The frame-publication shield added in `88a23449` checks for
pending cancellation only after a successful write. If actor
teardown closes the stream first, `ClosedResourceError` escaped
as `TransportClosed` and could defeat the caller's cancel scope.
Check for pending cancellation on the transport-error path before
normalizing the close. Genuine stream errors retain their existing
translation when no cancellation is active.
The cancellation-first path can swap which nested debugger
intermediary renders as the immediate source vs. relay. Keep
assertions over both actor levels while accepting either valid role.
Prompt-IO: ai/prompt-io/opencode/20260820T143845Z_559fd0f1_prompt_io.md
(this patch was generated in some part by `opencode` using
`gpt-5.6-sol` (`openai`))
Gud Boi