Codeman/test/tmux-capture-full-history.test.ts

/**
 * COD-47: full tmux scrollback replay on reload.
 *
 * Under VITEST, TmuxManager no-ops execSync (IS_TEST_MODE), so we can't drive
 * real tmux. Instead we assert the capture-arg construction directly from
 * source (same approach as tmux-capture-color.test.ts): a full-history capture
 * must use `capture-pane -p -e -J -S -<N>` (bounded to the configured history
 * limit, with an explicit exec maxBuffer) and skip the single-screen snapshot
 * repaint, while the visible capture keeps `capture-pane -p -e`.
 */
import { readFileSync } from 'node:fs';
import { resolve } from 'node:path';
import { describe, expect, it } from 'vitest';
import { formatCursorRestore, formatPaneSnapshot, hasVisibleContent, queryPaneCursor } from '../src/tmux-manager.js';

describe('tmux full-history pane capture (COD-47)', () => {
  const source = readFileSync(resolve(import.meta.dirname, '../src/tmux-manager.ts'), 'utf8');
  const methodStart = source.indexOf('capturePaneBuffer(muxName: string');
  // Bounded at the next method so `methodBody` really is one method: the
  // ordering assertions below would otherwise be satisfiable by a neighbour.
  const methodEnd = source.indexOf('captureActivePaneBuffer(muxName: string', methodStart);
  const methodBody = source.slice(methodStart, methodEnd);

  it('capturePaneBuffer accepts pane-capture options with a fullHistory flag', () => {
    expect(methodStart).toBeGreaterThan(-1);
    // The method signature must carry the opts channel...
    expect(source.slice(methodStart, methodStart + 160)).toContain('PaneCaptureOptions');
    // ...and the body must branch on opts.fullHistory.
    expect(methodBody).toContain('opts?.fullHistory === true');
  });

  it('full-history mode captures scrollback bounded to the configured history limit (-J -S -<N>)', () => {
    // `-S -<N>` (not unbounded `-S -`) keeps tmux from serializing more
    // scrollback than the configured history limit retains; `-J` re-joins
    // lines hard-wrapped at the capture-time pane width.
    expect(source).toContain('capture-pane -p -e -J -S -${historyLines}');
  });

  it('a full capture with a scrollbackOverride (remote history) reads the visible frame only (-J -S 0)', () => {
    // The remote tmux supplied the history; reading local history too would
    // splice two histories above one frame.
    expect(methodBody).toContain('scrollbackOverride !== undefined');
    expect(methodBody).toContain("'capture-pane -p -e -J -S 0'");
    expect(methodBody).toContain('joinScrollbackAndFrame(');
  });

  it('full-history exec sets an explicit maxBuffer (default 1MB would ENOBUFS multi-MB dumps)', () => {
    expect(methodBody).toContain('maxBuffer');
    expect(methodBody).toContain('FULL_HISTORY_CAPTURE_SLACK_BYTES');
  });

  it('still offers the visible single-screen capture for fast tab switches', () => {
    expect(source).toContain("'capture-pane -p -e'");
  });

  it('returns full-history capture as raw scrollback (skips the single-screen repaint)', () => {
    // The fullHistory branch returns before the formatPaneSnapshot repaint,
    // which is single-screen and would clip a multi-screen history.
    const branch = methodBody.indexOf('if (fullHistory) {\n        // Without geometry');
    const snapshot = methodBody.indexOf('formatPaneSnapshot(');
    expect(branch).toBeGreaterThan(-1);
    expect(snapshot).toBeGreaterThan(-1);
    expect(branch).toBeLessThan(snapshot);
    // …and what it returns is normalized linear scrollback, not a repaint.
    expect(methodBody.slice(branch, snapshot)).toContain('normalizeScrollbackEol(');
  });

  it('appends the pane cursor to the full-history capture', () => {
    // A linear replay leaves the caret wherever the last character landed — the
    // status line, for an agent CLI — and every cursor-relative update the CLI
    // sends afterwards is then measured from the wrong row.
    const restore = methodBody.indexOf('formatCursorRestore(geometry)');
    const snapshot = methodBody.indexOf('formatPaneSnapshot(');
    expect(restore).toBeGreaterThan(-1);
    expect(restore).toBeLessThan(snapshot);
  });

