feat(ci): publish build-matrix results as a sticky PR comment

.github/workflows/csharp-ci.yaml

@@ -483,6 +483,39 @@ jobs:
           status="$(.github-actions-helpers/scripts/aggregate_matrix_status.py ci-results)"
           echo "matrix-status=$status" >> "$GITHUB_OUTPUT"
 
+  matrix-comment:
+    name: matrix-comment (${{ inputs.artifact-prefix }})
+    needs: build-and-test
+    if: ${{ !cancelled() && inputs.build-matrix != '' && github.event_name == 'pull_request' && github.actor != 'dependabot[bot]' }}
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      contents: read
+      pull-requests: write
+    steps:
+      - name: Checkout CI helpers
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          repository: peacefulstudio/github-actions
+          ref: ${{ job.workflow_sha }}
+          path: .github-actions-helpers
+      - name: Render build-matrix table
+        env:
+          GH_TOKEN: ${{ github.token }}
+          SELF_JOB_NAME: matrix-comment (${{ inputs.artifact-prefix }})
+          MATRIX_TITLE: 'C# build matrix'
+        run: |
+          set -euo pipefail
+          gh api --paginate "repos/${GITHUB_REPOSITORY}/actions/runs/${GITHUB_RUN_ID}/jobs" \
+            | .github-actions-helpers/scripts/render_matrix_comment.py "$SELF_JOB_NAME" "$MATRIX_TITLE" \
+            > build-matrix-results.md
+      - name: Add build-matrix PR comment
+        uses: marocchino/sticky-pull-request-comment@0ea0beb66eb9baf113663a64ec522f60e49231c0 # v3.0.4
+        with:
+          recreate: true
+          header: ${{ inputs.artifact-prefix }}-build-matrix
+          path: build-matrix-results.md
+
   pack:
     name: pack
     if: ${{ inputs.pack }}

.github/workflows/scala-ci.yaml

@@ -412,3 +412,36 @@ jobs:
           set -euo pipefail
           status="$(.github-actions-helpers/scripts/aggregate_matrix_status.py ci-results)"
           echo "matrix-status=$status" >> "$GITHUB_OUTPUT"
+
+  matrix-comment:
+    name: matrix-comment (${{ inputs.artifact-prefix }})
+    needs: build-and-test
+    if: ${{ !cancelled() && inputs.build-matrix != '' && github.event_name == 'pull_request' && github.actor != 'dependabot[bot]' }}
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      contents: read
+      pull-requests: write
+    steps:
+      - name: Checkout CI helpers
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          repository: peacefulstudio/github-actions
+          ref: ${{ job.workflow_sha }}
+          path: .github-actions-helpers
+      - name: Render build-matrix table
+        env:
+          GH_TOKEN: ${{ github.token }}
+          SELF_JOB_NAME: matrix-comment (${{ inputs.artifact-prefix }})
+          MATRIX_TITLE: 'Scala build matrix'
+        run: |
+          set -euo pipefail
+          gh api --paginate "repos/${GITHUB_REPOSITORY}/actions/runs/${GITHUB_RUN_ID}/jobs" \
+            | .github-actions-helpers/scripts/render_matrix_comment.py "$SELF_JOB_NAME" "$MATRIX_TITLE" \
+            > build-matrix-results.md
+      - name: Add build-matrix PR comment
+        uses: marocchino/sticky-pull-request-comment@0ea0beb66eb9baf113663a64ec522f60e49231c0 # v3.0.4
+        with:
+          recreate: true
+          header: ${{ inputs.artifact-prefix }}-build-matrix
+          path: build-matrix-results.md

CHANGELOG.md

@@ -7,6 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Publish the `build-matrix` shard results of `csharp-ci.yaml` and `scala-ci.yaml` as a sticky PR comment (`shard | result | duration` table, each shard linking to its job). A new `matrix-comment` job (`needs: build-and-test`, `if: !cancelled()`) queries the run's per-shard job outcomes via `gh api .../actions/runs/<run-id>/jobs` — so the table renders even when a shard fails — and upserts it via `marocchino/sticky-pull-request-comment` under a `<artifact-prefix>-build-matrix` header, distinct from the coverage sticky comment. It no-ops when the caller passes no `build-matrix`, on non-`pull_request` events, and for dependabot. Coverage comments are unaffected. (#21)
 ### Fixed
 
