Struct App 

pub struct App {

    pub messages: Vec<ChatMessage>,
    pub viewport: ChatViewport,
    pub input: InputState,
    pub status: AppStatus,
    pub should_quit: bool,
    pub session_id: Option<SessionId>,
    pub conn: Option<Rc<ClientSideConnection>>,
    pub adapter_child: Option<Child>,
    pub model_name: String,
    pub cwd: String,
    pub cwd_raw: String,
    pub files_accessed: usize,
    pub mode: Option<ModeState>,
    pub login_hint: Option<LoginHint>,
    pub pending_compact_clear: bool,
    pub help_view: HelpView,
    pub pending_permission_ids: Vec<String>,
    pub cancelled_turn_pending_hint: bool,
    pub event_tx: UnboundedSender<ClientEvent>,
    pub event_rx: UnboundedReceiver<ClientEvent>,
    pub spinner_frame: usize,
    pub tools_collapsed: bool,
    pub active_task_ids: HashSet<String>,
    pub terminals: TerminalMap,
    pub force_redraw: bool,
    pub tool_call_index: HashMap<String, (usize, usize)>,
    pub todos: Vec<TodoItem>,
    pub show_header: bool,
    pub show_todo_panel: bool,
    pub todo_scroll: usize,
    pub todo_selected: usize,
    pub focus: FocusManager,
    pub available_commands: Vec<AvailableCommand>,
    pub cached_frame_area: Rect,
    pub selection: Option<SelectionState>,
    pub scrollbar_drag: Option<ScrollbarDragState>,
    pub rendered_chat_lines: Vec<String>,
    pub rendered_chat_area: Rect,
    pub rendered_input_lines: Vec<String>,
    pub rendered_input_area: Rect,
    pub mention: Option<MentionState>,
    pub slash: Option<SlashState>,
    pub pending_submit: bool,
    pub drain_key_count: usize,
    pub paste_burst: PasteBurstDetector,
    pub pending_paste_text: String,
    pub file_cache: Option<Vec<FileCandidate>>,
    pub cached_todo_compact: Option<Line<'static>>,
    pub git_branch: Option<String>,
    pub cached_header_line: Option<Line<'static>>,
    pub cached_footer_line: Option<Line<'static>>,
    pub update_check_hint: Option<String>,
    pub terminal_tool_calls: Vec<(String, usize, usize)>,
    pub needs_redraw: bool,
    pub perf: Option<PerfLogger>,
    pub fps_ema: Option<f32>,
    pub last_frame_at: Option<Instant>,
}

Fields

messages: Vec<ChatMessage>

viewport: ChatViewport

Single owner of all chat layout state: scroll, per-message heights, prefix sums.

input: InputState

status: AppStatus

should_quit: bool

session_id: Option<SessionId>

conn: Option<Rc<ClientSideConnection>>

ACP connection handle. None while connecting (before adapter is ready).

adapter_child: Option<Child>

Adapter child process handle. Held solely to keep the process alive – dropping Child kills the subprocess. Never read after being stored.

model_name: String

cwd: String

cwd_raw: String

files_accessed: usize

mode: Option<ModeState>

login_hint: Option<LoginHint>

Login hint shown when authentication is required. Rendered above the input field.

pending_compact_clear: bool

When true, the current/next turn completion should clear local conversation history. Set by /compact once the command is accepted for ACP forwarding.

help_view: HelpView

Active help overlay view when ? help is open.

pending_permission_ids: Vec<String>

Tool call IDs with pending permission prompts, ordered by arrival. The first entry is the “focused” permission that receives keyboard input. Up / Down arrow keys cycle focus through the list.

cancelled_turn_pending_hint: bool

Set when a cancel notification succeeds; consumed on TurnComplete to render a red interruption hint in chat.

event_tx: UnboundedSender<ClientEvent>

event_rx: UnboundedReceiver<ClientEvent>

spinner_frame: usize

tools_collapsed: bool

Session-level default for tool call collapsed state. Toggled by Ctrl+O - new tool calls inherit this value.

active_task_ids: HashSet<String>

IDs of Task tool calls currently InProgress – their children get hidden. Use insert_active_task(), remove_active_task().

terminals: TerminalMap

Shared terminal process map - used to snapshot output on completion.

force_redraw: bool

Force a full terminal clear on next render frame.

tool_call_index: HashMap<String, (usize, usize)>

O(1) lookup: tool_call_id -> (message_index, block_index). Use lookup_tool_call(), index_tool_call().

todos: Vec<TodoItem>

Current todo list from Claude’s TodoWrite tool calls.

show_header: bool

Whether the header bar is visible. Toggled by Ctrl+H.

show_todo_panel: bool

Whether the todo panel is expanded (true) or shows compact status line (false). Toggled by Ctrl+T.

todo_scroll: usize

Scroll offset for the expanded todo panel (capped at 5 visible lines).

