta).rem_euclid(n as i32) as usize;
    }

    /// Enter in the outline: scroll the preview to the selected heading and close the overlay.
    pub fn outline_jump(&mut self) {
        let line = self.md_outline().get(self.outline_sel).map(|(_, _, l)| *l);
        self.outline_open = false;
        if let Some(line) = line {
            let (row, _) = self.md_visual_span(line);
            self.preview_scroll = row.min(u16::MAX as usize) as u16;
        }
    }

    // --- タブ一覧オーバーレイ (`T`) ----------------------------------------
    pub fn is_tab_list(&self) -> bool {
        self.tab_list
    }
    /// `T`: open/close the tab list. Opening puts the selection on the active tab.
    pub fn toggle_tab_list(&mut self) {
        self.tab_list = !self.tab_list;
        if self.tab_list {
            self.tab_list_sel = self.active_tab;
        }
    }
    pub fn tab_list_sel(&self) -> usize {
        self.tab_list_sel
    }
    pub fn tab_list_move(&mut self, delta: i32) {
        let n = self.tabs.len();
        if n == 0 {
            return;
        }
        self.tab_list_sel = (self.tab_list_sel as i32 + delta).rem_euclid(n as i32) as usize;
    }
    /// Enter in the list: switch to the selected tab (closing the list; same tab = just close).
    pub fn tab_list_activate(&mut self) {
        let i = self.tab_list_sel;
        self.tab_list = false;
        self.tab_goto(i);
    }
    /// `w` in the list: close the **selected** tab (the list stays open, like the bookmark list).
    /// Closing the active tab switches to a neighbor; the last tab refuses with a flash.
    pub fn tab_list_close_selected(&mut self) {
        if self.tabs.len() <= 1 {
            self.flash = Some(tr(self.lang, crate::i18n::Msg::CantCloseLastTab).into());
            return;
        }
        let i = self.tab_list_sel;
        if i == self.active_tab {
            self.tab_close();
        } else {
            self.tabs.remove(i);
            if self.active_tab > i {
                self.active_tab -= 1;
            }
        }
        self.tab_list_sel = self.tab_list_sel.min(self.tabs.len() - 1);
        self.save_session();
    }
    /// Root directory of tab `i` (for the tab list's path column).
    pub fn tab_root(&self, i: usize) -> std::path::PathBuf {
        if i == self.active_tab {
            self.root.clone()
        } else {
            self.tabs
                .get(i)
                .map(|t| t.root.clone())
                .unwrap_or_else(|| self.root.clone())
        }
    }

    /// Format a path into a display string using the current path_style (shared by the tree/preview title).
    pub fn format_path(&self, path: &Path) -> String {
        match self.path_style {
            PathStyle::Full => path.display().to_string(),
            PathStyle::Home => home_relative(path),
            PathStyle::Relative => rel_to_open(&self.open_dir, path),
        }
    }
}

/// Common helper that moves a list cursor by delta and returns it clamped to `[0, len-1]`.
/// Even if the caller (`g`/`G`/Home/End) passes `delta=i32::MIN/MAX`, the computation is done in i64, so it
/// does not panic on overflow (the plain `as i32 + delta` addition used to crash in debug).
/// `len==0` returns 0. The behavior is unchanged from the previous `(cur as i32 + delta).clamp(0, len-1)`.
fn clamp_cursor(cur: usize, delta: i32, len: usize) -> usize {
    if len == 0 {
        return 0;
    }
    let last = len.saturating_sub(1) as i64;
    (cur as i64).saturating_add(delta as i64).clamp(0, last) as usize
}

/// Whether a span is a Markdown link (blue underline). Since konoma's StyleSheet.link()=underline+blue draws them,
/// these two conditions decide it (code/headings/rules have different colors, so no false positives).
fn is_link_span(span: &Span<'static>) -> bool {
    use ratatui::style::{Color, Modifier};
    span.style.add_modifier.contains(Modifier::UNDERLINED) && span.style.fg == Some(Color::Blue)
}

/// Scan collapsed decorated lines for Tab-cycle items (links / task checkboxes / code-block
/// headers) in document order. `targets` are the link URLs recovered by `collapse_links`, in the
/// same order the link spans appear. `fence_ords` are the **source** ordinals of the rendered
/// mermaid placements in order (from `ImagePlacement::fence_ord`) — the k-th sentinel takes the
/// k-th value. Shared by the cache build and the test-only decorate path.
/// Slugify a heading's text the way GitHub does for `#anchor` links: lowercase, drop punctuation
/// except `-`/`_`, spaces → `-` (consecutive spaces → consecutive `-`, not collapsed). Unicode
/// letters/digits are kept (CJK headings anchor too). Used to match `[x](#slug)` link targets.
fn github_slug(text: &str) -> String {
    let mut s = String::new();
    for c in text.trim().chars() {
        if c.is_alphanumeric() {
            s.extend(c.to_lowercase());
        } else if c == ' ' {
            s.push('-');
        } else if c == '-' || c == '_' {
            s.push(c);
        }
    }
    s
}

/// Build the in-page anchor map (slug → decorated logical-line index) from the rendered lines, in
/// document order, with GitHub's duplicate-slug disambiguation (`slug`, `slug-1`, `slug-2`, …).
fn compute_md_anchors(lines: &[Line<'static>]) -> Vec<(String, usize)> {
    use std::collections::HashMap;
    let mut anchors = Vec::new();
    let mut counts: HashMap<String, usize> = HashMap::new();
    for (i, line) in lines.iter().enumerate() {
        let Some(text) = crate::preview::markdown::heading_text(line) else {
            continue;
        };
        let base = github_slug(&text);
        if base.is_empty() {
            continue;
        }
        let n = counts.entry(base.clone()).or_insert(0);
        let slug = if *n == 0 {
            base.clone()
        } else {
            format!("{base}-{n}")
        };
        *n += 1;
        anchors.push((slug, i));
    }
    anchors
}

fn build_md_items(
    lines: &[Line<'static>],
    targets: &[String],
    fence_ords: &[usize],
) -> Vec<MdItem> {
    let mut items = Vec::new();
    let mut k = 0usize;
    for (li, line) in lines.iter().enumerate() {
        for span in &line.spans {
            if is_link_span(span) {
                let target = targets.get(k).cloned().unwrap_or_default();
                items.push(MdItem {
                    line: li,
                    kind: MdItemKind::Link { target },
                });
                k += 1;
            } else if crate::preview::markdown::is_task_span(span) {
                if let Some(state) =
                    crate::preview::markdown::task_span_state(span.content.as_ref())
                {
                    items.push(MdItem {
                        line: li,
                        kind: MdItemKind::Task { state },
                    });
                }
            } else if crate::preview::markdown::is_code_header_span(span) {
                items.push(MdItem {
                    line: li,
                    kind: MdItemKind::CodeBlock,
                });
            } else if crate::preview::markdown::is_mermaid_header_span(span) {
                let seen = items
                    .iter()
                    .filter(|it| matches!(it.kind, MdItemKind::MermaidFence { .. }))
                    .count();
                // 序数は placement 由来の**ソース順**(loading/失敗フェンス込みの通し番号)。
                // 描画済み番兵の個数で代用すると、上流に番兵を出さないフェンス(テキスト降格/
                // loading 中)があるとき Enter のソース再抽出とずれて**別の図**が開く。
                // fence_ords が無い経路(テスト互換)のみ従来の計数にフォールバック。
                let ordinal = fence_ords.get(seen).copied().unwrap_or(seen);
                items.push(MdItem {
                    line: li,
                    kind: MdItemKind::MermaidFence { ordinal },
                });
            } else if crate::preview::markdown::is_details_header_span(span) {
                let ordinal = items
                    .iter()
                    .filter(|it| matches!(it.kind, MdItemKind::Details { .. }))
                    .count();
                items.push(MdItem {
                    line: li,
                    kind: MdItemKind::Details { ordinal },
                });
            }
        }
    }
    items
}

/// Apply the focus inversion to one decorated line. `ordinal` = index of the focused marker span
/// within this line (counting link/task/code-header spans in order); `whole_line`=code-block
/// header (all spans inverted — one line, a clear focus cue). Other lines pass through untouched.
fn invert_focused_line(line: &Line<'static>, ordinal: usize, whole_line: bool) -> Line<'static> {
    use ratatui::style::Modifier;
    let style = line.style;
    let mut seen = 0usize;
    let spans = line
        .spans
        .iter()
        .cloned()
        .map(|mut span| {
            if whole_line {
                span.style = span.style.add_modifier(Modifier::REVERSED);
            } else if is_link_span(&span)
                || crate::preview::markdown::is_task_span(&span)
                || crate::preview::markdown::is_code_header_span(&span)
                || crate::preview::markdown::is_mermaid_header_span(&span)
                || crate::preview::markdown::is_details_header_span(&span)
            {
                if seen == ordinal {
                    span.style = span.style.add_modifier(Modifier::REVERSED);
                }
                seen += 1;
            }
            span
        })
        .collect::<Vec<_>>();
    Line::from(spans).style(style)
}

