ci(coverage): disable jacoco PR comments, relax overall delta threshold to 0.4%

[bladehan1]

What

Three targeted fixes to the coverage-gate CI job in pr-build.yml:

1. Add comment-type: summary to both jacoco-report steps — routes output to the workflow step summary instead of PR comments.
2. Relax MAX_DROP from -0.1% to -0.4%.

---

Why

Issue 1 — 403 errors on PR comment posting

The coverage-gate job declares only permissions: contents: read. The madrapps/jacoco-report action defaults to comment-type: pr_comment, which calls the GitHub PR comment API and requires pull-requests: write. Every CI run was producing a 403 error in the logs, though it did not block the gate because the action's own continue-on-error default is true.

Setting comment-type: summary makes the action write to $GITHUB_STEP_SUMMARY (a local file write, no API call), so the 403 disappears entirely without needing to grant broader token permissions.

Issue 2 — coverage-changed-files reports INSTRUCTION coverage, not LINE coverage

The value shown as Changed Files Coverage is bytecode instruction coverage, not source-line coverage. This is a fixed behavior of madrapps/jacoco-report@v1.7.2 — the action has no coverage-type parameter and internally reads only the INSTRUCTION counter from JaCoCo XML.

Why INSTRUCTION ≠ LINE and why it matters:

• JaCoCo XML records six counter types per source file: INSTRUCTION, BRANCH, LINE, COMPLEXITY, METHOD, CLASS.
• A single source line compiles to multiple bytecode instructions. For example, a null-check if (x != null) may emit 3–5 instructions; a fluent chain on one line may emit 10+.
• INSTRUCTION coverage is therefore sensitive to compiler expansion: generated code (constructors, getters/setters, toString, enum boilerplate) inflates the instruction count without adding meaningful semantic coverage.
• When a PR touches one method in a class that also has many generated accessors, the changed-file INSTRUCTION coverage can read significantly lower than the LINE coverage a reviewer would intuitively expect.
• Concretely: the 93.3% figure visible in recent CI runs is INSTRUCTION coverage of the diff files, not line coverage.

To switch to LINE coverage the action would need to be replaced with a custom script that reads the LINE counter (<counter type="LINE" covered="N" missed="M"/>) from each matching <sourcefile> node. The action itself does not expose this as a configuration option in any released version through v1.7.2.

Issue 3 — -0.1% delta threshold causes false failures

Normal variance in test execution timing, minor refactoring (renaming, extracting constants), or adding tests to previously uncovered edge-case paths can shift overall INSTRUCTION coverage by ±0.2%. A threshold of -0.1% triggered spurious gate failures in these scenarios. -0.4% still catches real coverage regressions while eliminating the noise.

Summary by CodeRabbit

• Chores
  • Updated format of coverage report comments in pull requests to display as summary-style comments.
  • Strengthened code coverage enforcement; pull requests will now fail if overall coverage drops more than 0.4%.

[coderabbitai]

📝 Walkthrough

Walkthrough

The GitHub Actions workflow modifies JaCoCo report aggregation to include summary-type comments and tightens code coverage enforcement by raising the maximum allowed coverage drop threshold from -0.1% to -0.4%.

Changes

Cohort / File(s)	Summary
Workflow Configuration .github/workflows/pr-build.yml	Added comment-type: summary to JaCoCo report aggregation steps; tightened coverage delta gate by changing MAX_DROP threshold from -0.1 to -0.4 and updated corresponding failure message.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Poem

🐰 With stricter gates and summary calls so bright,
The coverage threshold tightens—no more drops in sight!
From point-one to point-four, the standards now stand tall,
A rabbit's pledge for quality that covers all! ✨

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main changes: disabling JaCoCo PR comments and relaxing the coverage threshold to 0.4%, which align with the primary objectives documented in the PR.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/ci_coverage

---

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[coderabbitai]

🧹 Nitpick comments (2)

.github/workflows/pr-build.yml (2)

391-391: Keep the threshold message in sync with MAX_DROP.

The hardcoded 0.4% in the failure message will drift if MAX_DROP is tuned again. Consider interpolating the variable.

Proposed fix

-            echo "Coverage gate failed: overall coverage dropped more than 0.4%."
+            echo "Coverage gate failed: overall coverage dropped more than ${MAX_DROP#-}%."

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In @.github/workflows/pr-build.yml at line 391, The failure message currently
hardcodes "0.4%" which can go out of sync with the MAX_DROP setting; update the
echo that prints the coverage gate failure so it interpolates the MAX_DROP
variable (referencing MAX_DROP and the echo command) instead of a literal "0.4%"
so the message always reflects the configured threshold.

---

361-364: Minor: status string reads awkwardly with a negative threshold.

With MAX_DROP=-0.4, the summary renders as PASS (>= -0.4%) / FAIL (< -0.4%), which conflates the delta with the threshold. Consider phrasing in terms of the delta for clarity.

Proposed wording

-          OVERALL_STATUS="PASS (>= ${MAX_DROP}%)"
+          OVERALL_STATUS="PASS (delta ${DELTA}% >= ${MAX_DROP}%)"
           if [ "$DELTA_OK" -ne 1 ]; then
-            OVERALL_STATUS="FAIL (< ${MAX_DROP}%)"
+            OVERALL_STATUS="FAIL (delta ${DELTA}% < ${MAX_DROP}%)"
           fi

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In @.github/workflows/pr-build.yml around lines 361 - 364, The status message
uses the threshold variable MAX_DROP in a way that reads awkwardly when it's
negative; update the strings set to OVERALL_STATUS to phrase them in terms of
the observed delta instead of the threshold. Replace "PASS (>= ${MAX_DROP}%)"
and "FAIL (< ${MAX_DROP}%)" with clearer wording such as "PASS (delta >=
${MAX_DROP}%)" and "FAIL (delta < ${MAX_DROP}%)" (or "delta >=/ <" whatever
style you prefer), ensuring the branch that checks DELTA_OK continues to set
OVERALL_STATUS accordingly.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In @.github/workflows/pr-build.yml:
- Line 391: The failure message currently hardcodes "0.4%" which can go out of
sync with the MAX_DROP setting; update the echo that prints the coverage gate
failure so it interpolates the MAX_DROP variable (referencing MAX_DROP and the
echo command) instead of a literal "0.4%" so the message always reflects the
configured threshold.
- Around line 361-364: The status message uses the threshold variable MAX_DROP
in a way that reads awkwardly when it's negative; update the strings set to
OVERALL_STATUS to phrase them in terms of the observed delta instead of the
threshold. Replace "PASS (>= ${MAX_DROP}%)" and "FAIL (< ${MAX_DROP}%)" with
clearer wording such as "PASS (delta >= ${MAX_DROP}%)" and "FAIL (delta <
${MAX_DROP}%)" (or "delta >=/ <" whatever style you prefer), ensuring the branch
that checks DELTA_OK continues to set OVERALL_STATUS accordingly.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 3ff2d486-cf3d-476b-b392-960144f1732f

📥 Commits

Reviewing files that changed from the base of the PR and between 2de63bb and a4fffea.

📒 Files selected for processing (1)

• .github/workflows/pr-build.yml