perf(cli): Propagate compile cache to child_process workers

[yamadashy]

The existing enableCompileCache() in bin/repomix.cjs only applied to the main process. Tinypool child_process workers (defaultAction) were spawned without compile cache because NODE_COMPILE_CACHE env var was not set.

This PR captures the cache directory from enableCompileCache()'s return value and sets it as NODE_COMPILE_CACHE env var, so child_process workers inherit it at startup — before any ESM static imports are resolved.

Note: worker_threads workers (fileProcess, securityCheck, calculateMetrics) already benefit from the main process's enableCompileCache() call since they share the same V8 isolate.

Checklist

• Run npm run test
• Run npm run lint

🤖 Generated with Claude Code

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[coderabbitai]

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between f0393f7 and e0971a1.

📒 Files selected for processing (1)

• bin/repomix.cjs

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📝 Walkthrough

Walkthrough

The change modifies bin/repomix.cjs to capture the return value from nodeModule.enableCompileCache() and conditionally sets process.env.NODE_COMPILE_CACHE to the cache directory when not already set, enabling environment variable inheritance by child processes at startup.

Changes

Cohort / File(s)	Summary
Compile Cache Configuration bin/repomix.cjs	Captures the return value from enableCompileCache() and conditionally assigns the cache directory to process.env.NODE_COMPILE_CACHE if not already set, propagating compile cache location to child processes.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related PRs

• perf(cli): Enable Node.js module compile cache for faster startup #1181 — Directly related; this PR builds upon that change by capturing the return value from the enableCompileCache() call added in that PR.
• perf(website-server): Enable Node.js compile cache for faster cold starts #1066 — Related through shared Node.js compile-cache workflow and NODE_COMPILE_CACHE environment variable usage across processes.

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: propagating compile cache to child_process workers, which is the primary objective of this performance optimization PR.
Description check	✅ Passed	The description covers the problem (child_process workers lack compile cache), the solution (set NODE_COMPILE_CACHE env var), and includes the required checklist with completed items.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch perf/propagate-compile-cache-to-workers

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[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request optimizes application performance by addressing an oversight in the Node.js compile cache implementation. Previously, only the main process benefited from the compile cache, leaving child_process workers to start without this optimization. The changes now correctly configure the environment to ensure these workers inherit the compile cache, leading to more efficient module loading and faster startup times across all worker types.

Highlights

• Compile Cache Propagation: Extended Node.js compile cache functionality to child_process workers by capturing the cache directory and propagating it via the NODE_COMPILE_CACHE environment variable.
• Performance Improvement: Ensured child_process workers, particularly those spawned by tinypool for defaultAction, now benefit from compile caching, which is critical for ESM static imports and improves startup performance.

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[claude]

Code Review

Overall: Approve - Clean, minimal, and well-reasoned change.

Summary

This PR correctly propagates the compile cache directory to child_process workers by setting NODE_COMPILE_CACHE env var from the enableCompileCache() return value. The change is small (+7/-1), focused, and well-documented.

What's Good

• Correct guard logic: The !process.env.NODE_COMPILE_CACHE check respects externally-set values, avoiding overwriting user configuration
• Defensive null checks: result && result.directory safely handles cases where enableCompileCache() returns without a directory (e.g., status: 'failed')
• Stays inside the existing try/catch: Any unexpected behavior from the return value is already caught
• Clear comments explaining why this matters (ESM static imports in child_process workers)
• Good commit message with context about worker_threads vs child_process distinction

Minor Observations

Details

1. Node.js version compatibility: enableCompileCache() was added in Node.js v22.1.0 and the return type {status, directory, message} is stable. Since this code already guards on nodeModule.enableCompileCache existence, the new .directory access is safe on older Node versions too.

2. result.status not checked: The code doesn't check result.status === 'enabled' before using result.directory. Per the Node.js docs, directory can be present even when status is 'already_enabled', which is actually fine — the directory is still valid in that case. No issue here.

3. No test coverage: This is a bootstrap file (bin/repomix.cjs) that runs before any test infrastructure loads, so it's inherently difficult to unit test. The existing approach of no tests for this file is reasonable. The behavior can be verified manually by checking process.env.NODE_COMPILE_CACHE in a child worker.

Premortem Analysis

Details

Scenario	Risk	Mitigation
enableCompileCache() returns undefined on some Node version	Low	Guarded by result && result.directory
NODE_COMPILE_CACHE dir doesn't exist when child reads it	Very Low	Node.js handles this gracefully — cache misses are not errors
User sets NODE_COMPILE_CACHE externally to a different dir	None	The !process.env.NODE_COMPILE_CACHE guard preserves user preference
NODE_DISABLE_COMPILE_CACHE is set	None	Outer if already skips the entire block

No significant risks identified. This is a safe, backwards-compatible performance improvement.

LGTM — ready to merge.

🤖 Generated with Claude Code

[gemini-code-assist]

Code Review

This pull request improves performance by propagating the Node.js compile cache to child_process workers. The implementation correctly captures the cache directory from enableCompileCache() and sets the NODE_COMPILE_CACHE environment variable, allowing child processes to inherit and utilize the cache. The code is robust, with checks to ensure it only runs when caching is available and not explicitly disabled, and it safely handles potential errors. The change is well-contained and effectively addresses the issue of child processes not using the compile cache.

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 2 additional findings.

[cloudflare-workers-and-pages]

Deploying repomix with    Cloudflare Pages

Latest commit:	e0971a1
Status:	✅  Deploy successful!
Preview URL:	https://529a2c82.repomix.pages.dev
Branch Preview URL:	https://perf-propagate-compile-cache.repomix.pages.dev

View logs

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (main@f0393f7). Learn more about missing BASE report.
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1255   +/-   ##
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  Coverage        ?   87.18%           
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  Files           ?      115           
  Lines           ?     4324           
  Branches        ?     1002           
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  Hits            ?     3770           
  Misses          ?      554           
  Partials        ?        0           

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[github-actions]

⚡ Performance Benchmark

Packing the repomix repository with node bin/repomix.cjs

Runner	PR	main	Diff
Ubuntu	2.52s (±0.01s)	2.54s (±0.03s)	-0.02s (-0.8%)
macOS	1.37s (±0.13s)	1.39s (±0.11s)	-0.02s (-1.5%)
Windows	3.05s (±0.04s)	3.02s (±0.04s)	+0.03s (+1.0%)

Details

• Warmup: 2 runs (discarded)
• Measurement: 10 runs (median)
• ±: IQR (Interquartile Range) — middle 50% of measurements spread
• Workflow run