phase: 138_markdown_blockquotes

**Phase 138 final verification pass — all green, no defects found.**

- Verified: blockquote pass in `frontend/assets/markdown.js` (step 2b, between escape+inline and paragraphs), guard extended to `|blockquote`, docstring updated; `.md-quote` CSS (left border + padding + `--ink-soft`, no fill, palette vars only, contrast comments, user-bubble override); unit pins + node behavior; dedicated E2E (chat / viewer / restore); mock `QUOTE_TRIGGER`/`QUOTE_ANSWER`; fixture `tests/fixtures/quote_docs/`. Thinking block confirmed on the same shared renderer (app.js L2025/L3095).
- `uv run pytest tests/e2e/test_markdown_blockquotes.py -v --no-cov` → 3 passed (isolation)
- `uv run pytest --cov=app --cov-report=term-missing` → 3268 passed, 9 skipped; TOTAL **99%** (>90%)
- `uv run ruff check . && uv run pyright` → All checks passed; 0 errors
- Criteria: quotes render in chat/viewer/restore ✅ (E2E) + thinking ✅ (shared renderer + unscoped AA CSS); `>>` collapses, fence/table `>` untouched ✅ (unit+e2e); non-quote byte-identical ✅ (exact fixture; phase-44/renderer suites pass **unedited**, confirmed by empty `git diff --stat`)
- No deviations; commit + phase-dir move left to the harness per pipeline rules (working tree clean of stray changes — only phase-138 diffs present)
- Next pending phase: **139_read_range_tool_lines**

frontend/assets/styles.css

@@ -541,6 +541,37 @@ body::before {
 .md-table th, .md-table td { border: 1px solid var(--line); padding: 0.4rem 0.6rem; text-align: left; vertical-align: top; }
 .md-table thead th { background: var(--surface); color: var(--ink); }
 
+/* Markdown blockquotes (phase 138, 2026-09-30, TODO L3): the shared
+   renderer (markdown.js step 2b) turns a run of "> "-prefixed lines
+   into <blockquote class="md-quote"> — ONE rule set serves all three
+   rendering contexts (the chat .bubble, the details.thinking
+   scratchpad, the document viewer's .doc-md): every one sits on the
+   --surface canvas (the deflected bubble's --accent-bg holds too —
+   ink-soft there is 6.9:1), so a single AA pairing covers them all.
+   A visible-but-restrained left border + padding + a muted ink — NO
+   background fill (locked A2). Palette vars only (the :root-drift
+   test parses the built-ins from this file — no hex literal here):
+   border-left  --brand-ink — 9.9:1 on --surface, the rose accent bar
+                (--line would be invisible: 1.14:1 on the surface;
+                plain --brand vanishes on the user bubble, 1:1);
+   color        --ink-soft  — 8.2:1 on --surface, the same AA pairing
+                              the --ink-soft :root comment documents.
+   Static content — no animation (nothing for prefers-reduced-motion
+   to still). */
+.md-quote {
+  border-left: 3px solid var(--brand-ink);
+  padding: 0.25rem 0.75rem;
+  margin: 0.5rem 0;
+  color: var(--ink-soft);
+}
+/* The USER bubble also runs the question through the shared renderer
+   (app.js addMessage), on the --brand fill with --bg text: --ink-soft
+   there is 1.6:1 — an AA failure — so the quote keeps the bubble's
+   own dark ink, 5.2:1 on --brand (the :root --bg pairing). The
+   --brand-ink bar holds 1.9:1 against the fill — still visible, the
+   quote stays distinct. */
+.msg.user .bubble .md-quote { color: var(--bg); }
+
 .msg.user { justify-content: flex-end; }
 .msg.user .msg-body { align-items: flex-end; }
 .msg.user .bubble {