Add workflow to regenerate env files after dependency updates

.github/workflows/regenerate-env-files.yaml

@@ -0,0 +1,141 @@
+# Copyright 2026 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+# Regenerate compiled environment files when dependency inputs change.
+#
+# Dependabot updates dev_tools/requirements/deps/*.txt but cannot run
+# dev_tools/requirements/create-env-files.sh. This workflow runs that script
+# under maintainer control:
+#   * On pull requests that change deps inputs, results are pushed back to the
+#     same branch so reviewers can merge deps and env files together.
+#   * After a merge to main, a follow-up pull request is opened if env files
+#     are still out of date (requires the repository setting that allows GitHub
+#     Actions to create pull requests).
+#   * Manual invocation pushes directly to the selected branch.
+#
+# Manual invocation:
+# https://github.com/quantumlib/OpenFermion/actions/workflows/regenerate-env-files.yaml
+# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+name: Regenerate environment files
+run-name: >-
+  Regenerate environment files
+  ${{github.event_name == 'workflow_dispatch' && ' (manual)' || '' }}
+
+on:
+  workflow_dispatch:
+
+  push:
+    branches:
+      - main
+    paths:
+      - 'dev_tools/requirements/deps/**'
+
+  pull_request:
+    paths:
+      - 'dev_tools/requirements/deps/**'
+
+permissions: read-all
+
+concurrency:
+  group: regenerate-env-files-${{github.event.pull_request.number || github.ref}}
+  cancel-in-progress: true
+
+jobs:
+  regenerate:
+    name: Regenerate environment files
+    runs-on: ubuntu-24.04
+    timeout-minutes: 15
+    if: >-
+      github.event_name == 'workflow_dispatch'
+      || github.event_name == 'push'
+      || (github.event_name == 'pull_request'
+          && github.event.pull_request.head.repo.full_name == github.repository)
+    permissions:
+      contents: write
+      pull-requests: write
+    steps:
+      - name: Check out a copy of the git repository
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+        with:
+          ref: ${{github.event.pull_request.head.ref || github.ref}}
+          fetch-depth: 0
+          token: ${{secrets.GITHUB_TOKEN}}
+
+      - name: Install uv
+        run: |
+          curl -LsSf https://astral.sh/uv/0.11.28/install.sh | sh
+          echo "$HOME/.local/bin" >> "$GITHUB_PATH"
+
+      - name: Regenerate environment files
+        run: ./dev_tools/requirements/create-env-files.sh
+
+      - name: Commit and publish if changed
+        id: publish
+        env:
+          GH_TOKEN: ${{secrets.GITHUB_TOKEN}}
+        run: |
+          set -euo pipefail
+
+          if git diff --quiet -- dev_tools/requirements/envs dev_tools/requirements/max_compat; then
+            echo "Environment files are already up to date."
+            echo "changed=false" >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git add dev_tools/requirements/envs dev_tools/requirements/max_compat
+          git commit \
+            -m "Regenerate environment files after dependency update" \
+            -m "Automated commit from the regenerate-env-files workflow."
+
+          if [[ "${{github.event_name}}" == "pull_request" ]]; then
+            git push origin "HEAD:${{github.event.pull_request.head.ref}}"
+            echo "changed=true" >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+
+          if [[ "${{github.event_name}}" == "workflow_dispatch" ]]; then
+            git push origin "HEAD:${{github.ref_name}}"
+            echo "changed=true" >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+
+          if [[ "${{github.event_name}}" == "push" && "${{github.ref}}" == "refs/heads/main" ]]; then
+            branch="automation/regenerate-env-files-${GITHUB_RUN_ID}"
+            git checkout -b "${branch}"
+            git push origin "${branch}"
+            gh pr create \
+              --title "Regenerate environment files after dependency update" \
+              --body "Automated regeneration triggered by a push to \`main\` that changed files under \`dev_tools/requirements/deps/\`. Review and merge to keep compiled environment files in sync." \
+              --base main \
+              --head "${branch}"
+            echo "changed=true" >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+
+          git push origin "HEAD:${{github.ref_name}}"
+          echo "changed=true" >> "$GITHUB_OUTPUT"
+
+      - name: Comment on pull request
+        if: >-
+          steps.publish.outputs.changed == 'true'
+          && github.event_name == 'pull_request'
+        env:
+          GH_TOKEN: ${{secrets.GITHUB_TOKEN}}
+        run: |
+          gh pr comment "${{github.event.pull_request.number}}" \
+            --body "Regenerated compiled environment files in \`dev_tools/requirements/envs/\` and \`dev_tools/requirements/max_compat/\` using \`dev_tools/requirements/create-env-files.sh\`."

CONTRIBUTING.md

@@ -367,3 +367,15 @@ The lists of OpenFermion dependencies in `dev_tools/requirements/envs/` and
 pip install -r dev_tools/requirements/envs/dev.env.txt
 ./dev_tools/requirements/create-env-files.sh
 ```
+
+When a pull request changes files under `dev_tools/requirements/deps/`, the
+[`regenerate-env-files` workflow](.github/workflows/regenerate-env-files.yaml)
+automatically runs `create-env-files.sh` and pushes any resulting updates back to
+the same branch. After a dependency update is merged to `main`, that workflow can
+also open a follow-up pull request if the compiled environment files are still out
+of date. On `quantumlib/OpenFermion`, this follow-up pull request requires the
+repository setting **Allow GitHub Actions to create and approve pull requests**
+under Settings → Actions → General. Maintainers can trigger regeneration manually
+from the
+[Actions tab](https://github.com/quantumlib/OpenFermion/actions/workflows/regenerate-env-files.yaml);
+manual runs push updates directly to the selected branch.