refactor: show a flat file list in the Changes tab

[EyalShechtman]

Summary

The Changes tab stacked a commit-history list above a nested folder tree. In a narrow inspector the split flipped to a column capped at 45% height, so the commit list ate roughly half the panel before a single file was visible.

This replaces the tree with a flat, single-scope file list — a dimmed directory prefix that absorbs truncation beside a basename that always renders in full — and drops the commit list entirely. The whole-branch diff remains the default scope, Commit/Restore move to the panel header, and the inspector now opens on Changes.

Before / after

Before	After
Commit list (~45% of the panel) above a nested folder tree	One flat file list for the current scope
Basenames truncated away at narrow widths	Directory prefix truncates; basename always whole
Inspector opened on Details	Inspector opens on Changes

Screenshots

Inspector at 420px — the primary target width:

300px and 580px — the directory prefix absorbs truncation at every width. At 300px the per-row stats hide via the pre-existing @container (max-width: 320px) rule inherited from the old tree:

300px	580px

State variants — Commit/Restore appear only when uncommitted work exists; the "All changes" escape button and Revert appear only under a commit scope:

No uncommitted changes	Commit scope (via Details history graph)

Full window at 420px:

What changed

Added

• frontend/src/components/panels/diff/changesListModel.ts — buildChangesRows splits each path into a dir prefix and name; navigateList and typeAhead replace the tree's keyboard model.
• frontend/src/components/panels/diff/ChangesList.tsx — flat virtualized list. Ports the tree's virtualization, ResizeObserver measurement, useScrollSurface registration, perf marks, and click/double-click semantics unchanged.
• frontend/src/components/panels/diff/changesList.test.ts — unit coverage for the model.

Removed

• frontend/src/components/ExecutionList.tsx — the commit list.
• ChangesTree.tsx, changesTreeModel.ts, changesTree.test.ts — superseded by the flat list.
• .pane-review-* CSS and the @container (max-width: 600px) stacking block that caused the cramped layout.
• The sidebar-resize state, expansion state, and range-selection plumbing in CombinedDiffView.tsx (−197 lines).

Changed

• CombinedDiffView.tsx — single-column body; header carries the scope label, stats, Commit/Restore, Revert, and Refresh.
• ProjectView.tsx / SessionView.tsx — default inspector tab is now changes. DetailPanel's existing showDetails = inspectorTab === 'details' || !hostedPanel fallback means this degrades safely when no changes panel exists.

Deliberate decisions

• Commit ranges lose their UI, keep their types. Shift-click range selection went with the commit list, but commit-range and working-tree-range stay in shared/types/gitDiff so already-open and persisted editor diff tabs still resolve. No data migration.
• diff:view-commit still works. The Details tab's history graph can still hand a commit to this panel, which is why the header keeps an "All changes" button — without it, that handoff would be a one-way trip.
• Revert stayed. ExecutionList was the only other caller of the git:revert IPC; dropping it would have made revert unreachable from the entire app. It now renders gated on scope.kind === 'commit'.
• A11y role changed from tree to listbox. A flat list of files is a listbox; keeping tree would have had screen readers announcing nesting levels that no longer exist. This is why the spec files have a large diff.
• Perf mark names kept as pane-diff-tree-* despite no longer being a tree — they're a measurement contract with the perf harness. Commented as such.

Verification

• pnpm typecheck — clean across frontend, main, runpane, shared
• pnpm lint — 0 errors (5 pre-existing warnings in main/src/services/skillCacheManager.ts, unrelated); Knip clean
• pnpm --filter frontend test — 324 tests / 33 files
• pnpm test on the affected specs — 45 tests, including axe checks on .combined-diff-view
• pnpm run build:frontend and pnpm run build:main

Specs renamed changes-tree* → changes-list* and reworked for the new roles. theme-screenshots.spec.ts also queried the old treeitem role and needed the same swap.

Notes for review

• The load-bearing detail is the flex pair in .pane-changes-list-dir (flex: 0 1 auto, min-width: 0) and .pane-changes-list-name (flex: 0 0 auto). Inverting them would truncate filenames and preserve useless directory prefixes.
• At 300px the header truncates to "All …" while Commit/Restore compete for the same row. That reads worse than before now that the header carries actions — a reasonable follow-up, not addressed here.
• The screenshots are committed under screenshots/changes-redesign/ so they render above. Happy to drop that commit if you'd rather not carry them in the repo.

https://claude.ai/code/session_01RX4RqNL69dAxVoaETQE57D