fix(react/runtime): fix `runOnBackground()` failure in certain cases by Yradex · Pull Request #1878 · lynx-family/lynx-stack

Yradex · 2025-10-10T09:57:34Z

Fixes #1875.

Summary by CodeRabbit

Bug Fixes
- Fixed an issue where main-thread functions created during initial render could not call runOnBackground() after hydration, ensuring background tasks are correctly queued and executed.
Tests
- Expanded hydration and runOnBackground test coverage with clearer assertions and snapshots for first-screen vs. non-first-screen behavior.
Chores
- Added a changeset for a patch release, including a patch-level update to the @lynx-js/react dependency.

Checklist

Tests updated (or not required).
Documentation updated (or not required).
Changeset added, and when a BREAKING CHANGE occurs, it needs to be clearly marked (or not required).

changeset-bot · 2025-10-10T09:57:38Z

🦋 Changeset detected

Latest commit: d445fb1

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@lynx-js/react	Patch

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Click here if you're a maintainer who wants to add another changeset to this PR

coderabbitai · 2025-10-10T09:57:49Z

📝 Walkthrough

Walkthrough

Adds a changeset for a patch to @lynx-js/react and updates hydration logic to correctly handle main-thread functions created during initial render so they can call runOnBackground() post-hydration. Corresponding tests are expanded to assert hydration fields and delayed execution behavior.

Changes

Cohort / File(s)	Summary
Changeset `\.changeset/kind-rocks-spend.md`	Adds a patch-level changeset for `@lynx-js/react` documenting a fix for main-thread functions failing to call `runOnBackground()` after hydration.
Tests: runOnBackground hydration `packages/react/worklet-runtime/__test__/runOnBackground.test.js`	Refactors expectations and formatting; adds assertions for per-function hydration fields (`_isFirstScreen`, `_jsFnId`, `_execId`); snapshots and access patterns updated; logic behavior unchanged.
Runtime hydration logic `packages/react/worklet-runtime/src/hydrate.ts`	Formatting updates and a new branch in `hydrateDelayRunOnBackgroundTasks`: when no `_delayIndices`, update `firstScreenFnObj` with `_isFirstScreen=false`, set `execId`, and merge `fnObj`; call sites reformatted; no exported API changes.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related issues

[Bug]: runOnBackground() failure in certain cases #1875 — Implements the described fix for main-thread functions created during initial render to successfully call runOnBackground() after hydration.

Suggested labels

framework:React

Suggested reviewers

hzy
colinaaa
gaoachao

Poem

I thump my paws—hydration’s here,
Queues aligned, our threads run clear.
First-screen whispers, background hum,
Delay or not, the calls still come.
Patch-sized hop, but tidy tracks—
A bunny’s joy in well-queued stacks. 🐇✨

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 75.00% which is insufficient. The required threshold is 80.00%.	You can run `@coderabbitai generate docstrings` to improve docstring coverage.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title Check	✅ Passed	The title succinctly describes the main change—fixing runOnBackground() failures in the React runtime—and follows conventional commit style without unnecessary detail.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

✨ Finishing touches

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codecov · 2025-10-10T10:02:52Z

Codecov Report

✅ All modified and coverable lines are covered by tests.

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relativeci · 2025-10-10T10:13:49Z

React Example

#5833 Bundle Size — 237.56KiB (0%).

d445fb1(current) vs 7e06ca9 main#5831(baseline)

Bundle metrics no changes

	Current #5833	Baseline #5831
Initial JS	`0B`	`0B`
Initial CSS	`0B`	`0B`
Cache Invalidation	`0%`	`0%`
Chunks	`0`	`0`
Assets	`4`	`4`
Modules	`166`	`166`
Duplicate Modules	`68`	`68`
Duplicate Code	`46.82%`	`46.82%`
Packages	`2`	`2`
Duplicate Packages	`0`	`0`

Bundle size by type no changes

	Current #5833	Baseline #5831
IMG	`145.76KiB`	`145.76KiB`
Other	`91.8KiB`	`91.8KiB`

