fix(web): pin the Claude response viewer to the pane's own conversation

The viewer re-derived a pane's live conversation from the newest
~/.claude/history.jsonl entry for the pane's cwd. A cwd is shared with every
other Codeman tab on it, with tabs long since closed, and with any plain
`claude` the user runs in their own terminal, so the eye followed whichever of
those was typed into last — and since the match was written back through
adoptClaudeSessionId(), the mispin stuck.

Credit a history entry to a pane only when it lands within 10s of that pane's
own Enter and no other pane on the same cwd submitted closer, reusing the
last-submit correlation the Codex locator already relies on. Submit tracking
moves from _codexLastSubmitAt to a mode-agnostic Session.lastSubmitAt. With no
correlated entry the pane keeps the id it has: a viewer one turn behind beats a
viewer showing someone else's conversation.

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

docs/architecture-invariants.md

@@ -147,6 +147,8 @@ The general rule: **any new endpoint that turns a caller-supplied `sessionId` in
 **Multi-monitor button** (header, top-right; the notification bell it sits beside stays hidden — notifications live in Settings → Notifications). `app.launchMultiMonitor()` (in `panels-ui.js`) POSTs `/api/system/span-displays`, which spawns `scripts/span-codeman.sh` — a fresh, maximized browser `--app` window sized to the union of all displays (macOS; needs "Displays have separate Spaces" OFF). Supports the gesture layer's in-page floating session panels dragging across the physical monitor seam. **Opt-in:** hidden by default; enable under App Settings → Display → **Header Displays** ("Multi-monitor Button", `showMultiMonitorButton`). The button carries a `btn-multimonitor--hidden` class in the template; `renderIndexHtml` strips that class at render when the setting is on (a unique class token, not a brittle match on the aria-label/style copy), and `applyHeaderVisibilitySettings()` toggles the same class live on save. Solo (detached) windows hide it via `body.solo-mode`.
 **Response-viewer (eye) button** (header) is likewise **hidden by default** — enable under App Settings → Display → **Response Viewer** (`showResponseViewer`). Works for Claude AND Codex sessions (#152): Codex last-responses are located via a 4-layer rollout resolution under `CODEX_HOME` (history pin → originator match → resume-UUID → cwd fallback with other-pane exclusion), with injected-context filtering and event/legacy dedup — tests in `test/routes/session-routes-codex-last-response.test.ts`.
 
+⚠️ **A Claude pane's conversation is identified by the pane's own Enter, never by "newest entry for this cwd".** `~/.claude/history.jsonl` records every submitted prompt as `{project, sessionId, timestamp}`, and `/clear` moves the pane to a fresh `<uuid>.jsonl` that nothing on the PTY announces — so the viewer has to re-derive the live conversation. Keying that off `project` alone was the bug: a cwd is shared with every other Codeman tab on it, with tabs long since closed, and with any plain `claude` the user runs in their own terminal, so the eye followed whichever of those conversations was typed into last and showed a stranger's transcript. `resolveActiveClaudeSessionIdFromHistory()` instead credits an entry to a pane only when it lands within `CLAUDE_SUBMIT_MATCH_MS` of that pane's `Session.lastSubmitAt` **and** no other pane on the same cwd submitted closer — the same last-submit correlation the Codex locator uses. With no correlated entry the pane keeps the id it has: a viewer one turn behind beats a viewer showing someone else's conversation. `lastSubmitAt` is in-memory, so after a server restart a pane re-pins on its next Enter.
+
 ⚠️ **Claude transcripts are grouped at real human-turn boundaries, not per JSONL row.** A Claude transcript is an append-only event log, so one logical exchange spans many rows: tool-result rows, meta/image/skill rows, compact summaries, task/team notifications, sidechains, replayed assistant snapshots, and multi-block assistant output. Rendering a card per row was the bug: it produced duplicate and truncated cards that looked like the viewer had lost the response. The grouping walks to the next genuine user turn and dedups replayed assistant snapshots while preserving the tool/task/skill/compact/team metadata filtering. Related: a recovered `restored-<uuid8>` tmux placeholder carries a **stale cwd**, so transcript lookup by working directory finds nothing; it rebinds to the matching top-level Claude transcript UUID instead when that match is unambiguous. Tests: `test/routes/session-routes-claude-last-response.test.ts`. Purely client-side (no `renderIndexHtml` step): the template ships with `btn-response-viewer-header--hidden` and `applyHeaderVisibilitySettings()` (settings-ui.js) toggles it after settings load. Hiding must go through that marker class — the base rule is `display:inline-flex !important`, so an inline style can't override it. `showResponseViewer` is in the `displayKeys` per-device set (settings-ui.js), so it does NOT sync across devices.
 **File Viewer button** (header, 1.4.1) is **shown by default on desktop** since `211f3c0` (post-1.8.0): toggle under App Settings → Display → **Header Displays** → File Viewer (`showFileViewerButton`, in the per-device `displayKeys` set, fallback default `true`). Purely client-side like the response viewer: the template now ships the button VISIBLE (no `--hidden` class) and `applyHeaderVisibilitySettings()` toggles the `btn-file-viewer--hidden` marker class after settings load; phones still hide it via mobile.css. The button toggles the file-browser panel open/closed without opening the settings modal (`panels-ui.js`). The same commit set the **default desktop header** to WS/CPU/MEM + File Viewer + gear: the token-count chip (`showTokenCount`, no settings-UI toggle) and the lifecycle-log button (`showLifecycleLog`) both default **OFF** now (templates ship them hidden; stored prefs still honored). The plan-usage chip default is unchanged (opt-in, see Plan-usage chip). The **Cron toolbar button** joined the same opt-in pattern in 1.6.0: template ships `btn-cron--hidden`, `applyHeaderVisibilitySettings()` toggles it via the per-device `showCronButton` setting (default OFF, App Settings → Display → Header Displays); cron jobs themselves are unaffected.