todo_selected: usize

Selected todo index used for keyboard navigation in the open todo panel.

focus: FocusManager

Focus manager for directional/navigation key ownership.

available_commands: Vec<AvailableCommand>

Commands advertised by the agent via AvailableCommandsUpdate.

cached_frame_area: Rect

Last known frame area (for mouse selection mapping).

selection: Option<SelectionState>

Current selection state for mouse-based selection.

scrollbar_drag: Option<ScrollbarDragState>

Active scrollbar drag state while left mouse button is held on the rail.

rendered_chat_lines: Vec<String>

Cached rendered chat lines for selection/copy.

rendered_chat_area: Rect

Area where chat content was rendered (for selection mapping).

rendered_input_lines: Vec<String>

Cached rendered input lines for selection/copy.

rendered_input_area: Rect

Area where input content was rendered (for selection mapping).

mention: Option<MentionState>

Active @ file mention autocomplete state.

slash: Option<SlashState>

Active slash-command autocomplete state.

pending_submit: bool

Deferred submit: set true when Enter is pressed. If another key event arrives during the same drain cycle (paste), this is cleared and the Enter becomes a newline. After the drain, the main loop checks: if still true, strips the trailing newline and submits.

drain_key_count: usize

Count of key events processed in the current drain cycle. Used to detect paste: if >1 key events arrive in a single cycle, Enter is treated as a newline rather than submit.

paste_burst: PasteBurstDetector

Timing-based paste burst detector. Tracks rapid key events to distinguish paste from typing when Event::Paste is not available (Windows).

pending_paste_text: String

Buffered Event::Paste payload for this drain cycle. Some terminals split one clipboard paste into multiple chunks; we merge them and apply placeholder threshold to the merged content once per cycle.

file_cache: Option<Vec<FileCandidate>>

Cached file list from cwd (scanned on first @ trigger).

cached_todo_compact: Option<Line<'static>>

Cached todo compact line (invalidated on set_todos()).

git_branch: Option<String>

Current git branch (refreshed on focus gain + turn complete).

cached_header_line: Option<Line<'static>>

Cached header line (invalidated when git branch changes).

cached_footer_line: Option<Line<'static>>

Cached footer line (invalidated on mode change).

update_check_hint: Option<String>

Optional startup update-check hint rendered at the footer’s right edge.

terminal_tool_calls: Vec<(String, usize, usize)>

Indexed terminal tool calls: (terminal_id, msg_idx, block_idx). Avoids O(n*m) scan of all messages/blocks every frame.

needs_redraw: bool

Dirty flag: skip terminal.draw() when nothing changed since last frame.

perf: Option<PerfLogger>

Performance logger. Present only when built with --features perf. Taken out (Option::take) during render, used, then put back to avoid borrow conflicts with &mut App.

fps_ema: Option<f32>

Smoothed frames-per-second (EMA of presented frame cadence).

last_frame_at: Option<Instant>

Timestamp of the previous presented frame.

Implementations

impl App

pub fn mark_frame_presented(&mut self, now: Instant)

Mark one presented frame at now, updating smoothed FPS.

pub fn frame_fps(&self) -> Option<f32>

pub fn ensure_welcome_message(&mut self)

Ensure the synthetic welcome message exists at index 0.

pub fn update_welcome_model_if_pristine(&mut self)

Update the welcome message’s model name, but only before chat starts.

pub fn insert_active_task(&mut self, id: String)

Track a Task tool call as active (in-progress subagent).

pub fn remove_active_task(&mut self, id: &str)

Remove a Task tool call from the active set (completed/failed).

pub fn lookup_tool_call(&self, id: &str) -> Option<(usize, usize)>

Look up the (message_index, block_index) for a tool call ID.

pub fn index_tool_call(&mut self, id: String, msg_idx: usize, block_idx: usize)

Register a tool call’s position in the message/block arrays.

pub fn mark_message_layout_dirty(&mut self, msg_idx: usize)

Mark message layout caches dirty from msg_idx onward.

Non-tail changes invalidate prefix-sum fast path so a full rebuild happens once.

pub fn mark_all_message_layout_dirty(&mut self)

Mark all message layout caches dirty.

pub fn finalize_in_progress_tool_calls( &mut self, new_status: ToolCallStatus, ) -> usize

Force-finish any lingering in-progress tool calls. Returns the number of tool calls that were transitioned.

pub fn refresh_git_branch(&mut self)

Detect the current git branch and invalidate the header cache if it changed.

pub fn focus_owner(&self) -> FocusOwner

Resolve the effective focus owner for Up/Down and other directional keys.

pub fn is_help_active(&self) -> bool

pub fn claim_focus_target(&mut self, target: FocusTarget)

Claim key routing for a navigation target. The latest claimant wins.

pub fn release_focus_target(&mut self, target: FocusTarget)

Release key routing claim for a navigation target.

pub fn normalize_focus_stack(&mut self)

Drop claims that are no longer valid for current state.