fix: snapshot hook arrays at route registration to preserve order

[eL1fe]

Summary

Routes picked up hooks registered after them due to shared array references.

Problem

new Elysia()
  .get('/a', () => 'A')
  .onBeforeHandle(() => console.log('1'))
  .get('/b', () => 'B')              // should only have hook 1
  .onBeforeHandle(() => console.log('2'))
  .get('/c', () => 'C')              // should have hooks 1, 2

Request to /b triggered both hooks 1 and 2, but should only trigger 1.

Root cause

mergeHook has an early return when the local hook object is empty: return { ...a }. The spread operator copies array properties by reference, not value. So route.hooks.beforeHandle and this.event.beforeHandle pointed to the same array. Later onBeforeHandle calls pushed into that shared array, retroactively adding hooks to already-registered routes.

Changes

• src/utils.ts: the early return in mergeHook now copies array values to prevent shared references

Test plan

• /a has 0 hooks, /b has 1, /c has 2
• Full test suite passes (1525 pass, 0 fail)

Fixes #1826

Summary by CodeRabbit

• Bug Fixes
  • Improved object merging behavior to prevent shared array references from causing unintended side effects.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: c2266364-b164-4d16-8f44-ce6d36fec764

📥 Commits

Reviewing files that changed from the base of the PR and between 56310be and c4778db.

📒 Files selected for processing (1)

• src/utils.ts

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Walkthrough

The mergeHook function in src/utils.ts now properly clones array properties by spreading their contents instead of merely spreading the hook object itself, preventing shared array references that were causing incorrect hook execution order~ ♡

Changes

Cohort / File(s)	Summary
Hook Merging Logic src/utils.ts	Modified mergeHook to spread array properties individually when b contains no defined values, ensuring arrays are cloned rather than referenced, fixing hook trigger sequencing~ ♡

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related PRs

• fix: apply macros before merging hooks in group method #1624 — Also modifies mergeHook behavior and hook merging logic, directly related to this fix~

Poem

Array refs were sharing~ ♡ *What a mess you made, dummy ヽ(´ー)ノ* *Spread those properties right,* (´；ω；)
Hooks in proper order tonight~ ♡♡♡
How incompetent you've been... (´∀｀)♡

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The PR title accurately describes the main change: fixing hook array snapshots to preserve registration order, which directly addresses the core issue of shared array references causing incorrect hook trigger ordering.
Linked Issues check	✅ Passed	The code change resolves the linked issue #1826 by fixing the mergeHook function to snapshot array values instead of copying references, ensuring routes only receive hooks registered before them.
Out of Scope Changes check	✅ Passed	All modifications in src/utils.ts are directly related to fixing the hook array reference issue described in #1826; no out-of-scope changes detected.
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 unit tests (beta)

• Create PR with unit tests

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