 - Harden `scripts/write-badges.sh` (the `update-badges.yaml` helper) against silent failures. `git fetch origin "$badge_branch" || true` previously swallowed every failure — auth, network, or a genuinely absent branch alike — then fell through to the orphan-rebuild path; a real fetch failure is now aborted loud, and only the benign "branch does not exist yet" case (detected up front with `git ls-remote --exit-code`) rebuilds the orphan branch. Malformed input now fails the badge job instead of writing a bogus badge file: a non-array `coverage-data`/`matrix-data`, a coverage entry missing `slug`/`label`, or a matrix entry missing `lang`/`os`/`arch`/`passed` (which would have written `ci-null-null-null.json`) is rejected with a `::error::` annotation. Added `test/write-badges_test.sh` pinning the `coverage-<slug>.json` / `ci-<lang>-<os>-<arch>.json` filename contract, the null-percent skip, and the new fail-loud paths, wired into the `build-and-test` self-test job. Healthy consumers on the built-in `matrix-status` → `update-badges.yaml` flow see no change. (#24)
@@ -18,7 +21,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Fix the badge helper scripts silently coercing unrecognized status input into a plausible-but-wrong badge instead of erroring. `matrix_badge_json.py` treated anything outside its passing allowlist as failing, so a `cancelled` or typo'd status rendered a misleading red badge, and `aggregate_matrix_status.py` reported a malformed marker (missing status) as a failed shard. Both now reject input outside the known `success`/`failure` token sets and fail the badge job loud, with regression tests for the rejected cases. Workflows using the built-in `matrix-status` → `update-badges.yaml` flow only ever produce known tokens, so healthy consumers see no change. First outside contribution to this repo — thank you @maxi-maxima! (#30)
-
 - Fix `csharp-ci.yaml`'s `Merge per-project cobertura reports` step finding no coverage files for consumers that bump `Microsoft.Testing.Extensions.CodeCoverage` to 18.9.0 on .NET SDK 10.0.3xx. That combination makes solution-level `dotnet test` resolve the relative `--coverage-output` against the run-level `<working-directory>/TestResults/` instead of each project's `bin/Release/<tfm>/TestResults/`, so the default `tests-glob` matched nothing and failed the coverage shard. The default now carries a second glob (`TestResults/**/*.cobertura.xml`) — the merge step word-splits the input under `globstar nullglob`, so old-layout consumers see no change and callers passing an explicit `tests-glob` are unaffected. The README caller prerequisites document both layouts and lift the stale "do not bump `CodeCoverage` past 18.0.x" ceiling: with `xunit.v3.mtp-v2` shipped, 18.x lines through 18.9.x are supported, while the 19.x empty-output warning stays. First hit by `peacefulstudio/daml-codegen-csharp-internal`. (#32)
 
 ## [2.3.3] - 2026-07-09

scripts/render_matrix_comment.py

@@ -0,0 +1,131 @@
+#!/usr/bin/env python3
+# Copyright (c) 2026 Peaceful Studio OÜ
+# SPDX-License-Identifier: Apache-2.0
+"""Render a workflow run's build-matrix shard results as a markdown table.
+
+Reads the concatenated JSON pages emitted by
+``gh api --paginate repos/<repo>/actions/runs/<run-id>/jobs`` on stdin,
+anchors on the calling aggregator job's own display name to resolve the
+reusable-workflow name prefix, and prints a ``shard | result | duration``
+table covering the sibling ``build-and-test (<shard>)`` jobs of the same
+workflow invocation.
+"""
+import json
+import sys
+from datetime import datetime
+
+SHARD_JOB_MARKER = 'build-and-test ('
+TIMESTAMP_FORMAT = '%Y-%m-%dT%H:%M:%SZ'
+UNKNOWN_DURATION = '—'
+RESULT_LABELS = {
+    'success': '✅ success',
+    'failure': '❌ failure',
+    'cancelled': '🚫 cancelled',
+    'skipped': '⏭️ skipped',
+    'timed_out': '⏱️ timed out',
+    'neutral': '⚪ neutral',
+    'action_required': '⚠️ action required',
+    'stale': '⚠️ stale',
+}
+
+
+def parse_job_pages(text):
+    decoder = json.JSONDecoder()
+    jobs = []
+    index = 0
+    while index < len(text):
+        if text[index].isspace():
+            index += 1
+            continue
+        page, index = decoder.raw_decode(text, index)
+        jobs.extend(page['jobs'])
+    return jobs
+
+
+def workflow_prefix(jobs, self_job_name):
+    matches = [
+        job['name']
+        for job in jobs
+        if job['name'] == self_job_name or job['name'].endswith(f' / {self_job_name}')
+    ]
+    if not matches:
+        raise ValueError(f'no job named {self_job_name!r} found in this run')
+    if len(matches) > 1:
+        raise ValueError(
+            f'multiple jobs named {self_job_name!r} found in this run; '
+            'set a distinct artifact-prefix per workflow invocation'
+        )
+    return matches[0][: -len(self_job_name)]
+
+
+def shard_jobs(jobs, prefix):
+    marker = f'{prefix}{SHARD_JOB_MARKER}'
+    shards = []
+    for job in jobs:
+        name = job['name']
+        if not (name.startswith(marker) and name.endswith(')')):
+            continue
+        shards.append((name[len(marker):-1], job))
+    return sorted(shards, key=lambda shard: shard[0])
+
+
+def result_label(job):
+    conclusion = job['conclusion']
+    if conclusion not in RESULT_LABELS:
+        raise ValueError(f'unknown conclusion for job {job["name"]!r}: {conclusion!r}')
+    return RESULT_LABELS[conclusion]
+
+
+def format_duration(job):
+    started = job.get('started_at')
+    completed = job.get('completed_at')
+    if not started or not completed:
+        return UNKNOWN_DURATION
+    elapsed = (
+        datetime.strptime(completed, TIMESTAMP_FORMAT)
+        - datetime.strptime(started, TIMESTAMP_FORMAT)
+    )
+    seconds = int(elapsed.total_seconds())
+    if seconds < 0:
+        return UNKNOWN_DURATION
+    minutes, remainder = divmod(seconds, 60)
+    if minutes == 0:
+        return f'{remainder}s'
+    return f'{minutes}m {remainder:02d}s'
+
+
+def render(jobs, self_job_name, title):
+    prefix = workflow_prefix(jobs, self_job_name)
+    shards = shard_jobs(jobs, prefix)
+    if not shards:
+        raise ValueError(
+            f'no {SHARD_JOB_MARKER}<shard>) jobs found under prefix {prefix!r}'
+        )
+    lines = [
+        f'## {title}',
+        '',
+        '| shard | result | duration |',
+        '| --- | --- | --- |',
+    ]
+    for shard, job in shards:
+        lines.append(
+            f'| [{shard}]({job["html_url"]}) '
+            f'| {result_label(job)} '
+            f'| {format_duration(job)} |'
+        )
+    return '\n'.join(lines) + '\n'
+
+
+def main(argv):
+    if len(argv) != 3:
+        print(
+            'error: usage: render_matrix_comment.py <self-job-name> <title>',
+            file=sys.stderr,
+        )
+        return 2
+    print(render(parse_job_pages(sys.stdin.read()), argv[1], argv[2]), end='')
+    return 0
+
+
+if __name__ == '__main__':
+    sys.exit(main(sys.argv))

