Difftray

Difftray is a local-first macOS desktop app for reviewing Git changes across multiple projects. It tracks which files have been reviewed, automatically invalidates that review state when the relevant diff changes, and turns review comments into a ready-made prompt for your favorite agent or AI tool.

Keep track of what changed, what you already reviewed, and what needs another look.

Difftray is not an IDE, not an AI agent host, and not a pull request platform. It is a focused review desk for local Git changes.

Why Difftray?

Why not just use a regular Git diff client?

I built this because I kept losing track of my own reviews. I'd skim a diff, an agent would iterate, I'd come back, and I had no idea which files were still the ones I'd looked at and which had moved underneath me.

A few things came out of that:

• Reviewed files don't stay reviewed if they change. Mark a file as reviewed; if the diff for that file changes later, Difftray drops it back to unreviewed so you know to look again. It doesn't tell you what changed, just that something did, and your previous pass is no longer trustworthy.
• It's built around the iteration loop. Working tree changes, branch changes, or a single committed patch, same flow. You're not preparing a PR, you're checking what the agent (or you) just did.
• Comments are meant to go back to the agent. Leave line-level notes while reviewing, then copy them out as a prompt.

Current Features

• Keep several local repositories open in one review desk.
• See which projects still need attention without switching context.
• Review working tree changes, branch changes against a local ref, or a single recent/pasted commit with the same focused workflow.
• Move through changed files quickly, with noisy generated files out of the way by default.
• Read diffs in the shape that fits the moment: side-by-side, unified, expanded context, or focused on one side.
• Mark files reviewed and Difftray will flag them if they change later.
• Leave line-level review notes and copy a ready-made prompt to paste back into your favorite agent or AI tool.
• Drive review from the keyboard, command palette, or dense file list controls.
• Pair Difftray Companion on a phone to review the same local projects from your couch, tablet stand, or another machine on your private network.
• Open the selected file in the system default editor or an installed common editor preset.
• Configure app appearance, default diff mode, line wrapping, generated-file visibility, drift notifications, phone companion access, and editor launch behavior.
• Stay local by design: no fetching, pushing, staging, editing, or repository metadata writes.

Phone Companion

The phone companion server is off by default. Enable it from Settings -> Phone companion, then pair a device with the QR code or six-digit manual code.

When enabled, Difftray starts a local HTTP/WebSocket server on the preferred companion port, falling back within 48620-48629 if the preferred port is busy, and advertises _difftray._tcp with Bonjour/mDNS. macOS may show a local-network or firewall prompt the first time the server binds; allow it if you want phones on the same trusted network to find the Mac.

Paired devices can see the projects already known to Difftray, their local repository paths, review targets, file paths, diff text or binary markers, review state, review comments, and generated comment reports. They can mark or unmark files as reviewed, create/edit/delete comments, change the active diff target, and receive encrypted workspace-change events. The companion never gets Git credentials, shell access, staging/push/fetch controls, or arbitrary file system access.

Use the companion on networks you trust. Same-LAN discovery is automatic when mDNS works; Tailscale MagicDNS addresses are also included when available, which is the recommended path for private cross-network use. See docs/companion-protocol.md for the protocol and security model.

Screenshots

Review workflow with inline comments and a ready-made agent handoff prompt:

Reviewed-file drift notification after a diff changes:

Expandable unchanged context in split diff mode:

Focused new-side diff view:

Install

Download the latest macOS build from the Releases page:

• Apple Silicon (M-series): Difftray-arm64.dmg
• Intel: Difftray-x64.dmg

Open the .dmg and drag Difftray into your Applications folder.

Agent workflows

The app includes a CLI at /Applications/Difftray.app/Contents/Resources/bin/difftray. It runs without a separate Node or npm installation. doctor --json checks the selected app and connection; review commands can start the installed app automatically. If the app is in ~/Applications, use that path instead. The bundled launcher follows its own app when it is moved.

The portable Difftray skill provides review workflows for Codex, Claude Code, and Pi. Packaged apps include the canonical skill and CLI. In Settings → Agents, choose Install to link the skill into Claude Code (~/.claude/skills/difftray), Codex (~/.agents/skills/difftray), Pi (~/.pi/agent/skills/difftray), or a folder you choose for another agent. The link follows skill updates in place; if you move the app, use Repair to update it. The skill finds the owning app from its link, including Alpha and custom-named bundles. DIFFTRAY_APP_PATH remains an explicit override for manual or developer use. Settings → Agents also offers an optional Install command-line tool action for terminal convenience; it does not edit shell startup files. See agent setup and review commands.

Development

Prerequisites:

• Node.js 22 or newer
• pnpm 10.11.0 or newer
• Git available on PATH
• macOS for the intended desktop runtime

Install dependencies:

pnpm install

Run the desktop app in development:

pnpm dev

Build the app:

pnpm build

Run the full local CI gate before committing:

./ci.sh

pnpm check delegates to the same script.

Useful focused checks:

pnpm format
pnpm lint
pnpm typecheck
pnpm test
pnpm test:visual
pnpm bench:performance

Run pnpm bench:performance before and after changes that can affect large changesets, workspace loading, file selection, mark-reviewed flow, diff loading, diff rendering, review-state resolution, or bundle size.

License

Apache-2.0.