Merge pull request #395 from irisitymichaelgrundberg/fix/full-history-replay-row-alignment

fix(terminal): keep row alignment in the full-history pane replay

CLAUDE.md

@@ -247,7 +247,7 @@ Codeman is a Claude Code session manager with web interface and autonomous Ralph
 
 **Circuit breakers**: the Ralph breaker prevents respawn thrashing (`CLOSED` → `HALF_OPEN` → `OPEN`; reset via `/api/sessions/:id/ralph-circuit-breaker/reset`). **Distinct: the PTY-exit breaker** (`session-pty-exit-breaker.ts`) trips after repeated rapid PTY exits and blocks auto-restarts. ⚠️ It resets ONLY via an explicit `{clearBreaker:true}` body on `POST /api/sessions/:id/interactive`; the frontend's auto-reattach in `selectSession()` sends no body and must never clear it. → [architecture-invariants#circuit-breakers-ralph--pty-exit](docs/architecture-invariants.md#circuit-breakers-ralph-and-pty-exit)
 
-**Full-scrollback replay**: `GET /api/sessions/:id/terminal?full=1` returns the entire tmux scrollback, bounded by the configured history limit. On success the capture is returned ALONE (`source='mux-full-history'`), superseding the byte buffer so nothing duplicates. The first load of each non-shell TUI session per page requests `full=1` (`_fullHistoryLoaded` Set); Shell selection and automatic drop recovery always use a bounded 1 MiB `?tail=` window. Shell loads the rest only when **Load full history** is pressed; ordinary scrolling must not trigger a multi-megabyte reset+replay on xterm's main thread. Other modes may re-pull at the TOP (cooldown-guarded — tmux repaints bursty output in place, so browser scrollback shrinks while tmux's history stays complete). Live writes are one-chunk-in-flight, released by xterm's parse callback, so xterm's private queue cannot bypass the browser's 128 KiB render cap. While WebSocket owns terminal I/O, duplicate SSE terminal events are dropped before JSON parsing, and recovery is single-flight per active session. ⚠️ A full re-pull must never DOWNGRADE the buffer: a repaint-mode CLI pane keeps no tmux history, so its capture is one frame and the reset+rewrite would delete history mid-scroll — `_replayWouldShrinkBuffer()` refuses it and slows that session's cooldown to 60s. → [architecture-invariants#full-scrollback-replay](docs/architecture-invariants.md#full-scrollback-replay)
+**Full-scrollback replay**: `GET /api/sessions/:id/terminal?full=1` returns the entire tmux scrollback, bounded by the configured history limit. On success the capture is returned ALONE (`source='mux-full-history'`), superseding the byte buffer so nothing duplicates. The first load of each non-shell TUI session per page requests `full=1` (`_fullHistoryLoaded` Set); Shell selection and automatic drop recovery always use a bounded 1 MiB `?tail=` window. Shell loads the rest only when **Load full history** is pressed; ordinary scrolling must not trigger a multi-megabyte reset+replay on xterm's main thread. Other modes may re-pull at the TOP (cooldown-guarded — tmux repaints bursty output in place, so browser scrollback shrinks while tmux's history stays complete). Live writes are one-chunk-in-flight, released by xterm's parse callback, so xterm's private queue cannot bypass the browser's 128 KiB render cap. While WebSocket owns terminal I/O, duplicate SSE terminal events are dropped before JSON parsing, and recovery is single-flight per active session. ⚠️ **A `full=1` capture ENDS with a cursor move back to the pane's own caret position**, counted UP from the last replayed row — without it the caret stays where the last character landed, which for an agent CLI is the status line, and every cursor-relative update the CLI sends afterwards is measured from the wrong row. The move is relative, not `CUP`: absolute row addressing is only right while the browser's rows equal the pane's, and `resizeWindow` does not wait for tmux, so a capture can be taken before a requested resize applies. That makes row alignment load-bearing on this path: no transform that can DELETE A LINE may run over the capture, so it keeps its trailing blank rows and skips redraw-bloat stripping, the banner trim and the leading-whitespace strip. ⚠️ Those three skips key on whether a capture actually CAME BACK (`isFullCapture`), never on `?full=1` alone — the fallback to the byte history is a stream of successive frames that must still be stripped, and a session with no mux takes it on every load. A capture holding nothing visible returns '' so the byte history survives instead of a blank screen replacing it. ⚠️ A full re-pull must never DOWNGRADE the buffer: a repaint-mode CLI pane keeps no tmux history, so its capture is one frame and the reset+rewrite would delete history mid-scroll — `_replayWouldShrinkBuffer()` refuses it and slows that session's cooldown to 60s. → [architecture-invariants#full-scrollback-replay](docs/architecture-invariants.md#full-scrollback-replay)
 
