react

Summary Fixes #36460. React Compiler adds a runtime import for compiled functions. When a source file starts with a JSX pragma such as , inserting that runtime import at the very start of the program moves the pragma after a code statement in the generated output. Downstream JSX transforms such as Oxc, SWC, and TypeScript only honor these pragmas before code statements. This preserves leading JSX pragma comments by moving them onto the first generated compiler import before inserting it. Non-JSX leading comments are left on the original first statement, which avoids changing existing compiler fixture output for test-only config comments. How did you test this change?

Summary Fixes #36124. Fixes #36006. The Profiler commit tree can receive duplicate add operations for a fiber that is already present in the reconstructed tree. Instead of throwing while rendering Profiler charts, skip the duplicate add payload and continue applying later operations for that commit. How did you test this change? yarn test --build --project devtools packages/react-devtools-shared/src/__tests__/profilingCommitTreeBuilder-test.js --runInBand

React version: 19.2.6 Steps To Reproduce 1. Open the repro repository: https://github.com/andyzhan7/react-suspense-fallback-throttle 2. Open either reproduction file: 3. Wait until the and loaders have been preloaded. 4. Click or . Link to code example: https://github.com/andyzhan7/react-suspense-fallback-throttle The current behavior A route component loaded through can be delayed by about 300ms on its first render, even when the loader promise has already resolved before that render. The repro uses this minimal lazy route wrapper: The route loaders are preloaded on page load. They simulate network/chunk loading with a short , so by the time the user clicks or , the loader promise has already resolved. However, the first render of the lazy route still commits about 300ms later: Because the Suspense boundary has no fallback, this appears as a blank content area for about 300ms. The expected behavior If a loader promise has already resolved, React should render the loaded component as soon as that resolved promise is observed, instead of waiting for the 300ms fallback throttle window. In this case, after clicking or , the route content should commit immediately or near-immediately because the lazy loader promise was already resolved by preload.