fix(mosaic): resume machine actors after stop instead of resetting them by alexcarpenter · Pull Request #10477 · clerk/javascript

alexcarpenter · 2026-10-27T23:21:15Z

Description

Brings over the machine fix from #10341, without its React 19.2 Vitest project.

Machine actors now resume after stop() / start() instead of resetting to the initial state:

A start() after stop() resumes in the current state. Entry actions and invokes are not run again. The first start() is unchanged.
after timers are paused on stop and re-armed on start.
Invoke results and events that arrive while stopped are applied in arrival order on start.
An actor created with a snapshot keeps it across a restart. Before, StrictMode's stop/start sent useMachine(machine, { snapshot }) back to the initial state.
useMachine fires onDone once per actor. Before, a machine that starts in a final state called it twice under StrictMode.
useMachine subscribes with useSyncExternalStore before its start effect, so a flow shown again inside React 19.2 <Activity> renders the resumed snapshot. This one is not covered by a test here, since the repo runs React 18.3.

Also makes a few tests independent of how many times React renders or runs effects:

use-transition: the requestAnimationFrame mock keys callbacks by a stable id, so cancelling a frame from an earlier batch no longer leaves a hole in the queue.
use-layout-animation: asserts one live animator while mounted and every animator disposed once, instead of counting dispose calls.
useSelector render tests: assert no re-render after an unrelated change and a re-render after a related one, instead of exact render counts.

Checklist

pnpm test runs as expected.
pnpm build runs as expected.
(If applicable) JSDoc comments have been added or updated for any package exports
(If applicable) Documentation has been updated

Type of change

Ports the machine fix from #10341 without its React 19.2 test project, and makes a few tests independent of render and effect counts.

vercel · 2026-10-27T23:21:21Z

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated
clerk-js-sandbox	Ready	Preview	Oct 28, 2026 12:16am UTC
swingset	Ready	Preview	Oct 28, 2026 12:16am UTC

changeset-bot · 2026-10-27T23:21:25Z

🦋 Changeset detected

Latest commit: 2de79e4

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

This PR includes changesets to release 0 packages

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Not sure what this means? Click here to learn what changesets are.

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

coderabbitai · 2026-10-27T23:21:37Z

Important

Review skipped

Review was skipped as selected files did not have any reviewable changes.

Run configuration

Source mode: Auto
Repository: clerk/javascript
Branch: carp/mosaic-testing-improvements
File: .coderabbit.yaml
Commit: 2de79e4
Layers: Repository YAML (base), Organization UI (inherited)
Review profile: ASSERTIVE
Plan: Team
Run ID: c4c7b652-7f76-43c2-993e-79bba0f85cb3

Commits

Reviewing files that changed from the base of the PR and between 4699f37 and 2de79e4.

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

🔍 Trigger review

No actionable comments were generated in the recent review.

Recent review info

Run configuration

Source mode: Auto
Repository: clerk/javascript
Branch: carp/mosaic-testing-improvements
File: .coderabbit.yaml
Commit: 4699f37
Layers: Repository YAML (base), Organization UI (inherited)
Review profile: ASSERTIVE
Plan: Team
Run ID: 14d2db4f-8cdb-4d03-bf3c-2eb9882cc860

Commits

Reviewing files that changed from the base of the PR and between debfc72 and 4699f37.

Files selected for processing: 9

.changeset/mosaic-machine-resume.md
packages/mosaic/src/machine/__tests__/machine.test.ts
packages/mosaic/src/machine/__tests__/use-machine.test.tsx
packages/mosaic/src/machine/__tests__/wizard-migration.test.tsx
packages/mosaic/src/machine/create-actor.ts
packages/mosaic/src/machine/types.ts
packages/mosaic/src/machine/use-machine.ts
packages/mosaic/src/primitives/hooks/__tests__/use-layout-animation.test.tsx
packages/mosaic/src/primitives/hooks/__tests__/use-transition.test.ts

Linked repositories identified

CodeRabbit considers these linked repositories for cross-repo context during reviews:

clerk/clerk_go (manual)
clerk/dashboard (manual)
clerk/accounts (manual)
clerk/backoffice (manual)
clerk/clerk (manual)
clerk/clerk-docs (manual)
clerk/cloudflare-workers (manual)
clerk/clerk-android (auto-detected)
clerk/cli (auto-detected)
clerk/clerk-ios (auto-detected)

Included review availability: This review used your included allowance. Your plan provides up to 10 included reviews per hour; 0 remain after this review.

