fix(hydration): prevent lazy hydration for updated components #13511

edison1105 · 2025-06-22T02:16:46Z

Summary by CodeRabbit

Tests
- Added a new test to verify correct hydration behavior when an async component's props change after parent mount but before the component resolves.
Refactor
- Improved internal handling of async component hydration to better manage state updates and warnings during hydration.

coderabbitai · 2025-06-22T02:16:53Z

Walkthrough

The changes introduce a new SSR hydration test for async components and refactor the internal hydration logic in the async component wrapper. The test simulates updating an async component's props before it resolves, while the refactor ensures hydration is skipped if the component has already been patched, logging a warning in development mode.

Changes

File(s)	Change Summary
packages/runtime-core/tests/hydration.spec.ts	Added a test for updating async component props before resolution during SSR hydration.
packages/runtime-core/src/apiAsyncComponent.ts	Refactored internal hydration logic to check for patched state and skip hydration if already patched.

Sequence Diagram(s)

sequenceDiagram
    participant Server
    participant Client
    participant ParentComponent
    participant AsyncComponent

    Server->>Client: Render SSR HTML with async component placeholder
    Client->>ParentComponent: Mounts with toggle=true
    Note over AsyncComponent: Async component not yet resolved
    Client->>ParentComponent: Update toggle=false before async resolves
    AsyncComponent->>Client: Async resolves, hydration begins
    alt Component already patched
        AsyncComponent->>Client: Log warning, skip hydration
    else
        AsyncComponent->>Client: Perform hydration
    end
    Client->>DOM: Update to "Updated async component"

Assessment against linked issues

Objective	Addressed	Explanation
Prevent async components with lazy hydration from breaking when interacted with quickly after hydration (#13510)	✅
Ensure hydration skips if async component is already patched (#13510)	✅
Log warning when hydration is skipped due to patched state (#13510)	✅
Add test to verify correct hydration behavior for async components updated before resolution (#13510)	✅

Suggested labels

ready to merge

Poem

A patch for hydration, so sly and neat,
Async awaits, but bugs face defeat!
With warnings and checks, the flow is just right,
No broken UI in the morning light.
🐇✨
Now Vue’s async dance is a joyous sight!

📜 Recent review details

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📥 Commits

Reviewing files that changed from the base of the PR and between 5f8314c and 2a74d10.

📒 Files selected for processing (2)

packages/runtime-core/__tests__/hydration.spec.ts (1 hunks)
packages/runtime-core/src/apiAsyncComponent.ts (1 hunks)

⏰ Context from checks skipped due to timeout of 90000ms (3)

GitHub Check: Redirect rules
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GitHub Check: Pages changed

🔇 Additional comments (4)

packages/runtime-core/src/apiAsyncComponent.ts (3)

125-126: LGTM! Clean implementation of the patched tracking mechanism.

The use of the beforeUpdate (bu) lifecycle hook to track when the component has been patched is appropriate and ensures the flag is set at the right time in the component lifecycle.

127-137: Excellent implementation of the hydration skip logic.

The performHydrate function correctly:

Checks the patched flag before proceeding with hydration

Provides a clear warning message in development mode that includes the component name/file

Gracefully skips hydration when the component has been updated, preventing potential hydration mismatches

The warning message is informative and will help developers understand why lazy hydration was skipped.

138-147: Clean refactor of the hydration strategy logic.

The conditional assignment of doHydrate maintains the existing behavior while incorporating the new patched component check. When no hydrateStrategy is provided, it now correctly uses performHydrate instead of the raw hydration function.

packages/runtime-core/__tests__/hydration.spec.ts (1)

1163-1224: Excellent comprehensive test for the async component hydration fix.

This test case effectively validates the fix by:

Realistic scenario simulation: Creates an async component with props that change after parent mount but before resolution

Proper async handling: Uses promises and nextTick() to control timing accurately

Comprehensive assertions:

Verifies the warning about skipping lazy hydration is logged

Ensures no hydration mismatch warnings occur

Confirms the final DOM reflects the updated state

Good test structure: Clear setup, execution, and verification phases

The test directly addresses issue #13510 and provides strong regression protection for this edge case.

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github-actions · 2025-06-22T02:17:50Z

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	101 kB (+6 B)	38.3 kB (+5 B)	34.6 kB (+67 B)
vue.global.prod.js	159 kB (+6 B)	58.5 kB (+2 B)	52 kB (+20 B)

Usages

Name	Size	Gzip	Brotli
createApp (CAPI only)	46.5 kB	18.2 kB	16.7 kB
createApp	54.5 kB	21.2 kB	19.4 kB
createSSRApp	58.7 kB	22.9 kB	20.9 kB
defineCustomElement	59.4 kB	22.8 kB	20.8 kB
overall	68.5 kB	26.4 kB	24 kB

pkg-pr-new · 2025-06-22T02:18:03Z

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@vue/compiler-sfc

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@vue/compiler-ssr

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@vue/runtime-dom

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@vue/server-renderer

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@vue/compat

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commit: 2a74d10

edison1105 · 2025-06-23T05:19:59Z

/ecosystem-ci run

vue-bot · 2025-06-23T05:27:01Z

📝 Ran ecosystem CI: Open

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

edison1105 force-pushed the edison/fix/13510 branch from 890ac42 to dbdf1f1 Compare June 22, 2025 02:20

fix(hydration): prevent lazy hydration for updated components

028aaae

edison1105 force-pushed the edison/fix/13510 branch from dbdf1f1 to 028aaae Compare June 22, 2025 02:27

edison1105 added 🔨 p3-minor-bug Priority 3: this fixes a bug, but is an edge case that only affects very specific usage. scope:hydration labels Jun 22, 2025

test: add tests

2a74d10

edison1105 marked this pull request as ready for review June 23, 2025 05:16

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