name: Build (nix)

on:
  workflow_run:
    workflows:
      - Update flake lock
    types:
      - completed

permissions:
  contents: read

jobs:
  build:
    if: ${{ gitea.event.workflow_run.conclusion == 'success' }}
    runs-on: ubuntu-latest

    steps:
      - name: Check out repository
        uses: actions/checkout@v4
        with:
          # The update workflow may have pushed a newer flake.lock commit.
          ref: ${{ gitea.event.workflow_run.head_branch }}

      - name: Install upstream Nix
        uses: cachix/install-nix-action@v31

      - name: Build flake
        run: nix build