markdown-tui-explorer 1.34.70

use super::gutter::render_text_with_gutter;
use super::highlight::{
    apply_block_highlight, apply_visual_or_cursor_highlight, highlight_matches,
};
use super::mermaid_draw::{MermaidDrawParams, draw_mermaid_block};
use super::state::VisualRange;
use crate::action::Action;
use crate::app::{App, Focus};
use crate::markdown::{DocBlock, MermaidBlockId, update_mermaid_heights, update_text_layouts};
use crate::mermaid::MermaidRenderConfig;
use crate::ui::table_render::layout_table;
use ratatui::{
    Frame,
    layout::{Position, Rect},
    style::{Color, Style},
    text::{Span, Text},
    widgets::{Block, Borders, Paragraph},
};
use std::borrow::Cow;

/// How many display lines above and below the viewport to prefetch mermaid
/// renders. Large enough that normal scrolling rarely hits an unrendered
/// placeholder; small enough that unused diagrams don't waste CPU.
const LAZY_RENDER_LOOKAHEAD: u32 = 50;

// ---------------------------------------------------------------------------
// Draw-instruction types — private to this module; used only in `draw`.
// ---------------------------------------------------------------------------

/// Deferred text-block render instruction.
struct TextDraw {
    y: u16,
    height: u16,
    text: Text<'static>,
    first_line_number: u32,
    /// Number of visual rows to skip from the top of `text` when rendering.
    /// Always `0` for cached table layouts (where text already matches the
    /// visible slice) and for Text blocks fully visible from their top edge;
    /// non-zero for Text blocks scrolled past their top.
    scroll_skip: u16,
    /// `physical_to_logical` from the `WrappedTextLayout` for this block,
    /// or `None` for Table blocks (their layout is already pre-sized).
    /// Used by `render_text_with_gutter` to emit line numbers correctly.
    physical_to_logical: Option<Vec<u32>>,
}

/// Deferred mermaid-block render instruction.
struct MermaidDraw {
    y: u16,
    height: u16,
    fully_visible: bool,
    id: MermaidBlockId,
    source: String,
    /// Absolute logical-line index where this block starts in the document.
    block_start: u32,
    /// Total height of this block in logical lines.
    block_height: u32,
    /// Lines into the block that are above the viewport (0 when the block's
    /// top is fully visible). Text-mode renderers (`AsciiDiagram`,
    /// `SourceOnly`, `Failed`) slice the diagram by this offset so scrolling
    /// inside a tall diagram reveals lower rows instead of always showing
    /// the top.
    clip_start: u32,
    /// Visual selection at the time of the draw instruction capture.
    visual_mode: Option<VisualRange>,
}

/// Render the markdown preview panel into `area`.
///
/// # Arguments
///
/// * `f`       – the ratatui frame to render into.
/// * `app`     – mutable application state (tabs, caches, settings).
/// * `area`    – the terminal rectangle allocated to this panel.
/// * `focused` – whether the viewer panel currently has keyboard focus.
#[allow(clippy::many_single_char_names, clippy::too_many_lines)]
pub fn draw(f: &mut Frame, app: &mut App, area: Rect, focused: bool) {
    let p = app.palette;

    let active_tab = app.tabs.active_tab();
    let file_name = active_tab.map_or("", |t| t.view.file_name.as_str());

    // Build the title string before the block so its lifetime covers the block
    // borrow.  It is only used in the bordered path, but must be declared in
    // the outer scope regardless so the borrow checker is satisfied.
    let title: Cow<str> = if file_name.is_empty() {
        Cow::Borrowed(" Preview ")
    } else {
        Cow::Owned(format!(" {file_name} "))
    };

