Files Changed: show cross-project edits (merge server + tool-metadata diffs)

[jeonghun-jj-lee]

Important

Problem — Files Changed only shows diffs within the session's project directory (the VS Code workspace folder). Cross-package developers editing files outside the project — common in monorepo or multi-project workflows — are blind to those changes. Before the server-diff trust fix (ca5a1be2), the panel accidentally showed all edits because the client-side accumulateDiffs() fallback scraped every tool-edit part regardless of directory. The fix correctly prioritized the server endpoint but lost cross-project visibility as a side effect.

Approach — Merge both diff sources in the reviewDiffs memo: server shadow-git diffs (authoritative for in-project files) unioned with tool-metadata diffs (for files outside the project directory), deduplicated by normalized file path with server winning on conflict. Cross-project visibility is the emergent effect of server-wins dedup — no explicit "is this under the project?" check, just set subtraction. The file tree's buildCollapsedTree already computes a common root from all paths and adjusts the dropdown automatically.

Scope — in: the reviewDiffs memo in session.tsx (~30 lines). out: server endpoint, shadow-git system, accumulateDiffs(), buildCollapsedTree, the diff viewer.

Assumptions — Tool-metadata quality is acceptable for cross-project diffs (misses bash sed on external files, which is rare for cross-project work). The server endpoint continues to be the ground truth for in-project files.

Acceptance Criteria

• Files edited by the agent outside the session's project directory appear in the Files Changed panel
• In-project files still use server shadow-git diffs (filesystem truth, not tool metadata)
• When both sources report the same file, the server version is displayed (server-wins dedup)
• The file tree dropdown adjusts its common root to encompass both in-project and cross-project files
• When the server hasn't responded yet, tool-metadata diffs display alone (current fallback behavior preserved — all files shown, including in-project)

Testing Decisions

Extend the existing fast suite (pnpm --filter amicode test). The reviewDiffs memo is pure computation — testable with mock server-diff and tool-metadata inputs without a running server.

Key Decisions

• Server-wins dedup (D1): when a file path appears in both sources, the server diff is kept — it carries a real git cumulative patch; tool-metadata patches are last-edit-only approximations for multi-edit files.
• Always compute tool-metadata, merge via set subtraction (D2): the tool-metadata scrape runs unconditionally. The merge drops any tool-metadata entry whose normalized path appears in the server set. In the fallback branch (server not yet responded), there is no server set to subtract, so all tool-metadata diffs are shown (preserving current behavior).
• Unified path normalization (D3): the two sources currently use different normalization — server diffs use an inline conditional, tool-metadata uses toHomePath(). Both must normalize through toHomePath() for dedup to work correctly on edge cases (absolute paths under $HOME).
• Tool-metadata gaps accepted (D4): tool metadata misses bash sed/bash rm on external files. Extending the server to snapshot multiple directories is out of scope (fork-level change).

Constraints & Invariants

• The server endpoint, shadow-git system, and accumulateDiffs() function are not modified
• buildCollapsedTree receives whatever paths the merged set contains — no special-casing
• The touchedFilesQuery (separate query) is not affected
• No new dependencies

Prior Art

• The reviewDiffs memo in session.tsx (lines 708–759) — the merge point
• accumulate-diffs.ts — the accumulateDiffs function and ToolEditPart type
• review-panel-v2.tsx (lines 158–177) — buildCollapsedTree and common-root computation
• Commit ca5a1be2 — the server-diff trust fix that introduced the current scoping

Source

Spec: spec-20260903-134500-cross-project-files-changed · Review: approved-mechanical (3 advisories resolved: D2/AC5 tension, D3 normalization divergence, filtering mechanism)

[jeonghun-jj-lee]

Implemented across #774 (mergeServerAndToolDiffs with projectPrefix dedup, server-wins, cross-project tool-metadata fallback) and #845 (per-session file watcher for external-change refresh + crossProjectStatus). All five acceptance criteria are met in accumulate-diffs.ts.