 **Terminal touch gestures: link taps and text selection**: on a touch device xterm's own handlers see neither — `touch-action: none` plus touchstart's preventDefault suppress the browser's compatibility mouse events, `_installMobileTapMouseGuard` drops the trusted ones that still arrive, and the synthetic `mousedown`/`mouseup` pair dispatched for mouse REPORTING goes to the `.xterm` root, an ANCESTOR of the screen element the linkifier and SelectionService listen on. So both gestures are driven explicitly. ⚠️ **A tap activates the link under it** through the SAME provider that feeds the hover linkifier (`_terminalLinkAtPoint`, containment mirroring xterm's `_linkAtPosition`), synchronously inside `touchend` — that is what keeps the user gesture `window.open` needs — and BEFORE any mouse report, mirroring `_handleDesktopTerminalClick`'s skip for a hovered link. Two rows keep their meaning: the caret's logical line (`_tapIsOnCaretLine`, where a tap places the cursor in text the USER typed) and TUI-owned rows (`_isActionableMobileTerminalTap`, answering a dialog). ⚠️ The caret line is the boundary rather than the tap INTENT, because a shell classifies every tap as `'input'` and gating on that would leave every URL in shell output inert. ⚠️ **Long-press selects** by driving xterm's public `select()` (renderer-independent — under WebGL the glyphs are pixels and native selection cannot exist), drag or a further tap extends, and Copy goes through `copyTerminalSelection()` for its execCommand fallback on plain-HTTP installs. Three guards are load-bearing and each came from a real phone: the compat mouse pair after `touchend` (xterm focuses on mousedown and SelectionService resets the model there, so the keyboard sprang up and the selection vanished on lift), the platform's own ~500ms long-press (Android Chrome focuses the nearest editable element — the helper textarea — through no event a handler can preventDefault, so a bounded focus guard blurs it and `contextmenu` is suppressed for the gesture window), and `copyTerminalSelection()`'s closing `terminal.focus()` (right on desktop, wrong on a phone). Tests: `test/terminal-touch-tap.test.ts`.
 

src/mux-interface.ts

@@ -137,7 +137,12 @@ export interface RespawnPaneOptions {
 
 /** Options for pane buffer capture (COD-47 full-history mode). */
 export interface PaneCaptureOptions {
-  /** Capture the entire tmux scrollback instead of just the visible frame. */
+  /**
+   * Capture the entire scrollback instead of just the visible frame, as linear
+   * text ending with a cursor move back to the pane's caret position. An
+   * implementation returns '' when the pane holds nothing visible, which the
+   * caller reads as "nothing to replay" and keeps its existing history.
+   */
   fullHistory?: boolean;
   /** Bound the full-history capture to this many scrollback lines (`-S -<N>`). */
   historyLimitLines?: number;

src/tmux-manager.ts

@@ -528,6 +528,73 @@ export function normalizeScrollbackEol(buffer: string): string {
   return buffer.replace(/\r?\n/g, '\r\n');
 }
 