    // When the tree is hidden the viewer expands to the full terminal width.
    // Drawing borders in that state wastes 2 columns and 2 rows, and the border
    // box looks odd with nothing alongside it.  Skip borders entirely and let
    // the tab bar (which already spans the full width) serve as the visual
    // separator.
    let block = if app.tree_hidden {
        Block::default().style(Style::default().bg(p.background))
    } else {
        let border_style = if focused {
            p.border_focused_style()
        } else {
            p.border_style()
        };
        Block::default()
            .title(title.as_ref())
            .title_style(p.title_style())
            .borders(Borders::ALL)
            .border_style(border_style)
            .style(Style::default().bg(p.background))
    };

    // When borderless the inner area equals the outer area (no 1-cell border on
    // each edge), so the viewport is 2 rows taller than in bordered mode.
    app.tabs.view_height = u32::from(block.inner(area).height);

    let has_content = app
        .tabs
        .active_tab()
        .is_some_and(|t| !t.view.content.is_empty());

    if !has_content {
        let empty = Paragraph::new("No file selected. Select a markdown file from the tree.")
            .style(p.dim_style().bg(p.background))
            .block(block);
        f.render_widget(empty, area);
        return;
    }

    let view_height = app.tabs.view_height;
    let inner = block.inner(area);
    f.render_widget(block, area);

    // When line numbers are on, the gutter steals cells from the left of the
    // content area. Tables must be laid out against the actual content width
    // or their rows wrap inside ratatui's Paragraph and the grid breaks.
    // Width of the line-number gutter (0 when line numbers are off).
    // Hybrid mode's cursor placement also reads this so the terminal cursor
    // lands at the same x-offset as the rendered text instead of overlapping
    // the gutter.
    let gutter_width: u16 = if app.show_line_numbers {
        let estimate = app
            .tabs
            .active_tab()
            .map_or(10, |t| t.view.total_lines.max(10));
        let num_digits = crate::cast::u16_from_u32((estimate.ilog10() + 1).max(4));
        num_digits + 3
    } else {
        0
    };
    let effective_width = inner.width.saturating_sub(gutter_width);

    // If the effective width has changed, all layout caches are stale.
    // Recompute heights for every block and update total_lines.
    {
        // Safety: `has_content` is true so there is always an active tab here.
        // Use a guard instead of `.unwrap()` to satisfy the no-unwrap rule.
        let Some(tab) = app.tabs.active_tab_mut() else {
            return;
        };
        if tab.view.layout_width == effective_width {
            // Populate cache for any tables not yet laid out (e.g. first draw).
            // Track whether any new table was added so we know to recompute positions.
            let mut layout_changed = false;
            for doc_block in &mut tab.view.rendered {
                if let DocBlock::Table(table) = doc_block
                    && let std::collections::hash_map::Entry::Vacant(e) =
                        tab.view.table_layouts.entry(table.id)
                {
                    let (text, height, physical_to_source) =
                        layout_table(table, effective_width, &p);
                    table.rendered_height = height;
                    e.insert(super::state::TableLayout {
                        text,
                        physical_to_source,
                    });
                    layout_changed = true;
                }
            }
            // update_mermaid_heights returns true when any block's height changed.
            // Only recompute positions (O(blocks)) when something actually moved —
            // calling it unconditionally every frame was the source of UI freezes on
            // large documents.
            let mermaid_changed = update_mermaid_heights(
                &tab.view.rendered,
                &app.mermaid_cache,
                app.mermaid_max_height,
            );
            // Populate text layout cache for any Text blocks not yet wrapped
            // (e.g. first draw). Returns true when any height changed.
            let text_changed = update_text_layouts(
                &tab.view.rendered,
                &mut tab.view.text_layouts,
                effective_width,
            );
            if layout_changed || mermaid_changed || text_changed {
                tab.view.total_lines = tab
                    .view
                    .rendered
                    .iter()
                    .map(|b: &DocBlock| b.height())
                    .sum();
                tab.view.recompute_positions();
                let max_scroll = tab.view.total_lines.saturating_sub(view_height / 2);
                tab.view.scroll_offset = tab.view.scroll_offset.min(max_scroll);
            }
        } else {
            tab.view.layout_width = effective_width;
            tab.view.table_layouts.clear();
            tab.view.text_layouts.clear();
            // AsciiDiagram entries are fixed-width text — they need to
            // re-render at the new width.  Clearing the whole cache is
            // cheap; image entries will re-populate via ensure_queued on
            // the next draw, and text entries re-render synchronously.
            app.mermaid_cache.clear();

