phase: 87_big_read_progress

All criteria verified — no defects found, nothing to fix. Final report:

**Phase 87 — big read progress: final verification pass (all tasks already complete in `complete/`)**
- Verified implementation vs. overview: `TOOL_LINE_ELAPSED_AFTER_MS = 5_000`, single live `armToolLineClock` site, settle on thinking/retry/delta, `stopToolLineClock` in `setUiState`, visible `.typing-elapsed` (aria kept byte-identical), CSS AA pairing — all match design; `app/` byte-identical (0 changes)
- **Tests/lint (exact outcomes):**
  - `uv run pytest --cov=app --cov-report=term` → 1732 passed, coverage **99%** (>90% ✓)
  - `uv run pytest tests/e2e/test_big_read_progress.py -v --no-cov` → **4 passed** (ticking suffix, visible hint, settle, no-timer restore)
  - `test_thinking_display.py` → 5 passed · `test_agent_document_tools.py` → 4 passed · `test_smoke.py` → 3 passed (all isolated)
  - 3 pinned frontend suites + new unit pins → 62 passed · `uv run ruff check . && uv run pyright` → clean, 0 errors
- **Completion criteria:** E2E pins 1–4 ✓ · guard/state-machine byte-identical ✓ (diff is additive only) · diff scope limited to `app.js`, `styles.css`, 2 new test files, phase files; nothing in `app/` ✓
- **Notable:** no deviations; commit + `00_phase.md` move left to the harness per executor rules (task files already in `complete/`)
- **Next pending phase:** none — `todo/` contains only this phase (87 is the last)

frontend/assets/styles.css

@@ -606,6 +606,17 @@ details.thinking .thinking-text ul { margin: 0 0 0.5rem; }
   border-radius: 5px;
   overflow-wrap: anywhere;
 }
+/* Phase 87 (TODO.md L5): the latest tool line's visible "processing"
+   suffix — ticking "(Ns)" while ≥5s of the turn's stream stay silent
+   after the call; removed on the next frame (settle). ink-soft on the
+   bubble surface (the AA pairing), small mono like every status line. */
+.tool-elapsed {
+  font-family: var(--mono);
+  font-size: 0.75rem;
+  color: var(--ink-soft);
+  margin-left: 0.5rem;
+  white-space: nowrap;
+}
 
 .msg-meta {
   font-size: 0.75rem;
@@ -1113,8 +1124,29 @@ details.thinking .thinking-text ul { margin: 0 0 0.5rem; }
   0%, 60%, 100% { transform: translateY(0); opacity: 0.4; }
   30% { transform: translateY(-5px); opacity: 1; }
 }
+/* Phase 87 (TODO.md L5): the visible pre-token elapsed hint — the
+   10s thinking clock promoted from aria-only to sighted users.
+   ink-soft on the bubble surface (the AA pairing), small mono like
+   every status line. Plain text: no animation, no motion opt-out.
+   The span is a sibling of the dots inside the same .typing bubble, so
+   it resets the dot geometry (.typing span) it would otherwise inherit. */
+.typing-elapsed {
+  width: auto;
+  height: auto;
+  border-radius: 0;
+  background: none;
+  opacity: 1;
+  animation: none;
+  font-family: var(--mono);
+  font-size: 0.75rem;
+  color: var(--ink-soft);
+  margin-left: 0.5rem;
+}
 @media (prefers-reduced-motion: reduce) {
   .typing span { animation: none; opacity: 0.7; }
+  /* Phase 87 (TODO.md L5): the elapsed hint is plain text, not motion —
+     it keeps full opacity (the AA pairing) under reduced motion. */
+  .typing span.typing-elapsed { opacity: 1; }
   /* Phase 17 thinking block: the chevron stills (no rotation motion). */
   details.thinking summary::before { transition: none; }
 }