Deats,
- notify optional backend observers after subscriber mutations
- gate replay advancement on real `Feed.pause()` state changes
- exercise `pikerd`, `datad`, `samplerd`, SHM and typed IPC
- prove repeatable transcripts, acknowledged faults and teardown
Prompt-IO: ai/prompt-io/opencode/20260903T192743Z_aadfd1cf_prompt_io.md
(this patch was generated in some part by `opencode` using `gpt-5.6-sol` (`openai`))