            for doc_block in &mut tab.view.rendered {
                if let DocBlock::Table(table) = doc_block {
                    let (text, height, physical_to_source) =
                        layout_table(table, effective_width, &p);
                    table.rendered_height = height;
                    tab.view.table_layouts.insert(
                        table.id,
                        super::state::TableLayout {
                            text,
                            physical_to_source,
                        },
                    );
                }
            }

            // Width changed — all block heights may have shifted; always recompute.
            update_mermaid_heights(
                &tab.view.rendered,
                &app.mermaid_cache,
                app.mermaid_max_height,
            );
            // Re-wrap each Text block at the new width so `block.height()` and
            // the layout cache are accurate for all downstream callers.
            update_text_layouts(
                &tab.view.rendered,
                &mut tab.view.text_layouts,
                effective_width,
            );
            tab.view.total_lines = tab
                .view
                .rendered
                .iter()
                .map(|b: &DocBlock| b.height())
                .sum();
            tab.view.recompute_positions();
            let max_scroll = tab.view.total_lines.saturating_sub(view_height / 2);
            tab.view.scroll_offset = tab.view.scroll_offset.min(max_scroll);
        }
    }

    // Safety: `has_content` is true so there is always an active tab here.
    let Some(tab) = app.tabs.active_tab() else {
        return;
    };
    let scroll_offset = tab.view.scroll_offset;
    let cursor_line = tab.view.cursor_line;
    // Copy the visual selection so we can use it while iterating over blocks
    // without holding a borrow into `app.tabs`.
    let visual_mode = tab.view.visual_mode;

    let doc_search_query =
        if !tab.doc_search.query.is_empty() && !tab.doc_search.match_lines.is_empty() {
            Some((
                tab.doc_search.query.clone(),
                tab.doc_search
                    .match_lines
                    .get(tab.doc_search.current_match)
                    .copied(),
            ))
        } else {
            None
        };

    // Build a flat list of (block_start_line, block) to find which blocks
    // intersect [scroll_offset, scroll_offset + view_height).
    let viewport_end = scroll_offset + view_height;

    // Mermaid blocks within this extended window are queued for rendering even
    // if not yet visible, so that scrolling rarely hits an unrendered placeholder.
    let lookahead_start = scroll_offset.saturating_sub(LAZY_RENDER_LOOKAHEAD);
    let lookahead_end = viewport_end + LAZY_RENDER_LOOKAHEAD;

    // ── Hybrid active-block index ─────────────────────────────────────────────
    //
    // When in hybrid mode, one block renders as raw markdown source while all
    // others render formatted as usual.  Extract the index once before the
    // block loop so each iteration can check "is this the active block?" in O(1).
    // We also capture the hybrid source string for the raw-rendering path.
    let active_block_index: Option<usize> = if app.focus == Focus::HybridEditor {
        app.tabs
            .active_tab()
            .and_then(|t| t.hybrid.as_ref())
            .and_then(|h| h.active_block.as_ref().map(|ab| ab.index))
    } else {
        None
    };
    // Clone the source string while we have a shared borrow; the draw loop
    // later needs `&mut App` for mermaid queuing, so we can't hold a borrow
    // into `app.tabs` across that call.
    let hybrid_source: Option<String> = if active_block_index.is_some() {
        app.tabs
            .active_tab()
            .and_then(|t| t.hybrid.as_ref())
            .map(|h| h.source.clone())
    } else {
        None
    };