Walkthrough

Actors now resume their initialized state after stopping. They retain paused timer delays and apply queued events and invoke settlements on restart. useMachine subscribes to snapshots earlier and calls onDone at most once. Tests cover actor restart behavior, hook rendering and completion, and animation cleanup. A Changeset file with empty frontmatter was added.

Priority: Normal

Estimated code review effort: 3 (Moderate) | ~25 minutes

Suggested reviewers: ephem

Merge Risk: Minimal · previous review 4699f

No identified issue blocks merging after normal checks.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 16.67% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Documentation-only edits and deletions within surv…	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Title check		The title names the main change: machine actors now resume after stop() and start() instead of being reset to their initial state. It also follows the conventional commit prefix and scope. The title m…
Description check		The description states that the PR ports the machine fix from `#10341` without its React 19.2 Vitest project. It lists the behavior changes: resume after stop/start, paused and re-armed after timers, qu…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Title check

Explanation

The title names the main change: machine actors now resume after stop() and start() instead of being reset to their initial state. It also follows the conventional commit prefix and scope. The title matches the PR objectives and the create-actor.ts and types.ts changes.

Full details: Description check

Explanation

The description states that the PR ports the machine fix from #10341 without its React 19.2 Vitest project. It lists the behavior changes: resume after stop/start, paused and re-armed after timers, queued invoke results and events, snapshot retention, and a single onDone call in useMachine. It also covers the test changes in use-transition, use-layout-animation, and the useSelector render tests. Each of these matches the file summaries.

Full details: Docstring Coverage

Explanation

Docstring coverage is 16.67% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Documentation-only edits and deletions within surviving functions are included; unchanged diff context and fully deleted functions are excluded. Analyzed 12 functions across 8 files. (1 skipped: 1 unsupported.)

Resolution

Write docstrings for the functions missing them to satisfy the coverage threshold.

Finishing Touches: 💡 1

🛠️ Fix failing CI checks: 💡

Commit to this branch
Create a new PR

Autofix · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts

Warning

Linked repositories: Some configured repositories could not be included in this review. Cross-repository analysis may be incomplete. Please check linked-repository access and settings.