/// Fold the accompanying URL of the "label (URL)" that tui-markdown emits, leaving **only the label** in link style (blue underline,
/// with a leading link icon when `icons=true`). The URLs are collected in order into `targets` and returned (hidden destinations).
/// Pattern: `[label]` `" ("` `[URL(blue underline)]` `")"`. Spans that do not match are passed through unchanged.
fn collapse_links(lines: Vec<Line<'static>>, icons: bool) -> (Vec<Line<'static>>, Vec<String>) {
    use ratatui::style::{Color, Modifier, Style};
    let link_style = Style::new()
        .fg(Color::Blue)
        .add_modifier(Modifier::UNDERLINED);
    let mut out = Vec::with_capacity(lines.len());
    let mut targets = Vec::new();
    for line in lines {
        let style = line.style;
        let spans = line.spans;
        let n = spans.len();
        let mut new: Vec<Span<'static>> = Vec::with_capacity(n);
        let mut i = 0;
        while i < n {
            // 表セル由来の「ラベル＋隠しターゲット」ペア(markdown::render_table が生成):
            // ラベルはそのまま残し(幅を変えない=表の桁揃え維持のためアイコンも付けない)、
            // 隠しスパンを取り除いて URL を targets へ回収する(Tab/Enter は通常リンクと同じ)。
            if i + 1 < n
                && is_link_span(&spans[i])
                && crate::preview::markdown::is_hidden_link_target(&spans[i + 1])
            {
                targets.push(spans[i + 1].content.to_string());
                new.push(spans[i].clone());
                i += 2;
                continue;
            }
            let is_link_pattern = i + 2 < n
                && spans[i + 1].content.as_ref() == " ("
                && is_link_span(&spans[i + 2])
                && spans.get(i + 3).is_some_and(|s| s.content.starts_with(')'));
            if is_link_pattern {
                let label = spans[i].content.as_ref();
                targets.push(spans[i + 2].content.to_string());
                let text = if icons {
                    format!("{} {label}", crate::ui::icons::link_icon())
                } else {
                    label.to_string()
                };
                new.push(Span::styled(text, link_style));
                // 閉じ括弧 ")" の後ろに続く文字(句読点等)は保持する。
                let closer = spans[i + 3].content.as_ref();
                if closer.len() > 1 {
                    new.push(Span::styled(closer[1..].to_string(), spans[i + 3].style));
                }
                i += 4;
            } else {
                new.push(spans[i].clone());
                i += 1;
            }
        }
        out.push(Line::from(new).style(style));
    }
    (out, targets)
}

/// Trim trailing punctuation from a matched URL run, GFM-style: drop a trailing run of
/// `? ! . , : * _ ~ ' "` and any `)` that has no matching `(` inside the run (iteratively).
fn trim_url_end(s: &str) -> &str {
    let mut end = s.len();
    loop {
        let sub = &s[..end];
        let Some(last) = sub.chars().last() else {
            break;
        };
        if "?!.,:*_~'\"".contains(last) {
            end -= last.len_utf8();
            continue;
        }
        if last == ')' && sub.matches(')').count() > sub.matches('(').count() {
            end -= 1;
            continue;
        }
        break;
    }
    &s[..end]
}

/// A character that ends a bare-URL run: whitespace, `<`, or CJK/fullwidth punctuation. The last set
/// matters for konoma's CJK audience — Japanese text often abuts a URL with no ASCII space
/// (`https://x.example、と`), and GFM's "stop only at whitespace/`<`" would swallow the trailing
/// characters into the link. Stopping at these keeps the URL clean.
fn is_url_stop(c: char) -> bool {
    c.is_whitespace()
        || c == '<'
        || matches!(
            c,
            '、' | '。'
                | '，'
                | '．'
                | '！'
                | '？'
                | '；'
                | '：'
                | '（'
                | '）'
                | '「'
                | '」'
                | '『'
                | '』'
                | '【'
                | '】'
                | '〈'
                | '〉'
                | '《'
                | '》'
                | '…'
                | '・'
                | '〜'
                | '”'
                | '“'
        )
}

/// Match a bare URL autolink at the start of `rest` (`http://…`, `https://…`, or `www.…`). Returns
/// the matched byte length and the target to open (`www.` gains an `http://` prefix). The run stops
/// at whitespace / `<` / CJK punctuation (`is_url_stop`), then trailing punctuation is trimmed. None
/// if `rest` does not start a URL.
fn match_bare_url(rest: &str) -> Option<(usize, String)> {
    let is_www = rest.starts_with("www.");
    if !(is_www || rest.starts_with("http://") || rest.starts_with("https://")) {
        return None;
    }
    let run_end = rest.find(is_url_stop).unwrap_or(rest.len());
    let run = trim_url_end(&rest[..run_end]);
    // Need a host after the scheme (or after `www.` a further alphanumeric char).
    let valid = if is_www {
        run.len() > 4 && run[4..].contains(|c: char| c.is_ascii_alphanumeric())
    } else {
        run.find("://").is_some_and(|p| run.len() > p + 3)
    };
    if !valid {
        return None;
    }
    let target = if is_www {
        format!("http://{run}")
    } else {
        run.to_string()
    };
    Some((run.len(), target))
}

fn is_email_local(c: char) -> bool {
    c.is_ascii_alphanumeric() || matches!(c, '.' | '_' | '%' | '+' | '-')
}
fn is_email_domain(c: char) -> bool {
    c.is_ascii_alphanumeric() || matches!(c, '.' | '-')
}

/// Match a bare email autolink at the start of `rest` (`local@domain.tld`). Returns the matched byte
/// length and a `mailto:` target. Requires a non-empty local part, an `@`, and a domain with a dot
/// whose last label is ≥2 ASCII letters. Trailing `.`/`-` are trimmed from the domain.
fn match_bare_email(rest: &str) -> Option<(usize, String)> {
    let local_len: usize = rest
        .chars()
        .take_while(|&c| is_email_local(c))
        .map(char::len_utf8)
        .sum();
    if local_len == 0 || !rest[local_len..].starts_with('@') {
        return None;
    }
    let after_at = &rest[local_len + 1..];
    let mut dom_len: usize = after_at
        .chars()
        .take_while(|&c| is_email_domain(c))
        .map(char::len_utf8)
        .sum();
    // Trim trailing '.'/'-' from the domain.
    while dom_len > 0 && matches!(after_at.as_bytes()[dom_len - 1], b'.' | b'-') {
        dom_len -= 1;
    }
    let domain = &after_at[..dom_len];
    let tld_ok = domain
        .rsplit_once('.')
        .is_some_and(|(_, tld)| tld.len() >= 2 && tld.chars().all(|c| c.is_ascii_alphabetic()));
    if !tld_ok {
        return None;
    }
    let end = local_len + 1 + dom_len;
    Some((end, format!("mailto:{}", &rest[..end])))
}

/// Find bare autolinkable spans (GFM autolink literals) in `text`: `http(s)://…`, `www.…`, and
/// `local@domain.tld` emails. Returns `(start_byte, end_byte, target)` in document order,
/// non-overlapping. A pragmatic subset of GFM §6.9: a match may start only at the beginning or after
/// a non-alphanumeric byte, the run stops at whitespace/`<`, and trailing punctuation (plus
/// unbalanced `)`) is trimmed. `www.` gets an `http://` prefix; emails a `mailto:` prefix.
fn find_bare_links(text: &str) -> Vec<(usize, usize, String)> {
    let bytes = text.as_bytes();
    let n = bytes.len();
    let mut out: Vec<(usize, usize, String)> = Vec::new();
    let mut i = 0usize;
    while i < n {
        let boundary_ok = i == 0 || !bytes[i - 1].is_ascii_alphanumeric();
        if boundary_ok {
            let rest = &text[i..];
            if let Some((len, target)) = match_bare_url(rest).or_else(|| match_bare_email(rest)) {
                out.push((i, i + len, target));
                i += len.max(1);
                continue;
            }
        }
        i += text[i..].chars().next().map_or(1, char::len_utf8);
    }
    out
}

