# CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

## Project Overview

PR-Helper is a self-hosted web service that auto-generates PR descriptions from Git history and performs AI-powered code review. Designed for internal/local use only (no auth).

## Tech Stack

- **Backend**: Go + Gin + MySQL + go-git
- **Frontend**: Go html/template + HTMX + D3.js + diff2html + Tailwind CSS
- **LLM**: OpenAI-compatible API (SSE streaming)
- **Deploy**: Docker

## Build & Run

```bash
# Build
go build -o pr-helper .

# Configure — copy .env.example to .env and set MySQL credentials
cp .env.example .env

# Run (requires MySQL server)
./pr-helper
# Server listens on :8080

# Docker (includes MySQL container)
docker compose up --build
```

## Architecture

```
handlers/   → HTTP handlers (pages + JSON API + SSE endpoints)
services/   → Business logic (git ops, LLM calls, PDF gen, cache management)
models/     → Data models (repository, settings, analysis)
database/   → MySQL init and migrations
config/     → Configuration loading
templates/  → Go HTML templates (layouts/, pages/, partials/)
static/     → CSS (Tailwind output), JS (graph, diff-viewer, sse), vendor libs
```

**Data flow**: Browser ↔ Gin handlers → services (git/llm) → MySQL + filesystem (`data/`)

**Key service layer responsibilities**:
- `services/git.go` — clone, diff, graph data extraction via go-git
- `services/llm.go` — OpenAI-compatible API calls with SSE streaming
- `services/generate.go` — PR description generation (commits + diff → LLM → structured output)
- `services/review.go` — AI code review (per-file analysis + summary, Top-N strategy for large diffs)
- `services/cache.go` — repository cache lifecycle (clone, expiry cleanup)

## Key Patterns

- **SSE streaming**: Clone progress, PR generation, and AI review all use Server-Sent Events. Handlers write `event:` / `data:` lines; frontend consumes via `static/js/sse.js`.
- **Large diff handling**: Diffs are split per-file, sorted by change size, truncated to Top-N (configurable, default 20). Each file analyzed independently by LLM, then a summary prompt aggregates results.
- **Review notes**: Three-level scoping — `overall`, `file`, `suggestion` — stored in `review_notes` table. AI output is read-only; users append notes separately.
- **Diff rendering**: diff2html in Split view by default. AI review suggestions are inline-embedded next to code lines via `line` + `side` fields from SSE.

## Frontend Libraries (vendored in static/lib/)

- HTMX 2.x, D3.js 7.x, diff2html 3.x, highlight.js 11.x
- Tailwind CSS compiled to `static/css/style.css`
- Custom JS: `sse.js` (SSE client), `graph.js` (D3 git graph with click selection), `diff-viewer.js` (diff2html + file tree sidebar), `review-inline.js` (inline AI suggestions)

## Data Storage

- MySQL database `pr_helper` — settings (KV), repositories, analyses, review_notes
- Cloned repos cached at `data/repos/` with configurable expiry (default 7 days)
- Database connection configured via `.env` file (see `.env.example`)

## Development Notes

- No authentication — do not expose to public internet.
- LLM prompts are in `services/generate.go` and `services/review.go`; model/endpoint/key are configurable via the settings page.
- SSE event formats are defined in `handlers/generate.go` and `handlers/review.go` (server) and consumed by `static/js/sse.js` (client).