name: Set up core toolchain
description: >-
  Node, dependencies, and a zero-extension registry: the prologue every
  core-build job needs before it can lint, build, or test. The caller must check
  the repository out first, because a local composite action cannot be resolved
  until the workspace containing it exists.

runs:
  using: composite
  steps:
    - uses: actions/setup-node@249970729cb0ef3589644e2896645e5dc5ba9c38 # v6
      with:
        node-version: 20

    # Restore-only, deliberately never `save`. A cache written from a
    # pull_request run is scoped to that PR's ref, so no other run can ever read
    # it: PR-side saves are pure quota burn. Fourteen dead 284 MB copies (4 GB,
    # 40% of the repo quota) accumulated in a single day the last time a naive
    # `cache: npm` was left on, which is why test-pg-real.yml still runs
    # uncached. The entries read here are written on main by ci-cache.yml, and
    # default-branch entries are restorable from every PR.
    - name: Restore npm cache
      uses: actions/cache/restore@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
      with:
        path: ~/.npm
        key: npm-${{ runner.os }}-node20-${{ hashFiles('package-lock.json') }}
        restore-keys: |
          npm-${{ runner.os }}-node20-

    - name: Install dependencies
      shell: bash
      run: npm ci

    # CI builds core with zero extensions enabled: that property is the entire
    # reason this workflow exists, so every job that compiles or runs code needs
    # the registry regenerated from an empty config first.
    - name: Reset extensions config
      shell: bash
      run: echo '{"extensions":[]}' > extensions.config.json

    - name: Generate extension registry
      shell: bash
      run: npm run setup:extensions