# Feature Implementation Plan: Git Diff Panel

A Files / Git tab in the right-side file panel that reads the project repository's diff (two modes) and stages, unstages, commits, and discards whole files — built entirely in `apps/server` ([D-1](artifacts/implementation-decision-log.md#d-1-both-git-read-and-git-write-live-in-appsserver)), shipped via a single docker rebuild, in two phases (read/display, then write actions) with no schema change, no migration, and no `@boocode/contracts` change.

## Source Specification

- **Feature specification:** [feature-specification.md](feature-specification.md)
- **Specification decision log:** [artifacts/decision-log.md](artifacts/decision-log.md)
- **Specification team findings:** [artifacts/team-findings.md](artifacts/team-findings.md)
- **Specification decisions this plan inherits:** D1–D18
- **Specification open items this plan must respect or resolve:** None — the spec's only open item (commit identity) was settled at spec time (F3, D12).

## Outcome

When this plan is executed, the right-side file panel gains a Files / Git tab. Selecting **Git** shows the project repository's changed files (Uncommitted or Committed mode), each expandable to a syntax-highlighted unified diff. The user can stage, unstage, commit (with a server-derived identity), and discard whole files without leaving the session. The work is delivered by a new `apps/server/src/services/git_diff.ts` (read logic + git-write helpers + pure helpers), new read and write routes in `apps/server/src/routes/projects.ts`, and new `apps/web` UI (`GitDiffView`, a tab in `RightRail.tsx`, a `useGitDiff` hook, and a `git_diff_refresh` sessionEvent). No apps/coder change, no Postgres schema change, no new env var.

## Context

- **Driving constraint:** A direct user request (2026-06-02) to add a Paseo-style git diff panel shown "instead of the file browser." Not deadline-bound; scoped to ship as a coherent v1.
- **Stakeholders:** The single session user (reviews and commits their own repo changes in-session). The project's security posture (the write surface must not become an assistant-reachable path). On-call/operability (the panel must not stall on large or slow repos or fail opaquely under index contention).
- **Future-state concern:** The git-write surface now lives in `apps/server`. Watch for a third consumer of git ops (would trigger a shared-`packages/` extraction, [D-1](artifacts/implementation-decision-log.md#d-1-both-git-read-and-git-write-live-in-appsserver)) and for working-tree diffs routinely exceeding the 10MB read buffer ([D-7](artifacts/implementation-decision-log.md#d-7-read-deadline-30s--maxbuffer-10mb-index-lock--http-409-in-progress-detection-disables-writes)).
- **Out-of-scope boundary:** No remote operations (push/pull/PR/merge), no side-by-side layout, no per-hunk staging, no continuous file-watch streaming, no rename of the pending-changes panel, no per-line review/re-prompt surface — all deferred in the spec under YAGNI.

## Team Composition and Participation

| Specialist | Status | Key Input |
|------------|--------|-----------|
| `project-manager` | Coordinator | Facilitated R1, corrected the service-owner decision against evidence, synthesized the plan. |
| `software-architect` | Active | Recommended a read-server/write-coder split (R1); the split's premise was refuted by evidence and recorded as the rejected alternative on [D-1](artifacts/implementation-decision-log.md#d-1-both-git-read-and-git-write-live-in-appsserver). Owns the read shape, base resolution, refresh wiring, two-phase sequencing. |
| `adversarial-security-analyst` | Active | Argv-safety, path-traversal, server-derived identity, tool-registry exclusion, artifact-sandbox evidence ([D-3](artifacts/implementation-decision-log.md#d-3-write-ops-via-argv-safe-rungitexecfile-with----separators)–[D-5](artifacts/implementation-decision-log.md#d-5-commit-identity-server-derived-request-schema-strict-with-no-author-fields), [D-13](artifacts/implementation-decision-log.md#d-13-write-endpoints-excluded-from-the-assistant-tool-registry-artifact-sandbox-closes-the-indirect-path)). |
| `on-call-engineer` | Active | Read deadline + maxBuffer, index-lock 409, refresh coalescence, in-progress detection, partial-failure honesty ([D-7](artifacts/implementation-decision-log.md#d-7-read-deadline-30s--maxbuffer-10mb-index-lock--http-409-in-progress-detection-disables-writes), [D-8](artifacts/implementation-decision-log.md#d-8-refresh-via-client-git_diff_refresh-sessionevent-coalesced--not-a-ws-frame)). |
| `test-engineer` | Active | T1–T12: pure-helper units + temp-repo integration; skip Shiki/layout (no web harness). |
| `junior-developer` | Reframer | Flagged the cross-service coupling of the write-in-coder split, which seeded the evidence correction on [D-1](artifacts/implementation-decision-log.md#d-1-both-git-read-and-git-write-live-in-appsserver); confirmed the read-only-session Git tab needs no extra label (F21). |

