[CI] implement a bot to remind prs to link issues if not.

.github/workflows/pr_link_issue_reminder.yml

@@ -0,0 +1,33 @@
+name: PR Issue Link Reminder
+
+on:
+  schedule:
+    - cron: "30 7 * * *"
+  workflow_dispatch:
+
+jobs:
+  remind_or_close:
+    name: Remind or close PRs without a linked issue
+    if: github.repository == 'huggingface/diffusers'
+    runs-on: ubuntu-22.04
+    permissions:
+      contents: read
+      pull-requests: write
+      issues: write
+    env:
+      GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
+
+      - name: Setup Python
+        uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405  # v6
+        with:
+          python-version: "3.10"
+
+      - name: Install requirements
+        run: |
+          pip install PyGithub requests
+
+      - name: Run reminder script
+        run: |
+          python utils/remind_link_issue.py

utils/remind_link_issue.py

@@ -0,0 +1,104 @@
+# Copyright 2025 The HuggingFace Team. All rights reserved.
+#
+# 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
+#
+#     http://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.
+"""
+Script to remind PR authors to link an issue.
+
+Behavior:
+- Scans open, non-draft PRs.
+- A PR is considered "linked" if GitHub's GraphQL `closingIssuesReferences` returns > 0
+  (covers both `Fixes #N` keywords in the body and issues linked via the GitHub UI).
+- If a PR is not linked and no prior reminder is present, the script posts a single
+  friendly reminder comment.
+- PRs labeled `no-issue-needed` and bot-authored PRs are skipped.
+"""
+
+import os
+
+import requests
+from github import Github
+
+
+REPO = "huggingface/diffusers"
+REMINDER_MARKER = "<!-- pr-link-issue-reminder -->"
+BYPASS_LABELS = {"no-issue-needed"}
+CONTRIBUTION_GUIDE_URL = "https://huggingface.co/docs/diffusers/main/en/conceptual/contribution#coding-with-ai-agents"
+
+GRAPHQL_URL = "https://api.github.com/graphql"
+GRAPHQL_QUERY = """
+query($owner: String!, $name: String!, $number: Int!) {
+  repository(owner: $owner, name: $name) {
+    pullRequest(number: $number) {
+      closingIssuesReferences(first: 1) {
+        totalCount
+      }
+    }
+  }
+}
+"""
+
+
+def has_linked_issue(token, owner, name, number):
+    response = requests.post(
+        GRAPHQL_URL,
+        json={"query": GRAPHQL_QUERY, "variables": {"owner": owner, "name": name, "number": number}},
+        headers={"Authorization": f"Bearer {token}"},
+        timeout=30,
+    )
+    response.raise_for_status()
+    payload = response.json()
+    return payload["data"]["repository"]["pullRequest"]["closingIssuesReferences"]["totalCount"] > 0
+
+
+def has_existing_reminder(pr):
+    return any(REMINDER_MARKER in (c.body or "") for c in pr.get_issue_comments())
+
+
+def reminder_body(author):
+    return (
+        f"{REMINDER_MARKER}\n"
+        f"Hi @{author}, thanks for the PR! It does not appear to link an issue it fixes. "
+        "If this PR addresses an existing issue, please add a closing keyword "
+        "(e.g. `Fixes #1234`) to the PR description so the issue is linked. "
+        f"See the [contribution guide]({CONTRIBUTION_GUIDE_URL}) for more details. "
+        "If this PR intentionally does not fix a tracked issue, a maintainer can "
+        "add the `no-issue-needed` label to silence this reminder."
+    )
+
+
+def main():
+    token = os.environ["GITHUB_TOKEN"]
+    g = Github(token)
+    repo = g.get_repo(REPO)
+    owner, name = REPO.split("/", 1)
+
+    for pr in repo.get_pulls(state="open"):
+        if pr.draft:
+            continue
+        if pr.user is None:
+            continue
+        author = pr.user.login
+        if not author or author.endswith("[bot]") or pr.user.type == "Bot":
+            continue
+        labels = {label.name for label in pr.labels}
+        if labels & BYPASS_LABELS:
+            continue
+        if has_linked_issue(token, owner, name, pr.number):
+            continue
+        if has_existing_reminder(pr):
+            continue
+        pr.create_issue_comment(reminder_body(author))
+
+
+if __name__ == "__main__":
+    main()