Bundle analysis report Branch Yradex:mts/fix-hydration Project dashboard

^{Generated by RelativeCI Documentation Report issue}

codspeed-hq · 2025-10-10T10:15:05Z

CodSpeed Performance Report

Merging #1878 will degrade performances by 6.13%

_{Comparing Yradex:mts/fix-hydration (d445fb1) with main (7e06ca9)}

Summary

❌ 1 regression
✅ 52 untouched
⏩ 3 skipped¹

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	`BASE`	`HEAD`	Change
❌	`transform 1000 view elements`	42.2 ms	45 ms	-6.13%

3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

relativeci · 2025-10-10T10:15:41Z

Web Explorer

#5829 Bundle Size — 364.3KiB (0%).

d445fb1(current) vs 7e06ca9 main#5827(baseline)

Bundle metrics

1 change

	Current #5829	Baseline #5827
Initial JS	`144.52KiB`	`144.52KiB`
Initial CSS	`32KiB`	`32KiB`
Cache Invalidation	`0%`	`0%`
Chunks	`8`	`8`
Assets	`8`	`8`
Modules	`220`(`+0.92%`)	`218`
Duplicate Modules	`16`	`16`
Duplicate Code	`3.23%`	`3.23%`
Packages	`4`	`4`
Duplicate Packages	`0`	`0`

Bundle size by type no changes

	Current #5829	Baseline #5827
JS	`238.5KiB`	`238.5KiB`
Other	`93.8KiB`	`93.8KiB`
CSS	`32KiB`	`32KiB`

