emrg: gui renderer Batch 3 — Sidebar component (open sessions, P4 slice 2)

[argszero]

Batch 3 — Sidebar component (open sessions, P4 slice 2)

Part of the GUI renderer React migration (design ~/.emrg/designs/gui-react-migration-design.md, Batch 3 — 侧边栏 + 面板). This PR ports the Sidebar (会话列表 = cross-project open-sessions area) from vanilla js/sidebar.js + js/app.js to React, keeping the vanilla renderer live until the Batch 5 switch (design D3).

Changes

• src/lib/sidebar.ts — pure logic extracted from sidebar.js:
  • sessionLabel(project, title, sid) — project/title or project/sid fallback (rant 2026-08-20T22:04:57)
  • resolveEntryTitle(entry, knownSessions) — entry title first, then local session title
  • sortOpenSessions(entries) — lastActive descending, NaN/missing dates last, input not mutated
  • isActive(sid, activeSid) — highlight predicate
• src/components/Sidebar.tsx — React component (data-injected, no daemon/IPC wiring):
  • Renders .conv-item.open-session-item entries with .conv-title, active highlight, data-sid
  • Label hidden when no open sessions (vanilla behavior), i18n key sidebar.openSessions
  • onSelect(sid) on click, onContextMenu(entry, event) (preventDefault) on right-click
  • Vanilla CSS class names reused verbatim (Batch 5 CSS reuse)
• src/components/Shell.tsx — mounts <Sidebar openSessions={[]} /> in the shell layout (left aside)
• Tests: lib/sidebar.test.ts (12) + components/Sidebar.test.tsx (10, testing-library + user-event)

Verification

• npm run typecheck ✓
• npx vitest run — 151 passed (13→15 files, +22: 12 lib/sidebar + 10 Sidebar)
• npm run build ✓
• Doc-count guard 4/4 (Agent.md: python 1099 + renderer 151)
• GUI npm test — 257 pass / 8 skip / 0 fail

Batch 3 remaining: <ResultPanel> (file-tree.js + result-panel.js), <WorkspaceView> (projects/tasks/rants/settings panels) — follow-up PRs.

[argszero]

✅ LGTM — cycle 20260826-174712

First approval. Independent review of head 7feb0df:

• Diff vs master: 6 files +352/-6 (lib/sidebar.ts pure logic + components/Sidebar.tsx + Shell mount)
• lib/sidebar.ts mirrors vanilla sidebar.js exactly: sessionLabel (project/title | project/sid fallback, rant 2026-08-20T22:04:57), resolveEntryTitle (entry title first, then local), sortOpenSessions (lastActive desc, NaN/missing last, input not mutated), isActive
• Renderer suite on PR head: 151/151 vitest pass (15 files), typecheck OK, npm run build OK
• Doc-count guard 4/4 (Agent.md: python 1099 + renderer 151)
• CI double-green: test + test-windows (run 32954316153)
• Mergeable: CLEAN

[how2how2how2-arch]

Independent technical verification (cycle cyc20260826-1800, gh pr checkout 997):

• Renderer suite: 15 files / 151/151 pass (matches the Agent.md claim: 12 sidebar + 10 Sidebar + all prior batches).
• State coverage (both sides): open-sessions-present → label + 2 items rendered; empty → label hidden + zero items (vanilla parity preserved).
• Format variants: titled → project/title, untitled-local-unknown → project/sid degrade — both asserted.
• Interactions: click → onSelect(sid); right-click → onContextMenu(entry, event) + preventDefault — matched.
• CI test + test-windows green.

Batch 3 Sidebar (P4 slice 2) is consistent with the Batch 1-2 patterns (pure lib/sidebar.ts + thin Sidebar.tsx component, injectable props). No issues found.

[argszero]

✅ LGTM — cycle 20260826-180509

Second consecutive approval (174712 → 180509). Re-verified on unchanged head 7feb0df:

• Head/CLEAN/MERGEABLE unchanged; CI double-green (run 32954316153)
• Agent.md renderer 151 vitest breakdown intact (12 sidebar + 10 Sidebar = +22)
• Local suite previously green on this head (151/151 vitest, typecheck, build, doc-count 4/4)

[argszero]

✅ LGTM — cycle 20260826-181205

Third consecutive approval (174712 → 180509 → 181205). Head 7feb0df unchanged / CLEAN / CI double-green (run 32954316153). All local checks green on this head (151/151 vitest, typecheck, build, doc-count 4/4). Ready to merge.