# CLAUDE.md

Concise guidance for agents working in this repository.

## Project

ComputerCraft / CC:Tweaked Lua APIs, servers, and programs for Minecraft 1.21. Code runs in the ComputerCraft sandbox, not standard Lua.

Use `docs/README.md` as the entrypoint for CC:Tweaked, CraftOS-PC, Advanced Peripherals, and Create integration documentation links. Use `docs/adrs/README.md` for repository architecture decisions.

## Constraints

- Do not add a standalone Lua test harness unless asked. Local execution happens through the CraftOS-PC harness (see `docs/install-craftos-pc.md`, `docs/craftos_pc_glossary.md`, and ADR-0005); code otherwise executes in-game.
- Do not run `just repl` as an LLM agent; it is a human-only interactive CraftOS-PC wrapper. Use `just craftos --headless ...` for automated probes.
- When changing behavior, add as many useful CraftOS-PC tests as practical. It is acceptable to skip tests that require human-only validation, such as complex turtle motion, in-game UX feel, or visual approval, but still add unit-style non-regression tests for deterministic parts when possible.
- Use `/apis/libtest.lua` for test scripts under `tests/`; `/programs/runtest.lua` prints `__TRAPOS_TEST_OK__` only after the suite passes.
- After editing Lua, run `just check` and fix all `luacheck` warnings.
- Use 2-space indent, semicolons, and `local function`.
- `require` paths are absolute ComputerCraft paths, for example `require('/apis/net')()`.
- Most API modules return factories; call the required module once before use.

## Architecture

- `apis/eventloop.lua` is the single-threaded event loop around `os.pullEventRaw`; consider using it everywhere async behavior is needed. A handler that returns `api.STOP` auto-unregisters.
- `apis/libtest.lua` is the lightweight test helper used by scripts under `tests/`; `/programs/runtest.lua` discovers tests, renders suite output, and owns the `__TRAPOS_TEST_OK__` success marker.
- `apis/net.lua` builds modem packet messaging, routing, and request/response RPC on the event loop. `sendRequest` returns `ok, result, packet` and defaults to a 0.5s timeout.
- A router (`/programs/router.lua`) must be running somewhere on the network; without it, packets lack `routerId`, `isPacketOk` rejects them, and cross-machine messaging silently fails.
- `servers/` listen for requests and start loops; `programs/` are clients that send requests and exit.
- Well-known channels: `9` ping, `10` router/default routing. Keep duplicated constants in sync.

## Boot And Install

- `startup/servers.lua` starts `/programs`, the shell, and configured servers via `parallel.waitForAll`.
- Preserve `periphemu` guards used for CraftOS-PC emulation; see `docs/craftos_pc_glossary.md` for upstream emulator references.
- `install.lua` downloads files listed in `LIST_FILES` from `master` by default, or from `next` with `--beta`; add shipped files there.
- Add new servers to `startup/servers.lua` as needed.

## Conventions

- Bump `local _VERSION = '...'` when changing module behavior.
- Programs support `-version`/`--version` and `-help`/`--help`; router also supports `-silent`/`--silent`.
- French or English comments are fine; match surrounding code.
- Commit messages use lightweight conventional style: `topic(scope): description` or `topic: description`.

See `DEVELOPMENT.md` for local setup.