Build stage 1: fallback header suffix Home (xterm)

[jonocodes]

Part of #116 — build ticket from the spec in #123.

Question

Implement the stage-1 fallback header suffix per the spec resolved in #123.

Build checklist

1. Protocol — add is_default: bool to LayoutMessage in daemon/deckd/protocol.py; mirror in client/src/protocol.ts.
2. Daemon — set the flag in daemon/deckd/server.py (push_current/_on_focus): is_default: true only on a genuine focus-driven fallback to store.default(). Force false whenever serving a pinned layout/view (demo ?layout= pin or select_view chrome pin), even if that pinned layout is itself the default.
3. Client — render the suffix in client/src/App.tsx (~line 403). When is_default is true and focused_app is present, append (<id>) where <id> = focused_app.wm_class || focused_app.app_id. Raw string, no prettifying. Otherwise render the name as today (display_name || app).
4. Verify the auto-ignore hold: confirm _on_focus returns early for the deckd window so no push carries deckd's own identity — the suffix must freeze on the last real app, never show Home (deckd).

Tests

• Fake-backend focus of an unmatched app → push has is_default: true, focused_app.wm_class set; header shows Home (xterm).
• Focus of an identity-matched app → is_default: false, no suffix.
• Pinned view active → is_default: false regardless of underlying resolution.
• Null wm_class (X11 path) falls back to app_id.

[jonocodes]

Built per the spec in #123. Implementation: 08dbb11

Daemon (commits the wire flag, sets it correctly across all push paths)

• daemon/deckd/protocol.py: added is_default: bool = False to LayoutMessage.
• daemon/deckd/server.py:
  • New Server._current_is_default flag, updated alongside _current_layout in __init__, _on_focus (focus-driven resolution; true iff new_layout is self.layouts.default()), reload_layouts (re-derived from the resolved object), and _apply_layout_override (forced false — overrides aren't focus-driven).
  • Session.push_current reads Server._current_is_default and forces is_default=False when pin (demo ?layout=) or view_id (chrome select_view) is set, so a pinned default never shows the suffix.

Client (renders the suffix from the flag)

• client/src/protocol.ts: mirrored is_default?: boolean.
• client/src/App.tsx: a small programSuffix helper (closed over layout) returns " (wm_class||app_id)" when is_default === true && focused_app. Appended to both headingText (screen-reader h1) and appName (visible chrome badge), and to the aria-live Layout: X announcement so screen-reader users hear the same name.

Tests

• 5 new daemon tests in tests/test_focus.py: unmatched-focus (is_default: true + wm_class), identity-match (is_default: false), pinned-view (is_default: false even when the pinned layout is default), null wm_class (X11 path), and the auto-ignore hold (deckd-window focus stays silent; no Home (deckd)).
• 6 new client tests in client/src/App.test.tsx: heading with wm_class, heading with null wm_class → app_id fallback, no suffix when is_default: false, no suffix when focused_app: null, aria-live announcement includes suffix, visible chrome badge includes suffix.

Verification

• pytest — 580 passed
• npx tsc --noEmit — clean
• npm run test:unit — 291 passed (incl. 6 new App tests)
• scripts/smoke.py — OK

Pre-existing lint errors in App.tsx (setState-in-effect at lines 433/443, unchanged from main) are not touched. Stage 2 (running-programs list, #120) is the next frontier ticket now that #124 closes.