_{Comment @coderabbitai help to get the list of available commands.}

pkg-pr-new · 2026-10-27T23:25:40Z

Open in StackBlitz

@clerk/astro

npm i https://pkg.pr.new/@clerk/astro@10477

@clerk/backend

npm i https://pkg.pr.new/@clerk/backend@10477

@clerk/chrome-extension

npm i https://pkg.pr.new/@clerk/chrome-extension@10477

@clerk/clerk-js

npm i https://pkg.pr.new/@clerk/clerk-js@10477

@clerk/electron

npm i https://pkg.pr.new/@clerk/electron@10477

@clerk/electron-passkeys

npm i https://pkg.pr.new/@clerk/electron-passkeys@10477

@clerk/eslint-plugin

npm i https://pkg.pr.new/@clerk/eslint-plugin@10477

@clerk/expo

npm i https://pkg.pr.new/@clerk/expo@10477

@clerk/expo-biometrics

npm i https://pkg.pr.new/@clerk/expo-biometrics@10477

@clerk/expo-google-signin

npm i https://pkg.pr.new/@clerk/expo-google-signin@10477

@clerk/expo-native-components

npm i https://pkg.pr.new/@clerk/expo-native-components@10477

@clerk/expo-passkeys

npm i https://pkg.pr.new/@clerk/expo-passkeys@10477

@clerk/express

npm i https://pkg.pr.new/@clerk/express@10477

@clerk/fastify

npm i https://pkg.pr.new/@clerk/fastify@10477

@clerk/hono

npm i https://pkg.pr.new/@clerk/hono@10477

@clerk/localizations

npm i https://pkg.pr.new/@clerk/localizations@10477

@clerk/mosaic

npm i https://pkg.pr.new/@clerk/mosaic@10477

@clerk/nextjs

npm i https://pkg.pr.new/@clerk/nextjs@10477

@clerk/nuxt

npm i https://pkg.pr.new/@clerk/nuxt@10477

@clerk/react

npm i https://pkg.pr.new/@clerk/react@10477

@clerk/react-router

npm i https://pkg.pr.new/@clerk/react-router@10477

@clerk/shared

npm i https://pkg.pr.new/@clerk/shared@10477

@clerk/tanstack-react-start

npm i https://pkg.pr.new/@clerk/tanstack-react-start@10477

@clerk/testing

npm i https://pkg.pr.new/@clerk/testing@10477

@clerk/ui

npm i https://pkg.pr.new/@clerk/ui@10477

@clerk/upgrade

npm i https://pkg.pr.new/@clerk/upgrade@10477

@clerk/vue

npm i https://pkg.pr.new/@clerk/vue@10477

commit: 2de79e4

fix(mosaic): resume machine actors after stop instead of resetting them

4699f37

Ports the machine fix from #10341 without its React 19.2 test project, and makes a few tests independent of render and effect counts.

alexcarpenter mentioned this pull request Oct 27, 2026

fix(mosaic): resume machine actors after stop instead of resetting them #10341

Closed

4 of 9 tasks

github-actions Bot added the mosaic label Oct 27, 2026

vercel Bot deployed to Preview – clerk-js-sandbox October 27, 2026 23:21

View deployment

vercel Bot deployed to Preview – swingset October 27, 2026 23:25

View deployment

austincalvelage approved these changes Oct 27, 2026

View reviewed changes

Merge branch 'main' into carp/mosaic-testing-improvements

2de79e4

vercel Bot deployed to Preview – clerk-js-sandbox October 28, 2026 00:14

View deployment

vercel Bot deployed to Preview – swingset October 28, 2026 00:16

View deployment

alexcarpenter merged commit e785d99 into main Oct 28, 2026
90 of 92 checks passed

alexcarpenter deleted the carp/mosaic-testing-improvements branch October 28, 2026 00:34

Navigation Menu

Repository navigation

fix(mosaic): resume machine actors after stop instead of resetting them - #10477

fix(mosaic): resume machine actors after stop instead of resetting them#10477
alexcarpenter merged 2 commits into
mainfrom
carp/mosaic-testing-improvements

alexcarpenter commented Oct 27, 2026

Uh oh!

vercel Bot commented Oct 27, 2026 •

edited

Loading

Uh oh!

changeset-bot Bot commented Oct 27, 2026 •

edited

Loading

Uh oh!

coderabbitai Bot commented Oct 27, 2026 •

edited

Loading

Review skipped

Uh oh!

pkg-pr-new Bot commented Oct 27, 2026 •

edited

Loading

Uh oh!

Uh oh!

This branch was successfully deployed

Reviewers

Uh oh!

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

Conversation

alexcarpenter commented Oct 27, 2026

Description

Checklist

Type of change

Uh oh!

vercel Bot commented Oct 27, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

changeset-bot Bot commented Oct 27, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

🦋 Changeset detected

Uh oh!

coderabbitai Bot commented Oct 27, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Review skipped

Uh oh!

pkg-pr-new Bot commented Oct 27, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Uh oh!

This branch was successfully deployed

Reviewers

Uh oh!

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

vercel Bot commented Oct 27, 2026 •

edited

Loading

changeset-bot Bot commented Oct 27, 2026 •

edited

Loading

coderabbitai Bot commented Oct 27, 2026 •

edited

Loading

pkg-pr-new Bot commented Oct 27, 2026 •

edited

Loading