Improve Files and Changes workflow

[powerfooI]

Summary

• share Git diff summary state between Files and Changes, with bounded cache lifecycle and post-mutation refreshes
• align Git status badges and preserve staged/unstaged entries for partially staged files
• embed per-file changes in the file preview while preserving wrap and split/unified preferences
• add hunk navigation plus reliable virtualized-line targeting
• add VS Code-style file-tree keyboard navigation and accessible File/Changes tabs and context menus
• harden preview and diff request races, invalidation, and resource cleanup

Verification

• bun test — 699 passed, 1 skipped
• bun run format:check
• bun run lint
• cd web && bun run typecheck
• cd web && bun run build
• browser smoke test for file-tree navigation, keyboard context menus, and File/Changes tab navigation

[Copilot]

🟡 Changes recommended

The file explorer’s immediate onActiveDiffEntriesChange emission can publish diff entries in an inconsistent order, causing incorrect default/primary entry selection for embedded per-file changes.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

This PR enhances the workspace “Files” and “Changes” inspector experience in web/src by sharing and reusing Git diff summary state, improving per-file change visibility, and adding richer navigation/accessibility for file trees and diffs.

Changes:

• Introduces a shared, keyed Git diff summary store with deduping, queuing, and resource retirement, plus unit tests.
• Unifies git status badge presentation via normalized U/A/M/D/C codes, and preserves multiple entries for partially staged files.
• Embeds per-file diffs into the file preview, adds diff hunk navigation, and improves keyboard navigation + ARIA roles for the file tree and menus.

File summaries

File	Description
web/src/styles.css	Adds styling for focused rows, git status code badges, embedded diff view, preview tabs, and hunk navigation UI.
web/src/gitDiffSummaryStore.ts	New shared external-store cache for diff summaries with bounded retention and race handling.
web/src/gitDiffSummaryStore.test.ts	Tests deduping, queued refresh, retirement behavior for the shared diff summary store.
web/src/gitDiffStatus.ts	Adds normalization for git diff entry kinds/statuses into U/A/M/D/C plus human labels.
web/src/gitDiffStatus.test.ts	Tests code normalization for mixed explorer/diff-viewer states.
web/src/components/WorkspaceInspectorHost.tsx	Wires file explorer to provide active diff entries; adds embedded per-file changes view and keyboard focus handoff.
web/src/components/FilePreviewContent.tsx	Adds accessible File/Changes tabs and supports rendering embedded changes content.
web/src/components/FileExplorerDialog.tsx	Integrates shared diff summary, adds keyboard tree navigation + context menu roles, improves preview cache invalidation.
web/src/components/FileExplorerDialog.test.ts	Adds tests for partial-stage entry preservation and preview invalidation behavior.
web/src/components/DiffViewerPanel.tsx	Switches to shared diff summary store, adds working-entry selection helpers, aligns status badges to U/A/M/D/C.
web/src/components/DiffViewerPanel.test.ts	Updates/extends directory expansion behavior tests for refreshed trees.
web/src/components/DiffContentView.tsx	Adds embedded mode, hunk navigation with virtualized targeting, and inline “Load diff/Retry” actions.
web/src/components/DiffContentView.test.ts	Tests hunk target parsing and hunk index navigation behavior.
CHANGELOG.md	Documents the user-visible workflow improvements under Unreleased.

Review details

• Files reviewed: 14/14 changed files
• Comments generated: 1
• Review effort level: Lite

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[Copilot]

🔵 Needs a closer look

The change set spans multiple stateful UI surfaces (shared caching, keyboard navigation, embedded diff rendering) where subtle regressions are hard to rule out via diff-only review.

Review details

Suppressed comments (2)

Previously missed (1) — in code that hasn't changed since the last review.

web/src/components/DiffViewerPanel.tsx:1273

• statusCodes is derived from a Set, so its iteration order depends on child.entries ordering. Sorting the resulting array makes badge order stable across refreshes and avoids unnecessary DOM churn.

      const statusCodes = Array.from(
        new Set(child.entries.map((entry) => gitDiffCode(entry))),
      );

web/src/components/FileExplorerDialog.tsx:546

• Directory codes are built from a Set and converted with Array.from(...), which keeps insertion order and can vary based on server entry ordering. Sorting the result avoids non-deterministic badge ordering.

      codes: Array.from(directoryCodes.get(path) ?? []),

• Files reviewed: 14/14 changed files
• Comments generated: 1
• Review effort level: Lite

[Copilot]

🔵 Needs a closer look

DiffViewerPanel can leave summaryRequestLoading stuck true when the diff context changes during an in-flight refresh, disabling the UI until reload.

Review details

Suppressed comments (2)

Previously missed (1) — in code that hasn't changed since the last review.

web/src/components/DiffViewerPanel.tsx:817

• loadSummary uses summaryRequestLoading to disable/animate refresh controls, but it can get stuck true if the diff scope/workspace context changes while a refresh is in flight (the finally guard prevents clearing it). Track the latest summary refresh with a request sequence/token so only the newest request clears the loading flag, regardless of scope changes.

This issue also appears on line 945 of the same file.

  const pendingWorkingEntriesRef = useRef<GitDiffEntry[]>([]);
  const preferredSummarySelectionRef = useRef<GitDiffEntry | null>(null);
  const diffScopeRef = useRef(diffScope);
  diffScopeRef.current = diffScope;
  const onSelectionChangeRef = useRef(onSelectionChange);

web/src/components/DiffViewerPanel.tsx:949

• The finally block only clears summaryRequestLoading when isCurrentContext(workspaceId, scope) is still true. If the user switches scope/workspace during an in-flight refresh, this leaves summaryRequestLoading stuck true (and the UI disabled). Use a request sequence/token to ensure only the most recent refresh clears the flag even when context changes.

    const scope = diffScope;
    preferredSummarySelectionRef.current = previousSelected;
    advanceDiffCacheRevision(
      diffCacheKey(connectionClient, workspaceId, scope, cacheResourceKey),
    );

• Files reviewed: 14/14 changed files
• Comments generated: 0 new
• Review effort level: Lite

[Copilot]

🔵 Needs a closer look

The changes span multiple interdependent UI state/caching paths (shared summary store, embedded diffs, and keyboard navigation) where subtle race/focus regressions are hard to fully validate from diff review alone.

Review details

• Files reviewed: 14/14 changed files
• Comments generated: 0 new
• Review effort level: Lite