Add PR test failure summary comment

Posts a sticky comment on each PR listing which matrix test jobs failed,
with direct links to their logs. Updates on re-run; clears to a pass
message if all jobs succeed.

Uses only actions/github-script (already in repo) and the built-in
GITHUB_TOKEN with pull-requests: write — no S3, no AWS credentials,
no new third-party actions.

Author: ramakrishnap-nv

.github/workflows/pr.yaml

@@ -620,3 +620,24 @@ jobs:
     with:
       build_type: pull-request
       script: ci/test_self_hosted_service.sh
+  pr-test-summary:
+    needs:
+      - conda-cpp-tests
+      - conda-python-tests
+      - wheel-tests-cuopt
+      - wheel-tests-cuopt-server
+      - test-self-hosted-server
+    if: always()
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      pull-requests: write
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+          sparse-checkout: ci/utils/pr_test_summary.py
+          sparse-checkout-cone-mode: false
+      - run: python3 ci/utils/pr_test_summary.py
+        env:
+          GH_TOKEN: ${{ github.token }}

ci/utils/pr_test_summary.py

@@ -0,0 +1,146 @@
+# SPDX-FileCopyrightText: Copyright (c) 2026, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+"""Post or update a sticky PR comment summarizing CI test job failures.
+
+Reads GITHUB_REPOSITORY, GITHUB_RUN_ID, GITHUB_REF, and GH_TOKEN from the
+environment.  Finds every test job in the current workflow run, then posts (or
+updates) a single comment on the pull request listing any failed jobs with
+direct log links.
+
+Usage (called from a GitHub Actions step):
+    python3 ci/utils/pr_test_summary.py
+"""
+
+import json
+import os
+import sys
+import urllib.error
+import urllib.request
+
+# Job name prefixes that are considered test jobs.
+_TEST_PREFIXES = (
+    "conda-cpp-tests",
+    "conda-python-tests",
+    "wheel-tests-cuopt",
+    "wheel-tests-cuopt-server",
+    "test-self-hosted-server",
+)
+
+_MARKER = "<!-- pr-test-summary -->"
+
+
+def _headers(token):
+    return {
+        "Authorization": f"Bearer {token}",
+        "Accept": "application/vnd.github+json",
+        "X-GitHub-Api-Version": "2022-11-28",
+    }
+
+
+def _paginate(path, token):
+    """Yield all items from a paginated GitHub REST API GET endpoint."""
+    url = f"https://api.github.com{path}?per_page=100"
+    while url:
+        req = urllib.request.Request(url, headers=_headers(token))
+        with urllib.request.urlopen(req) as resp:
+            data = json.loads(resp.read())
+            # Jobs endpoint wraps items in {"jobs": [...]}; comments is a bare list.
+            yield from (data["jobs"] if isinstance(data, dict) else data)
+            link = resp.headers.get("Link", "")
+            url = next(
+                (
+                    p.split(";")[0].strip().strip("<>")
+                    for p in link.split(",")
+                    if 'rel="next"' in p
+                ),
+                None,
+            )
+
+
+def _api(path, token, method, payload):
+    req = urllib.request.Request(
+        f"https://api.github.com{path}",
+        data=json.dumps(payload).encode(),
+        method=method,
+        headers={**_headers(token), "Content-Type": "application/json"},
+    )
+    with urllib.request.urlopen(req) as resp:
+        return json.loads(resp.read())
+
+
+def _is_test_job(name):
+    return any(name == p or name.startswith(p + " (") for p in _TEST_PREFIXES)
+
+
+def _build_body(failed, passed, skipped):
+    lines = [_MARKER, "## CI Test Summary", ""]
+    if not failed:
+        lines.append(f"✅ All {len(passed)} test job(s) passed.")
+    else:
+        lines.append(
+            f"**{len(failed)} failed** · {len(passed)} passed · {len(skipped)} skipped"
+        )
+        lines += ["", "| Job | Logs |", "|-----|------|"]
+        for job in failed:
+            lines.append(
+                f"| ❌ `{job['name']}` | [View logs]({job['html_url']}) |"
+            )
+        lines += [
+            "",
+            "_Click a job link above to see which tests failed in that matrix combination._",
+        ]
+    return "\n".join(lines)
+
+
+def main():
+    token = os.environ["GH_TOKEN"]
+    repo = os.environ["GITHUB_REPOSITORY"]
+    run_id = os.environ["GITHUB_RUN_ID"]
+    ref = os.environ["GITHUB_REF"]  # refs/heads/pull-request/NNN
+
+    branch = ref.removeprefix("refs/heads/")
+    if not branch.startswith("pull-request/"):
+        print(f"Not a PR branch ({branch}), skipping.", file=sys.stderr)
+        return
+    pr_number = int(branch.removeprefix("pull-request/"))
+
+    jobs = list(_paginate(f"/repos/{repo}/actions/runs/{run_id}/jobs", token))
+    test_jobs = [j for j in jobs if _is_test_job(j["name"])]
+    if not test_jobs:
+        print("No test jobs found in this run, skipping.", file=sys.stderr)
+        return
+
+    failed = [j for j in test_jobs if j["conclusion"] == "failure"]
+    passed = [j for j in test_jobs if j["conclusion"] == "success"]
+    skipped = [j for j in test_jobs if j["conclusion"] == "skipped"]
+
+    body = _build_body(failed, passed, skipped)
+
+    comments = list(
+        _paginate(f"/repos/{repo}/issues/{pr_number}/comments", token)
+    )
+    existing = next(
+        (c for c in comments if c.get("body", "").startswith(_MARKER)), None
+    )
+
+    if existing:
+        _api(
+            f"/repos/{repo}/issues/comments/{existing['id']}",
+            token,
+            "PATCH",
+            {"body": body},
+        )
+        print(f"Updated comment {existing['id']} on PR #{pr_number}.")
+    else:
+        result = _api(
+            f"/repos/{repo}/issues/{pr_number}/comments",
+            token,
+            "POST",
+            {"body": body},
+        )
+        print(f"Posted comment {result['id']} on PR #{pr_number}.")
+
+
+if __name__ == "__main__":
+    main()