/// Post-pass over collapsed lines: turn bare URLs/emails in plain-text spans into link spans, and
/// interleave their targets into `targets` in document order (so `build_md_items` pairs each link
/// span with the right URL). Skips spans that already carry a link, a background (inline code / code
/// fence content), or a konoma sentinel (task / code-header / mermaid / hidden-target) — matching
/// GitHub, which never auto-links inside code.
fn autolink_bare_urls(
    lines: Vec<Line<'static>>,
    in_targets: Vec<String>,
) -> (Vec<Line<'static>>, Vec<String>) {
    use ratatui::style::{Color, Modifier, Style};
    let link_style = Style::new()
        .fg(Color::Blue)
        .add_modifier(Modifier::UNDERLINED);
    let mut out_lines = Vec::with_capacity(lines.len());
    let mut out_targets = Vec::new();
    let mut ti = 0usize;
    for line in lines {
        // Code-block lines never auto-link (a URL in a fence stays literal). Keep as-is; for any
        // existing link span (none in practice) carry its target through 1:1 so the k-th link span
        // in `out_lines` still maps to `out_targets[k]` — no drift if a code line ever holds a link.
        if crate::preview::markdown::is_code_line(&line) {
            for span in &line.spans {
                if is_link_span(span) {
                    out_targets.push(in_targets.get(ti).cloned().unwrap_or_default());
                    ti += 1;
                }
            }
            out_lines.push(line);
            continue;
        }
        let style = line.style;
        let mut new: Vec<Span<'static>> = Vec::with_capacity(line.spans.len());
        for span in line.spans {
            // Existing link span → keep as-is; it owns the next input target (preserve order).
            if is_link_span(&span) {
                out_targets.push(in_targets.get(ti).cloned().unwrap_or_default());
                ti += 1;
                new.push(span);
                continue;
            }
            // Never auto-link inside code (inline code / bg-filled code) or over a konoma sentinel.
            if span.style.bg.is_some()
                || crate::preview::markdown::is_inline_code_span(&span)
                || crate::preview::markdown::is_task_span(&span)
                || crate::preview::markdown::is_code_header_span(&span)
                || crate::preview::markdown::is_mermaid_header_span(&span)
                || crate::preview::markdown::is_hidden_link_target(&span)
            {
                new.push(span);
                continue;
            }
            let text = span.content.into_owned();
            let matches = find_bare_links(&text);
            if matches.is_empty() {
                new.push(Span::styled(text, span.style));
                continue;
            }
            let mut pos = 0usize;
            for (s, e, url) in matches {
                if s > pos {
                    new.push(Span::styled(text[pos..s].to_string(), span.style));
                }
                new.push(Span::styled(text[s..e].to_string(), link_style));
                out_targets.push(url);
                pos = e;
            }
            if pos < text.len() {
                new.push(Span::styled(text[pos..].to_string(), span.style));
            }
        }
        out_lines.push(Line::from(new).style(style));
    }
    (out_lines, out_targets)
}

/// Replace `:shortcode:` runs in `text` with Unicode emoji (gemoji names, e.g. `:rocket:` → 🚀).
/// Returns `None` when nothing changed (so the caller reuses the original span untouched). A
/// shortcode with no Unicode mapping (GitHub-custom like `:shipit:`) and non-shortcode `:` (times,
/// ratios) are left exactly as they were.
fn replace_emoji_shortcodes(text: &str) -> Option<String> {
    if !text.contains(':') {
        return None;
    }
    let mut out = String::new();
    let mut changed = false;
    let mut rest = text;
    while let Some(start) = rest.find(':') {
        out.push_str(&rest[..start]);
        let after = &rest[start + 1..];
        if let Some(end) = after.find(':') {
            let code = &after[..end];
            let looks_like_code = !code.is_empty()
                && code
                    .chars()
                    .all(|c| c.is_ascii_alphanumeric() || matches!(c, '_' | '+' | '-'));
            if looks_like_code {
                if let Some(e) = emojis::get_by_shortcode(code) {
                    out.push_str(e.as_str());
                    changed = true;
                    rest = &after[end + 1..];
                    continue;
                }
            }
            // Not a known shortcode: keep this `:` and resume scanning right after it.
            out.push(':');
            rest = after;
        } else {
            out.push(':');
            out.push_str(after);
            rest = "";
        }
    }
    out.push_str(rest);
    changed.then_some(out)
}

/// Post-pass over decorated Markdown lines: convert `:shortcode:` emoji to Unicode in plain-text
/// spans. Skips spans that carry a background (inline code / code fence), a link, or a konoma
/// sentinel (task / code-header / mermaid / hidden-target) — matching GitHub, which never converts
/// shortcodes inside code, and keeping Tab-item spans byte-stable.
fn substitute_emoji(lines: Vec<Line<'static>>) -> Vec<Line<'static>> {
    lines
        .into_iter()
        .map(|line| {
            // Code-block lines keep their `:shortcode:` literal (a fence is verbatim).
            if crate::preview::markdown::is_code_line(&line) {
                return line;
            }
            let style = line.style;
            let spans = line
                .spans
                .into_iter()
                .map(|span| {
                    if span.style.bg.is_some()
                        || is_link_span(&span)
                        || crate::preview::markdown::is_inline_code_span(&span)
                        || crate::preview::markdown::is_task_span(&span)
                        || crate::preview::markdown::is_code_header_span(&span)
                        || crate::preview::markdown::is_mermaid_header_span(&span)
                        || crate::preview::markdown::is_hidden_link_target(&span)
                    {
                        return span;
                    }
                    match replace_emoji_shortcodes(span.content.as_ref()) {
                        Some(new) => Span::styled(new, span.style),
                        None => span,
                    }
                })
                .collect::<Vec<_>>();
            Line::from(spans).style(style)
        })
        .collect()
}

/// Within line `line` (multiple colored spans), highlight the parts matching `query` (substring, case-insensitive)
/// in a highlighter style (background color + black text + bold). Even for matches crossing span boundaries, each span is split at the
/// match boundaries and the background is applied (the original fg/bold/italic are kept). If the byte length changes when lowercasing
/// (multibyte), it does nothing to avoid mis-slicing.
/// When `current_occurrence`=Some(occurrence rank within the line, 0-based), **only that one occurrence is orange**, and
/// the others are yellow (vim's CurSearch/Search style; `n`/`N` change the color of only the selected occurrence). None means all yellow.
/// Since occurrences are identified by rank rather than column (byte position), the current match stays stable even if the byte sequence shifts from tab expansion (#14).
fn highlight_query_in_line(
    line: Line<'static>,
    query: &str,
    current_occurrence: Option<usize>,
) -> Line<'static> {
    use ratatui::style::{Color, Modifier};
    if query.is_empty() {
        return line;
    }
    let full: String = line.spans.iter().map(|s| s.content.as_ref()).collect();
    let lower = full.to_lowercase();
    let q = query.to_lowercase();
    if lower.len() != full.len() {
        return line; // 非 ASCII でバイト長が変わる場合は安全側で強調なし
    }
    // 一致バイト範囲を収集。
    let mut ranges: Vec<(usize, usize)> = Vec::new();
    let mut i = 0;
    while let Some(rel) = lower[i..].find(&q) {
        let s = i + rel;
        let e = s + q.len();
        ranges.push((s, e));
        i = e;
    }
    if ranges.is_empty() {
        return line;
    }
    let style = line.style;
    let mut out: Vec<Span<'static>> = Vec::new();
    let mut pos = 0usize; // full 内のバイト位置
    for span in line.spans {
        let text = span.content.into_owned();
        let span_start = pos;
        let span_end = pos + text.len();
        // この span 内の分割点(span 端＋一致境界)。
        let mut points = vec![span_start, span_end];
        for (s, e) in &ranges {
            if *s > span_start && *s < span_end {
                points.push(*s);
            }
            if *e > span_start && *e < span_end {
                points.push(*e);
            }
        }
        points.sort_unstable();
        points.dedup();
        for w in points.windows(2) {
            let (a, b) = (w[0], w[1]);
            if let Some(seg) = text.get(a - span_start..b - span_start) {
                if seg.is_empty() {
                    continue;
                }
                // この区間が属する一致範囲の出現順位(あれば)。その順位が current_occurrence
                // なら現在の出現=オレンジ、他の一致は黄色。範囲外は素のまま。
                let hit = ranges.iter().position(|(s, e)| a >= *s && b <= *e);
                let st = if let Some(idx) = hit {
                    let bg = if current_occurrence == Some(idx) {
                        Color::Rgb(0xff, 0x8c, 0x00) // 現在の出現
                    } else {
                        Color::Yellow // 他の出現
                    };
                    span.style
                        .bg(bg)
                        .fg(Color::Black)
                        .add_modifier(Modifier::BOLD)
                } else {
                    span.style
                };
                out.push(Span::styled(seg.to_string(), st));
            }
        }
        pos = span_end;
    }
    Line::from(out).style(style)
}