    // We can't hold a borrow into `app.tabs` while also accessing
    // `app.mermaid_cache`, so we collect rendering instructions first.
    let mut text_draws: Vec<TextDraw> = Vec::new();
    let mut mermaid_draws: Vec<MermaidDraw> = Vec::new();
    let mut mermaid_to_queue: Vec<(MermaidBlockId, String)> = Vec::new();

    {
        // Safety: same guard — active tab is guaranteed by `has_content`.
        let Some(tab) = app.tabs.active_tab() else {
            return;
        };
        let mut block_start = 0u32;
        // Parallel tracker in *logical* lines so the gutter can show
        // source-line numbers that don't drift through wrapped paragraphs.
        // For Text blocks the logical count is `text.lines.len()`; for
        // Mermaid/Table it equals their visual height (no wrapping happens
        // inside those, so logical and visual coincide).
        let mut block_start_logical = 0u32;
        for (block_index, doc_block) in tab.view.rendered.iter().enumerate() {
            // ── Active-block raw rendering (hybrid mode) ──────────────────────
            //
            // When this block is the hybrid cursor's active block, we render it
            // as plain unwrapped source text instead of the formatted version.
            // The formatted cache in `text_layouts` is NOT used for this block;
            // only the source slice matters.  All other blocks (block_index !=
            // active_block_index) render formatted as normal — zero behaviour change.
            //
            // Height accounting: the raw block may occupy a different number of
            // visual rows than the formatted block.  We compute the raw height
            // from wrap_spans and use it for this block's `block_height` so the
            // Y positions of all subsequent blocks in this frame are correct.
            // `view.total_lines` (used for scroll clamping) is NOT updated here
            // — that would require a mutable borrow and produce per-frame flicker.
            // The height mismatch is acceptable in sub-phase 5; sub-phase 6 will
            // keep total_lines consistent by updating it on cursor movement.
            let is_active_block = active_block_index == Some(block_index);

            // Compute raw height if this is the active block and we have the source.
            let raw_height_opt: Option<u32> = if is_active_block {
                hybrid_source.as_deref().map(|src| {
                    let (b_start, b_end) = doc_block.source_byte_range();
                    let slice = &src[b_start.min(src.len())..b_end.min(src.len())];
                    let raw_span = Span::raw(slice);
                    let wrapped = crate::text_layout::wrap_spans(&[raw_span], effective_width);
                    crate::cast::u32_sat(wrapped.len()).max(1)
                })
            } else {
                None
            };

            let block_height: u32 = raw_height_opt.unwrap_or_else(|| DocBlock::height(doc_block));
            let block_end = block_start + block_height;
            let block_logical_height: u32 = match doc_block {
                DocBlock::Text { text, .. } => crate::cast::u32_sat(text.lines.len()),
                _ => block_height,
            };

            // Queue mermaid blocks within the lookahead window.
            if let DocBlock::Mermaid { id, source, .. } = doc_block
                && block_end > lookahead_start
                && block_start < lookahead_end
            {
                mermaid_to_queue.push((MermaidBlockId(id.0), source.clone()));
            }

            if block_end > scroll_offset && block_start < viewport_end {
                // Lines within this block that are visible.
                let clip_start = scroll_offset.saturating_sub(block_start);
                let clip_end = (viewport_end - block_start).min(block_height);
                let visible_lines = clip_end.saturating_sub(clip_start);

                // Y offset in the inner rect.
                let y_in_viewport = block_start.saturating_sub(scroll_offset);
                let rect_y = inner
                    .y
                    .saturating_add(crate::cast::u16_from_u32(y_in_viewport));

                if rect_y < inner.y + inner.height && visible_lines > 0 {
                    let draw_height = crate::cast::u16_from_u32(
                        visible_lines.min(u32::from(inner.y + inner.height - rect_y)),
                    );

