What is fouine?

fouine is a self-hosted AI code reviewer for GitHub. It connects as a GitHub App, receives pull request webhooks, and runs an AI agent against the full codebase to post reviews with inline comments.

How it works

┌─────────────┐     pull_request webhook     ┌─────────────────┐
│   GitHub     │ ────────────────────────────▶│  fouine (Elysia) │
│              │                              │                  │
│              │◀── inline comments + ──────│  OpenCode agent  │
│              │     review summary           │  + custom prompt │
└─────────────┘                              └────────┬────────┘
                                                       │
                                                bare repo + worktree
                                                (per-PR checkout)

1. GitHub sends a webhook — pull_request (opened, synchronize, reopened) or an issue_comment starting with /fouine (the old /review still works, but is deprecated)
2. Elysia server verifies the HMAC signature, extracts PR info
3. Bare repo + worktree — first PR from a repo triggers git clone --bare, cached on disk. Each review gets a lightweight git worktree add at the PR head SHA
4. OpenCode agent runs programmatically on the worktree with a configurable review prompt. It reads the diff, explores context, and posts results
5. GitHub API — the agent posts a review summary as a PR comment + inline comments on specific lines via custom tools
6. Cleanup — the worktree is removed after review; the bare repo stays cached for next time

Key design decisions

Decision	Why
Full codebase via worktree	The agent decides what context matters, not a rigid diff parser
GitHub App over personal tokens	Clean per-repo install, no token juggling
One LLM call per review	Models are smart enough for a thorough review in one pass
Agent posts comments directly	Simpler than having the server parse structured output
Configurable prompt via dashboard	Review style, focus areas, language, strictness — per repo

Tech stack

Layer	Choice
Runtime	Bun
Server	Elysia
Code agent	OpenCode (programmatic)
GitHub	GitHub App + octokit
Dashboard	React + TanStack Router + Tailwind
Database	SQLite (WAL mode)
Self-hosting	Docker