/// Editor-style git change status of one line in the previewed (working-tree) file, for the left gutter.
#[derive(Clone, Copy, PartialEq, Eq, Debug)]
enum GutterMark {
    /// Newly inserted line (no matching removal): green bar.
    Added,
    /// Line replaced/edited (part of a hunk that also removed lines): blue bar.
    Modified,
    /// One or more lines were removed just above this line: red boundary marker.
    Deleted,
}

// Gutter marker colors, matching Zed: green added, amber modified, red deleted.
const GUTTER_ADDED: ratatui::style::Color = ratatui::style::Color::Rgb(87, 171, 90);
const GUTTER_MODIFIED: ratatui::style::Color = ratatui::style::Color::Rgb(216, 166, 74);
const GUTTER_DELETED: ratatui::style::Color = ratatui::style::Color::Rgb(199, 84, 80);

/// Derive a per-new-line git gutter map from a file's working-tree diff. Keyed by 1-based new-file line
/// number. A change block is a maximal run of Added/Removed lines (Context breaks it): with additions it
/// marks each added line Modified (if the block also removed lines) or Added (pure insertion); a
/// pure-deletion block marks the following line Deleted (or the preceding line if the deletion is at EOF).
fn gutter_marks(diff: &[crate::git::DiffLine]) -> std::collections::HashMap<u32, GutterMark> {
    use crate::git::DiffLineKind;
    let mut marks = std::collections::HashMap::new();
    let mut i = 0;
    while i < diff.len() {
        if diff[i].kind == DiffLineKind::Context {
            i += 1;
            continue;
        }
        let start = i;
        let mut removed = 0usize;
        let mut added: Vec<u32> = Vec::new();
        while i < diff.len() && diff[i].kind != DiffLineKind::Context {
            match diff[i].kind {
                DiffLineKind::Removed => removed += 1,
                DiffLineKind::Added => {
                    if let Some(n) = diff[i].new_no {
                        added.push(n);
                    }
                }
                DiffLineKind::Context => {}
            }
            i += 1;
        }
        if !added.is_empty() {
            let mark = if removed > 0 {
                GutterMark::Modified
            } else {
                GutterMark::Added
            };
            for n in added {
                marks.insert(n, mark);
            }
        } else if removed > 0 {
            // Pure deletion: anchor the marker to the line just below the removed block; if the block is
            // at EOF, anchor to the last real line above it (deletion below).
            let anchor = diff
                .get(i)
                .and_then(|d| d.new_no)
                .or_else(|| diff[..start].iter().rev().find_map(|d| d.new_no));
            if let Some(a) = anchor {
                marks.entry(a).or_insert(GutterMark::Deleted);
            }
        }
    }
    marks
}

/// Prepend a one-cell git change marker to each line (before the line-number gutter, Zed-style). Only
/// applied when the file has changes (`marks` non-empty) — unchanged files / non-repos keep their layout.
/// The displayed line `i` maps to 1-based file line `top_line + i + 1`; unchanged lines get a blank cell.
fn with_git_gutter(
    lines: Vec<Line<'static>>,
    top_line: usize,
    marks: &std::collections::HashMap<u32, GutterMark>,
) -> Vec<Line<'static>> {
    use ratatui::style::{Color, Style};
    if marks.is_empty() {
        return lines;
    }
    lines
        .into_iter()
        .enumerate()
        .map(|(i, line)| {
            let n = (top_line + i + 1) as u32;
            let (glyph, color) = match marks.get(&n) {
                Some(GutterMark::Added) => ("▌", GUTTER_ADDED),
                Some(GutterMark::Modified) => ("▌", GUTTER_MODIFIED),
                // Thin bar hugging the TOP edge of the line below a deletion, so it
                // sits on the seam between the two lines instead of looking like the
                // line itself was removed. (A terminal cell can't draw in the inter-row
                // gap, so the top edge is the closest we can get without adding a row.)
                Some(GutterMark::Deleted) => ("▔", GUTTER_DELETED),
                None => (" ", Color::Reset),
            };
            let style = line.style;
            let mut spans = Vec::with_capacity(line.spans.len() + 1);
            spans.push(Span::styled(glyph, Style::new().fg(color)));
            spans.extend(line.spans);
            Line::from(spans).style(style)
        })
        .collect()
}

/// The active visual selection in a windowed preview, normalized so `start ≤ end`.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum PreviewSelection {
    /// Not selecting (only the block caret is drawn).
    None,
    /// Charwise (`v`): an inclusive `(line, col)` character range across one or more lines.
    Char {
        start: (usize, usize),
        end: (usize, usize),
    },
    /// Linewise (`V`): whole logical lines `lo..=hi`.
    Line { lo: usize, hi: usize },
}

/// Extract the text of a charwise selection from the file's logical lines (`start`/`end` end-inclusive,
/// columns are char indices). Slicing by chars (not bytes) keeps multibyte/CJK content intact.
fn selection_char_text(lines: &[&str], start: (usize, usize), end: (usize, usize)) -> String {
    let (sl, sc) = start;
    let (el, ec) = end;
    if sl >= lines.len() {
        return String::new();
    }
    let el = el.min(lines.len() - 1);
    if sl == el {
        // 単一行: [sc..=ec](正規化済みで sc ≤ ec)
        lines[sl]
            .chars()
            .skip(sc)
            .take((ec + 1).saturating_sub(sc))
            .collect()
    } else {
        let mut out = String::new();
        out.push_str(&lines[sl].chars().skip(sc).collect::<String>());
        for l in &lines[sl + 1..el] {
            out.push('\n');
            out.push_str(l);
        }
        out.push('\n');
        out.push_str(&lines[el].chars().take(ec + 1).collect::<String>());
        out
    }
}

/// The character range `[lo, hi)` to highlight on absolute line `abs` for a charwise selection, or None.
/// `usize::MAX` for `hi` means "to end of line". End is inclusive, so the last covered char is `end.1`.
fn char_range_for_line(
    abs: usize,
    start: (usize, usize),
    end: (usize, usize),
) -> Option<(usize, usize)> {
    if abs < start.0 || abs > end.0 {
        return None;
    }
    let lo = if abs == start.0 { start.1 } else { 0 };
    let hi = if abs == end.0 {
        end.1.saturating_add(1)
    } else {
        usize::MAX
    };
    Some((lo, hi))
}

/// Paint the 2D caret and selection onto the visible content lines (char-column based, applied BEFORE the
/// line-number/git gutters so column indices align with the file text). The whole-line cases also set the
/// line's base style so the gutter cells inherit the tint; charwise partial ranges tint only the spanned chars.
fn apply_preview_caret(
    lines: Vec<Line<'static>>,
    top_line: usize,
    cursor_line: usize,
    cursor_col: usize,
    sel: PreviewSelection,
) -> Vec<Line<'static>> {
    use ratatui::style::Color;
    // 暗色テーマ向け: 控えめな現在行背景と、選択範囲の少し強い青系背景。
    const CURSOR_BG: Color = Color::Rgb(55, 60, 74);
    const SEL_BG: Color = Color::Rgb(40, 66, 104);
    lines
        .into_iter()
        .enumerate()
        .map(|(i, line)| {
            let abs = top_line + i;
            let caret = if abs == cursor_line {
                Some(cursor_col)
            } else {
                None
            };
            let (range, whole): (Option<(usize, usize, Color)>, bool) = match sel {
                PreviewSelection::None => {
                    if abs == cursor_line {
                        (Some((0, usize::MAX, CURSOR_BG)), true)
                    } else {
                        (None, false)
                    }
                }
                PreviewSelection::Line { lo, hi } => {
                    if abs >= lo && abs <= hi {
                        (Some((0, usize::MAX, SEL_BG)), true)
                    } else {
                        (None, false)
                    }
                }
                PreviewSelection::Char { start, end } => match char_range_for_line(abs, start, end)
                {
                    Some((lo, hi)) => (Some((lo, hi, SEL_BG)), lo == 0 && hi == usize::MAX),
                    None => (None, false),
                },
            };
            if range.is_none() && caret.is_none() {
                return line;
            }
            restyle_line(line, range, whole, caret)
        })
        .collect()
}