## Implementation Approach

Both the git read and the git write operations live in `apps/server` ([D-1](artifacts/implementation-decision-log.md#d-1-both-git-read-and-git-write-live-in-appsserver)) — reusing the existing safe argv `runGit` and the `project_bootstrap.ts` server-side git-write precedent, and avoiding a cross-service proxy hop, a second deploy surface, and coder coupling. The feature reuses Shiki (`lang:'diff'`) already in `apps/web`, the `useProjectGit` dirty signal, and the existing `RightRail.tsx` file-panel host; it introduces one new server service, new routes, one new web view + hook, and one new client `sessionEvents` event.

### Architecture and Integration Points

- **New `apps/server/src/services/git_diff.ts`** — read logic, git-write helpers, and TDD-first pure helpers (`parseNameStatus`, `splitDiffByFile`, `resolveCommittedBase`, `autoSelectMode`, `classify`, `detectInProgress`) ([D-2](artifacts/implementation-decision-log.md#d-2-read-route--git_diffts-pure-helpers-tdd-first)). `autoSelectMode` and `canCommit` are inline tested helpers, not separate modules ([D-12](artifacts/implementation-decision-log.md#trivial-decisions)).
- **New routes in `apps/server/src/routes/projects.ts`**, beside `GET /api/projects/:id/git`: read `GET /api/projects/:id/git/diff?mode=<uncommitted|committed>` ([D-2](artifacts/implementation-decision-log.md#d-2-read-route--git_diffts-pure-helpers-tdd-first)); writes for stage / unstage / commit / discard ([D-3](artifacts/implementation-decision-log.md#d-3-write-ops-via-argv-safe-rungitexecfile-with----separators)). The repository root is derived server-side via `path_guard.ts` `resolveProjectRoot`, never from the request ([D-4](artifacts/implementation-decision-log.md#d-4-path-validation--repo-relative-pathguard-reject-escape-and-repo-root-discard)).
- **Frontend** — a Files / Git tab in the existing `RightRail.tsx` header (replacing the static "Files" label, fitting one line); a new `GitDiffView` in the same slot as the file tree; a `useGitDiff` hook; the dirty dot fed by `useProjectGit`'s existing `is_dirty` ([D-15](artifacts/implementation-decision-log.md#d-15-frontend--rightrail-filesgit-tab-gitdiffview-with-lazy-shiki-dirty-dot-from-useprojectgit)). Per-file expand/collapse is local state in `GitDiffView`, not a shared hook ([D-11](artifacts/implementation-decision-log.md#trivial-decisions)).

### Data Model and Persistence

None. The panel reads git state at request time and writes the project repository directly via git; nothing is persisted in Postgres — no schema change, no migration, no new env var ([D-10](artifacts/implementation-decision-log.md#trivial-decisions)).

