name: CI

on:
  push:
    branches: [main]
  pull_request:
  schedule:
    # Mondays 06:00 UTC. A new Rust release lands on its own schedule, so
    # without this the advisory `stable` job below only runs when someone
    # happens to push, and breakage can sit unnoticed for weeks.
    - cron: '0 6 * * 1'

env:
  CARGO_TERM_COLOR: always

permissions:
  contents: read

jobs:
  test:
    runs-on: ubuntu-latest
    # Nothing it covers can change on a timer: the toolchain is pinned and
    # the dependencies are locked. The weekly run is for `stable` only.
    if: github.event_name != 'schedule'
    steps:
      - uses: actions/checkout@v4
      # Pinned, and kept in step with `devVersion` in flake.nix, so CI and
      # the dev shell agree and a new stable release cannot turn a lint
      # failure into an unrelated red build.
      - uses: dtolnay/rust-toolchain@1.99.1
        with:
          components: rustfmt, clippy
      - run: cargo build --all-targets
      - run: cargo test
      - run: cargo fmt --check
      - run: cargo clippy --all-targets -- -D warnings

  msrv:
    name: Build on the declared MSRV
    runs-on: ubuntu-latest
    if: github.event_name != 'schedule'
    steps:
      - uses: actions/checkout@v4
      # Must match `rust-version` in Cargo.toml and `msrvVersion` in
      # flake.nix. Builds only — lint and format output varies by release,
      # and pinning those to the oldest supported toolchain is not useful.
      - uses: dtolnay/rust-toolchain@1.88.0
      - run: cargo test

  stable:
    name: Latest stable (advisory)
    runs-on: ubuntu-latest
    # Deliberately NOT `continue-on-error`: a failure here should render as
    # a real red X, not a green check with an annotation nobody reads.
    #
    # This job is advisory all the same — it tracks a moving toolchain, so a
    # new clippy lint can break it through no fault of the change under
    # test. **Keep it out of the required status checks** in branch
    # protection; that, rather than a flag in this file, is what stops it
    # blocking merges. Expect it red sometimes, and fix it when bumping
    # `devVersion`.
    steps:
      - uses: actions/checkout@v4
      - uses: dtolnay/rust-toolchain@stable
        with:
          components: clippy
      - run: cargo test
      - run: cargo clippy --all-targets -- -D warnings