Struct TerminalSnapshot 

pub struct TerminalSnapshot {
    pub cells: Arc<[Cell]>,
    pub rows: u16,
    pub cols: u16,
    pub cursor_row: u16,
    pub cursor_col: u16,
    pub cursor_visible: bool,
    pub cursor_shape: CursorShape,
    pub title: Option<String>,
    pub alt_screen: bool,
    pub scroll_offset: u32,
    pub scrollback_rows: u32,
    pub seq: u64,
}

One published frame. Renderer reads via Arc<ArcSwap<TerminalSnapshot>> — .load() is wait-free.

The cells slice is row-major: cell at (row, col) lives at cells[row * cols + col]. Always exactly rows * cols long.

seq is a monotonic frame counter — renderers can skip a repaint when the loaded snapshot’s seq matches the last-painted one.

Fields

cells: Arc<[Cell]>

rows: u16

cols: u16

cursor_row: u16

cursor_col: u16

cursor_visible: bool

cursor_shape: CursorShape

title: Option<String>

None = no OSC 0/2 title received yet; renderer falls back to the buffer’s label.

alt_screen: bool

True while the program is on the xterm “alternate screen” buffer (vim, less, htop, etc.). Renderers can use this to disable the modeline-scrollback indicator.

scroll_offset: u32

T3 (2026-05-25): rows scrolled back from the live edge. 0 = live; positive values expose scrollback. Renderers surface this on the modeline so the user can tell at a glance they’re viewing history.

scrollback_rows: u32

T3 (2026-05-25): current number of rows held in scrollback (history that has scrolled off the live screen). Grows as rows roll off; bounded by the configured terminal.scrollback-lines. Used by the modeline / status line to render a “row N of M” indicator and to gate scroll-up motions.

seq: u64

Monotonic per-terminal frame counter.

Implementations

impl TerminalSnapshot

pub fn empty() -> Self

Empty 24×80 snapshot — the vim/xterm-conventional fallback size for contexts with no real spawn geometry yet (tests, Default). NOT used by spawn()’s initial publish — see Self::empty_sized.

pub fn empty_sized(rows: u16, cols: u16) -> Self

Empty snapshot at a CALLER-SUPPLIED size. spawn() publishes this (at the real SpawnConfig::{rows,cols}) as the placeholder shown before the reader thread processes the child’s first output chunk.

Regression (2026-07-02): spawn() used to publish Self::empty() unconditionally — a hardcoded 24×80 disconnected from the real spawn size. The alacritty Term (build_term) and the kernel PTY (openpty) were ALWAYS sized correctly from SpawnConfig; only this placeholder lied about it. When the real pane is taller than 24 rows (the common case), a paint landing in the placeholder’s brief window caps rows_to_paint at 24, and — critically — the mismatch does NOT self-correct via a renderer resize the way the old doc comment claimed: SetPaneViewport’s diff-then-send gate only fires a PTY resize when the computed row count DIFFERS from the pane’s already- published viewport_height, which do_terminal_spawn already read to size the spawn — so there is no delta to trigger a correcting resize. The window closes only once the reader thread republishes a snapshot from real output, whenever that first arrives.

pub fn cell_at(&self, row: u16, col: u16) -> Cell

Cell at (row, col). Returns the default cell (space on default bg/fg) for out-of-range indices so renderers can iterate naively without bounds checks.

Trait Implementations

impl Clone for TerminalSnapshot

fn clone(&self) -> TerminalSnapshot

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for TerminalSnapshot

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for TerminalSnapshot

fn default() -> Self

Returns the “default value” for a type.