Sample
startTransition executes its callback synchronously, returns undefined, and scopes the transition batch config exclusively to synchronous execution.
sha256:42584324b1a44d5a5ea2b27faf3c3895e201b0bc97e6791e7e97b81bd4439f5f
PUBLISHED
L3_CONTRACT_PASS
MIT-0
Execution evidence
Declared environment and signed verification runs are separated so you can see exactly what this sample proves.
Evidence basisSigned contract pass
Verification receipts1
Verification levelL3_CONTRACT_PASS
Declared environment
- Execution context
- node
- Operating system
- linux
- Architecture
- x64
- Runtime
- node
- Language
- node
- Package manager
- npm
Verification-run environments
- Execution context
- node 22
- Operating system
- linux alpine · musl
- Architecture
- x64
- Runtime
- node 22
- Language
- javascript
- Package manager
- npm
- Execution
- container · docker
CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · node-typescript@1 · 2026-08-17
Case
- Goal
- startTransition executes its callback synchronously, returns undefined, and scopes the transition batch config exclusively to synchronous execution. HOW
- Packages
-
react 18.3.1
- Environment
- node
- Created
- 2026-08-17T06:44:11Z
Commonly assumed
startTransition defers callback execution asynchronously or returns a Promise that keeps async continuations within the transition context.
The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.
Contract
- startTransition executes its callback synchronously on the calling thread, returns undefined rather than a Promise, and resets ReactCurrentBatchConfig.transition to null immediately before returning so asynchronous continuations run outside the transition context.
- startTransition returns undefined even when the callback returns a Promise or value
- ReactCurrentBatchConfig.transition is an active object during synchronous callback execution and is restored to null upon return
- asynchronous work scheduled inside startTransition executes after the transition context has already been reset to null
- synchronous errors thrown inside startTransition propagate immediately while reliably restoring the previous transition context
- nested startTransition calls maintain and restore the enclosing transition batch configuration
Files
- NOTES.md
- csx.json
- package-lock.json
- package.json
- test/contract.mjs
Download the source artifact (tar.gz)
Origin Seeder
csx-seed
Verification receipts
- node 22 · linux alpine/x64 · docker · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · node-typescript@1 · 2026-08-17 · ed25519:d91480838ac982c9