/// Rebuild a line applying a background to chars in `range` `(lo, hi, color)` and the REVERSED modifier to the
/// `caret` char. When `whole` is set, the line's base style also gets the bg (so gutters inherit it). Consecutive
/// chars with the same resulting style are coalesced into one span to keep the span count low.
fn restyle_line(
    line: Line<'static>,
    range: Option<(usize, usize, ratatui::style::Color)>,
    whole: bool,
    caret: Option<usize>,
) -> Line<'static> {
    use ratatui::style::Modifier;
    let base = line.style;
    let mut out: Vec<Span<'static>> = Vec::new();
    let mut idx = 0usize; // char index within the line content
    let mut cur = String::new();
    let mut cur_style: Option<ratatui::style::Style> = None;
    for span in line.spans.into_iter() {
        for ch in span.content.chars() {
            let mut style = span.style;
            if let Some((lo, hi, color)) = range {
                if idx >= lo && idx < hi {
                    style = style.bg(color);
                }
            }
            if caret == Some(idx) {
                style = style.add_modifier(Modifier::REVERSED);
            }
            if cur_style != Some(style) {
                if !cur.is_empty() {
                    out.push(Span::styled(std::mem::take(&mut cur), cur_style.unwrap()));
                }
                cur_style = Some(style);
            }
            cur.push(ch);
            idx += 1;
        }
    }
    if !cur.is_empty() {
        out.push(Span::styled(cur, cur_style.unwrap_or(base)));
    }
    let mut line = Line::from(out);
    line.style = if whole {
        if let Some((_, _, color)) = range {
            base.bg(color)
        } else {
            base
        }
    } else {
        base
    };
    line
}

/// Prepend a line-number gutter (right-aligned + a space) to each line. The first line's number is `top_line+1` (1-based).
/// A dim color (DarkGray) distinguishes it from the body. The original line style (background, etc.) is kept.
fn with_line_numbers(lines: Vec<Line<'static>>, top_line: usize) -> Vec<Line<'static>> {
    use ratatui::style::{Color, Style};
    let last = top_line + lines.len().max(1);
    let width = last.to_string().len().max(3); // 最低 3 桁ぶんの幅を確保
    lines
        .into_iter()
        .enumerate()
        .map(|(i, line)| {
            let n = top_line + i + 1;
            let gutter = Span::styled(format!("{n:>width$} "), Style::new().fg(Color::DarkGray));
            let style = line.style;
            let mut spans = Vec::with_capacity(line.spans.len() + 1);
            spans.push(gutter);
            spans.extend(line.spans);
            Line::from(spans).style(style)
        })
        .collect()
}

/// The rectangle that centers an image of size `cells` (natural size) within `inner` while preserving the aspect ratio.
/// With `allow_upscale=false`, downscale only (scale<=1=fit behavior); with `true`, it may upscale to fill the area.
fn centered_rect(cells: (u16, u16), inner: Rect, allow_upscale: bool) -> Rect {
    let (cw, ch) = cells;
    if cw == 0 || ch == 0 || inner.width == 0 || inner.height == 0 {
        return inner;
    }
    let mut scale = (inner.width as f64 / cw as f64).min(inner.height as f64 / ch as f64);
    if !allow_upscale {
        scale = scale.min(1.0);
    }
    let w = ((cw as f64 * scale).round() as u16).clamp(1, inner.width);
    let h = ((ch as f64 * scale).round() as u16).clamp(1, inner.height);
    let x = inner.x + (inner.width - w) / 2;
    let y = inner.y + (inner.height - h) / 2;
    Rect {
        x,
        y,
        width: w,
        height: h,
    }
}

/// Max reserved rows for one inline Markdown image; a taller image is scaled down (keeping aspect) so it never dominates the viewport.
const MD_IMAGE_MAX_ROWS: u16 = 24;

/// Resolve a Markdown image URL to a local file path. A remote (`http(s)://`) URL resolves to its
/// download-cache path, but only once it has been fetched (so callers treat a cached remote image
/// exactly like a local one). `data:` URLs return None. Relative paths are resolved against the
/// Markdown file's directory. Returns the path only if the file exists.
fn resolve_md_image_path(url: &str, base: Option<&Path>) -> Option<PathBuf> {
    let u = url.trim();
    if u.is_empty() {
        return None;
    }
    if crate::preview::markdown::is_remote_image_url(u) {
        let p = md_remote_cache_path(u)?;
        return p.is_file().then_some(p);
    }
    let lower = u.to_ascii_lowercase();
    if lower.starts_with("data:") {
        return None;
    }
    let u = u.strip_prefix("file://").unwrap_or(u);
    let p = PathBuf::from(u);
    let p = if p.is_absolute() {
        p
    } else if let Some(b) = base {
        b.join(p)
    } else {
        p
    };
    p.is_file().then_some(p)
}

/// Pixel dimensions of a cached inline-image file, accepting both raster formats and SVG (parsed cheaply
/// via usvg, without rasterizing). None if the file is neither a known raster image nor an SVG.
fn md_image_dims(path: &Path) -> Option<(u32, u32)> {
    crate::preview::image::dimensions(path).or_else(|| crate::preview::svg::intrinsic_size(path))
}

/// Decode a cached inline-image file to an image, rasterizing SVG (at `svg_max_px`) when the raster
/// decoders reject it (GitHub READMEs are full of SVG badges/logos). None if it is not a decodable image.
fn md_decode_image(path: &Path, svg_max_px: u32) -> Option<image::DynamicImage> {
    crate::preview::image::decode_static(path)
        .or_else(|| crate::preview::svg::rasterize(path, svg_max_px))
}

/// The source-pixel band `(y0, height)` of an image `dh` pixels tall that corresponds to the visible
/// cell rows `[row_off, row_off + vis_rows)` out of `full_rows` total. The result is always within
/// `[0, dh]` (so `crop_imm(0, y0, _, height)` never exceeds the image and never panics), and the height
/// is at least 1.
fn md_band_pixels(full_rows: u16, row_off: u16, vis_rows: u16, dh: u32) -> (u32, u32) {
    let fr = full_rows.max(1) as u32;
    let y0 = (row_off as u32 * dh) / fr;
    let y1 = ((row_off as u32 + vis_rows as u32).min(fr) * dh) / fr;
    (y0, y1.saturating_sub(y0).max(1))
}

/// Root of konoma's on-disk cache (`$XDG_CACHE_HOME` or `~/.cache`). None if neither is available.
fn cache_root() -> Option<PathBuf> {
    if let Some(x) = std::env::var_os("XDG_CACHE_HOME") {
        if !x.is_empty() {
            return Some(PathBuf::from(x));
        }
    }
    let home = std::env::var_os("HOME")?;
    if home.is_empty() {
        return None;
    }
    Some(PathBuf::from(home).join(".cache"))
}

/// Deterministic cache path for a remote image URL: `<cache>/konoma/remote-images/<hash>`. The file is
/// stored without an extension (the content type is unknown until fetched) and read via content sniffing.
fn md_remote_cache_path(url: &str) -> Option<PathBuf> {
    use std::hash::{Hash, Hasher};
    let root = cache_root()?;
    let mut hasher = std::collections::hash_map::DefaultHasher::new();
    url.trim().hash(&mut hasher);
    Some(
        root.join("konoma")
            .join("remote-images")
            .join(format!("{:016x}", hasher.finish())),
    )
}

/// Maximum bytes to download for one remote image (guards against huge / hostile responses).
const MD_REMOTE_MAX_BYTES: u64 = 25 * 1024 * 1024;

/// Download a remote image with `curl` into `dest` (atomically, via a temp file), validating that the
/// bytes decode as an image before committing. Returns whether a valid image now exists at `dest`.
/// Runs on a background thread. Uses the system `curl` (always present on macOS) to avoid adding a
/// TLS/HTTP dependency — consistent with konoma's external-tool delegation model (PRD §5).
fn fetch_remote_image(url: &str, dest: &Path) -> bool {
    use std::process::{Command, Stdio};
    let Some(parent) = dest.parent() else {
        return false;
    };
    if std::fs::create_dir_all(parent).is_err() {
        return false;
    }
    let tmp = dest.with_extension("part");
    let status = Command::new("curl")
        .args([
            "-sSL", // silent, show errors, follow redirects (GitHub proxies images via camo)
            "--fail",
            "--max-time",
            "20",
            "--max-filesize",
            &MD_REMOTE_MAX_BYTES.to_string(),
            "-A",
            "konoma image preview",
            "-o",
        ])
        .arg(&tmp)
        .arg(url)
        .stdin(Stdio::null())
        .stdout(Stdio::null())
        .stderr(Stdio::null())
        .status();
    let downloaded = matches!(status, Ok(s) if s.success());
    if !downloaded {
        let _ = std::fs::remove_file(&tmp);
        return false;
    }
    // Reject non-images (e.g. an HTML error page served with 200) before caching them (accepts SVG).
    if md_image_dims(&tmp).is_none() {
        let _ = std::fs::remove_file(&tmp);
        return false;
    }
    let ok = std::fs::rename(&tmp, dest).is_ok();
    if ok {
        prune_remote_cache(parent, MD_REMOTE_CACHE_MAX);
    }
    ok
}