### Runtime Behavior

- **Read:** the read route runs argv `runGit` calls under a 30s deadline and a 10MB `maxBuffer` ([D-7](artifacts/implementation-decision-log.md#d-7-read-deadline-30s--maxbuffer-10mb-index-lock--http-409-in-progress-detection-disables-writes)); `parseNameStatus` builds the file list, `splitDiffByFile` segments the unified diff, `classify` marks binary/large bodies, `detectInProgress` reads `.git` sentinels, and the response carries the resolved base label and the in-progress flag.
- **Mode/base:** `autoSelectMode` picks Uncommitted (dirty) or Committed (clean) on first open only ([D-12](artifacts/implementation-decision-log.md#trivial-decisions)); `resolveCommittedBase` resolves `@{upstream}` → `origin/HEAD` → null, falling back to a labeled Uncommitted on null ([D-6](artifacts/implementation-decision-log.md#d-6-committed-mode-base-resolution-via-upstream--originhead--null)).
- **Refresh:** the client `git_diff_refresh` sessionEvent fires on the five triggers, coalesced behind an in-flight ref so a running refresh absorbs later triggers ([D-8](artifacts/implementation-decision-log.md#d-8-refresh-via-client-git_diff_refresh-sessionevent-coalesced--not-a-ws-frame)).
- **Diff render:** `GitDiffView` highlights a file's diff via Shiki `lang:'diff'` lazily on expand, with a per-file loading state ([D-15](artifacts/implementation-decision-log.md#d-15-frontend--rightrail-filesgit-tab-gitdiffview-with-lazy-shiki-dirty-dot-from-useprojectgit)).

### External Interfaces

New HTTP routes only (read + four writes) under `/api/projects/:id/git/…`. Refresh is a client-side `sessionEvents` event (`git_diff_refresh`), **not** a WS frame, so `@boocode/contracts` is not touched or rebuilt; the only parity step is a no-op `case 'git_diff_refresh'` in `useSidebar.ts` `applyEvent` ([D-8](artifacts/implementation-decision-log.md#d-8-refresh-via-client-git_diff_refresh-sessionevent-coalesced--not-a-ws-frame), [D-9](artifacts/implementation-decision-log.md#trivial-decisions)).

## Decomposition and Sequencing

Two phases on a single deploy surface ([D-14](artifacts/implementation-decision-log.md#d-14-two-phase-build--readdisplay-phase-1-then-write-actions-phase-2)); both ship via `docker compose up --build -d boocode`.

| # | Work Unit | Delivers | Depends On | Verification |
|---|-----------|----------|------------|--------------|
| 1 | `git_diff.ts` pure helpers (TDD-first) | `parseNameStatus`, `splitDiffByFile`, `resolveCommittedBase`, `autoSelectMode`, `classify`, `detectInProgress` ([D-2](artifacts/implementation-decision-log.md#d-2-read-route--git_diffts-pure-helpers-tdd-first), [D-6](artifacts/implementation-decision-log.md#d-6-committed-mode-base-resolution-via-upstream--originhead--null)) | — | Unit tests T1–T7 |
| 2 | Read route `GET /api/projects/:id/git/diff?mode=` | Diff payload (files, counts, base label, in-progress flag) under 30s/10MB bounds ([D-2](artifacts/implementation-decision-log.md#d-2-read-route--git_diffts-pure-helpers-tdd-first), [D-7](artifacts/implementation-decision-log.md#d-7-read-deadline-30s--maxbuffer-10mb-index-lock--http-409-in-progress-detection-disables-writes)) | 1 | Temp-repo integration T8 |
| 3 | `useGitDiff` + RightRail Files/Git tab + dirty dot | Read-only panel, tab switch, dirty indicator from `useProjectGit` ([D-15](artifacts/implementation-decision-log.md#d-15-frontend--rightrail-filesgit-tab-gitdiffview-with-lazy-shiki-dirty-dot-from-useprojectgit)) | 2 | Manual (no web harness) |
| 4 | `GitDiffView` read-only + lazy Shiki + refresh wiring | Per-file expand, lazy `lang:'diff'`, `git_diff_refresh` sessionEvent + `useSidebar.ts` no-op case, coalescence ref ([D-8](artifacts/implementation-decision-log.md#d-8-refresh-via-client-git_diff_refresh-sessionevent-coalesced--not-a-ws-frame), [D-15](artifacts/implementation-decision-log.md#d-15-frontend--rightrail-filesgit-tab-gitdiffview-with-lazy-shiki-dirty-dot-from-useprojectgit)) | 3 | Manual |
| 5 | Write helpers + routes (stage/unstage/commit/discard) | Argv-safe writes with `--` separators, `pathGuard`, server-derived `-c` identity, `.strict()` commit schema, 409 on index-lock ([D-3](artifacts/implementation-decision-log.md#d-3-write-ops-via-argv-safe-rungitexecfile-with----separators), [D-4](artifacts/implementation-decision-log.md#d-4-path-validation--repo-relative-pathguard-reject-escape-and-repo-root-discard), [D-5](artifacts/implementation-decision-log.md#d-5-commit-identity-server-derived-request-schema-strict-with-no-author-fields), [D-7](artifacts/implementation-decision-log.md#d-7-read-deadline-30s--maxbuffer-10mb-index-lock--http-409-in-progress-detection-disables-writes)); endpoints kept out of `ALL_TOOLS` ([D-13](artifacts/implementation-decision-log.md#d-13-write-endpoints-excluded-from-the-assistant-tool-registry-artifact-sandbox-closes-the-indirect-path)) | 1, 2 | Temp-repo integration T9–T12 |
| 6 | Write affordances + in-progress disable | Stage/unstage/commit/discard UI, tracked/untracked discard confirmation, in-progress disable ([D-7](artifacts/implementation-decision-log.md#d-7-read-deadline-30s--maxbuffer-10mb-index-lock--http-409-in-progress-detection-disables-writes), [D-15](artifacts/implementation-decision-log.md#d-15-frontend--rightrail-filesgit-tab-gitdiffview-with-lazy-shiki-dirty-dot-from-useprojectgit)) | 4, 5 | Manual |

