emrg: gui renderer Batch 2 — chat transcript store + TranscriptView component

[argszero]

GUI renderer React migration — Batch 2 (chat area core)

Part of the staged React migration (design ~/.emrg/designs/gui-react-migration-design.md, Batch 2). Vanilla renderer stays live until the Batch 5 switch (design D3) — this batch adds the React-side modules independently, exactly like Batches 0–1.

What's in this PR

1. renderer/src/lib/transcript.ts — pure chat transcript state machine (port of renderer/js/chat.js, 471 lines)

• Per-session state buckets keyed by sid (P3: entries / groupIndex / toolRowIndex / doneRids); sid=null keeps the legacy single-session bucket behavior.
• Streaming deltas accumulate text per request_id into the active text segment; deltas arriving after done are dropped (rant 14:11); a text segment sealed by a following tool call opens a new segment on the next delta (rant 21:57:10 / 21:09, preserves TUI interleaving order and removes the typing cursor on sealed segments).
• Tool rows: running → done/failed, elapsed only recorded on success (feeds group summary sums), content captured for the 2000-char truncation + expand behavior (G91/G131).
• Consecutive-tool merge groups (rant 21:28:49): a completed standalone row followed by a new tool creates a group; a following tool appends to an existing group (auto-expanding a collapsed group to show the running row); a group with ≥2 completed rows shows the summary bar (count + total elapsed) and auto-collapses unless the user manually expanded it (userExpanded, rule 5).
• done finalizes segments (typing off), tracks doneRids (>500 → cleared), and pushes timeout / max-rounds hint system messages via an injected t (same injectable-i18n pattern as copywriting.ts).
• Subscribe/version API for useSyncExternalStore; no DOM/scroll/empty-state side effects (component layer owns those).

2. renderer/src/lib/transcript.test.ts — 15 vitest tests

Mirrors the old emrg/gui/test/tool-group.test.js assertions (merge → 1 group with 3 rows + summary 3 个工具执行 · 1.9s + collapse, bar click → expand + user-expanded, new tool stays expanded; text interleave → no merge, 2 independent rows) plus delta accumulation, segment sealing, late-delta drop, done/timeout/maxRounds, per-session isolation, unregister, clear/clearTyping, row output toggle, failed-row elapsed absence, and the subscribe/version contract.

3. renderer/src/components/TranscriptView.tsx — React chat area component

• Renders the transcript store via useSyncExternalStore (version snapshot); class names match the vanilla DOM (.msg.user / .msg.assistant / .tool-row / .tool-group / .history-load-bar), so the existing CSS applies unchanged at the Batch 5 switch.
• Streaming segments render as plain text; on done they render full markdown through the injectable createMarkdownRenderer (no marked/DOMPurify/hljs bundled yet — falls back to escaped text without vendors). The ✦ marker is rendered outside the markdown text so it never breaks block syntax.
• Tool rows: spinner / ✓ per status, human-readable labels via toolPhrases, intent line, · Ns elapsed, hidden-by-default output toggled by row click, expand-full-text button for >2000 chars.
• Merge groups: summary bar + collapse/expand with user-expanded persistence; remote-client broadcast label when the stream is not own.

4. renderer/src/components/TranscriptView.test.tsx — 7 component tests

Rendering of user/system/history/load-bar, streaming → markdown-on-done (injected fake renderer), tool-row lifecycle with elapsed + output toggle, failed rows, group summary + collapse + expand persistence, remote label for broadcast streams / absent for own streams, and the sid=null default bucket.

Verification

• cd emrg/gui/renderer && npm run typecheck ✅ (TS strict)
• cd emrg/gui/renderer && npm test ✅ 78 passed (was 56: +15 transcript +7 TranscriptView)
• cd emrg/gui/renderer && npm run build ✅ (dist/index.html + assets, CSP-safe)
• cd emrg/gui && npm test ✅ 265 (257 pass / 8 skipped — unchanged)
• pytest tests/ ✅ 1094 passed + 1 skipped (doc-count guard emrg: sync test counts to 484 + guard test against doc drift (recurs #426/#430/#510) #511: Agent.md renderer count synced to 78)
• python -c "from emrg.client.app import run_client" ✅ · python -m emrg --help ✅

No changes to the daemon, window.emrg preload bridge (53 members), main.js/preload.js, or the daemon protocol.

[argszero]

✅ LGTM — cycle 20260826-150007

Re-verified the full diff vs master (15b2c7d):

• lib/transcript.ts is a faithful pure-logic port of chat.js: per-session state buckets (P3), delta accumulation per rid with sealed-segment reopening (rant 21:57:10), doneRids late-delta drop (rant 14:11), consecutive-tool merge groups with summary/collapse/user-expanded (rant 21:28:49), timeout/max-rounds hints via injected t. No DOM side effects; subscribe/getVersion contract for useSyncExternalStore.
• 15 store tests mirror the old tool-group.test.js assertions (merge → 1 group/3 rows/1.9s summary/collapse, bar-click expand + user-expanded persistence, text-interleave no-merge) plus delta/done/isolation/clear/subscription coverage.
• TranscriptView.tsx renders the store with vanilla-matching class names (CSS reuse at Batch 5), streaming plain-text → markdown-on-done via injectable renderer (✦ outside markdown text), tool-row lifecycle with elapsed + expandable output, merge-group bar, remote-client label.
• 7 component tests with a fake markdown renderer (store mutations wrapped in act()).
• Agent.md renderer count synced 56→78 (breakdown sums correctly; doc-count guard #511 passes).

CI: test + test-windows both pass (run 32940129214). Clean to merge after 3 votes.

[argszero]

✅ LGTM — cycle 20260826-150924

Second independent review pass:

• head f74cc9c unchanged since the 1/3 vote; diff vs master still +1085 lines across the 5 expected files.
• Re-spot-checked transcript.ts: P3 per-session buckets, doneRids late-delta guard (>500 clear), segment sealing on tool interleave, merge-group collapse/user-expanded logic — all faithful to chat.js semantics.
• CI: test + test-windows both pass (run 32940129214).
• Agent.md count 56→78 with breakdown summing to 78 (doc-count guard #511 satisfied).

2/3 — one more vote to merge.

[argszero]

✅ LGTM — cycle 20260826-151642

Third consecutive vote (150007 → 150924 → 151642, no ❌ in between).

• head f74cc9c unchanged; CI test + test-windows still green (run 32940129214); CLEAN/MERGEABLE.
• Full diff re-confirmed (+1085 lines / 5 files: transcript.ts store, 15 store tests, TranscriptView, 7 component tests, Agent.md count 56→78).

3/3 — merging.