name: Nix

# The flake builds with the model catalog revision pinned in
# nix/model-catalog.json. This workflow keeps that pin usable independently of
# releases: after pi.dev publishes a catalog from main, it replaces the pin with
# the newest catalog only if the current one no longer hydrates main (for
# example after a provider was added) or its provider/type/API model groups
# differ from the newest catalog for one of main's providers (for example after
# a provider gained classifier models or switched APIs), builds the flake, and
# commits the new pin to main.
#
# Release tags are built exactly as tagged, with their committed pin. Once all
# systems build, the stable branch is fast-forwarded to the tag so that
# `nix run github:earendil-works/pi/stable` runs the latest release.

on:
  push:
    tags:
      - 'v*.*.*'
  pull_request:
    branches: [main]
    paths:
      - '.github/workflows/nix.yml'
      - 'flake.lock'
      - 'flake.nix'
      - 'nix/**'
      - 'package-lock.json'
      - 'packages/*/package.json'
      - 'packages/coding-agent/install-lock/**'
      - 'packages/ai/scripts/hydrate-model-catalog.ts'
      - 'scripts/update-model-catalog-pin.mjs'
  workflow_run:
    workflows:
      - Publish Model Catalog
    types:
      - completed
  # Catches packaging drift from changes pushed to main without a pull request.
  schedule:
    - cron: '43 5 * * *'
  workflow_dispatch:

permissions: {}

concurrency:
  group: nix-${{ (github.event_name == 'pull_request' || github.ref_type == 'tag') && github.ref || 'main' }}
  cancel-in-progress: ${{ github.event_name == 'pull_request' }}

jobs:
  pin:
    if: ${{ github.event_name != 'workflow_run' || (github.event.workflow_run.conclusion == 'success' && github.event.workflow_run.head_branch == 'main') }}
    runs-on: ubuntu-latest
    permissions:
      contents: read
    outputs:
      revision: ${{ steps.pin.outputs.revision }}
      updated: ${{ steps.pin.outputs.updated }}
    steps:
      - name: Checkout
        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          persist-credentials: false

      - name: Setup Node.js
        uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
        with:
          node-version: 22

      - name: Refresh the model catalog pin if stale
        id: pin
        run: |
          set -euo pipefail
          # A release tag must build with its committed pin; it cannot be changed.
          if [[ "${GITHUB_REF_TYPE}" != "tag" ]]; then
            node scripts/update-model-catalog-pin.mjs --if-stale
          fi
          revision="$(node -p 'require("./nix/model-catalog.json").revision')"
          echo "revision=${revision}" >> "${GITHUB_OUTPUT}"
          if git diff --quiet -- nix/model-catalog.json; then
            echo "updated=false" >> "${GITHUB_OUTPUT}"
          else
            echo "updated=true" >> "${GITHUB_OUTPUT}"
            if [[ "${GITHUB_EVENT_NAME}" == "pull_request" ]]; then
              echo "::warning::The model catalog pin on main is stale; this build uses ${revision}. The pin is refreshed on main after pi.dev publishes a catalog."
            fi
          fi

  build:
    needs: pin
    # After a catalog publication, only build when the pin changed.
    if: ${{ github.event_name != 'workflow_run' || needs.pin.outputs.updated == 'true' }}
    strategy:
      fail-fast: false
      matrix:
        include:
          - runner: ubuntu-latest
            system: x86_64-linux
          - runner: ubuntu-24.04-arm
            system: aarch64-linux
          - runner: macos-latest
            system: aarch64-darwin
    runs-on: ${{ matrix.runner }}
    permissions:
      contents: read
    steps:
      - name: Checkout
        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          persist-credentials: false

      - name: Use the resolved model catalog pin
        env:
          REVISION: ${{ needs.pin.outputs.revision }}
        run: |
          printf '{\n  "revision": "%s"\n}\n' "${REVISION}" > nix/model-catalog.json

      - name: Install Nix
        uses: cachix/install-nix-action@13d8dd58da0234aa297dedd986986ccb8e7f3e24 # v31.11.1
        with:
          github_access_token: ${{ github.token }}

      - name: Evaluate all systems
        if: ${{ matrix.system == 'x86_64-linux' }}
        run: nix flake check --all-systems --no-build

      - name: Build
        run: nix build -L .

      - name: Smoke-test
        run: |
          ./result/bin/pi --version
          ./result/bin/pi --help > /dev/null
          if [[ "${GITHUB_REF_TYPE}" == "tag" ]]; then
            test "$(./result/bin/pi --version)" = "${GITHUB_REF_NAME#v}"
          fi

  update-stable:
    needs: build
    if: ${{ github.ref_type == 'tag' }}
    runs-on: ubuntu-latest
    permissions:
      contents: write
    steps:
      # Full history, so git can verify that the push to stable is a fast-forward.
      - name: Checkout
        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          fetch-depth: 0

      # Without --force, the push fails unless it is a fast-forward, so stable
      # never moves back to an older release.
      - name: Fast-forward stable to the release
        run: git push origin "${GITHUB_SHA}:refs/heads/stable"

  commit-pin:
    needs:
      - pin
      - build
    if: ${{ github.event_name != 'pull_request' && github.ref == 'refs/heads/main' && needs.pin.outputs.updated == 'true' }}
    runs-on: ubuntu-latest
    permissions:
      contents: write
    steps:
      - name: Checkout
        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          ref: main

      - name: Commit and push the model catalog pin
        env:
          REVISION: ${{ needs.pin.outputs.revision }}
        run: |
          set -euo pipefail
          git config user.name "github-actions[bot]"
          git config user.email "github-actions[bot]@users.noreply.github.com"
          printf '{\n  "revision": "%s"\n}\n' "${REVISION}" > nix/model-catalog.json
          git add nix/model-catalog.json
          if git diff --staged --quiet; then
            echo "Model catalog pin is already ${REVISION}."
            exit 0
          fi
          git commit -m "chore: update Nix model catalog pin"
          for attempt in 1 2 3; do
            if git push origin HEAD:main; then
              exit 0
            fi
            sleep $((attempt * 5))
            git pull --rebase origin main
          done
          exit 1