Phase 1 = units 1–4 (read + display); Phase 2 = units 5–6 (write actions).

## RAID Log

### Assumptions

| ID | Assumption | What Changes If Wrong | Verifier | Status |
|----|------------|-----------------------|----------|--------|
| A1 | The boocode container keeps the `/opt:/opt` read-write mount, so apps/server can write project paths. | [D-1](artifacts/implementation-decision-log.md#d-1-both-git-read-and-git-write-live-in-appsserver) reopens — writes would need a host service. | `docker-compose.yml:16` | Verified (R1) |
| A2 | A realistic single-user working-tree diff stays under 10MB. | The read truncates/errors; the streaming reader reopens (Deferred YAGNI). | `on-call-engineer` | Unverified — bounded by [D-7](artifacts/implementation-decision-log.md#d-7-read-deadline-30s--maxbuffer-10mb-index-lock--http-409-in-progress-detection-disables-writes) |

### Dependencies

| ID | Dependency | Owner | Status |
|----|------------|-------|--------|
| Dep1 | Shiki `^1.29.2` (`lang:'diff'`) already in `apps/web`. | `apps/web` | Present (no install) |
| Dep2 | `useProjectGit` already returns `is_dirty` for the dirty dot. | `apps/web` | Present (no new fetch) |

## Testing Strategy

Sourced from `test-engineer` (T1–T12). Server-side only — `apps/web` has no test harness, so Shiki rendering and layout/tab behavior are verified manually, not in the suite. Vitest conventions: `globals:false` (import `describe`/`it`/`expect`), `.js` import suffixes, include glob `src/**/__tests__/**/*.test.ts`.

- **Observable behaviors to test:** porcelain → file-list parse with change types (T1); unified-diff split per file (T2); base resolution `@{upstream}` → `origin/HEAD` → null (T3); auto-select mode by dirty/clean (T4); binary/large classify (T5); in-progress sentinel detection (T6); `canCommit` gating (T7); read route over a temp repo (T8); stage/unstage round-trip (T9); commit with server-derived identity (T10); discard tracked vs untracked (T11); path-guard rejection of `..`/absolute/symlink-escape and repo-root discard (T12).
- **Test doubles posture:** pure helpers tested directly with fixture strings (no git spawn); route/write tests use a real temp repo via `mkdtemp` + `git init` (the `path_guard.test.ts` integration pattern).
- **Edge cases requiring coverage:** binary file, oversized diff, no resolvable base, in-progress state, index-lock 409, untracked-discard partial failure, path-escape attempts ([D-4](artifacts/implementation-decision-log.md#d-4-path-validation--repo-relative-pathguard-reject-escape-and-repo-root-discard), [D-7](artifacts/implementation-decision-log.md#d-7-read-deadline-30s--maxbuffer-10mb-index-lock--http-409-in-progress-detection-disables-writes)).
- **Test levels:** unit (T1–T7, pure helpers) + integration (T8–T12, temp-repo). No end-to-end / web-layer automation.

