fix(terminal): stop the scroll-to-top re-pull from deleting history, page the CLI when local scrollback is hollow (#205)

The 1.12.0 retest on #205 reported it still broken in two shapes: a wheel that
did nothing at all on Firefox/macOS (while Fn+Up paged back through intact
text), and iPhone history that went back a little, repeated blocks and got
worse the further up it went. Both come from a Claude pane's LOCAL buffer being
hollow: tmux keeps no history for a repaint-mode pane (history_size 0), so
xterm holds only replayed repaint frames.

1. The scroll-to-top full=1 re-pull now refuses a DOWNGRADE. It resets the
   terminal and rewrites it from the capture, which is a win when tmux holds
   more than the browser, but for a repaint-mode pane that capture is roughly
   ONE frame and the rewrite deleted history mid-scroll. Measured A/B on a live
   pane, same gesture: guard off collapses 341 rows to 42, guard on preserves
   all 341. _replayWouldShrinkBuffer() estimates the capture's rendered rows
   (escapes stripped, capture-pane -J re-wrapping accounted for) and skips the
   rewrite when it is more than one screen short; a refused session's cooldown
   goes from 4s to 60s so a hollow pane stops re-fetching megabytes.

2. A false forwarding gate on a Claude session no longer means a dead gesture.
   Under a triple guard (claude mode, gate false, baseY 0), wheel and touch
   travel becomes coalesced PageUp/PageDown through the same 40ms queue as the
   SGR reports, at half a screen of travel per page key. Shift is excluded: it
   keeps meaning "local scrollback".

3. getClaudeCliVersion() no longer caches FAILURE. It stored null on any
   exception and guarded on !== undefined, so one timed-out or PATH-starved
   probe at the first Claude session start disabled wheel-forwarding for every
   Claude session until the server restarted, which fits a report of breakage on
   phone, tablet and laptop at once. Success is still cached for the process
   lifetime; failures retry with a 1/2/4 up to 15min backoff, and the policy is
   a pure function so the semantics are testable without spawning claude.

4. The terminalWheelLocalScrollback footgun is handled by pairing rather than
   scoping: the setting keeps meaning exactly what it says, and fix 2 catches
   the case where "local" is empty. The App Settings tooltip now says to leave
   it off for Claude/Codex sessions.

5. _logScrollRouting() prints one line per session per distinct decision:
   forward-sgr / page-keys / local-scrollback / repull-refused-downgrade, with
   mode, cliVersion, the opt-out state, mouse tracking and local scrollback
   depth. #205 ran two rounds of remote guesswork over questions that line
   answers directly.

Verified end to end against a real isolated instance (own data dir and tmux
socket) with real wheel events: forwarding still sends SGR reports, the opt-out
now sends real PageUp/PageDown where the wheel was dead, a tab-switch collapse
(401 rows to 44) is still fully recovered by the re-pull (back to 401), and a
seeded 341-row Claude buffer survives the same gesture that destroys it with the
guard disabled.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -206,9 +206,9 @@ 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 session per page load requests `full=1` (`_fullHistoryLoaded` Set); tab switches keep the cheap `?tail=` path, and scrolling up at the TOP of the buffer re-pulls `full=1` on demand (cooldown-guarded — tmux repaints bursty output in place, so browser scrollback shrinks while tmux's history stays complete). → [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 session per page load requests `full=1` (`_fullHistoryLoaded` Set); tab switches keep the cheap `?tail=` path, and scrolling up at the TOP of the buffer re-pulls `full=1` on demand (cooldown-guarded — tmux repaints bursty output in place, so browser scrollback shrinks while tmux's history stays complete). ⚠️ That 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 scrollback strip + wheel/touch forwarding** (#205): codex/claude/gemini get the FULL strip (alt-screen, `3J`, mouse DECSETs); tmux-backed shell/opencode/antigravity get a NARROW strip (alt-screen toggles only — it removes tmux's own attach-time `smcup`, which otherwise parks xterm in the scrollback-less alt buffer and turns the wheel into arrow keys). ⚠️ Gated on `useMux`: direct-PTY fallback sessions must keep the alt screen for vim/less/htop. Wheel AND touch forward to the CLI transcript for codex/claude ≥ 2.1.187 at ANY scroll position (snap-to-bottom first); Shift+wheel and the `terminalWheelLocalScrollback` setting stay local. `_wheelScrollLines()` reads `ev.deltaMode` (Firefox = LINE units). → [architecture-invariants#terminal-scrollback-strip-flavors-and-wheeltouch-forwarding](docs/architecture-invariants.md#terminal-scrollback-strip-flavors-and-wheeltouch-forwarding)
+**Terminal scrollback strip + wheel/touch forwarding** (#205): codex/claude/gemini get the FULL strip (alt-screen, `3J`, mouse DECSETs); tmux-backed shell/opencode/antigravity get a NARROW strip (alt-screen toggles only — it removes tmux's own attach-time `smcup`, which otherwise parks xterm in the scrollback-less alt buffer and turns the wheel into arrow keys). ⚠️ Gated on `useMux`: direct-PTY fallback sessions must keep the alt screen for vim/less/htop. Wheel AND touch forward to the CLI transcript for codex/claude ≥ 2.1.187 at ANY scroll position (snap-to-bottom first); Shift+wheel and the `terminalWheelLocalScrollback` setting stay local. `_wheelScrollLines()` reads `ev.deltaMode` (Firefox = LINE units). ⚠️ When that gate is FALSE on a claude session whose local buffer is hollow (`baseY === 0`), the gesture becomes coalesced PageUp/PageDown key sends (`_maybePageCliTranscript`) instead of a no-op; ⚠️ and `getClaudeCliVersion()` must never cache a FAILED probe (one timeout used to disable forwarding process-wide until restart). `_logScrollRouting()` prints the routing decision and its inputs once per session — read it before diagnosing a scroll report. → [architecture-invariants#terminal-scrollback-strip-flavors-and-wheeltouch-forwarding](docs/architecture-invariants.md#terminal-scrollback-strip-flavors-and-wheeltouch-forwarding)
 
 **Self-update** (App Settings → Updates): in-app updater for git-clone installs supervised by systemd/launchd (`systemd`, `launchd`, `launchd-daemon`, else `none` → "restart manually"). The update restarts the very process running it, so the real work runs in a DETACHED `scripts/self-update.sh` that outlives the restart and writes progress to `update-status.json`, which the browser polls across the connection drop. `src/web/self-update.ts` splits pure helpers (unit-tested) from IO wrappers. npm installs report as non-updatable. → [architecture-invariants#self-update](docs/architecture-invariants.md#self-update)