diff --git a/.github/workflows/pr.yaml b/.github/workflows/pr.yaml
index 8c05b5d1b0..7af98d9c9d 100644
--- a/.github/workflows/pr.yaml
+++ b/.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 }}
diff --git a/ci/utils/pr_test_summary.py b/ci/utils/pr_test_summary.py
new file mode 100644
index 0000000000..5e2775b4e2
--- /dev/null
+++ b/ci/utils/pr_test_summary.py
@@ -0,0 +1,236 @@
+# 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 and a collapsible list of individual failed test names.
+
+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 -->"
+_HTTP_TIMEOUT_SEC = 30
+# Maximum failed test names shown per job dropdown.
+_MAX_TESTS = 50
+
+# Ordered by specificity; first match wins.
+_CRASH_PATTERNS = [
+    ("Segmentation fault", "SIGSEGV (segfault)"),
+    ("SIGSEGV", "SIGSEGV (segfault)"),
+    ("signal 11", "SIGSEGV (signal 11)"),
+    ("Aborted (core dumped)", "SIGABRT"),
+    ("SIGABRT", "SIGABRT"),
+    ("signal 6", "SIGABRT (signal 6)"),
+    ("SIGKILL", "SIGKILL"),
+    ("signal 9", "SIGKILL (signal 9)"),
+    ("Out of memory", "OOM"),
+    ("oom-kill", "OOM"),
+    ("core dumped", "core dumped"),
+]
+
+
+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, timeout=_HTTP_TIMEOUT_SEC) 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 _analyze_job_log(job_id, repo, token):
+    """Return (failed_test_ids, crash_description_or_None) from a job's log."""
+    req = urllib.request.Request(
+        f"https://api.github.com/repos/{repo}/actions/jobs/{job_id}/logs",
+        headers=_headers(token),
+    )
+    try:
+        with urllib.request.urlopen(req, timeout=_HTTP_TIMEOUT_SEC) as resp:
+            # Stream the log, retaining only the last 512 KB so the pytest
+            # summary section at the end of the output is always captured.
+            chunks = []
+            total = 0
+            while chunk := resp.read(65536):
+                chunks.append(chunk)
+                total += len(chunk)
+                if total > 512 * 1024:
+                    chunks = chunks[-8:]
+                    total = sum(len(c) for c in chunks)
+    except (urllib.error.HTTPError, urllib.error.URLError):
+        return [], None
+
+    text = b"".join(chunks).decode("utf-8", errors="replace")
+
+    crash = next(
+        (desc for pattern, desc in _CRASH_PATTERNS if pattern in text), None
+    )
+
+    failed = []
+    in_summary = False
+    for raw in text.splitlines():
+        # Strip GHA timestamp prefix: "2024-01-15T10:30:45.1234567Z content"
+        parts = raw.split("Z ", 1)
+        line = parts[1] if len(parts) > 1 and len(parts[0]) < 35 else raw
+
+        if "short test summary info" in line:
+            in_summary = True
+        elif in_summary:
+            if line.startswith(("FAILED ", "ERROR ")):
+                test_id = line.split(" ", 1)[1].split(" - ")[0].strip()
+                if test_id:
+                    failed.append(test_id)
+            elif line.startswith("=") and failed:
+                break
+
+    return failed[:_MAX_TESTS], crash
+
+
+def _build_body(failed, passed, skipped, job_analysis):
+    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']}) |"
+            )
+
+        for job in failed:
+            tests, crash = job_analysis.get(job["id"], ([], None))
+            if not tests and not crash:
+                continue
+            if crash and not tests:
+                summary = f"💥 crashed ({crash})"
+                detail = "Process was terminated before pytest completed."
+            else:
+                n = len(tests)
+                noun = "test" if n == 1 else "tests"
+                summary = f"{n} failed {noun}" + (
+                    f" · 💥 {crash}" if crash else ""
+                )
+                detail = "\n".join(f"- `{t}`" for t in tests)
+            lines += [
+                "",
+                "<details>",
+                f"<summary><code>{job['name']}</code> — {summary}</summary>",
+                "",
+                detail,
+                "",
+                "</details>",
+            ]
+
+    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
+
+    passed = [j for j in test_jobs if j["conclusion"] == "success"]
+    skipped = [j for j in test_jobs if j["conclusion"] == "skipped"]
+    failed = [j for j in test_jobs if j not in passed and j not in skipped]
+
+    job_analysis = {
+        job["id"]: _analyze_job_log(job["id"], repo, token) for job in failed
+    }
+
+    body = _build_body(failed, passed, skipped, job_analysis)
+
+    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()
diff --git a/cpp/tests/routing/unit_tests/breaks.cu b/cpp/tests/routing/unit_tests/breaks.cu
index 0d8a578b6e..2ccb4f2a17 100644
--- a/cpp/tests/routing/unit_tests/breaks.cu
+++ b/cpp/tests/routing/unit_tests/breaks.cu
@@ -430,6 +430,12 @@ TEST(vehicle_breaks, non_uniform_breaks)
   check_route(data_model, h_routing_solution);
 }
 
+// Intentional failure to exercise the PR test summary comment feature.
+TEST(vehicle_breaks, ci_summary_demo_failure)
+{
+  EXPECT_TRUE(false) << "Intentional failure: remove after verifying PR summary comment.";
+}
+
 }  // namespace test
 }  // namespace routing
 }  // namespace cuopt
diff --git a/python/cuopt/cuopt/tests/test_ci_summary_demo.py b/python/cuopt/cuopt/tests/test_ci_summary_demo.py
new file mode 100644
index 0000000000..dd3d16303e
--- /dev/null
+++ b/python/cuopt/cuopt/tests/test_ci_summary_demo.py
@@ -0,0 +1,17 @@
+# SPDX-FileCopyrightText: Copyright (c) 2026, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+# Intentional failures to exercise the PR test summary comment feature.
+# Remove after verifying the summary comment shows correct output.
+
+
+def test_ci_summary_demo_failure():
+    assert False, (
+        "Intentional failure: remove after verifying PR summary comment."
+    )
+
+
+def test_ci_summary_demo_failure_2():
+    raise RuntimeError(
+        "Intentional error: remove after verifying PR summary comment."
+    )