/// Keep at most `keep` files in the remote-image cache directory, deleting the oldest (by mtime).
/// The cache is content-addressed (one file per distinct URL) with no cleanup, so without this it
/// grows unbounded over a machine's lifetime. Runs only after a **new** download (rare), so the
/// directory scan is cheap. Best-effort: any IO error just leaves the cache as-is.
fn prune_remote_cache(dir: &Path, keep: usize) {
    let Ok(rd) = std::fs::read_dir(dir) else {
        return;
    };
    let mut files: Vec<(std::time::SystemTime, PathBuf)> = rd
        .flatten()
        .filter(|e| e.file_type().map(|t| t.is_file()).unwrap_or(false))
        .filter_map(|e| {
            let p = e.path();
            // 進行中の一時ファイル(.part)は対象外。
            if p.extension().is_some_and(|x| x == "part") {
                return None;
            }
            let mtime = e.metadata().and_then(|m| m.modified()).ok()?;
            Some((mtime, p))
        })
        .collect();
    if files.len() <= keep {
        return;
    }
    files.sort_by_key(|(t, _)| *t); // oldest first
    for (_, p) in files.iter().take(files.len() - keep) {
        let _ = std::fs::remove_file(p);
    }
}

/// Max files kept in the remote-image disk cache (`~/.cache/konoma/remote-images`).
const MD_REMOTE_CACHE_MAX: usize = 256;

/// Compute the display size in terminal cells for an image of `pw`x`ph` pixels, given the terminal
/// font cell size (`fw`x`fh` px). The image is fit to `avail_cols` (never upscaled beyond its natural
/// cell size) and then capped to `max_rows`, preserving aspect ratio in both steps.
fn md_image_cells(
    pw: u32,
    ph: u32,
    fw: u16,
    fh: u16,
    avail_cols: u16,
    max_rows: u16,
) -> (u16, u16) {
    let fw = (fw.max(1)) as f64;
    let fh = (fh.max(1)) as f64;
    let nat_cols = (pw as f64 / fw).ceil().max(1.0);
    let nat_rows = (ph as f64 / fh).ceil().max(1.0);
    let avail = avail_cols.max(1) as f64;
    let (mut cols, mut rows) = if nat_cols <= avail {
        (nat_cols, nat_rows)
    } else {
        let s = avail / nat_cols;
        (avail, (nat_rows * s).round().max(1.0))
    };
    let maxr = max_rows.max(1) as f64;
    if rows > maxr {
        let s = maxr / rows;
        rows = maxr;
        cols = (cols * s).round().max(1.0);
    }
    (cols as u16, rows as u16)
}

/// Cell box for an inline mermaid diagram: **fill to `target_rows`** (up- or downscale, keeping
/// the aspect from the layout pixels), clamped by the available width. Unlike raster images
/// (`md_image_cells`, never upscaled), diagrams are vector-backed — the raster follows the
/// display size via sharpening re-rasters, so growing beyond the natural size stays crisp.
fn mermaid_cells(pw: u32, ph: u32, fw: u16, fh: u16, avail: u16, target_rows: u16) -> (u16, u16) {
    let (fw, fh) = (fw.max(1) as f64, fh.max(1) as f64);
    let ar = (pw.max(1) as f64) / (ph.max(1) as f64); // px アスペクト
    let mut rows = target_rows.max(1) as f64;
    let mut cols = (rows * fh * ar / fw).round().max(1.0);
    let avail = avail.max(1) as f64;
    if cols > avail {
        cols = avail;
        rows = (cols * fw / ar / fh).round().max(1.0);
    }
    (cols as u16, rows as u16)
}

/// Cell box for an inline math image, sized proportionally from the SVG's intrinsic **em** units
/// (RaTeX renders at 40 units/em) so equations sit at roughly text scale: em-height → rows, intrinsic
/// aspect → cols. Display math gets a touch more height than inline. Clamped to the available width
/// (aspect preserved) and a sane row cap. Vector-backed, so the once-rendered raster is fit crisply.
fn math_cells(uw: u32, uh: u32, fw: u16, fh: u16, avail: u16, display: bool) -> (u16, u16) {
    let (fw, fh) = (fw.max(1) as f64, fh.max(1) as f64);
    let em_h = (uh.max(1) as f64) / 40.0;
    let rows_per_em = if display { 1.5 } else { 1.3 };
    let mut rows = (em_h * rows_per_em).round().max(1.0);
    let ar = (uw.max(1) as f64) / (uh.max(1) as f64);
    let mut cols = (rows * fh * ar / fw).round().max(1.0);
    let avail = avail.max(1) as f64;
    if cols > avail {
        cols = avail;
        rows = (cols * fw / ar / fh).round().max(1.0);
    }
    // 極端に高い式(行列など)が画面を埋め尽くさないための上限。
    let maxr = 24.0;
    if rows > maxr {
        let s = maxr / rows;
        rows = maxr;
        cols = (cols * s).round().max(1.0);
    }
    (cols as u16, rows as u16)
}

/// Source-pixel crop rectangle (x, y, w, h).
type PxRect = (u32, u32, u32, u32);

/// Crop window for the in-place zoom of an inline diagram. `f` is the visible fraction, i.e.
/// 1/zoom, of the source; `center` is clamped so the window stays inside the image. Returns the
/// crop px rect plus the clamped center. Fractions are scale-free, so the same zoom and center
/// map onto a sharper re-raster unchanged.
fn fence_crop(dims: (u32, u32), f: f64, center: (f64, f64)) -> (PxRect, (f64, f64)) {
    let (sw, sh) = dims;
    let f = f.clamp(0.0, 1.0);
    let cx = center.0.clamp(f / 2.0, 1.0 - f / 2.0);
    let cy = center.1.clamp(f / 2.0, 1.0 - f / 2.0);
    let cw = ((sw as f64 * f).round() as u32).clamp(1, sw);
    let ch = ((sh as f64 * f).round() as u32).clamp(1, sh);
    let x0 = ((cx * sw as f64) as i64 - cw as i64 / 2).clamp(0, (sw - cw) as i64) as u32;
    let y0 = ((cy * sh as f64) as i64 - ch as i64 / 2).clamp(0, (sh - ch) as i64) as u32;
    ((x0, y0, cw, ch), (cx, cy))
}

/// Compute the display layout for an image/GIF frame (a pure function shared by prepare_image / prepare_gif).
/// From (source image src, font_size, zoom, center[0,1], display area inner, render_scale), returns
/// `(target, crop_rect, center, frac)` (None if size 0).
///
/// - `target`  : the render-target rectangle (centered; z=1=fit, grows when zooming, clips when exceeding the viewport)
/// - `crop_rect`: the source-image window of the visible portion (px: x,y,w,h)
/// - `center`  : the center clamped to where the visible window fits within the image [0,1]
/// - `frac`    : the visible fraction per axis (<1=clipped=pan possible)
#[allow(clippy::type_complexity)]
fn image_layout(
    src: &image::DynamicImage,
    font_size: ratatui_image::FontSize,
    zoom: f64,
    center: (f64, f64),
    inner: Rect,
    render_scale: f64,
    logical: Option<(u32, u32)>,
) -> Option<(Rect, PxRect, (f64, f64), (f64, f64))> {
    use image::GenericImageView;
    let (sw, sh) = src.dimensions();
    if sw == 0 || sh == 0 || inner.width == 0 || inner.height == 0 {
        return None;
    }
    // z=1 のフィット表示サイズ(セル, 拡大しない)。ベクタ由来のプレビューは **論理サイズ**
    // (初回ラスタの寸法) で計るので、シャープなラスタへ差し替えても画面上の大きさ・切り出し窓は
    // 一切動かない(HiDPI のバッキングストア方式。切り出し自体は比率で実ピクセルに写像される)。
    let (nw, nh) = match logical {
        Some((lw, lh)) if lw > 0 && lh > 0 => (
            (lw as u16).div_ceil(font_size.width.max(1)),
            (lh as u16).div_ceil(font_size.height.max(1)),
        ),
        _ => {
            let n = Resize::natural_size(src, font_size);
            (n.width, n.height)
        }
    };
    let base = centered_rect((nw, nh), inner, false);
    // ズーム後の論理表示サイズ。
    let disp_w = (base.width as f64 * zoom).max(1.0);
    let disp_h = (base.height as f64 * zoom).max(1.0);
    // 画面に出る大きさ = min(表示サイズ, 表示領域)。
    let tw = (disp_w.min(inner.width as f64).round() as u16).max(1);
    let th = (disp_h.min(inner.height as f64).round() as u16).max(1);
    // 各軸の可視率(<1 なら見切れ＝パン可能)。
    let fw = (tw as f64 / disp_w).min(1.0);
    let fh = (th as f64 / disp_h).min(1.0);
    // 中心を可視窓が画像内に収まる範囲へクランプ。
    let cx = center.0.clamp(fw / 2.0, 1.0 - fw / 2.0);
    let cy = center.1.clamp(fh / 2.0, 1.0 - fh / 2.0);
    // 元画像から見える窓を切り出す(px)。
    let cw = ((sw as f64 * fw).round() as u32).clamp(1, sw);
    let ch = ((sh as f64 * fh).round() as u32).clamp(1, sh);
    let x0 = ((cx * sw as f64) as i64 - cw as i64 / 2).clamp(0, (sw - cw) as i64) as u32;
    let y0 = ((cy * sh as f64) as i64 - ch as i64 / 2).clamp(0, (sh - ch) as i64) as u32;
    let crop_rect = (x0, y0, cw, ch);
    // 表示矩形(中央寄せ)。任意で render_scale により縮小(転送量=描画待ち削減)。
    let scale = render_scale.clamp(0.1, 1.0);
    let (tw, th) = if scale >= 0.999 {
        (tw, th)
    } else {
        (
            ((tw as f64 * scale).round() as u16).max(1),
            ((th as f64 * scale).round() as u16).max(1),
        )
    };
    let target = Rect {
        x: inner.x + (inner.width - tw.min(inner.width)) / 2,
        y: inner.y + (inner.height - th.min(inner.height)) / 2,
        width: tw.min(inner.width),
        height: th.min(inner.height),
    };
    Some((target, crop_rect, (cx, cy), (fw, fh)))
}

