🌈 improve(health): reduce cognitive complexity in health check handler

[UniquePixels]

Summary

• Extract respond(), handleLiveness(), and handleReadiness() helpers from the nested closure in createHealthCheckHandler
• Reduces cognitive complexity from 18 to within the Biome limit of 15
• No behavior changes — all existing tests pass without modification

Test plan

• bun biome check src/health-check.ts — zero findings
• bun test — 608 tests pass, 100% coverage on health-check.ts
• bun qa:tsc — passes clean

🤖 Generated with Claude Code

Summary by CodeRabbit

• Refactor
  • Improved health check service implementation through better code organization and streamlined internal operations. Enhanced overall code quality and maintainability with consolidated response handling and improved security header management. All health check endpoints continue to operate as expected with no visible changes to the public API or functionality.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro

Run ID: 6f088e60-7928-4e9e-af60-f0298d18d69b

📥 Commits

Reviewing files that changed from the base of the PR and between b4448fc and c0dcf99.

📒 Files selected for processing (1)

• src/health-check.ts

📜 Recent review details

🧰 Additional context used

📓 Path-based instructions (1)

**

⚙️ CodeRabbit configuration file

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• Runtime is Bun, not Node.js. Do not suggest node/npm/yarn patterns.
• Zod v4 is used. z.enum() handles native TS enums directly;
  z.nativeEnum() is deprecated. Do not flag z.enum(SomeEnum) as incorrect.
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• Biome enforces kebab-case filenames and organized imports.

Files:

• src/health-check.ts

🔇 Additional comments (4)

src/health-check.ts (4)

10-20: LGTM!

Clean helper that centralizes response construction with security headers. The conditional spread for extra headers is efficient.

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22-25: LGTM!

Simple and focused liveness probe handler.

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27-37: LGTM!

Correctly prioritizes shutdown state over client readiness, and the distinct response bodies ("Shutting Down" vs "Not Ready") aid operational debugging.

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50-69: LGTM!

The refactored handler is cleaner and maintains identical behavior. The new URL(req.url) parsing is safe since Bun.serve() guarantees absolute URLs in the fetch handler, and all response paths now consistently apply security headers via respond().

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📝 Walkthrough

Walkthrough

Refactors health check handler to introduce internal helper functions (respond, handleLiveness, handleReadiness) that centralize header and response construction logic. Updates pathname extraction to use URL parsing instead of direct property access, while maintaining existing public API and functionality.

Changes

Cohort / File(s)	Summary
Health Check Refactoring src/health-check.ts	Introduces internal helpers to centralize response construction with security headers; refactors pathname extraction using URL parsing; consolidates response creation for liveness (200), readiness (200/503), method-not-allowed (405), and not-found (404) handlers.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and specifically describes the main change: extracting helper functions to reduce cognitive complexity in the health check handler, which is the primary objective of the PR.
Description check	✅ Passed	The description provides a clear summary of changes, rationale (complexity reduction), test coverage, and verification results. It matches the template intent and includes substantive details beyond the template requirement.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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

✨ Finishing Touches

• 📝 Generate docstrings (stacked PR)
• 📝 Generate docstrings (commit on current branch)

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch fix/health-check-complexity

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud