setThreadId

Rebind this transport to a different thread.

client.threads.stream(threadId, { transport }) calls this (when implemented) whenever the framework binds or re-binds the active thread — including the lazily-minted id from the first submit() on a threadId: null controller. Implementing it lets an adapter be constructed once (optionally with no threadId) and reused as the active thread becomes known, so the framework doesn't have to tear down and rebuild a custom transport when the thread id appears.

Optional: adapters that bake threadId at construction can omit it, in which case the per-call threadId is ignored (prior behaviour).