## Security Posture

`adversarial-security-analyst` contributed the full write-surface posture. Threat vectors and the mitigations this plan commits to:

- **Command/flag injection** — every git invocation uses discrete argv with explicit `--` separators between options and user-supplied paths and a flag-injection guard (reject path args starting with `-`); never `hostExec(shell)` ([D-3](artifacts/implementation-decision-log.md#d-3-write-ops-via-argv-safe-rungitexecfile-with----separators)). User text (commit message, file targets) is always discrete argv.
- **Path traversal** — `pathGuard(repoRoot, file)` resolves each per-file argument and rejects absolute paths, `..` traversal, and symlink escape outside the server-derived root; discarding the repo root (`.`) is rejected ([D-4](artifacts/implementation-decision-log.md#d-4-path-validation--repo-relative-pathguard-reject-escape-and-repo-root-discard)). The root is derived from the project record via `path_guard.ts`, never the request.
- **Identity spoofing** — commit identity is server-derived (`-c user.name`/`-c user.email` from git config, falling back to the `project_bootstrap.ts` constants); the commit request schema is Zod `.strict()` with `{message, files?}` only — no author/email/date field can be supplied ([D-5](artifacts/implementation-decision-log.md#d-5-commit-identity-server-derived-request-schema-strict-with-no-author-fields)).
- **Assistant-driven invocation** — the write endpoints are never registered in `ALL_TOOLS`, so no assistant tool surface reaches them; the indirect artifact path is already closed by the artifact iframe's `connect-src 'none'` sandbox (F1), so no new CSRF mitigation is built ([D-13](artifacts/implementation-decision-log.md#d-13-write-endpoints-excluded-from-the-assistant-tool-registry-artifact-sandbox-closes-the-indirect-path)).

## Operational Readiness

- **Deploy surface:** single — `docker compose up --build -d boocode` (rebuilds web + server from the working tree). No `sudo systemctl restart boocoder`, because no apps/coder code changes ([D-1](artifacts/implementation-decision-log.md#d-1-both-git-read-and-git-write-live-in-appsserver)).
- **Schema / migration / env:** none — no Postgres change, no migration, no new env var ([D-10](artifacts/implementation-decision-log.md#trivial-decisions)).
- **Contracts package:** not touched — refresh is a client `sessionEvents` event, not a WS frame, so `packages/contracts/` is not rebuilt ([D-9](artifacts/implementation-decision-log.md#trivial-decisions)).
- **Feature flag / rollout:** none — the panel is additive and inert until the Git tab is opened; rollback is reverting the build.

## On-Call Resilience Posture

`on-call-engineer` contributed; each commitment maps to a flagged failure mode.