+/** Pane geometry and caret position, as `display-message` reports them. */
+interface PaneCursorGeometry {
+  cols: number;
+  rows: number;
+  cursorX: number;
+  cursorY: number;
+}
+
+/**
+ * Read the pane's cursor and size, or null when tmux cannot say.
+ *
+ * Every field is validated together: a caller that gets a value back can place
+ * a caret with it, and one that gets null must not try.
+ */
+export function queryPaneCursor(run: () => string): PaneCursorGeometry | null {
+  let raw: string;
+  try {
+    raw = run().trim();
+  } catch (cursorErr) {
+    console.error('[TmuxManager] Failed to query pane cursor after capture:', cursorErr);
+    return null;
+  }
+  const [cursorX, cursorY, cols, rows] = raw.split(/\s+/).map((value) => parseInt(value, 10));
+  if (
+    !Number.isFinite(cursorX) ||
+    !Number.isFinite(cursorY) ||
+    !Number.isFinite(cols) ||
+    !Number.isFinite(rows) ||
+    cursorX < 0 ||
+    cursorY < 0 ||
+    cols <= 0 ||
+    rows <= 0
+  ) {
+    return null;
+  }
+  return { cols, rows, cursorX, cursorY };
+}
+
+/** SGR attributes, which is all `capture-pane -e` emits. */
+// eslint-disable-next-line no-control-regex
+const CAPTURE_STYLE_SEQUENCE = /\x1b\[[0-9;:]*m/g;
+
+/** Whether a capture holds anything a reader would see, styles discounted. */
+export function hasVisibleContent(capture: string): boolean {
+  return /\S/.test(capture.replace(CAPTURE_STYLE_SEQUENCE, ''));
+}
+
+/**
+ * Put the caret back where the pane has it, counting UP from the bottom of what
+ * was just replayed.
+ *
+ * Relative rather than absolute (`CUP`) on purpose. `\x1b[<row>;<col>H` numbers
+ * rows from the top of the browser's screen, so it only lands correctly while
+ * the browser's row count equals the pane's — and it need not, because
+ * `resizeWindow` fires its tmux resize without waiting, so a capture can be
+ * taken before a requested resize has been applied. Counting up from the last
+ * replayed row is anchored to the content instead, which is the thing both ends
+ * genuinely share.
+ */
+export function formatCursorRestore(geometry: PaneCursorGeometry): string {
+  const up = Math.max(0, geometry.rows - 1 - geometry.cursorY);
+  const right = Math.max(0, geometry.cursorX);
+  // `\r` first so the column is known: the replay leaves the caret wherever the
+  // last row's text ended.
+  return `${up > 0 ? `\x1b[${up}A` : ''}\r${right > 0 ? `\x1b[${right}C` : ''}`;
+}
+
 export function formatPaneSnapshot(
   lines: string[],
   geometry: { cols: number; rows: number; cursorX: number; cursorY: number }
@@ -3199,11 +3266,14 @@ export class TmuxManager extends EventEmitter implements TerminalMultiplexer {
    *   the browser xterm reproduces the live frame. Used for fast tab switches.
    * - Full history (`opts.fullHistory`): `capture-pane -p -e -J -S -<N>` grabs
    *   the tmux scrollback (COD-47, bounded to the configured history limit),
-   *   returned as linear scrollback text with SGR codes preserved (NOT
-   *   repositioned — a multi-screen history can't be painted into a single
-   *   visible frame, so the snapshot repaint is skipped). `-J` re-joins lines
-   *   hard-wrapped at the pane width so they reflow in the browser xterm.
-   *   Used for full page reloads so the user gets back their scroll history.
+   *   returned as linear scrollback text with SGR codes preserved. Rows are not
+   *   repainted at absolute positions — a multi-screen history can't be painted
+   *   into a single visible frame — but the capture DOES end with a cursor move
+   *   putting the caret back where the pane has it, counted up from the last
+   *   replayed row. `-J` re-joins lines hard-wrapped at the pane width so they
+   *   reflow in the browser xterm. Used for full page reloads so the user gets
+   *   back their scroll history. Returns '' for a pane holding nothing visible,
+   *   so the caller keeps whatever history it already had.
    *   Caveat: lines tmux has already evicted past its history-limit are gone.
    */
   /**
@@ -3262,42 +3332,41 @@ export class TmuxManager extends EventEmitter implements TerminalMultiplexer {
         execOpts.maxBuffer =
           (opts?.maxCaptureBytes ?? DEFAULT_TERMINAL_BUFFER_MAX_BYTES) + FULL_HISTORY_CAPTURE_SLACK_BYTES;
       }
-      const buffer = execSync(`${this.tmux()} ${captureFlags} -t ${shellescape(target)}`, execOpts).replace(
-        /\n+$/g,
-        ''
-      );
-      // Full-history spans many screens — return it as raw linear scrollback
-      // rather than repainting rows at single-screen absolute positions. tmux
-      // joins scrollback rows with a bare `\n`; normalize to `\r\n` so a fresh
-      // xterm (convertEol:false) starts each replayed line at column 0 instead
-      // of staircasing diagonally (COD-138).
-      if (fullHistory) {
-        return normalizeScrollbackEol(buffer);
-      }
-      try {
-        const cursor = execSync(
+      const rawCapture = execSync(`${this.tmux()} ${captureFlags} -t ${shellescape(target)}`, execOpts);
+      // Query the cursor BEFORE deciding anything else. On the full-history path
+      // it settles both how the capture is trimmed and whether a cursor move is
+      // appended, and those two have to agree: trailing blank rows are only safe
+      // to keep when a move follows to put the caret back above them.
+      const geometry = queryPaneCursor(() =>
+        execSync(
           `${this.tmux()} display-message -p -t ${shellescape(target)} '#{cursor_x} #{cursor_y} #{pane_width} #{pane_height}'`,
-          {
-            encoding: 'utf-8',
-            timeout: EXEC_TIMEOUT_MS,
-          }
-        ).trim();
-        const [cursorX, cursorY, cols, rows] = cursor.split(/\s+/).map((value) => parseInt(value, 10));
-        if (
-          Number.isFinite(cursorX) &&
-          Number.isFinite(cursorY) &&
-          Number.isFinite(cols) &&
-          Number.isFinite(rows) &&
-          cursorX >= 0 &&
-          cursorY >= 0 &&
-          cols > 0 &&
-          rows > 0
-        ) {
-          return formatPaneSnapshot(buffer.split('\n'), { cols, rows, cursorX, cursorY });
-        }
-      } catch (cursorErr) {
-        console.error('[TmuxManager] Failed to query pane cursor after capture:', cursorErr);
+          { encoding: 'utf-8', timeout: EXEC_TIMEOUT_MS }
+        )
+      );
+
+      if (fullHistory) {
+        // Without geometry there is no cursor move, so fall back to the old trim.
+        // Keeping the blank rows here would park the caret at the bottom of the
+        // pane with nothing to correct it — worse than not trying at all.
+        if (!geometry) return normalizeScrollbackEol(rawCapture.replace(/\n+$/g, ''));
+        // Take the line terminator off and nothing else. The trailing blank rows
+        // that remain are the real bottom of the screen, and the cursor move
+        // below counts up from it. tmux joins rows with a bare `\n`; normalize to
+        // `\r\n` so a fresh xterm (convertEol:false) starts each replayed line at
+        // column 0 instead of staircasing diagonally (COD-138).
+        const trimmed = rawCapture.replace(/\n$/, '');
+        // An all-blank pane has to keep reading as "nothing to replay". The caller
+        // treats an empty string as "capture unavailable" and keeps the byte
+        // history; blank rows plus a cursor move are not empty, so without this a
+        // blank pane REPLACES that history with a blank screen — the downgrade
+        // `_replayWouldShrinkBuffer` exists to refuse, arriving from the server
+        // side where that guard cannot see it.
+        if (!hasVisibleContent(trimmed)) return '';
+        return `${normalizeScrollbackEol(trimmed)}${formatCursorRestore(geometry)}`;
       }
+
+      const buffer = rawCapture.replace(/\n+$/g, '');
+      if (geometry) return formatPaneSnapshot(buffer.split('\n'), geometry);
       // Cursor query failed or geometry was invalid, so we skip the absolute-
       // positioned snapshot repaint and fall back to the raw capture. Normalize
       // its bare `\n` line endings to `\r\n` so the replay doesn't staircase

