Add workflow and script to clean Dependabot description bodies

.github/workflows/dependabot-pr-cleaner.yaml

@@ -0,0 +1,87 @@
+# 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.
+
+name: Dependabot PR cleaner
+run-name: >-
+  Clean up description of PR ${{github.event.pull_request.number}} on
+  ${{github.ref_name}} by @${{github.actor}}
+
+# Dependabot's PR descriptions are written in HTML and contain repeated parts
+# that bloat git histories. This converts them to Markdown & cleans them up.
+
+on:
+  pull_request_target:
+    types:
+      - opened
+      - synchronize
+      - reopened
+
+  workflow_dispatch:
+    inputs:
+      pr-number:
+        description: 'The PR number of the PR to clean:'
+        required: true
+
+permissions: read-all
+
+jobs:
+  clean-pr-description:
+    if: >-
+      ${{github.actor == 'dependabot[bot]' &&
+        github.repository_owner == 'quantumlib'}}
+    name: Clean PR description
+    runs-on: ubuntu-slim
+    timeout-minutes: 5
+    permissions:
+      contents: read
+      pull-requests: write
+    env:
+      GH_REPO: ${{github.repository}}
+      PR_NUMBER: ${{inputs.pr-number || github.event.pull_request.number}}
+    steps:
+      - name: Set up Python
+        uses: actions/setup-python@83679a892e2d95755f2dac6acb0bfd1e9ac5d548 # v5
+        with:
+          cache: pip
+
+      - name: Install dependencies
+        run: pip install html2text==2025.4.15
+
+      - name: Get the PR description body
+        env:
+          GH_TOKEN: ${{secrets.GITHUB_TOKEN}}
+        run: gh pr view ${{env.PR_NUMBER}} --json body --jq .body > body.txt
+
+      - name: Clean up the description and convert it to Markdown
+        shell: python
+        run: |
+          import html2text
+
+          with open("body.txt", "r", encoding="utf-8") as f:
+            content = f.read()
+
+          # Delete everything starting with the commits list onward.
+          commits_start_re = r"<details>\s*<summary>Commits</summary>"
+          content = re.split(commits_start_re, content, flags=re.IGNORECASE)[0]
+
+          converter = html2text.HTML2Text()
+          markdown_content = converter.handle(content.strip()).strip()
+
+          with open("new-body.txt", "w", encoding="utf-8") as f:
+              f.write(markdown_content)
+
+      - name: Write the description back to the PR
+        env:
+          GH_TOKEN: ${{secrets.GITHUB_TOKEN}}
+        run: gh pr edit ${{env.PR_NUMBER}} --body-file new-body.txt