- **Timeouts and deadlines:** the read path runs under a 30s execution deadline and a 10MB `maxBuffer`, both distinct from the D5 per-file display-size cap; a read that exceeds the deadline exits loading, shows an error, and offers Refresh ([D-7](artifacts/implementation-decision-log.md#d-7-read-deadline-30s--maxbuffer-10mb-index-lock--http-409-in-progress-detection-disables-writes)).
- **Retry strategy:** none on the server. An index-lock write failure returns **HTTP 409 "repository busy"**; retry is user-driven, so no timer state or hidden busy state is introduced ([D-7](artifacts/implementation-decision-log.md#d-7-read-deadline-30s--maxbuffer-10mb-index-lock--http-409-in-progress-detection-disables-writes)).
- **Concurrency / coalescence:** the client holds an in-flight coalescence ref so concurrent `git_diff_refresh` triggers absorb into the running refresh — one read at a time, settling to a single final snapshot ([D-8](artifacts/implementation-decision-log.md#d-8-refresh-via-client-git_diff_refresh-sessionevent-coalesced--not-a-ws-frame)).
- **Graceful degradation:** `detectInProgress` (`.git` MERGE_HEAD / rebase / CHERRY_PICK_HEAD / BISECT_LOG sentinels) folds an in-progress flag into the read response; the client disables write affordances when set, so stage/commit/discard never fail with raw git errors mid-operation ([D-7](artifacts/implementation-decision-log.md#d-7-read-deadline-30s--maxbuffer-10mb-index-lock--http-409-in-progress-detection-disables-writes)).
- **Data integrity:** an untracked-file discard that fails partway reports honest partial failure on the next refresh rather than claiming an unenforceable "state unchanged" ([D-7](artifacts/implementation-decision-log.md#d-7-read-deadline-30s--maxbuffer-10mb-index-lock--http-409-in-progress-detection-disables-writes)).

## Definition of Done

- [ ] Opening the Git tab shows the project repo's changed files in the auto-selected mode; switching to Files restores the tree in the same slot ([D-15](artifacts/implementation-decision-log.md#d-15-frontend--rightrail-filesgit-tab-gitdiffview-with-lazy-shiki-dirty-dot-from-useprojectgit)).
- [ ] Committed mode labels its resolved base (`@{upstream}` → `origin/HEAD` → labeled Uncommitted fallback) ([D-6](artifacts/implementation-decision-log.md#d-6-committed-mode-base-resolution-via-upstream--originhead--null)).
- [ ] Stage / unstage / commit / discard operate at whole-file granularity in Uncommitted mode; discard prompts the tracked vs untracked confirmation; Committed mode is read-only ([D-3](artifacts/implementation-decision-log.md#d-3-write-ops-via-argv-safe-rungitexecfile-with----separators), [D-15](artifacts/implementation-decision-log.md#d-15-frontend--rightrail-filesgit-tab-gitdiffview-with-lazy-shiki-dirty-dot-from-useprojectgit)).
- [ ] Commit identity is server-derived; the request cannot set it; the schema is `.strict()` ([D-5](artifacts/implementation-decision-log.md#d-5-commit-identity-server-derived-request-schema-strict-with-no-author-fields)).
- [ ] Path-escape and repo-root discard are rejected; writes use argv + `--` separators ([D-3](artifacts/implementation-decision-log.md#d-3-write-ops-via-argv-safe-rungitexecfile-with----separators), [D-4](artifacts/implementation-decision-log.md#d-4-path-validation--repo-relative-pathguard-reject-escape-and-repo-root-discard)).
- [ ] Write endpoints are absent from `ALL_TOOLS` ([D-13](artifacts/implementation-decision-log.md#d-13-write-endpoints-excluded-from-the-assistant-tool-registry-artifact-sandbox-closes-the-indirect-path)).
- [ ] Read respects the 30s/10MB bounds; index-lock returns 409; in-progress disables writes; refresh coalesces ([D-7](artifacts/implementation-decision-log.md#d-7-read-deadline-30s--maxbuffer-10mb-index-lock--http-409-in-progress-detection-disables-writes), [D-8](artifacts/implementation-decision-log.md#d-8-refresh-via-client-git_diff_refresh-sessionevent-coalesced--not-a-ws-frame)).
- [ ] Tests T1–T12 pass (`pnpm -C apps/server test`).
- [ ] Phase 1 ships and is reviewable before Phase 2 lands ([D-14](artifacts/implementation-decision-log.md#d-14-two-phase-build--readdisplay-phase-1-then-write-actions-phase-2)).
- [ ] Post-ship owner: the session user (single-user app); no separate on-call rotation.

## Specialist Handoffs for Implementation

- **`test-engineer`** — dispatch at the start of unit 1 to own T1–T12; needs the helper signatures from `git_diff.ts` and the temp-repo integration pattern (`path_guard.test.ts`).
- **`adversarial-security-analyst`** — dispatch to review unit 5 before merge; needs the write-route handlers and the `.strict()` commit schema to confirm argv-safety, path-guard coverage, and identity derivation.
- **`user-experience-designer`** — dispatch during units 3–4 and 6; needs the `RightRail.tsx` header layout to confirm one-line fit (D18), tap-target minimum, and the tracked/untracked discard wording.

