fix(runtime-core): prevent currentInstance leak into sibling render during async setup re-entry

[cernymatej]

fix #14667

Summary by CodeRabbit

• Bug Fixes
  • Fixed instance context leakage in Suspense boundaries when rendering async sibling components, ensuring correct component identity during async setup and rendering.
• Tests
  • Added tests to verify async setup/render context preservation and correct DOM ordering under Suspense.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 960c095b-b4ec-4f7e-b87e-14055ec06c41

📥 Commits

Reviewing files that changed from the base of the PR and between bd4bb93 and 2f33bdd.

📒 Files selected for processing (2)

• packages/runtime-core/__tests__/apiSetupHelpers.spec.ts
• packages/runtime-core/src/components/Suspense.ts

🚧 Files skipped from review as they are similar to previous changes (1)

• packages/runtime-core/src/components/Suspense.ts

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📝 Walkthrough

Walkthrough

Clears a leaked component instance during Suspense async resolution by calling unsetCurrentInstance() before retrying a component render, and adds a test verifying no instance/context leakage across sibling async components in a Suspense boundary.

Changes

Cohort / File(s)	Summary
Suspense async resolution cleanup packages/runtime-core/src/components/Suspense.ts	Imported unsetCurrentInstance() and added a call in the async continuation path of registerDep before retrying the component render to avoid leaking the previous current instance.
Instance leakage regression test packages/runtime-core/__tests__/apiSetupHelpers.spec.ts	Added withAsyncContext test that mounts two async components under a Suspense boundary and asserts getCurrentInstance() does not leak between setup and slot render, and no false slot-warning occurs.

Sequence Diagram(s)

sequenceDiagram
  participant AsyncA as AsyncA (slow)
  participant Suspense as SuspenseBoundary
  participant Runtime as Runtime (currentInstance)
  participant AsyncB as AsyncB (fast)

  AsyncA->>Suspense: registerDep (starts async setup)
  AsyncB->>Suspense: registerDep (starts async setup)
  AsyncB->>Runtime: setCurrentInstance(AsyncB) / withAsyncContext
  AsyncB-->>Suspense: resolves quickly
  Suspense->>Runtime: retry render for AsyncB
  Runtime-->>AsyncB: render (slots invoked) 

  AsyncA-->>Runtime: setCurrentInstance(AsyncA) / withAsyncContext (still resolving)
  AsyncA-->>Suspense: resolves later
  Suspense->>Runtime: before retry for AsyncA calls unsetCurrentInstance() rgba(255,0,0,0.5)
  Runtime->>AsyncA: retry render for AsyncA (no lingering instance)
  Suspense->>AsyncB: ensures no leaked instance into AsyncB slot render

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Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Suggested labels

scope: suspense, :hammer: p3-minor-bug

Poem

🐰 I hopped between async blooms so bright,
Unsetting stray shadows in the night,
No more mixed-up instance song,
Each render hops where it belongs,
Hooray—order restored, what a delight!

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: preventing currentInstance leak during async setup re-entry in a Suspense boundary context.
Linked Issues check	✅ Passed	The code changes directly address the reported issue by inserting unsetCurrentInstance() to prevent instance leakage when retrying async component setup after resolution, matching the root cause hypothesis.
Out of Scope Changes check	✅ Passed	All changes are scoped to fixing the instance leak in Suspense.registerDep and include a focused test case; no unrelated modifications present.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[github-actions]

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	105 kB (+5 B)	39.8 kB (+4 B)	35.8 kB (+10 B)
vue.global.prod.js	164 kB (+5 B)	59.8 kB (+4 B)	53.2 kB (-46 B)

Usages

Name	Size	Gzip	Brotli
createApp (CAPI only)	48.3 kB	18.8 kB	17.2 kB
createApp	56.5 kB	21.8 kB	19.9 kB
createSSRApp	60.7 kB	23.6 kB	21.5 kB
defineCustomElement	62.6 kB	23.8 kB	21.7 kB
overall	71 kB (+5 B)	27.2 kB (+3 B)	24.7 kB (+4 B)

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commit: 2f33bdd

[edison1105]

/ecosystem-ci run

[vue-bot]

📝 Ran ecosystem CI: Open

suite	result	latest scheduled
nuxt	✅ success	✅ success
radix-vue	✅ success	✅ success
primevue	✅ success	✅ success
pinia	✅ success	✅ success
quasar	✅ success	✅ success
vue-simple-compiler	✅ success	✅ success
vue-macros	✅ success	✅ success
vue-i18n	✅ success	✅ success
vitepress	✅ success	✅ success
vant	✅ success	✅ success
language-tools	❌ failure	❌ failure
test-utils	✅ success	✅ success
vuetify	✅ success	✅ success
vite-plugin-vue	✅ success	✅ success
vueuse	✅ success	✅ success
router	✅ success	✅ success