Diffcity — AI skill for Claude Code

diffcity

AI code review for GitHub pull requests with your existing **Claude Code** or **OpenAI Codex** agent. Diff City is a desktop workspace for guided diffs, inline AI conversations, and local review drafts. Consequential changes come first; assessed routine changes fold into summaries you can expand.

**Status:** public macOS alpha. **Owner:** Christopher Smothers. **License:** [MIT](LICENSE).

[Download for Mac](https://github.com/crs48/diffcity/releases) · [Website](https://diff.city) · [Installation](docs/installation.md) · [Contributing](CONTRIBUTING.md)

Apple silicon (M1 or newer), macOS 14+. Download the DMG from Releases and drag Diff City into Applications. Early unsigned alphas are **not notarized** and require macOS approval on first launch; the release notes state the signing status. Bring your GitHub CLI login and a local Codex or Claude Code installation. No Diff City account is required. Updates are manual for now.

See the review workflow

These are full-window captures of the real macOS app reviewing the [mixed-edit demo PR](https://github.com/crs48/diffcity/pull/18): 20 files and more than 16,000 changed lines covering migrations, access policies, API contracts, localization, and renames. The guide and replies were generated with **Claude Code · Fable 5 · High**. The sample deliberately contains review issues and is not intended to be merged. Other account avatars are hidden for privacy. The guide surfaces its coverage limits for oversized or omitted changes.

**Ask your coding agent, right in the diff.** Select lines, click **+**, type a question, and read Claude’s response inline. Continue the same conversation in PR chat with the code context attached.


18-second recording of the real app, with AI waiting time shortened. No zoom or cropping; only the Diff Ci