fix(ssr): prevent watch() from firing after async setup await by edison1105 · Pull Request #14547 · vuejs/core

edison1105 · 2026-03-09T09:40:23Z

close #14546

Summary by CodeRabbit

Bug Fixes
- Improved server-side rendering async-state handling so SSR setup state is preserved and correctly restored across async boundaries and on errors.
Tests
- Added tests covering watcher behavior and state restoration in SSR scenarios to prevent incorrect watcher execution.

coderabbitai · 2026-03-09T09:40:45Z

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Review failed

The pull request is closed.

ℹ️ Recent review info

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Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: d81c200e-a55d-4704-85a3-e420a0a913ee

📥 Commits

Reviewing files that changed from the base of the PR and between 6b53d0e and 4fbd0d5.

📒 Files selected for processing (1)

packages/server-renderer/__tests__/ssrWatch.spec.ts

📝 Walkthrough

Walkthrough

Update preserves and restores SSR-specific setup state across async boundaries in withAsyncContext, exports the SSR setup state setter, and adds a test ensuring watchers registered after async restore are not run during SSR.

Changes

Cohort / File(s)	Summary
Async context SSR handling `packages/runtime-core/src/apiSetupHelpers.ts`	withAsyncContext now captures `isInSSRComponentSetup`, disables it while awaiting, and exposes a `restore()` that re-applies the original current instance and SSR state; `restore()` is invoked on errors, continuations, and cleanup to maintain SSR setup state across async boundaries.
SSR state setter export `packages/runtime-core/src/component.ts`	Made `setInSSRSetupState` a public export so apiSetupHelpers can toggle SSR setup state.
SSR watcher test `packages/server-renderer/__tests__/ssrWatch.spec.ts`	Added test "should not run non-immediate watchers registered after async context restore" and imported `withAsyncContext` to validate watchers registered after async restore do not fire during SSR.

Sequence Diagram(s)

sequenceDiagram
    participant ComponentSetup as "Component.setup()"
    participant withAsync as "withAsyncContext"
    participant SSRFlag as "isInSSRComponentSetup"
    participant Watcher as "watch() / reactivity"
    participant Renderer as "SSR renderer"

    ComponentSetup->>withAsync: enter async block
    withAsync->>SSRFlag: record & set false (disable SSR setup)
    withAsync->>ComponentSetup: await async work
    withAsync-->>ComponentSetup: restore() (re-apply instance & SSRFlag rgba(0,128,0,0.5))
    ComponentSetup->>Watcher: register watcher (post-restore)
    Renderer->>Watcher: evaluate during SSR (skipped because SSRFlag restored correctly)

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

fix(runtime-core): prevent instance leak in withAsyncContext #14445: Modifies withAsyncContext instance restoration logic; closely related to async context and instance-restore changes here.

Suggested labels

ready to merge, scope: reactivity, :hammer: p3-minor-bug

Poem

🐰 I hopped through async twilight, kept the SSR light,

I saved the flag, then set it right.
No watcher wakes from a false alarm,
Restore the thread, preserve the charm —
Hooray, quiet SSR through the night!

🚥 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 title accurately describes the main change: preventing watchers from firing after async setup await in SSR contexts.
Linked Issues check	✅ Passed	The PR successfully addresses the linked issue `#14546` by preserving isInSSRComponentSetup state across async boundaries in withAsyncContext.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to fixing the SSR watcher issue: exposing setInSSRSetupState, modifying withAsyncContext to preserve SSR state, and adding test coverage.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings (stacked PR)
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🧪 Generate unit tests (beta)

Create PR with unit tests
Post copyable unit tests in a comment
Commit unit tests in branch edison/fix/watchAfterAsync

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github-actions · 2026-03-09T09:41:19Z

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	105 kB (+42 B)	39.7 kB (+17 B)	35.7 kB (+43 B)
vue.global.prod.js	163 kB (+42 B)	59.7 kB (+16 B)	53.1 kB (-19 B)

Usages

Name	Size	Gzip	Brotli
createApp (CAPI only)	48.2 kB	18.7 kB	17.2 kB
createApp	56.3 kB	21.8 kB	19.9 kB
createSSRApp	60.6 kB	23.5 kB	21.5 kB
defineCustomElement	62.5 kB	23.7 kB	21.6 kB
overall	70.7 kB	27.1 kB	24.7 kB

pkg-pr-new · 2026-03-09T09:41:22Z

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commit: 4fbd0d5

edison1105 · 2026-03-09T09:44:36Z

/ecosystem-ci run

coderabbitai

🧹 Nitpick comments (1)

packages/server-renderer/__tests__/ssrWatch.spec.ts (1)
124-160: Add the rejected-await path too.

This spec covers the resolved restore flow, but packages/runtime-core/src/apiSetupHelpers.ts also changed the rejection branch at Lines 543-549. A matching SSR test with a rejected awaitable inside try/catch would pin down the new restore() behavior there as well.
🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed.

In `@packages/server-renderer/__tests__/ssrWatch.spec.ts` around lines 124 - 160,
Add a parallel test that exercises the rejected-await path: inside the async
setup of the App (the same structure using withAsyncContext -> [__temp,
__restore] and calling __restore()), await a Promise that rejects inside a
try/catch so the restoration branch that handles rejections in
withAsyncContext/restore() is exercised; register the same before-await and
after-await watchers around the await/restore sequence, mutate text.value,
assert ctx.__watcherHandles remains undefined, assert HTML output and that
neither beforeAwaitTriggered nor afterAwaitTriggered fire after nextTick, and
ensure the test name reflects the "rejected" case to mirror the existing
resolved test.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@packages/server-renderer/__tests__/ssrWatch.spec.ts`:
- Around line 124-160: Add a parallel test that exercises the rejected-await
path: inside the async setup of the App (the same structure using
withAsyncContext -> [__temp, __restore] and calling __restore()), await a
Promise that rejects inside a try/catch so the restoration branch that handles
rejections in withAsyncContext/restore() is exercised; register the same
before-await and after-await watchers around the await/restore sequence, mutate
text.value, assert ctx.__watcherHandles remains undefined, assert HTML output
and that neither beforeAwaitTriggered nor afterAwaitTriggered fire after
nextTick, and ensure the test name reflects the "rejected" case to mirror the
existing resolved test.

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 6b0b23eb-309f-4e51-9d38-28212021541c

📥 Commits

Reviewing files that changed from the base of the PR and between 9438cc5 and 6b53d0e.

📒 Files selected for processing (3)

packages/runtime-core/src/apiSetupHelpers.ts
packages/runtime-core/src/component.ts
packages/server-renderer/__tests__/ssrWatch.spec.ts

vue-bot · 2026-03-09T09:50:05Z

📝 Ran ecosystem CI: Open

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

fix(ssr): prevent watch() from firing after async setup await

6b53d0e

coderabbitai bot reviewed Mar 9, 2026

View reviewed changes

test: add more test

4fbd0d5

edison1105 added ready to merge The PR is ready to be merged. scope: ssr 🔨 p3-minor-bug Priority 3: this fixes a bug, but is an edge case that only affects very specific usage. labels Mar 9, 2026

edison1105 merged commit 6cda71d into main Mar 9, 2026
14 of 16 checks passed

edison1105 deleted the edison/fix/watchAfterAsync branch March 9, 2026 09:58

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fix(ssr): prevent watch() from firing after async setup await#14547

fix(ssr): prevent watch() from firing after async setup await#14547
edison1105 merged 2 commits intomainfrom
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