  it('keeps the trailing rows only when a cursor move will follow', () => {
    // Trailing blank rows are the bottom of the screen and the cursor move counts
    // up from them, so the two decisions travel together: no geometry, no move,
    // and the old trim applies instead.
    expect(methodBody).toContain("rawCapture.replace(/\\n$/, '')");
    expect(methodBody).toContain("const trimmed = rawCapture.replace(/\\n+$/g, '')");
  });

  it('defers to the byte history when the pane holds nothing visible', () => {
    expect(methodBody).toContain("if (!hasVisibleContent(trimmed)) return ''");
  });

  it('captureActivePaneBuffer forwards the capture options', () => {
    const sig = source.indexOf('captureActivePaneBuffer(muxName: string');
    expect(sig).toBeGreaterThan(-1);
    const body = source.slice(sig, sig + 800);
    expect(body).toContain('opts');
    expect(body).toContain('this.capturePaneBuffer(muxName, target, opts)');
  });
});

describe('full-history cursor restore', () => {
  it('counts up from the last replayed row rather than down from the top', () => {
    // Relative, not `CUP`: absolute row addressing is only correct while the
    // browser's row count equals the pane's, and resizeWindow does not wait for
    // tmux, so a capture can be taken before a requested resize has applied.
    expect(formatCursorRestore({ cols: 80, rows: 24, cursorX: 2, cursorY: 20 })).toBe('\x1b[3A\r\x1b[2C');
  });

  it('emits no row move when the caret is already on the last row', () => {
    expect(formatCursorRestore({ cols: 80, rows: 24, cursorX: 5, cursorY: 23 })).toBe('\r\x1b[5C');
  });

  it('emits no column move for column zero', () => {
    expect(formatCursorRestore({ cols: 80, rows: 10, cursorX: 0, cursorY: 0 })).toBe('\x1b[9A\r');
  });
});

describe('hasVisibleContent', () => {
  it('is false for a pane of blank rows', () => {
    expect(hasVisibleContent('\n'.repeat(23))).toBe(false);
  });

  it('is false for blank rows carrying only SGR attributes', () => {
    // `capture-pane -e` styles every row, so an all-blank pane is not an empty
    // string. Treating it as content would replace the byte history with a
    // blank screen.
    expect(hasVisibleContent('\x1b[m   \x1b[0m\n\x1b[m   \x1b[0m')).toBe(false);
  });

  it('is true as soon as one row carries a character', () => {
    expect(hasVisibleContent('\x1b[m   \x1b[0m\n\x1b[m x \x1b[0m')).toBe(true);
  });
});

describe('the geometry a capture reports back', () => {
  const source = readFileSync(resolve(import.meta.dirname, '../src/tmux-manager.ts'), 'utf8');
  const methodStart = source.indexOf('capturePaneBuffer(muxName: string');
  const methodEnd = source.indexOf('captureActivePaneBuffer(muxName: string', methodStart);
  const methodBody = source.slice(methodStart, methodEnd);

  it('writes the pane size onto the caller options before either replay path returns', () => {
    // IS_TEST_MODE no-ops execSync, so assert from source (same approach as the
    // capture-flag tests above). The write must precede the fullHistory branch:
    // both paths return from inside it, and a caller that got no geometry
    // cannot tell a mismatched frame from a matching one.
    const write = methodBody.indexOf('opts.capturedGeometry = { cols: geometry.cols, rows: geometry.rows }');
    // Anchor on the REPLAY branch, not the earlier `if (fullHistory)` that only
    // sizes the exec buffer.
    const replayBranch = methodBody.indexOf('if (!geometry) {');
    const visibleReturn = methodBody.indexOf('if (geometry) return formatPaneSnapshot(');
    expect(write).toBeGreaterThan(-1);
    expect(replayBranch).toBeGreaterThan(-1);
    expect(visibleReturn).toBeGreaterThan(-1);
    expect(write).toBeLessThan(replayBranch);
    expect(write).toBeLessThan(visibleReturn);
  });

  it('reports nothing when the cursor query gave no geometry', () => {
    // `queryPaneCursor` returns null on a failed or nonsensical query, and the
    // snapshot repaint is skipped in that case. Reporting a size anyway would
    // describe a frame that was never positioned.
    expect(methodBody).toContain('if (opts && geometry)');
  });
});

describe('the capture reports how much scrollback tmux holds (#{history_size})', () => {
  const source = readFileSync(resolve(import.meta.dirname, '../src/tmux-manager.ts'), 'utf8');
  const methodStart = source.indexOf('capturePaneBuffer(muxName: string');
  const methodBody = source.slice(methodStart, source.indexOf('captureActivePaneBuffer(muxName: string', methodStart));