                    // ── Active block raw render (hybrid mode) ──────────────
                    //
                    // When `is_active_block` is true, we bypass the entire
                    // formatted-render path for this block and instead wrap the
                    // raw source slice.  The result looks like plain text —
                    // no heading bars, no bullet glyphs, no syntax highlighting.
                    // That visual jump IS the "compile" event the user perceives
                    // when the cursor enters a block.
                    //
                    // For inactive blocks (is_active_block == false), all code
                    // paths below are identical to the pre-sub-phase-5 behaviour.
                    if is_active_block {
                        if let Some(src) = hybrid_source.as_deref() {
                            let (b_start, b_end) = doc_block.source_byte_range();
                            let slice = &src[b_start.min(src.len())..b_end.min(src.len())];
                            // Anchor the raw text to the theme's primary text colour.
                            // Without an explicit fg, terminals fall back to their own
                            // default (often green on classic schemes) which clashes
                            // hard with most light themes.
                            let raw_span = Span::styled(
                                slice.to_string(),
                                Style::default().fg(app.tokens.text.primary),
                            );
                            let wrapped =
                                crate::text_layout::wrap_spans(&[raw_span], effective_width);
                            // Convert WrappedLine to ratatui Lines (plain, no styling).
                            let raw_lines: Vec<ratatui::text::Line<'static>> =
                                wrapped.iter().map(|wl| wl.to_ratatui_line()).collect();
                            let raw_text = Text::from(raw_lines);
                            text_draws.push(TextDraw {
                                y: rect_y,
                                height: draw_height,
                                text: raw_text,
                                first_line_number: block_start_logical + 1,
                                scroll_skip: crate::cast::u16_from_u32(clip_start),
                                // No physical_to_logical for raw blocks — each wrapped row
                                // IS a source line in the raw view; the gutter will use
                                // first_line_number + sequential offsets, which is fine.
                                physical_to_logical: None,
                            });
                        }
                    } else {
                        match doc_block {
                            DocBlock::Text { id, text, .. } => {
                                // Look up the pre-wrapped layout for this block. On the
                                // very first draw the cache may not be populated yet
                                // (race between width-change path and first paint); call
                                // update_text_layouts immediately so we always have data.
                                //
                                // SAFETY: active tab is guaranteed by `has_content`.
                                let layout_opt = tab.view.text_layouts.get(id).map(|l| {
                                    // Clone the physical_to_logical mapping for the gutter;
                                    // the wrapped lines are converted to ratatui Lines below.
                                    l.physical_to_logical.clone()
                                });
                                let physical_to_logical = layout_opt;

                                // Build ratatui Lines from the pre-wrapped output.
                                // Single-source conversion via `WrappedLine::to_ratatui_line`.
                                let wrapped_lines: Vec<ratatui::text::Line<'static>> = tab
                                    .view
                                    .text_layouts
                                    .get(id)
                                    .map(|layout| {
                                        layout
                                            .wrapped
                                            .iter()
                                            .map(|wl| wl.to_ratatui_line())
                                            .collect()
                                    })
                                    .unwrap_or_else(|| {
                                        // Cache absent — fall back to logical lines (no wrap).
                                        text.lines.clone()
                                    });

                                // Apply search match highlights on the wrapped lines.
                                // `highlight_matches` operates on logical lines from the
                                // original `text`, keyed by block_start (visual row).
                                // Since wrapped_lines now IS the visual-row space, we
                                // pass it directly as both the data and index base.
                                let mut full_text =
                                    if let Some((query, current_line)) = &doc_search_query {
                                        // Build a temporary Text from wrapped lines and highlight.
                                        let tmp = Text::from(wrapped_lines.clone());
                                        highlight_matches(
                                            &tmp,
                                            query,
                                            *current_line,
                                            block_start,
                                            &app.tokens,
                                        )
                                    } else {
                                        Text::from(wrapped_lines)
                                    };

