guillaumearm/cc-libs
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
337a0fa7c8
cc-libs/docs/adrs/adr-0005-craftos-pc-harness.md

3.5 KiB
Raw Blame History

ADR 0005: CraftOS-PC As The Local Harness

Status

Accepted

Date

2026-06-08

Context

This repository targets CC:Tweaked on Minecraft 1.21. The Lua we ship runs inside the ComputerCraft sandbox: it depends on os.pullEventRaw, peripheral, rednet, textutils.serializeJSON, modem channels, and a handful of CC-specific globals. Standard Lua (or LuaJIT) cannot execute this code as-is, so a normal local test harness was never a serious option.

In practice contributors have been running the code in two places:

  • In-game on a real Minecraft server, which is slow to iterate on.
  • In CraftOS-PC (https://www.craftos-pc.cc/), a desktop emulator that ships the same ROM/BIOS as CC:Tweaked, supports modem peripherals via periphemu, and can run fully headless (--cli --headless --script <file>).

CraftOS-PC has been the de facto local harness for months, but that fact lived only as a single line in CLAUDE.md. There was no install guide, no minimum version, and just install did not check that the binary was present. The recent upgrade from v2.6.6 → v2.8.3 (the first one in years) made it obvious that this dependency needed to be made explicit.

Decision

Treat CraftOS-PC as a first-class local development dependency.

  • Minimum version v2.8.3 — recent enough to have the current CC:Tweaked ROM, old enough that contributors already on a 2.8.x build will not be forced to upgrade again immediately.
  • Documented install in docs/install-craftos-pc.md, with a SHA-256-verified macOS flow and pointers to the official Windows/Linux artifacts.
  • Verified by just install via a check-craftos recipe that runs craftos --version and requires v2.8.3 or newer. Failure prints a one-line pointer to the install guide instead of a long stack trace.
  • just ci is the local verification entry point. Today it runs check-craftos and check. The installed pre-commit hook invokes just ci directly. just test exists as the future home for CraftOS-PC-driven smoke tests.

The existing CLAUDE.md constraint ("Do not run Lua locally or add a test harness unless asked") is reframed rather than removed: there is still no standalone Lua harness, and we are not adding a Busted-style test runner. The harness is CraftOS-PC, invoked deliberately.

Consequences

  • Contributors must install CraftOS-PC before just install succeeds. The install guide makes this a 4-step copy/paste on macOS.
  • Future smoke tests have a clear home: a script under tests/ (or similar) driven by craftos --cli --headless --script tests/smoke.lua, called from just test.
  • The harness version becomes a project-level concern. When CC:Tweaked ships breaking changes that require a newer CraftOS-PC build, we bump the minimum version in docs/install-craftos-pc.md and check-craftos keeps contributors honest.
  • No CI integration yet. Running CraftOS-PC headless in GitHub Actions is feasible (the AppImage works on Ubuntu runners) but is out of scope here; the contract is local-only for now.

Future Work

  • Headless smoke test. A tests/smoke.lua that boots an emulated computer, requires /apis/eventloop, /apis/net, and the router, and asserts the wiring loads without errors. Hooked into just test, then into just ci when it is ready to run on every commit.
  • CI. Run the smoke test on push using the Linux AppImage.
  • Pinned ROM. CraftOS-PC ships its own copy of the CC:Tweaked ROM per release. If we ever need to test against a specific in-game version, point CraftOS-PC at a vendored ROM via --rom.