fix: cache rou3 compilation by options hash

[danielroe]

🔗 Linked issue

❓ Type of change

• 🐞 Bug fix (a non-breaking change that fixes an issue)

📚 Description

noticed that if we call nitro.routing.routeRules.compileToString with different options from the ones nitro passes to it, the wrong output can be cached.

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

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Project	Deployment	Review	Updated (UTC)
nitro.build	Ready	Preview, Comment	Dec 19, 2025 10:06am

[coderabbitai]

📝 Walkthrough

Walkthrough

The _compiled property in the Router class is refactored from storing a single cached compiled string to storing a map of strings keyed by options. The compileToString method now implements per-options caching, generating option keys and retrieving/storing compiled results per key.

Changes

Cohort / File(s)	Summary
Router caching refactor src/routing.ts	Changed _compiled property from string to Record<string, string> to support per-options caching. Updated compileToString method to compute option keys, initialize the map, check cache by key, and store/retrieve compiled strings per key instead of maintaining a single cached value.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

• Per-options key generation: Verify that the key computation from options is deterministic and correctly differentiates distinct option combinations
• Cache initialization and lookup logic: Confirm the map is properly initialized on first call and subsequent cache hits/misses work as intended
• Wildcard route optimization: Ensure the per-key cache storage for single wildcard routes maintains correct behavior and doesn't introduce edge cases
• Type compatibility: Review all call sites to ensure they correctly handle the new Record<string, string> type for _compiled

Pre-merge checks and finishing touches

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title follows conventional commits format with 'fix:' prefix and clearly describes the main change (caching by options hash).
Description check	✅ Passed	The description is related to the changeset, explaining the bug being fixed (caching issue with different options).
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch fix/cached-compile

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📜 Recent review details

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 3992c73 and 68deb13.

📒 Files selected for processing (1)

• src/routing.ts (3 hunks)

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (3)

• GitHub Check: tests-rollup (ubuntu-latest)
• GitHub Check: tests-rollup (windows-latest)
• GitHub Check: tests-rolldown (windows-latest)

🔇 Additional comments (3)

src/routing.ts (3)

147-147: LGTM! Type change enables per-options caching.

The change from string to Record<string, string> correctly supports storing multiple cached compilations keyed by options.

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203-204: LGTM! Wildcard optimization correctly updated.

The single wildcard route optimization now stores its result in the per-key cache, consistent with the new caching strategy.

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184-189: Cache implementation is sound. The per-options caching logic is correctly implemented:

• Deterministic key generation using hash(opts) from ohash, which handles the RouterCompilerOptions type correctly
• Proper lazy initialization and cache lookup with ||= pattern
• Cache invalidation on route updates (sets _compiled to undefined, which triggers reinitialization on next call)
• No external code accesses the private _compiled property

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