                                let block_end_visual = block_start + block_height;
                                if focused {
                                    // In Phase 3 the wrapped lines ARE the visual rows —
                                    // cursor_line and block_start are in the same coordinate
                                    // space as the indices into full_text.lines. No conversion
                                    // needed; the mapping is identity.
                                    apply_visual_or_cursor_highlight(
                                        &mut full_text.lines,
                                        visual_mode,
                                        cursor_line,
                                        block_start,
                                        block_end_visual,
                                        app.tokens.state.selection_bg,
                                    );

                                    // Single-cell cursor highlight at the cursor's physical
                                    // wrapped row. `cursor_visual_in_block` IS the index into
                                    // full_text.lines — no logical→visual conversion needed.
                                    if cursor_line >= block_start && cursor_line < block_end_visual
                                    {
                                        let cursor_visual_in_block =
                                            (cursor_line - block_start) as usize;
                                        if let Some(line) =
                                            full_text.lines.get(cursor_visual_in_block)
                                        {
                                            let col = app
                                                .tabs
                                                .active_tab()
                                                .map_or(0, |t| t.view.cursor_col);
                                            full_text.lines[cursor_visual_in_block] =
                                                super::highlight::highlight_columns(
                                                    line,
                                                    col,
                                                    col + 1,
                                                    app.tokens.accent.primary,
                                                );
                                        }
                                    }
                                }

                                text_draws.push(TextDraw {
                                    y: rect_y,
                                    height: draw_height,
                                    text: full_text,
                                    // Logical block start + 1 so the gutter
                                    // numbers each source line once; wrap
                                    // continuation rows get a blank gutter entry
                                    // (controlled by physical_to_logical in the
                                    // gutter renderer).
                                    first_line_number: block_start_logical + 1,
                                    scroll_skip: crate::cast::u16_from_u32(clip_start),
                                    physical_to_logical,
                                });
                            }
                            DocBlock::Mermaid { id, source, .. } => {
                                // Render the image when the block is as visible as
                                // it can get: fully visible for small blocks, or
                                // filling the viewport for blocks taller than the
                                // viewport. Show a placeholder only while the block
                                // is entering/exiting the viewport edges.
                                let max_renderable = block_height.min(u32::from(inner.height));
                                let fully_visible = visible_lines >= max_renderable
                                    && u32::from(draw_height) >= max_renderable;
                                mermaid_draws.push(MermaidDraw {
                                    y: rect_y,
                                    height: draw_height,
                                    fully_visible,
                                    id: MermaidBlockId(id.0),
                                    source: source.clone(),
                                    block_start,
                                    block_height,
                                    clip_start,
                                    visual_mode,
                                });
                            }
                            DocBlock::Table(table) => {
                                // Slice visible lines from the cached rendered text.
                                if let Some(cached) = tab.view.table_layouts.get(&table.id) {
                                    let start = clip_start as usize;
                                    let end = (clip_start + visible_lines)
                                        .min(crate::cast::u32_sat(cached.text.lines.len()))
                                        as usize;
                                    let mut visible_text =
                                        if let Some((query, current_line)) = &doc_search_query {
                                            let full = highlight_matches(
                                                &cached.text,
                                                query,
                                                *current_line,
                                                block_start,
                                                &app.tokens,
                                            );
                                            Text::from(full.lines[start..end].to_vec())
                                        } else {
                                            Text::from(cached.text.lines[start..end].to_vec())
                                        };
                                    // Apply highlight(s) when the viewer has focus.
                                    // In visual mode every line in the selection range is
                                    // highlighted; in normal mode only the cursor row.
                                    let block_end = block_start + block_height;
                                    if focused {
                                        apply_block_highlight(
                                            &mut visible_text.lines,
                                            visual_mode,
                                            cursor_line,
                                            block_start,
                                            block_end,
                                            start,
                                            app.tokens.state.selection_bg,
                                        );
                                    }
                                    text_draws.push(TextDraw {
                                        y: rect_y,
                                        height: draw_height,
                                        text: visible_text,
                                        first_line_number: block_start + clip_start + 1,
                                        scroll_skip: 0,
                                        // Tables are already pre-sliced to the visible
                                        // rows; no wrap continuation rows exist.
                                        physical_to_logical: None,
                                    });
                                }
                            }
                        }
                    } // closes `else` of `if is_active_block`
                }
            }

