# CLAUDE.md

Read @DESIGN.md before working on this project.


## Guidelines
**Tradeoff:** These guidelines bias toward caution over speed. For
trivial tasks, use judgment.

### 1. 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.

### 2. 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.

### 3. 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.
- **One thing at a time**: Never combine multiple refactoring,
  optimization, or feature items in a single edit session. Work on
  them sequentially: implement one, test it, get verification, commit
  it, and only then proceed to the next.

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.

### 4. 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.


## Do and Don'ts

### Sprite Environment

- Do not automatically call `sprite-env checkpoints create` or create
  checkpoints during the session unless explicitly requested by the
  user.

### GIt 

- Always run `make format` and `make clean test` before git commit.
- Always use `git merge --squash` when merging.

