`MsgStream.subscribe()` and `LinkedTaskChannel.subscribe()` omitted
`BroadcastReceiver.raise_on_lag`, forcing downstream consumers to
mutate a private receiver attribute when overruns were acceptable.
Add `raise_on_lag` to both public wrappers. The first subscription
sets the irreversible root broadcaster's policy, while every child
selects its own strict or warn/drop/resume behavior independently.
Document both fan-out APIs. Cover policy forwarding plus real IPC
and infected-asyncio paths.
Prompt-IO: ai/prompt-io/opencode/20260812T213117Z_51185487_prompt_io.md
(this patch was generated in some part by `opencode` using `gpt-5.6-sol` (`openai`))
Gud Boi