COD-47 replay full tmux scrollback on terminal reload

A full page reload (GET /api/sessions/:id/terminal with no ?tail=) now captures
the ENTIRE tmux scrollback via capture-pane -p -e -S -, so users get back history
that scrolled off Codeman's byte buffer. Tab switches (?tail=N) keep the fast
visible-frame capture.

- tmux-manager capturePaneBuffer/captureActivePaneBuffer take { fullHistory }:
  full-history returns raw linear scrollback (skips the single-screen
  formatPaneSnapshot repaint, which would clip multi-screen history).
- /terminal selects full-history on full reload, visible on tail; caps the
  payload at the configured terminalBufferMaxBytes (keeps most-recent bytes,
  line-aligned) and returns source/fullSize/truncated metadata.

Verified: tsc 0, tmux-capture-full-history 5/5, session-routes 68/68.
Caveat: lines tmux already evicted past its history-limit can't be recovered.

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

@@ -0,0 +1,51 @@
+/**
+ * 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 -S -` 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';
+
+describe('tmux full-history pane capture (COD-47)', () => {
+  const source = readFileSync(resolve(import.meta.dirname, '../src/tmux-manager.ts'), 'utf8');
+
+  it('capturePaneBuffer accepts a fullHistory option', () => {
+    const sig = source.indexOf('capturePaneBuffer(muxName: string');
+    expect(sig).toBeGreaterThan(-1);
+    // The method signature must carry the opts.fullHistory channel.
+    expect(source.slice(sig, sig + 160)).toContain('fullHistory');
+  });
+
+  it('full-history mode requests the entire scrollback with -S -', () => {
+    expect(source).toContain('capture-pane -p -e -S -');
+  });
+
+  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)', () => {
+    const sig = source.indexOf('capturePaneBuffer(muxName: string');
+    const body = source.slice(sig, sig + 2400);
+    // When fullHistory, return the raw buffer BEFORE the formatPaneSnapshot
+    // repaint (which is single-screen and would clip a multi-screen history).
+    const earlyReturn = body.indexOf('if (fullHistory)');
+    const snapshot = body.indexOf('formatPaneSnapshot(');
+    expect(earlyReturn).toBeGreaterThan(-1);
+    expect(snapshot).toBeGreaterThan(-1);
+    expect(earlyReturn).toBeLessThan(snapshot);
+  });
+
+  it('captureActivePaneBuffer forwards the fullHistory option', () => {
+    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)');
+  });
+});