/// The modification time of `path`, or None if it cannot be read. Used by the FS-driven media auto-reload guard.
fn file_mtime(path: &Path) -> Option<std::time::SystemTime> {
    std::fs::metadata(path).and_then(|m| m.modified()).ok()
}

/// Assemble the copy string (a pure function; does not touch the clipboard).
/// `open_dir` is the base for relative paths (the launch directory).
fn copy_text(path: &Path, open_dir: &Path, kind: CopyKind) -> String {
    match kind {
        CopyKind::Name => path
            .file_name()
            .map(|n| n.to_string_lossy().into_owned())
            .unwrap_or_default(),
        CopyKind::Full => path.display().to_string(),
        CopyKind::Parent => path
            .parent()
            .map(|p| p.display().to_string())
            .unwrap_or_default(),
        // 左上のタイトル表示 (format_path の Relative) と完全に同じ基準にする。
        CopyKind::Relative => rel_to_open(open_dir, path),
        CopyKind::AtRef => at_ref_text(open_dir, path),
    }
}

/// `@path` reference for AI agents (Claude Code's `@file` context syntax). Under `open_dir` the path is
/// strictly relative to it (`src/app.rs` — no leading dir name, unlike `rel_to_open`); outside it is
/// `..`-relative; if neither works, absolute. Prefixed with `@`.
fn at_ref_text(open_dir: &Path, path: &Path) -> String {
    let rel = match path.strip_prefix(open_dir) {
        Ok(r) if !r.as_os_str().is_empty() => r.display().to_string(),
        _ => match rel_from(open_dir, path) {
            Some(r) if !r.as_os_str().is_empty() => r.display().to_string(),
            _ => path.display().to_string(),
        },
    };
    format!("@{rel}")
}

/// A relative display string based on `open_dir` (the launch directory). For paths underneath, it puts the launch directory name first (e.g. `A/sub/x`),
/// and for things outside open_dir (siblings/ancestors) it relativizes with `..` (e.g. `../B/aaa.md`, `..`). If it cannot be relativized, `~/...`.
/// A shared function to guarantee the **same base** for the top-left path display (`format_path`'s Relative) and path copy (`cr`/`yr`).
fn rel_to_open(open_dir: &Path, path: &Path) -> String {
    if path.starts_with(open_dir) {
        // open_dir 配下: 起動ディレクトリ名を先頭に出すため、その親を基準に相対化 (例: A/sub/x)。
        let base = open_dir.parent().unwrap_or(open_dir);
        match path.strip_prefix(base) {
            Ok(rel) if !rel.as_os_str().is_empty() => rel.display().to_string(),
            _ => home_relative(path),
        }
    } else {
        // open_dir の外(兄弟/上位など): open_dir 基準の相対パスを `..` 込みで表示 (例: ../B/aaa.md)。
        // これが無いと兄弟 B のファイルが `B/aaa.md` のように見え、配下にあるかのように誤解される。
        match rel_from(open_dir, path) {
            Some(rel) if !rel.as_os_str().is_empty() => rel.display().to_string(),
            _ => home_relative(path),
        }
    }
}

/// Write to the clipboard. Returns Err on environments where arboard is unavailable (the caller shows a flash).
fn set_clipboard(text: &str) -> Result<()> {
    let mut cb = arboard::Clipboard::new()?;
    cb.set_text(text.to_string())?;
    Ok(())
}

/// `~/...` if under HOME, otherwise the full path.
pub(crate) fn home_relative(path: &Path) -> String {
    if let Some(home) = std::env::var_os("HOME") {
        let home = PathBuf::from(home);
        if let Ok(rel) = path.strip_prefix(&home) {
            if rel.as_os_str().is_empty() {
                return "~".to_string();
            }
            return format!("~/{}", rel.display());
        }
    }
    path.display().to_string()
}

/// Resolve a dropped (=pasted) string into a list of **existing paths**. Terminals (Ghostty, etc.) pass a drop
/// as shell-escaped text (spaces as `\ `; multiple files separated by unescaped spaces).
/// Undo the backslash escapes, split on unescaped whitespace/newlines, and return only the tokens that **exist on disk**
/// (= safely excludes plain text pastes, junk, and control-character mixes).
fn parse_dropped_paths(text: &str) -> Vec<PathBuf> {
    let mut tokens: Vec<String> = Vec::new();
    let mut cur = String::new();
    let mut escaped = false;
    for c in text.chars() {
        if escaped {
            cur.push(c); // 直前が `\` ＝ この文字はリテラル(空白入りパス名等)
            escaped = false;
        } else if c == '\\' {
            escaped = true;
        } else if c.is_whitespace() {
            if !cur.is_empty() {
                tokens.push(std::mem::take(&mut cur));
            }
        } else {
            cur.push(c);
        }
    }
    if !cur.is_empty() {
        tokens.push(cur);
    }
    tokens
        .into_iter()
        .map(PathBuf::from)
        .filter(|p| p.exists()) // 実在パスのみ採用(テキストペースト/不正入力を弾く安全網)
        .collect()
}

/// Build a plan for sequential rename. Number `targets` **in display order** as `{n}`=1,2,…,
/// expand the template, and create each (old, new) path. If the template has no extension, the original extension is kept automatically.
/// **Pre-validates** collisions: an empty name / a `/` mixed in / duplicate final names / a collision with an existing file (not vacated within the batch) is an Err.
fn build_rename_plan(targets: &[PathBuf], template: &str) -> Result<Vec<(PathBuf, PathBuf)>> {
    let mut plan: Vec<(PathBuf, PathBuf)> = Vec::with_capacity(targets.len());
    for (idx, src) in targets.iter().enumerate() {
        let n = idx + 1;
        let stem = src.file_stem().and_then(|s| s.to_str()).unwrap_or("");
        let ext = src.extension().and_then(|s| s.to_str()).unwrap_or("");
        let rendered = crate::fileops::render_rename_template(template, n, stem, ext);
        let rendered = rendered.trim().to_string();
        if rendered.is_empty() {
            anyhow::bail!("空の名前になります (n={n})");
        }
        if rendered.contains('/') {
            anyhow::bail!("名前に / は使えません: {rendered}");
        }
        // 拡張子: テンプレ結果に拡張子が無ければ元拡張子を自動付与(ユーザ決定)。
        let has_ext = Path::new(&rendered)
            .extension()
            .filter(|e| !e.is_empty())
            .is_some();
        let new_name = if !has_ext && !ext.is_empty() {
            format!("{rendered}.{ext}")
        } else {
            rendered
        };
        let dst = src
            .parent()
            .unwrap_or_else(|| Path::new("."))
            .join(&new_name);
        plan.push((src.clone(), dst));
    }
    // 最終名の重複検証。
    let mut seen = BTreeSet::new();
    for (_, dst) in &plan {
        if !seen.insert(dst.clone()) {
            anyhow::bail!("リネーム先が重複: {}", dst.display());
        }
    }
    // 既存ファイルとの衝突検証(バッチ内で「移動して空く」元パスは除外)。
    let vacated: BTreeSet<PathBuf> = plan
        .iter()
        .filter(|(s, d)| s != d)
        .map(|(s, _)| s.clone())
        .collect();
    for (src, dst) in &plan {
        // 名前据え置き(src == dst)は自分自身の存在を衝突と誤検出しないよう除外する(#11)。
        // 真の衝突=別ファイルと被る場合のみ、最終名重複検証(上)で弾く。
        if src == dst {
            continue;
        }
        if dst.exists() && !vacated.contains(dst) {
            anyhow::bail!("既に存在します: {}", dst.display());
        }
    }
    Ok(plan)
}