src/web/routes/session-routes.ts

@@ -2603,6 +2603,12 @@ export function registerSessionRoutes(
         ? 'mux-full-history'
         : 'mux-visible'
       : 'history';
+    // What the three row-preserving skips below must key on. `isFullReload` is
+    // only what the CLIENT ASKED FOR: when the capture comes back null — ENOBUFS,
+    // a timeout, a vanished pane, or a session with no mux at all — rawBuffer
+    // falls back to the byte history, which is a stream of successive frames with
+    // no row alignment to protect and every reason to be stripped.
+    const isFullCapture = isFullReload && hasLiveMuxBuffer;
     let rawBuffer: string;
     if (liveMuxBuffer !== null && liveMuxBuffer.length > 0) {
       // Full-history capture is the RENDERED form of everything already in the
@@ -2649,8 +2655,16 @@ export function registerSessionRoutes(
     // During long thinking phases, Ink rewrites the same rows thousands of times
     // (500KB+). Without stripping, tail mode returns only spinner frames and
     // the terminal appears empty when switching tabs.
+    // A full reload's buffer IS the rendered pane, one line per screen row, and
+    // it ends with an absolute cursor move back to the pane's own position.
+    // Every transform below that can DELETE A LINE would shift the rows out from
+    // under that position, leaving the caret a row off — on the composer's
+    // border rather than its input line. Redraw-bloat stripping exists for a
+    // byte stream of successive frames; a capture holds no successive frames.
     let strippedBuffer =
-      getCli(session.mode)?.capabilities.stripInkBloat === false ? rawBuffer : stripInkRedrawBloat(rawBuffer);
+      isFullCapture || getCli(session.mode)?.capabilities.stripInkBloat === false
+        ? rawBuffer
+        : stripInkRedrawBloat(rawBuffer);
 
     // Strip alt-screen toggles and scrollback-erase from Codex/Claude byte
     // streams. xterm.js obeys them by switching to its scrollback-less alt
@@ -2688,7 +2702,10 @@ export function registerSessionRoutes(
       cleanBuffer = strippedBuffer;
 
       // Find where Claude banner starts (has color codes before "Claude")
-      const claudeMatch = cleanBuffer.match(CLAUDE_BANNER_PATTERN);
+      // Skipped for a full reload: the banner sits at whatever row the pane has
+      // it, and cutting to it would drop the blank rows above and move every
+      // row up by that many.
+      const claudeMatch = isFullCapture ? null : cleanBuffer.match(CLAUDE_BANNER_PATTERN);
       if (claudeMatch && claudeMatch.index !== undefined && claudeMatch.index > 0) {
         let lineStart = claudeMatch.index;
         while (lineStart > 0 && cleanBuffer[lineStart - 1] !== '\n') {
@@ -2699,7 +2716,11 @@ export function registerSessionRoutes(
     }
 
     // Remove Ctrl+L and leading whitespace (cheap on tailed subset)
-    cleanBuffer = cleanBuffer.replace(CTRL_L_PATTERN, '').replace(LEADING_WHITESPACE_PATTERN, '');
+    // Leading whitespace goes too, except on a full reload where a leading
+    // blank line is the pane's own first row and dropping it shifts every row
+    // up by one.
+    cleanBuffer = cleanBuffer.replace(CTRL_L_PATTERN, '');
+    if (!isFullCapture) cleanBuffer = cleanBuffer.replace(LEADING_WHITESPACE_PATTERN, '');
 
     const finishedAt = performance.now();
     reply.header(

test/routes/session-routes.test.ts

@@ -851,6 +851,85 @@ describe('session-routes', () => {
       );
     });
 
