Injecting Into the SSR Stream
Rule 1
Nothing should be injected between two React synchronous writes.
- According to React's team, chunks should be injected "before React writes": https://github.com/reactwg/react-18/discussions/114#:~:text=Injecting%20Into%20the%20SSR%20Stream
- In practice, chunks indeed cannot be arbitrarily injected, as the app will eventually crash otherwise.
- It isn't clear what "before React writes" means. I interpret it like this: nothing should be injected between two React synchronous writes.
- So far, my interpreted rule seems to be working.
- It's also the interpretation of the Apollo GraphQL team: https://github.com/apollographql/apollo-client-nextjs/issues/325#issuecomment-2205375796
Rule 2
Nothing should be injected before the first React write.
- This doesn't seem to be documented by the React team.
- But, in practice, there seems to (always?) be a hydration mismatch if anything is injected before the first React write.
- Reproduction: https://github.com/vikejs/vike/commit/45e4ffea06335ddbcf2826b0113be7f925617daa
- Thus, we delay any write to the stream until React writes its first chunk.
Chunk promises
Being able to pass a chunk promise to injectToStream() is required for integrating Apollo GraphQL, see: