action.yml

name: "Build and verify rebuild is a no-op"
description: "Run a cargo command, then re-run it to verify all artifacts are cached"
inputs:
  command:
    description: "The cargo build command to run and verify (--message-format json is appended on the verification run)"
    required: true
runs:
  using: "composite"
  steps:
    - name: "Build"
      shell: bash
      run: ${{ inputs.command }}
    - name: "Verify rebuild is a no-op"
      shell: bash
      run: |
        stale=$(${{ inputs.command }} \
          --message-format json 2>/dev/null \
          | jq -r 'select(.reason == "compiler-artifact" and .fresh == false) | .target.name')
        if [ -n "$stale" ]; then
          echo "ERROR: Rebuild recompiled crates that should have been cached:"
          echo "$stale"
          exit 1
        fi