Claude Code Diff Review

Per-hunk review of every change Claude Code makes. Accept, reject, or ask "why?" — without leaving VS Code, and without touching git.

Claude Code can autonomously edit dozens of files in a single session. This extension surfaces every change as a session-aware review panel with per-hunk Accept / Reject / Ask Claude controls. No git required.

Highlights

• Session-aware review — every file Claude touched in one turn, grouped together.
• Per-hunk granularity — accept one refactor, reject an unrelated formatting change in the same file.
• In-context AI chat — click 💬 Ask on any hunk; chat streams in a side panel scoped to that hunk.
• Pro / Max plan support — uses your claude /login OAuth credentials automatically. API key still supported for those who have one.
• Source Control integration — files appear in a dedicated SCM panel grouped by review status.
• CodeLens gutter buttons — Accept / Reject directly above each hunk in the editor.
• Resilient — per-file mutex on actions, fuzz-tolerant hunk revert with snapshot fallback, drift detection on external edits.

Setup

1. Install

Install the extension from the VS Code Marketplace.

2. Open a workspace

Open the project folder you want Claude to edit. The extension writes its hooks to <workspace>/.claude/settings.json automatically.

3. Authenticate Claude

Three options, in resolution order:

Verify which auth path the extension picked: Claude Review: Use Claude Code Auth prints the active source as a toast (without revealing the token).

4. Run a Claude session

Open the integrated terminal in your workspace and run:

claude

Ask Claude to make some edits. When it finishes the turn, the review panel opens automatically.

Daily flow

1. Claude finishes a turn → review panel opens in a new editor tab.
2. File list on the left shows every file touched, color-coded by status.
3. Diff pane on the right shows split or unified view. Each hunk has three buttons:
   • ✓ Accept — keep the change, mark the hunk reviewed
   • ✗ Reject — revert just that hunk on disk, mark reviewed
   • 💬 Ask — open chat scoped to the hunk
4. CodeLens above each hunk in the underlying editor mirrors Accept / Reject.
5. Status bar shows total pending hunks across all sessions.

Bulk: per-file ✓ File / ✗ File and per-session Accept all / Reject all in the panel header. Bulk-reject takes a fast path that writes the captured original snapshot in one disk write.

Configuration

Commands

Troubleshooting

Stop hook returns 401

Cause: the integrated terminal predates the extension's activation, so it doesn't have CLAUDE_REVIEW_TOKEN in its environment.

Fix:

1. Developer: Reload Window
2. Close every existing integrated terminal
3. Open a fresh terminal and re-run claude

Verify by running $env:CLAUDE_REVIEW_TOKEN.Length (PowerShell) or echo ${#CLAUDE_REVIEW_TOKEN} (bash). Expect 64.

Review panel is blank

Open the webview's DevTools: command palette → Developer: Open Webview Developer Tools → Console tab. Any unhandled error renders inside the panel via the built-in <ErrorBoundary>. If it's blank with no error, the React tree may have un-mounted; reload the window.

"Extension host did not start under 10 seconds"

On slower machines the activation may flirt with VS Code's 10 s timeout. The extension externalises the Anthropic SDK and defers the hook-config write to keep activation fast (~1–2 s typical). If you still hit this, file an issue with the Output → Claude Code Review panel contents.

Chat says "No Claude credential found"

Run Claude Review: Use Claude Code Auth. It prints which source the resolver picked, or a warning if none matched. Resolution order:

1. CLAUDE_CODE_OAUTH_TOKEN env var
2. CLAUDE_REVIEW_OAUTH_TOKEN env var
3. SecretStorage OAuth (set via the command)
4. ~/.claude/.credentials.json (the file claude /login creates)
5. SecretStorage API key

Reject says "Could not cleanly revert a hunk"

A formatter (or another tool) ran after Claude's edit and the post-edit content has drifted too far for jsdiff's fuzzFactor: 2. The banner offers a Revert file to original snapshot button — that writes the captured before content back in one disk write.

Port 53117 already in use

The server falls back to an OS-assigned dynamic port automatically and rewrites the hook URL accordingly. Check the Output → Claude Code Review panel for the actual port. To force a fixed port, set claudeReview.port to a number that's free.

Known limitations

• Single workspace folder. Multi-root workspaces use the first folder for .claude/settings.json and history. v1.1 may shard.
• Remote / SSH / Dev Container / WSL. v1.0 is local-only. The hook server binds to 127.0.0.1; remote development needs the server to live in the remote host. Out of scope for v1.0.
• Claude Code version. Requires Claude Code ≥ 2.1.47 for last_assistant_message and stop_hook_active fields in the Stop hook payload.
• Sub-agent attribution. Claude Code sub-agents share the parent session ID; per-sub-agent attribution requires JSONL transcript parsing. Planned for v1.1.
• Localisation. English only in v1.0.

Privacy & security

• API keys / OAuth tokens are stored exclusively in VS Code's SecretStorage (OS-keychain backed). They never cross into the webview, never appear in logs, and never get written to a file.
• Loopback server binds to 127.0.0.1 only. Bearer authentication uses a 256-bit token, regenerated per activation, compared in constant time.
• Webview CSP sets connect-src 'none' — the webview cannot make network calls. All chat traffic flows through the extension host.
• Telemetry is opt-in (claudeReview.telemetry) and additionally gated by VS Code's global telemetry setting. Events are scrubbed for PII (file paths, message content, tokens) before emission.

License

MIT. See LICENSE.

Built to make Claude Code more reviewable. If something's off, run Claude Review: Show Log and file an issue with the output.