  it('reads it from the one cursor query the capture already makes', () => {
    // No extra tmux call: every capture is a synchronous exec on the server.
    expect(methodBody).toContain(
      "'#{cursor_x} #{cursor_y} #{pane_width} #{pane_height} #{history_size} #{alternate_on}'"
    );
    expect(methodBody.match(/display-message/g)).toHaveLength(1);
    expect(methodBody).toContain('opts.capturedHistoryLines = geometry.historyLines');
  });

  it('parses the fifth field as historyLines', () => {
    expect(queryPaneCursor(() => '3 5 120 40 812\n')).toEqual({
      cursorX: 3,
      cursorY: 5,
      cols: 120,
      rows: 40,
      historyLines: 812,
    });
    // A pane in the alternate screen (fullscreen claude) holds none.
    expect(queryPaneCursor(() => '0 31 187 32 0')?.historyLines).toBe(0);
  });

  it('never lets a missing or bad history field void the caret', () => {
    for (const raw of ['3 5 120 40', '3 5 120 40 ', '3 5 120 40 x', '3 5 120 40 -1']) {
      const geometry = queryPaneCursor(() => raw);
      expect(geometry).toEqual({ cursorX: 3, cursorY: 5, cols: 120, rows: 40 });
      expect(geometry && 'historyLines' in geometry).toBe(false);
    }
  });

  it('still returns null when the geometry itself is bad', () => {
    expect(queryPaneCursor(() => 'x 5 120 40 812')).toBeNull();
    expect(
      queryPaneCursor(() => {
        throw new Error('no pane');
      })
    ).toBeNull();
  });
});

describe('why a capture has to report its height', () => {
  it('a snapshot addresses rows the receiving terminal may not have', () => {
    // formatPaneSnapshot positions every row absolutely. A terminal shorter
    // than the pane clamps each address past its own height onto its last
    // line, so the overflow rows overwrite one another and the rows underneath
    // are lost. Nothing in the escape sequence tells the client this happened —
    // hence captureRows on the response.
    const lines = Array.from({ length: 50 }, (_, i) => `row-${i + 1}`);
    // cursorX 5 keeps the trailing cursor-restore move (`\x1b[50;6H`) out of the
    // `;1H` row-paint match below, so the count is row paints alone.
    const snapshot = formatPaneSnapshot(lines, { cols: 100, rows: 50, cursorX: 5, cursorY: 49 });
    const addressed = [...snapshot.matchAll(/\x1b\[(\d+);1H/g)].map((m) => Number(m[1]));

    expect(Math.max(...addressed)).toBe(50);
    // A 30-row terminal cannot honour 20 of those addresses.
    expect(addressed.filter((row) => row > 30)).toHaveLength(20);
  });
});

describe('queryPaneCursor history depth', () => {
  it('reads tmux history_size as an optional fifth field', () => {
    expect(queryPaneCursor(() => '4 22 133 24 25000\n')).toEqual({
      cols: 133,
      rows: 24,
      cursorX: 4,
      cursorY: 22,
      historyLines: 25000,
    });
  });

  it('keeps the geometry and omits the depth when the fifth field is missing or invalid', () => {
    for (const raw of ['4 22 133 24', '4 22 133 24 abc', '4 22 133 24 -1']) {
      const geometry = queryPaneCursor(() => raw);
      expect(geometry, raw).toEqual({ cols: 133, rows: 24, cursorX: 4, cursorY: 22 });
    }
  });

  it('reads tmux alternate_on as an optional sixth field', () => {
    expect(queryPaneCursor(() => '4 22 133 24 29 1\n')).toEqual({
      cols: 133,
      rows: 24,
      cursorX: 4,
      cursorY: 22,
      historyLines: 29,
      alternateOn: true,
    });
    expect(queryPaneCursor(() => '4 22 133 24 29 0')?.alternateOn).toBe(false);
    for (const raw of ['4 22 133 24 29', '4 22 133 24 29 2', '4 22 133 24 29 x']) {
      expect(
        queryPaneCursor(() => raw),
        raw
      ).not.toHaveProperty('alternateOn');
    }
  });

  it('asks tmux for the history depth and alternate screen in the same display-message as the cursor', () => {
    const source = readFileSync(resolve(import.meta.dirname, '../src/tmux-manager.ts'), 'utf8');
    expect(source).toContain("'#{cursor_x} #{cursor_y} #{pane_width} #{pane_height} #{history_size} #{alternate_on}'");
  });
});