+    it('full reload (?full=1) keeps every leading row so the restored cursor lands on the right line', async () => {
+      // The capture ends with an absolute cursor move, so its rows and the pane's
+      // rows must line up one for one. Three transforms used to run over it and
+      // each could delete a leading line: redraw-bloat stripping, the trim that
+      // cuts everything above the Claude banner, and a leading-whitespace strip.
+      // Any one of them shifted the frame up and left the caret a row off.
+      harness.ctx._session.mode = 'claude';
+      harness.ctx._session.terminalBuffer = '';
+      // A blank first row, then the banner — the shape a real pane has.
+      const rendered = ['', '\x1b[1mClaude Code v2.1.266', 'conversation', '\u276f ', '\x1b[4;3H'].join('\r\n');
+      (harness.ctx.mux as { captureActivePaneBuffer?: unknown }).captureActivePaneBuffer = vi.fn(
+        (_name: string, opts?: { fullHistory?: boolean }) => (opts?.fullHistory ? rendered : 'visible frame')
+      );
+
+      const res = await harness.app.inject({
+        method: 'GET',
+        url: `/api/sessions/${harness.ctx._sessionId}/terminal?full=1`,
+      });
+
+      expect(res.statusCode).toBe(200);
+      const body = JSON.parse(res.body);
+      expect(body.data.source).toBe('mux-full-history');
+      // The blank first row survives, so row N of the reply is row N of the pane.
+      expect(body.data.terminalBuffer.startsWith('\r\n')).toBe(true);
+      expect(body.data.terminalBuffer.split('\r\n')).toHaveLength(rendered.split('\r\n').length);
+    });
+
+    it('full reload (?full=1) still strips the byte history when no capture came back', async () => {
+      // The row-preserving skips exist for a rendered pane. When the capture is
+      // unavailable the reply IS the byte stream — successive Ink frames, no row
+      // alignment to protect — so keying the skips on the query parameter rather
+      // than on the capture returned it unstripped, which is the whole reason
+      // stripInkRedrawBloat exists. A session with no mux takes this path on
+      // every first selection, not just during an outage.
+      harness.ctx._session.mode = 'claude';
+      // A VPA cluster the stripper will collapse: >= 10 sequences, spanning the
+      // 32KB minimum, with real content after it.
+      const frame = '\x1b[12d' + 'spinner frame '.repeat(240);
+      harness.ctx._session.terminalBuffer = frame.repeat(20) + 'REAL CONTENT AFTER THE BLOAT';
+      (harness.ctx.mux as { captureActivePaneBuffer?: unknown }).captureActivePaneBuffer = vi.fn(() => null);
+
+      const res = await harness.app.inject({
+        method: 'GET',
+        url: `/api/sessions/${harness.ctx._sessionId}/terminal?full=1`,
+      });
+
+      expect(res.statusCode).toBe(200);
+      const body = JSON.parse(res.body);
+      expect(body.data.source).toBe('history');
+      expect(body.data.terminalBuffer).toContain('REAL CONTENT AFTER THE BLOAT');
+      // Stripped, not passed through whole.
+      expect(body.data.terminalBuffer.length).toBeLessThan(harness.ctx._session.terminalBuffer.length);
+    });
+
+    it('full reload (?full=1) keeps the byte history when the capture is empty', async () => {
+      // Pins the contract the capture side relies on: an empty capture means
+      // "nothing to replay" and the byte history survives. capturePaneBuffer
+      // returns '' for an all-blank pane precisely to reach this branch, since
+      // retaining trailing blank rows and appending a cursor move would
+      // otherwise make a blank screen non-empty and replace the history with it.
+      // (The blank-pane decision itself is unit-tested on hasVisibleContent —
+      // capturePaneBuffer short-circuits under IS_TEST_MODE and cannot run here.)
+      harness.ctx._session.mode = 'claude';
+      harness.ctx._session.terminalBuffer = 'a real conversation worth keeping';
+      (harness.ctx.mux as { captureActivePaneBuffer?: unknown }).captureActivePaneBuffer = vi.fn(
+        (_name: string, opts?: { fullHistory?: boolean }) => (opts?.fullHistory ? '' : 'visible frame')
+      );
+
+      const res = await harness.app.inject({
+        method: 'GET',
+        url: `/api/sessions/${harness.ctx._sessionId}/terminal?full=1`,
+      });
+
+      expect(res.statusCode).toBe(200);
+      const body = JSON.parse(res.body);
+      expect(body.data.source).toBe('history');
+      expect(body.data.terminalBuffer).toContain('a real conversation worth keeping');
+    });
+
     it('full reload (?full=1) falls back to the byte history when the capture is unavailable', async () => {
       harness.ctx._session.mode = 'claude';
       harness.ctx._session.terminalBuffer = 'byte history survives';

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

@@ -11,11 +11,15 @@
 import { readFileSync } from 'node:fs';
 import { resolve } from 'node:path';
 import { describe, expect, it } from 'vitest';
+import { formatCursorRestore, hasVisibleContent } 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');
-  const methodBody = source.slice(methodStart, methodStart + 4000);
+  // 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);
@@ -42,13 +46,37 @@ describe('tmux full-history pane capture (COD-47)', () => {
   });
 
   it('returns full-history capture as raw scrollback (skips the single-screen repaint)', () => {
-    // When fullHistory, return the raw buffer BEFORE the formatPaneSnapshot
-    // repaint (which is single-screen and would clip a multi-screen history).
-    const earlyReturn = methodBody.indexOf('return normalizeScrollbackEol(buffer);');
+    // 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(earlyReturn).toBeGreaterThan(-1);
+    expect(branch).toBeGreaterThan(-1);
     expect(snapshot).toBeGreaterThan(-1);
-    expect(earlyReturn).toBeLessThan(snapshot);
+    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$/, '')");
+    expect(methodBody).toContain("if (!geometry) return normalizeScrollbackEol(rawCapture.replace(/\\n+$/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', () => {
@@ -59,3 +87,37 @@ describe('tmux full-history pane capture (COD-47)', () => {
     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);
+  });
+});