# CLAUDE.md
This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
## Project Overview
**comma** is a Rust CLI tool that generates git commits using AI (OpenRouter API). It prompts users for API key and model selection on first run, then saves config to `~/.comma.json`.
## Build & Test Commands
```bash
cargo build # Build the project
cargo test # Run all tests
cargo test config_tests # Run specific test file
cargo test -- --nocapture # Run tests with output
cargo run # Run the application
```
## Architecture
```
src/
├── main.rs # Entry point; loads config or triggers first startup
├── config.rs # Config struct (api_key, model_id), load/save with atomic writes
├── openrouter.rs # OpenRouter API client for fetching models
├── setup.rs # First-startup flow: API key → model selection → save
└── ui.rs # User interface helpers (prompts, messages)
```
**Flow:** `main.rs` checks for `~/.comma.json` → if missing/malformed, delegates to `setup::run_first_startup()` which uses `openrouter::Client` to fetch available models and `ui` for prompts.
## Key Patterns
- Config file: `~/.comma.json` (created on first run)
- Permissions: 0o600 (readable only by owner) on Unix
- Atomic writes: write to `.json.tmp` then rename
- API errors: `Unauthorized` (401), `Forbidden` (403), `RateLimited` (429) are handled specially in setup flow
## Behavioral Guidelines
**Tradeoff:** These guidelines bias toward caution over speed. For trivial tasks, use judgment.
## Think Before Coding
**Don't assume. Don't hide confusion. Surface tradeoffs.**
Before implementing:
- State your assumptions explicitly. If uncertain, ask.
- If multiple interpretations exist, present them - don't pick silently.
- If a simpler approach exists, say so. Push back when warranted.
- If something is unclear, stop. Name what's confusing. Ask.
## Simplicity First
**Minimum code that solves the problem. Nothing speculative.**
- No features beyond what was asked.
- No abstractions for single-use code.
- No "flexibility" or "configurability" that wasn't requested.
- No error handling for impossible scenarios.
- If you write 200 lines and it could be 50, rewrite it.
Ask yourself: "Would a senior engineer say this is overcomplicated?" If yes, simplify.
## Surgical Changes
**Touch only what you must. Clean up only your own mess.**
When editing existing code:
- Don't "improve" adjacent code, comments, or formatting.
- Don't refactor things that aren't broken.
- Match existing style, even if you'd do it differently.
- If you notice unrelated dead code, mention it - don't delete it.
When your changes create orphans:
- Remove imports/variables/functions that YOUR changes made unused.
- Don't remove pre-existing dead code unless asked.
The test: Every changed line should trace directly to the user's request.
## Goal-Driven Execution
**Define success criteria. Loop until verified.**
Transform tasks into verifiable goals:
- "Add validation" → "Write tests for invalid inputs, then make them pass"
- "Fix the bug" → "Write a test that reproduces it, then make it pass"
- "Refactor X" → "Ensure tests pass before and after"
For multi-step tasks, state a brief plan:
```
1. [Step] → verify: [check]
2. [Step] → verify: [check]
3. [Step] → verify: [check]
```
Strong success criteria let you loop independently. Weak criteria ("make it work") require constant clarification.
---
**These guidelines are working if:** fewer unnecessary changes in diffs, fewer rewrites due to overcomplication, and clarifying questions come before implementation rather than after mistakes.