# CLAUDE.md

## Project: Cartograph

A browser-based world map creation tool (like Wonderdraft/Inkarnate). C99 compiled to WebAssembly via Emscripten.

### Stack
- **Graphics:** Sokol (WebGPU backend, `SOKOL_WGPU`) — `lib/sokol/`
- **UI:** Dear ImGui via cimgui — `lib/imgui/`
- **Math:** cglm (types are C arrays: `vec2` = `float[2]`, `mat4` = `float[4][4]` column-major) — `lib/cglm/`
- **Shaders:** WGSL in `src/shaders/`, compiled to C headers via `xxd -i` into `src/generated/`

### Build
- `make` (release) / `make debug` — outputs `app.html`
- All includes go through `src/api.h` which defines `SOKOL_IMPL`, `SOKOL_WGPU`, and pulls in every library header
- Include paths: `lib/sokol`, `lib/imgui`, `lib/imgui/imgui`, `lib/util`, `lib/cglm/include`

### Key files
- `src/main.c` — entry point, sokol init, render loop, input (zoom/pan/drag)
- `src/api.h` — central include hub, backend defines
- `src/sprite.h` — sprite batching, texture manager, file import stubs
- `src/util.h` — `vector_t` (dynamic array) and `mem_pool_t` (free-list pool), both stripe-based
- `src/rand.h` — xorshift32 PRNG

### Conventions
- No malloc/free directly — use `ALLOC`/`FREE` macros (wired to smemtrack in main.c)
- Assert is encouraged for invariant checks
- Data structures use stripe-based allocation (byte stride per element, not sizeof)

---

**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.

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.