ci: add coverage gate to reject PRs below 90% coverage

[yordis]

Summary

Adds insightsengineering/coverage-action to enforce test coverage on PRs.

Changes

• Run cargo llvm-cov with Cobertura XML output
• Add coverage-action with 90% threshold
• Fail PRs when coverage drops below threshold or when overall coverage rate decreases vs main
• Publish coverage summary and diff as PR comments

Coverage

Current coverage ~92.5%, threshold set to 90%.

[cursor]

PR Summary

Low Risk
CI-only change that may increase PR failures due to stricter coverage enforcement, but does not affect runtime code paths.

Overview
Updates the Rust CI workflow to emit a Cobertura XML coverage report (cargo llvm-cov ... --cobertura --output-path coverage.xml) and adds insightsengineering/coverage-action@v3 to publish coverage results and fail PRs when coverage drops below 90% or regresses versus main (including new/uncovered-statement checks).

Adds coverage.xml to .gitignore so the generated report isn’t committed.

^{Written by Cursor Bugbot for commit 61095d3. This will update automatically on new commits. Configure here.}

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📥 Commits

Reviewing files that changed from the base of the PR and between 9d2addb and 61095d3.

📒 Files selected for processing (2)

• .github/workflows/ci-rust.yml
• .gitignore

Walkthrough

CI workflow enhanced with code coverage reporting and enforcement. The Rust CI pipeline now generates Cobertura-formatted coverage reports and enforces a 90% minimum coverage threshold with main branch comparison. Coverage artifact added to gitignore.

Changes

Cohort / File(s)	Summary
CI Coverage Integration .github/workflows/ci-rust.yml	Added cargo llvm-cov step with Cobertura output flag and new coverage-action step to enforce 90% minimum coverage threshold, publish reports, and fail on coverage reduction relative to main branch.
Build Artifacts .gitignore	Added coverage.xml to ignored files under Coverage section.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Poem

🐰 Coverage hops along so neat,
90 percent, can't accept defeat!
Cobertura reports in gleaming XML,
Bunny approves—regression? Null!
Branch by branch, we hopping guard,
Code quality standards? Not very hard! 🎯

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: adding a coverage gate that rejects PRs below 90% coverage, which is the primary purpose of the workflow modifications.
Description check	✅ Passed	The description is clearly related to the changeset, providing detailed explanation of coverage action setup, threshold enforcement, and reporting functionality that matches the actual modifications.
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
• Post copyable unit tests in a comment
• Commit unit tests in branch ci/coverage-gate

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[github-actions]

Code Coverage Summary

Details

Filename                                     Stmts    Miss  Cover    Missing
-----------------------------------------  -------  ------  -------  --------------------------------------------
crates/acp-nats/src/config.rs                  122       0  100.00%
crates/trogon-nats/src/messaging.rs            507      12  97.63%   14-16, 51-52, 135-140, 150-151, 203-205
crates/trogon-nats/src/connect.rs               96      16  83.33%   21-23, 36, 50, 69-152
crates/trogon-nats/src/auth.rs                 114       3  97.37%   49-51
crates/trogon-nats/src/client.rs                25      25  0.00%    47-86
crates/trogon-nats/src/mocks.rs                196      14  92.86%   137-144, 175-180
crates/acp-nats/src/agent/authenticate.rs      180       2  98.89%   106, 111
crates/acp-nats/src/agent/new_session.rs       207      24  88.41%   104-106, 118-146, 175, 180
crates/acp-nats/src/agent/initialize.rs        196       2  98.98%   113, 118
crates/acp-nats/src/agent/mod.rs                74       0  100.00%
crates/trogon-std/src/env/system.rs             17       0  100.00%
crates/trogon-std/src/env/in_memory.rs          76       3  96.05%   48-50
crates/acp-nats/src/telemetry/metrics.rs        32       7  78.12%   39-47
crates/trogon-std/src/time/mock.rs             123       0  100.00%
crates/trogon-std/src/time/system.rs            24       0  100.00%
crates/trogon-std/src/dirs/system.rs            98      11  88.78%   57, 65, 67, 75, 77, 85, 87, 96, 98, 109, 154
crates/trogon-std/src/dirs/fixed.rs             84       0  100.00%
crates/trogon-std/src/fs/mem.rs                220      10  95.45%   61-63, 77-79, 133-135, 158
crates/trogon-std/src/fs/system.rs              29      12  58.62%   17-19, 31-45
crates/acp-nats/src/nats/subjects.rs            12       3  75.00%   14-16
crates/acp-nats/src/nats/extensions.rs           3       3  0.00%    15-17
TOTAL                                         2435     147  93.96%

Results for commit: 61095d3

Minimum allowed coverage is 90%

♻️ This comment has been updated with latest results

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

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

Inline comments:
In @.github/workflows/ci-rust.yml:
- Around line 49-59: Add a permissions block to the workflow job that runs the
"Coverage report and gate" (uses: insightsengineering/coverage-action@v3) so the
GITHUB_TOKEN has the required scopes: grant pull-requests: write (for publish:
true) and contents: write (for diff-storage: _xml_coverage_reports); update the
job (e.g., check job) to include a top-level permissions mapping with those keys
so the action can post PR comments and write the coverage XML without "Resource
not accessible by integration" errors.

---

ℹ️ Review info

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 94326f7 and 9d2addb.

📒 Files selected for processing (2)

• .github/workflows/ci-rust.yml
• .gitignore

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.