            block_start = block_end;
            block_start_logical += block_logical_height;
            if block_start >= lookahead_end {
                break;
            }
        }
    }

    // Queue any mermaid diagrams in the lookahead window that haven't been
    // rendered yet. This is the only site that calls ensure_queued — rendering
    // is fully lazy and driven by viewport proximity.
    if let Some(tx) = &app.action_tx {
        let in_tmux = std::env::var("TMUX").is_ok();
        let tx: tokio::sync::mpsc::UnboundedSender<Action> = Clone::clone(tx);
        let bg_rgb = match p.background {
            Color::Rgb(r, g, b) => (r, g, b),
            _ => (0, 0, 0),
        };
        // `effective_width` is the inner content width computed earlier in
        // this frame (accounting for the gutter when line numbers are on).
        // Cast from u16 to usize is always safe — terminal widths never
        // approach usize::MAX even on 32-bit targets.
        let render_cfg = MermaidRenderConfig {
            picker: app.picker.as_ref(),
            action_tx: &tx,
            in_tmux,
            bg_rgb,
            mode: app.mermaid_mode,
            max_height: app.mermaid_max_height,
            content_width: Some(usize::from(effective_width)),
            text_backend: app.mermaid_text_backend,
        };
        for (id, source) in mermaid_to_queue {
            app.mermaid_cache.ensure_queued(id, &source, &render_cfg);
        }
    }

    let total_doc_lines = app.tabs.active_tab().map_or(0, |t| t.view.total_lines);

    // Render text blocks.
    for td in text_draws {
        let rect = Rect {
            x: inner.x,
            y: td.y,
            width: inner.width,
            height: td.height,
        };
        if app.show_line_numbers {
            render_text_with_gutter(
                f,
                rect,
                td.text,
                td.first_line_number,
                total_doc_lines,
                &app.tokens,
                td.scroll_skip,
                td.physical_to_logical.as_deref(),
            );
        } else {
            let mut para = Paragraph::new(td.text);
            // Text blocks are pre-wrapped — no Paragraph::wrap() needed.
            // Tables pass physical_to_logical = None and are also pre-sized.
            if td.scroll_skip > 0 {
                para = para.scroll((td.scroll_skip, 0));
            }
            f.render_widget(para, rect);
        }
    }

    // Render mermaid blocks.
    for md in mermaid_draws {
        let rect = Rect {
            x: inner.x,
            y: md.y,
            width: inner.width,
            height: md.height,
        };
        let params = MermaidDrawParams {
            fully_visible: md.fully_visible,
            id: md.id,
            source: &md.source,
            focused,
            cursor_line,
            block_start: md.block_start,
            block_end: md.block_start + md.block_height,
            clip_start: md.clip_start,
            visual_mode: md.visual_mode,
        };
        draw_mermaid_block(f, app, rect, &p, &params);
    }

