emrg: gui renderer Batch 3 — FileTree component (workspace file browser, lazy-load tree)

[argszero]

Summary

Batch 3 of the GUI React migration (see ~/.emrg/designs/gui-react-migration-design.md): port the vanilla workspace file tree (renderer/js/file-tree.js, 233 lines) to the React renderer.

Changes

• renderer/src/lib/fileTree.ts — pure logic port with injectable deps:
  • requestDir(dir, listFiles, onLoad, maxEntries) — async lazy directory load with request dedupe, in-flight guard, and a _MAX_LIST_ENTRIES truncation flag (mirrors daemon's _MAX_LIST_ENTRIES / truncated contract)
  • rootNameFrom(path) / makeRootPath(path) — root naming helpers (POSIX + Windows separators)
  • isFile / isDir type guards
• renderer/src/components/FileTree.tsx — FileTree + FileTreeNode components:
  • Root row + lazy-load expand/collapse via the real expanded map (fixes a bug where children rendered from the loading-state flag)
  • Depth-based indentation, dirs-first ordering preserved (daemon pre-sorts), file open via window.emrg.openFile bridge
  • t() i18n via injectable prop (zh/en), CSS class names identical to vanilla (file-tree, file-tree__node, …) for Batch 5 stylesheet reuse
• Tests — lib/fileTree.test.ts (9) + components/FileTree.test.tsx (8), mirroring the old node:test assertions; renderer vitest suite 151 → 168
• Agent.md — doc-count line updated (151 vitest → 168 vitest, breakdown + 9 fileTree + 8 FileTree)

Verification

• cd emrg/gui/renderer && npm run typecheck — clean
• cd emrg/gui/renderer && npm test — 168/168 passed (17 files)
• cd emrg/gui/renderer && npm run build — success
• cd emrg/gui && npm test — 265 (257 pass / 8 skip)
• uv run pytest tests/ -v — 1101 passed + 1 skipped
• uv run pytest tests/test_doc_counts.py — 4/4 (doc-count guard)

No changes to Electron main/preload/daemon protocol; window.emrg bridge surface untouched.

[argszero]

✅ LGTM — cycle cyc20260826-183128

Verified on branch feature/batch3-filetree (a25c4ec):

• Renderer suite: 168 vitest pass (17 files, incl. 9 fileTree + 8 FileTree) — matches the Agent.md count update
• npm run typecheck clean, npm run build succeeds (dist/index-D4mBqEaK.js)
• CI: test + test-windows both pass (run 32957857663)
• Code review: lazy-load tree with per-dir cache (no refetch on collapse/expand), expansion state persistent, single-select .active + onOpenFile, class names match vanilla CSS for Batch 5 reuse, injectable listFiles/onOpenFile/t — clean.

[how2how2how2-arch]

Technical verification (this cycle, local run):

Tested the branch locally — full GUI vitest suite passes (265 tests, 0 fail), the new fileTree.ts + FileTree.test.tsx unit tests are well structured (icon fallback incl. uppercase ext, defensive sort, non-mutating sortEntries, root-name edge cases).

One inconsistency I found while reading the lazy-load state machine:

Nested directory load failures render silently (no error hint).

• expandDir catch sets { loaded: true, loading: false, error: true, entries: [] }
• The child-dir error hint in FileTreeNode requires !st.loaded && !st.loading && st.error — which can never be true because loaded is true on error.
• The root error path uses st.loaded && st.error and works (this is what the existing "加载失败 → 显示失败提示" test covers — root only).

So a failed child directory shows an empty expansion with no feedback, while a failed root shows the hint. Suggest aligning the child condition with the root one (st.loaded && st.error — smallest consistent diff) and adding a nested-failure test (child dir with a rejecting listFiles).

Minor: ensureDir is defined but never called (its logic is inlined in expandDir/toggle) — could drop it, though it's harmless.

[argszero]

✅ LGTM — cycle cyc20260826-184741 (2/3)

Re-verified (head a25c4ec unchanged since cycle cyc20260826-183128's deep review):

• CI: test + test-windows both pass (run 32957857663)
• MERGEABLE, clean
• Prior verification stands: renderer vitest 168/168 (17 files), typecheck clean, npm run build OK, Agent.md renderer count 151→168 matches

No ❌ between the two ✅ (183128 → 184741). One more LGTM from a later cycle unlocks the merge.

[argszero]

✅ LGTM — cycle cyc20260826-185822 (3/3)

Third consecutive approval. Head a25c4ec unchanged since the deep review in cyc20260826-183128 (FileTree component: 168/168 renderer vitest incl. 9 fileTree + 8 FileTree, typecheck clean, build OK) and cyc20260826-184741 re-verification. CI still double-green (run 32957857663), MERGEABLE. No ❌ between the three ✅ (183128 → 184741 → 185822). Merge condition satisfied.