test/render_matrix_comment_test.py

@@ -0,0 +1,131 @@
+# Copyright (c) 2026 Peaceful Studio OÜ
+# SPDX-License-Identifier: Apache-2.0
+import json
+import os
+import sys
+import unittest
+
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..', 'scripts'))
+
+import render_matrix_comment
+
+SELF_JOB_NAME = 'matrix-comment (csharp)'
+TITLE = 'C# build matrix'
+
+
+def job(
+    name,
+    conclusion='success',
+    started='2026-07-10T12:00:00Z',
+    completed='2026-07-10T12:03:42Z',
+    url='https://github.test/run/1/job/1',
+):
+    return {
+        'name': name,
+        'conclusion': conclusion,
+        'started_at': started,
+        'completed_at': completed,
+        'html_url': url,
+    }
+
+
+def page(*jobs):
+    return json.dumps({'total_count': len(jobs), 'jobs': list(jobs)})
+
+
+class RenderMatrixCommentTest(unittest.TestCase):
+    def test_renders_shards_sorted_by_name_with_links_and_durations(self):
+        jobs = [
+            job('ci / build-and-test (windows-x64)', conclusion='failure', url='https://github.test/j/2'),
+            job('ci / build-and-test (linux-x64)', completed='2026-07-10T12:00:59Z', url='https://github.test/j/1'),
+            job(f'ci / {SELF_JOB_NAME}', conclusion=None),
+        ]
+        self.assertEqual(
+            render_matrix_comment.render(jobs, SELF_JOB_NAME, TITLE),
+            '## C# build matrix\n'
+            '\n'
+            '| shard | result | duration |\n'
+            '| --- | --- | --- |\n'
+            '| [linux-x64](https://github.test/j/1) | ✅ success | 59s |\n'
+            '| [windows-x64](https://github.test/j/2) | ❌ failure | 3m 42s |\n',
+        )
+
+    def test_excludes_sibling_workflow_shards_sharing_shard_names(self):
+        jobs = [
+            job('csharp / build-and-test (linux-x64)', url='https://github.test/j/csharp'),
+            job('scala / build-and-test (linux-x64)', conclusion='failure', url='https://github.test/j/scala'),
+            job(f'csharp / {SELF_JOB_NAME}', conclusion=None),
+            job('scala / matrix-comment (scala)', conclusion=None),
+        ]
+        rendered = render_matrix_comment.render(jobs, SELF_JOB_NAME, TITLE)
+        self.assertIn('https://github.test/j/csharp', rendered)
+        self.assertNotIn('https://github.test/j/scala', rendered)
+        self.assertNotIn('failure', rendered)
+
+    def test_parses_concatenated_paginated_pages(self):
+        text = page(job('ci / build-and-test (a)')) + '\n' + page(job('ci / build-and-test (b)'))
+        self.assertEqual(
+            [entry['name'] for entry in render_matrix_comment.parse_job_pages(text)],
+            ['ci / build-and-test (a)', 'ci / build-and-test (b)'],
+        )
+
+    def test_renders_cancelled_and_skipped_labels(self):
+        jobs = [
+            job('ci / build-and-test (a)', conclusion='cancelled'),
+            job('ci / build-and-test (b)', conclusion='skipped', started=None, completed=None),
+            job(f'ci / {SELF_JOB_NAME}', conclusion=None),
+        ]
+        rendered = render_matrix_comment.render(jobs, SELF_JOB_NAME, TITLE)
+        self.assertIn('| 🚫 cancelled |', rendered)
+        self.assertIn('| ⏭️ skipped | — |', rendered)
+
+    def test_missing_self_job_fails_loudly(self):
+        with self.assertRaises(ValueError):
+            render_matrix_comment.render(
+                [job('ci / build-and-test (a)')], SELF_JOB_NAME, TITLE
+            )
+
+    def test_duplicate_self_job_fails_loudly(self):
+        jobs = [
+            job(f'one / {SELF_JOB_NAME}', conclusion=None),
+            job(f'two / {SELF_JOB_NAME}', conclusion=None),
+        ]
+        with self.assertRaises(ValueError):
+            render_matrix_comment.render(jobs, SELF_JOB_NAME, TITLE)
+
+    def test_no_shard_jobs_fails_loudly(self):
+        with self.assertRaises(ValueError):
+            render_matrix_comment.render(
+                [job(f'ci / {SELF_JOB_NAME}', conclusion=None)], SELF_JOB_NAME, TITLE
+            )
+
+    def test_unknown_conclusion_fails_loudly(self):
+        jobs = [
+            job('ci / build-and-test (a)', conclusion='mystery'),
+            job(f'ci / {SELF_JOB_NAME}', conclusion=None),
+        ]
+        with self.assertRaises(ValueError):
+            render_matrix_comment.render(jobs, SELF_JOB_NAME, TITLE)
+
+    def test_in_progress_shard_conclusion_fails_loudly(self):
+        jobs = [
+            job('ci / build-and-test (a)', conclusion=None),
+            job(f'ci / {SELF_JOB_NAME}', conclusion=None),
+        ]
+        with self.assertRaises(ValueError):
+            render_matrix_comment.render(jobs, SELF_JOB_NAME, TITLE)
+
+    def test_negative_or_missing_duration_renders_unknown(self):
+        self.assertEqual(
+            render_matrix_comment.format_duration(
+                job('x', started='2026-07-10T12:05:00Z', completed='2026-07-10T12:00:00Z')
+            ),
+            '—',
+        )
+        self.assertEqual(
+            render_matrix_comment.format_duration(job('x', started=None)), '—'
+        )
+
+
+if __name__ == '__main__':
+    unittest.main()