## Deferred (YAGNI)

### Shared `packages/` runGit extraction
- **Why deferred:** Rule of Three not met — only apps/server consumes the git ops for this feature (coder is untouched); a single-consumer abstraction is premature.
- **Reopen when:** a third consumer needs the same git ops.
- **Source:** R1, software-architect.

### New WS frame for refresh
- **Why deferred:** Replaced by the simpler client `sessionEvents` event `git_diff_refresh` — no trigger needs a server push, so a WS frame and a `@boocode/contracts` rebuild are unnecessary (simpler-version test).
- **Reopen when:** a refresh trigger genuinely originates server-side (an out-of-band repo mutation the client cannot observe).
- **Source:** R1, software-architect / junior-developer.

### Server-side retry on index-lock
- **Why deferred:** "Try again" is user-driven; a server retry hides the busy state and adds timer state (evidence test — no observed contention).
- **Reopen when:** index-lock contention is observed frequent in practice.
- **Source:** R1, on-call-engineer (F5).

### Streaming diff reader (cap mid-stream)
- **Why deferred:** `execFile` maxBuffer 10MB covers any realistic single-user working-tree diff; ~40–50 LoC for a transient memory spike that does not matter at this scale (simpler-version test).
- **Reopen when:** working-tree diffs routinely exceed 10MB.
- **Source:** R1, on-call-engineer.

### CSRF custom-header on the write routes
- **Why deferred:** `connect-src 'none'` on artifacts + the SameSite=Lax Authelia cookie + a same-origin SPA cover it at single-user scale (evidence test — no exposed cross-origin path).
- **Reopen when:** the write routes are exposed to a less-controlled origin.
- **Source:** R1, adversarial-security-analyst.

### Separate per-file expand-state hook
- **Why deferred:** Replaced by local state in `GitDiffView` — one consumer (single-implementation abstraction).
- **Reopen when:** a second component needs the same expand state.
- **Source:** R1, software-architect.

### `autoSelectMode` / `canCommit` as separate modules
- **Why deferred:** Kept as inline tested pure helpers in `git_diff.ts` — splitting into modules adds files without a second consumer (simpler-version test).
- **Reopen when:** a second module needs to import them independently.
- **Source:** R1, software-architect / test-engineer.

## Open Items

- None. Every Round-1 open question resolved from evidence; the spec's only open item (commit identity) was settled at spec time. The plan is shippable as written.

## Summary

- **Outcome delivered:** A Files / Git tab in the right-side file panel that reads and (whole-file) stages, unstages, commits, and discards the project repository's changes, built entirely in `apps/server`.
- **Team size:** 6 specialists — see [artifacts/implementation-iteration-history.md](artifacts/implementation-iteration-history.md)
- **Rounds of facilitation:** 1 — see [artifacts/implementation-iteration-history.md](artifacts/implementation-iteration-history.md)
- **Decisions committed:** 15 — see [artifacts/implementation-decision-log.md](artifacts/implementation-decision-log.md)
- **Decisions settled by evidence:** 15 — see [artifacts/implementation-decision-log.md](artifacts/implementation-decision-log.md)
- **Decisions settled by junior-developer reframing:** 0 (the junior-developer's coupling flag seeded the evidence correction on D-1, but the resolution was evidence) — see [artifacts/implementation-decision-log.md](artifacts/implementation-decision-log.md)
- **Decisions settled by user input:** 0 — see [artifacts/implementation-decision-log.md](artifacts/implementation-decision-log.md)
- **Rejected alternatives recorded:** 22 — see [artifacts/implementation-decision-log.md](artifacts/implementation-decision-log.md)
- **Open items remaining:** 0
- **Recommendation:** Ship as planned — build Phase 1 (units 1–4) first, then Phase 2 (units 5–6).