    // ── Hybrid-mode cursor placement ─────────────────────────────────────────
    //
    // When the active tab is in hybrid mode (`tab.hybrid` is `Some`), place the
    // real terminal cursor at the visual position that corresponds to the hybrid
    // editor's current source byte offset.
    //
    // Sub-phase 5 adds the critical branch: when the cursor is inside the active
    // block (which renders as raw source), the `text_layouts` cache holds the
    // *formatted* layout for that block — not the raw layout.  Using the cached
    // layout would produce a wrong column.  We therefore branch:
    //
    //   • Cursor in the active block → use `byte_to_visual_raw`, which wraps the
    //     raw source slice directly and locates the byte within the wrapped rows.
    //   • Cursor in any other (inactive) block → use the existing `byte_to_visual`
    //     path, which consults the `text_layouts` cache as before (those blocks are
    //     rendered formatted, so the cache is the correct source of truth).
    //
    // This is the only branch in the cursor-placement code; all other code paths
    // (scroll offset subtraction, terminal coordinate clamping) are shared.
    if app.focus == Focus::HybridEditor
        && let Some(tab) = app.tabs.active_tab()
        && let Some(hybrid) = tab.hybrid.as_ref()
    {
        // Translate edtui cursor position (row, col) → source byte offset.
        let cursor_byte = crate::ui::hybrid_editor::byte_offset_from_editor_state(
            &hybrid.editor_state,
            &hybrid.line_boundaries,
        );

        // Determine which block the cursor is in.
        let cursor_block_idx = if tab.view.rendered.is_empty() {
            None
        } else {
            Some(crate::markdown::cursor_bridge::byte_offset_to_block(
                &tab.view.rendered,
                cursor_byte,
            ))
        };

        // Branch: active block (raw layout) vs inactive block (formatted layout).
        let visual_pos: Option<(u32, u16)> = if cursor_block_idx == active_block_index
            && let Some(idx) = cursor_block_idx
            && let Some(block) = tab.view.rendered.get(idx)
            && let Some(src) = hybrid_source.as_deref()
        {
            // Compute the visual start row for this block (sum of heights of
            // all preceding blocks).  Note: for the active block we use the
            // *raw* height (already in `block_height` from the draw loop), but
            // here we only need block_start for the cursor row, not block_height.
            // Re-compute block_visual_start by summing preceding blocks' heights.
            // We use the formatted heights for inactive blocks and the raw height
            // for the active block — consistent with the draw loop above.
            let block_visual_start: u32 = {
                let mut acc = 0u32;
                for (i, b) in tab.view.rendered.iter().enumerate() {
                    if i == idx {
                        break;
                    }
                    // For inactive blocks use the formatted height.
                    // The active block itself is not summed (we stop before idx).
                    acc += if Some(i) == active_block_index {
                        // Another active block? Shouldn't happen (only one active),
                        // but be safe.
                        b.height()
                    } else {
                        b.height()
                    };
                }
                acc
            };
            Some(crate::markdown::cursor_bridge::byte_to_visual_raw(
                block,
                src,
                block_visual_start,
                effective_width,
                cursor_byte,
            ))
        } else {
            // Cursor is in an inactive block — use the formatted layout cache.
            crate::markdown::cursor_bridge::byte_to_visual(
                &tab.view.rendered,
                &tab.view.text_layouts,
                cursor_byte,
            )
        };

        if let Some((visual_row, visual_col)) = visual_pos {
            // Translate from document-absolute visual row to viewport-relative
            // row by subtracting the current scroll offset, then add the
            // inner rect's y offset to get an absolute terminal row.
            let viewport_row = visual_row.saturating_sub(scroll_offset);
            let abs_y = inner
                .y
                .saturating_add(crate::cast::u16_from_u32(viewport_row));
            // Shift the cursor past the line-number gutter (zero when line
            // numbers are off) so it lands inside the rendered text column,
            // not overlapping the gutter digits.
            let abs_x = inner
                .x
                .saturating_add(gutter_width)
                .saturating_add(visual_col);

            // Only place the cursor when it's within the visible viewport.
            if abs_y >= inner.y && abs_y < inner.y + inner.height {
                f.set_cursor_position(Position::new(abs_x, abs_y));
            }
        }
        // When neither path returns Some (cursor in Mermaid/Table block for
        // inactive path, or source unavailable), we simply don't show the cursor.
        // Sub-phase 8 will handle active mermaid blocks.
    }
}