Bundle analysis report Branch Yradex:mts/fix-hydration Project dashboard

^{Generated by RelativeCI Documentation Report issue}

This PR was opened by the [Changesets release](https://github.com/changesets/action) GitHub action. When you're ready to do a release, you can merge this and the packages will be published to npm automatically. If you're not ready to do a release yet, that's fine, whenever you add more changesets to main, this PR will be updated. # Releases ## @lynx-js/web-core@0.18.0 ### Minor Changes - fix: ([#1837](#1837)) 1. `LynxView.updateData()` cannot trigger `dataProcessor`. 2. **This is a break change:** The second parameter of `LynxView.updateData()` has been changed from `UpdateDataType` to `string`, which is the `processorName` (default is `default` which will use `defaultDataProcessor`). This change is to better align with Native. The current complete type is as follows: ```ts LynxView.updateData(data: Cloneable, processorName?: string | undefined, callback?: (() => void) | undefined): void ``` ### Patch Changes - Updated dependencies \[[`77397fd`](77397fd), [`7d90ed5`](7d90ed5)]: - @lynx-js/web-worker-runtime@0.18.0 - @lynx-js/web-constants@0.18.0 - @lynx-js/web-mainthread-apis@0.18.0 - @lynx-js/web-worker-rpc@0.18.0 ## @lynx-js/react@0.114.2 ### Patch Changes - fix: main thread functions created during the initial render cannot correctly call `runOnBackground()` after hydration ([#1878](#1878)) ## @lynx-js/rspeedy@0.11.6 ### Patch Changes - Should apply `dev.hmr` and `dev.liveReload` to Rsbuild config. ([#1882](#1882)) - Support CLI flag `--root` to specify the root of the project. ([#1836](#1836)) ## @lynx-js/react-rsbuild-plugin@0.11.2 ### Patch Changes - Fix using wrong version of `@lynx-js/react/refresh`. ([#1756](#1756)) - Updated dependencies \[]: - @lynx-js/react-alias-rsbuild-plugin@0.11.2 - @lynx-js/use-sync-external-store@1.5.0 - @lynx-js/react-refresh-webpack-plugin@0.3.4 - @lynx-js/react-webpack-plugin@0.7.1 ## @lynx-js/web-constants@0.18.0 ### Patch Changes - fix: ([#1837](#1837)) 1. `LynxView.updateData()` cannot trigger `dataProcessor`. 2. **This is a break change:** The second parameter of `LynxView.updateData()` has been changed from `UpdateDataType` to `string`, which is the `processorName` (default is `default` which will use `defaultDataProcessor`). This change is to better align with Native. The current complete type is as follows: ```ts LynxView.updateData(data: Cloneable, processorName?: string | undefined, callback?: (() => void) | undefined): void ``` - Updated dependencies \[]: - @lynx-js/web-worker-rpc@0.18.0 ## @lynx-js/web-elements@0.8.8 ### Patch Changes - fix: ([#1837](#1837)) 1. `LynxView.updateData()` cannot trigger `dataProcessor`. 2. **This is a break change:** The second parameter of `LynxView.updateData()` has been changed from `UpdateDataType` to `string`, which is the `processorName` (default is `default` which will use `defaultDataProcessor`). This change is to better align with Native. The current complete type is as follows: ```ts LynxView.updateData(data: Cloneable, processorName?: string | undefined, callback?: (() => void) | undefined): void ``` - Updated dependencies \[]: - @lynx-js/web-elements-template@0.8.8 ## @lynx-js/web-explorer@0.0.10 ### Patch Changes - chore: update `@lynx-js/lynx-core` to `0.1.3`, `@lynx-js/web-core` to `0.17.1`. ([#1839](#1839)) ## @lynx-js/web-mainthread-apis@0.18.0 ### Patch Changes - fix: ([#1837](#1837)) 1. `LynxView.updateData()` cannot trigger `dataProcessor`. 2. **This is a break change:** The second parameter of `LynxView.updateData()` has been changed from `UpdateDataType` to `string`, which is the `processorName` (default is `default` which will use `defaultDataProcessor`). This change is to better align with Native. The current complete type is as follows: ```ts LynxView.updateData(data: Cloneable, processorName?: string | undefined, callback?: (() => void) | undefined): void ``` - feat: mouse event output structures remain aligned ([#1820](#1820)) - Updated dependencies \[[`77397fd`](77397fd)]: - @lynx-js/web-constants@0.18.0 - @lynx-js/web-style-transformer@0.18.0 ## @lynx-js/web-worker-runtime@0.18.0 ### Patch Changes - fix: ([#1837](#1837)) 1. `LynxView.updateData()` cannot trigger `dataProcessor`. 2. **This is a break change:** The second parameter of `LynxView.updateData()` has been changed from `UpdateDataType` to `string`, which is the `processorName` (default is `default` which will use `defaultDataProcessor`). This change is to better align with Native. The current complete type is as follows: ```ts LynxView.updateData(data: Cloneable, processorName?: string | undefined, callback?: (() => void) | undefined): void ``` - Updated dependencies \[[`77397fd`](77397fd), [`7d90ed5`](7d90ed5)]: - @lynx-js/web-constants@0.18.0 - @lynx-js/web-mainthread-apis@0.18.0 - @lynx-js/web-worker-rpc@0.18.0 ## create-rspeedy@0.11.6 ## @lynx-js/react-alias-rsbuild-plugin@0.11.2 ## upgrade-rspeedy@0.11.6 ## @lynx-js/web-core-server@0.18.0 ## @lynx-js/web-elements-template@0.8.8 ## @lynx-js/web-rsbuild-server-middleware@0.18.0 ## @lynx-js/web-style-transformer@0.18.0 ## @lynx-js/web-worker-rpc@0.18.0 Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

fix(react/runtime): fix runOnBackground() failure in certain cases

d445fb1

Yradex requested a review from hzy as a code owner October 10, 2025 09:57

coderabbitai bot added the framework:React label Oct 10, 2025

hzy approved these changes Oct 10, 2025

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Yradex merged commit 2da147d into lynx-family:main Oct 10, 2025
51 of 52 checks passed

Yradex deleted the mts/fix-hydration branch October 10, 2025 11:32

github-actions bot mentioned this pull request Oct 10, 2025

chore: Release 2025-10-12 05:03:35 #1871

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coderabbitai bot mentioned this pull request Oct 13, 2025

fix(react/runtime): fix MainThreadRef modification failure in certain cases #1884

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fix(react/runtime): fix `runOnBackground()` failure in certain cases#1878

fix(react/runtime): fix `runOnBackground()` failure in certain cases#1878
Yradex merged 1 commit intolynx-family:mainfrom
Yradex:mts/fix-hydration

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React Example

#5833 Bundle Size — 237.56KiB (0%).

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CodSpeed Performance Report

Merging #1878 will degrade performances by 6.13%

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#5829 Bundle Size — 364.3KiB (0%).

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Yradex commented Oct 10, 2025 •

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