/// Return the byte position in `s` corresponding to character index `char_idx` (past the end gives `s.len()`).
/// A conversion to safely compute insertion/deletion positions even for multibyte text (e.g. Japanese file names).
fn char_byte(s: &str, char_idx: usize) -> usize {
    s.char_indices()
        .nth(char_idx)
        .map(|(b, _)| b)
        .unwrap_or(s.len())
}

/// Compute the relative path from `base` to `target`, including `..` (equivalent to pathdiff). It removes the common leading components and
/// pushes one `..` for each remaining level on the base side. None if the root kinds (absolute/drive) disagree and it cannot be relativized.
fn rel_from(base: &Path, target: &Path) -> Option<PathBuf> {
    use std::path::Component;
    let bc: Vec<Component> = base.components().collect();
    let tc: Vec<Component> = target.components().collect();
    let mut i = 0;
    while i < bc.len() && i < tc.len() && bc[i] == tc[i] {
        i += 1;
    }
    // 共通成分が無く、かつ一方がルート(絶対/Prefix)で始まる=相対化不能。
    if i == 0 {
        let is_root = |c: Option<&Component>| {
            matches!(c, Some(Component::Prefix(_)) | Some(Component::RootDir))
        };
        if is_root(bc.first()) || is_root(tc.first()) {
            return None;
        }
    }
    let mut rel = PathBuf::new();
    for _ in i..bc.len() {
        rel.push("..");
    }
    for c in &tc[i..] {
        rel.push(c.as_os_str());
    }
    Some(rel)
}

/// Append one directory's worth of entries to out. Recurse into expanded subdirectories.
/// Bundles the decision info for one entry for sorting. Lowercased sort keys are precomputed
/// once per entry (sort_by runs O(n log n) comparisons — lowercasing inside the comparator
/// allocated two Strings per comparison). The stat is taken only when the sort key needs
/// size/mtime, or when the entry is a symlink (is_dir must follow the link like fs::metadata).
struct ChildMeta {
    path: PathBuf,
    /// Lowercased file name (also the stable tiebreak for every sort key).
    name_lower: String,
    /// Lowercased extension; filled only when sorting by extension.
    ext_lower: String,
    is_dir: bool,
    size: u64,
    mtime: Option<std::time::SystemTime>,
}

fn child_meta(path: PathBuf, ft: Option<std::fs::FileType>, sort: Sort) -> ChildMeta {
    let need_stat = matches!(sort.key, SortKey::Size | SortKey::Modified);
    let is_symlink = ft.map(|t| t.is_symlink()).unwrap_or(true);
    let (is_dir, size, mtime) = if need_stat || is_symlink {
        // fs::metadata follows symlinks, so a symlink to a directory stays expandable.
        let md = std::fs::metadata(&path).ok();
        (
            md.as_ref().map(|m| m.is_dir()).unwrap_or(false),
            md.as_ref().map(|m| m.len()).unwrap_or(0),
            md.as_ref().and_then(|m| m.modified().ok()),
        )
    } else {
        // DirEntry::file_type is free on macOS (readdir d_type) — no extra syscall.
        (ft.map(|t| t.is_dir()).unwrap_or(false), 0, None)
    };
    let name_lower = path
        .file_name()
        .map(|s| s.to_string_lossy().to_lowercase())
        .unwrap_or_default();
    let ext_lower = if matches!(sort.key, SortKey::Ext) {
        path.extension()
            .and_then(|e| e.to_str())
            .unwrap_or("")
            .to_lowercase()
    } else {
        String::new()
    };
    ChildMeta {
        path,
        name_lower,
        ext_lower,
        is_dir,
        size,
        mtime,
    }
}

/// Compare two entries according to the settings. dirs_first → key → reverse, finally stabilized by name.
fn sort_cmp(a: &ChildMeta, b: &ChildMeta, sort: Sort) -> std::cmp::Ordering {
    use std::cmp::Ordering;
    if sort.dirs_first {
        let d = b.is_dir.cmp(&a.is_dir); // ディレクトリ(true)を先頭に
        if d != Ordering::Equal {
            return d;
        }
    }
    let mut ord = match sort.key {
        SortKey::Name => a.name_lower.cmp(&b.name_lower),
        SortKey::Size => a.size.cmp(&b.size),
        SortKey::Modified => a.mtime.cmp(&b.mtime),
        SortKey::Ext => a.ext_lower.cmp(&b.ext_lower),
    };
    if sort.reverse {
        ord = ord.reverse();
    }
    // 同値は名前(昇順)で安定化して並びがブレないようにする。
    ord.then_with(|| a.name_lower.cmp(&b.name_lower))
}

/// Take the title label for the graph base from refs (`%D`). From `(HEAD -> main, origin/main)`, etc.,
/// pick one branch name (strip the HEAD-> and skip tag:). If there is no branch ref, the short hash.
#[cfg_attr(not(feature = "git"), allow(dead_code))]
fn base_label_from(refs: &str, short: &str) -> String {
    for part in refs.split(',').map(str::trim) {
        let p = part.strip_prefix("HEAD -> ").unwrap_or(part);
        if p.is_empty() || p.starts_with("tag:") {
            continue;
        }
        return p.to_string();
    }
    short.to_string()
}

fn build_dir(
    dir: &Path,
    depth: usize,
    expanded_dirs: &std::collections::HashSet<PathBuf>,
    show_hidden: bool,
    sort: Sort,
    out: &mut Vec<Entry>,
) -> Result<()> {
    let mut children: Vec<ChildMeta> = std::fs::read_dir(dir)?
        .filter_map(|r| r.ok())
        .map(|e| {
            let ft = e.file_type().ok();
            (e.path(), ft)
        })
        .filter(|(p, _)| {
            if show_hidden {
                return true;
            }
            !p.file_name()
                .and_then(|n| n.to_str())
                .map(|n| n.starts_with('.'))
                .unwrap_or(false)
        })
        .map(|(p, ft)| child_meta(p, ft, sort))
        .collect();

    children.sort_by(|a, b| sort_cmp(a, b, sort));

    for c in children {
        let expanded = c.is_dir && expanded_dirs.contains(&c.path);
        out.push(Entry {
            path: c.path.clone(),
            is_dir: c.is_dir,
            depth,
            expanded,
        });
        if expanded {
            build_dir(&c.path, depth + 1, expanded_dirs, show_hidden, sort, out)?;
        }
    }
    Ok(())
}

/// Recursively collect files/directories under `root` (the population for filtering). Hidden ones are excluded via `show_hidden`,
/// and symlink directories are not descended into (to prevent loops). The scan count is capped as a cost limit.
/// The return value is in ascending path order (grouped per directory). Each Entry is flat with depth=0 and expanded=false.
fn collect_all(root: &Path, show_hidden: bool) -> Vec<Entry> {
    const CAP: usize = 50_000;
    let mut out = Vec::new();
    let mut stack = vec![root.to_path_buf()];
    while let Some(dir) = stack.pop() {
        if out.len() >= CAP {
            break;
        }
        let Ok(rd) = std::fs::read_dir(&dir) else {
            continue;
        };
        for path in rd.filter_map(|r| r.ok()).map(|e| e.path()) {
            if out.len() >= CAP {
                break;
            }
            let hidden = path
                .file_name()
                .and_then(|n| n.to_str())
                .map(|n| n.starts_with('.'))
                .unwrap_or(false);
            if hidden && !show_hidden {
                continue;
            }
            // シンボリックリンクの dir には潜らない(循環回避)。is_dir はリンク先を辿るので別途判定。
            let is_symlink = std::fs::symlink_metadata(&path)
                .map(|m| m.file_type().is_symlink())
                .unwrap_or(false);
            let is_dir = path.is_dir();
            out.push(Entry {
                path: path.clone(),
                is_dir,
                depth: 0,
                expanded: false,
            });
            if is_dir && !is_symlink {
                stack.push(path);
            }
        }
    }
    out.sort_by(|a, b| a.path.cmp(&b.path));
    out
}

#[cfg(test)]
mod tests;