---
model: openai/gpt-5.6-sol
service: opencode
timestamp: 2026-08-12T15:00:27Z
git_ref: c2a6ccef
diff_cmd: git diff HEAD~1..HEAD
---

The user requested the third iterative refinement for Tractor PR 490: closing
one broadcast subscriber must not set another receiver owner's shared event
and create a runnable hot loop, then stop for a complete commit plan.

> `git diff HEAD~1..HEAD -- tractor/trionics/_broadcast.py`

Added receiver-local wait cancellation and source-read ownership scopes.
Closing a non-owner waiting behind another source reader cancels only that
receiver's private wait and maps it to `ClosedResourceError`; the shared event
remains untouched. Closing the active source owner cancels only its private
source-read scope, wakes peers after cleanup, and lets one peer take ownership.

Source outcomes are captured inside the owner scope and classified only after
checking close/cancel state. A cancellation-shielding source therefore cannot
publish a returned value, ordinary error, or EOC after its owner was closed.
The private scope's `cancel_called` bit is asserted to imply receiver closure;
outer task cancellation remains `trio.Cancelled` and is not translated into
`ClosedResourceError`. Owner-key comments document that only the receiver
identified by `recv_ready[0]` may cancel the shared source-read scope. The
same explicit-close invariant is enforced symmetrically for private peer-wait
scope cancellation.

> `git diff HEAD~1..HEAD -- tests/test_task_broadcasting.py`

Added deterministic bounded regressions for both close positions. The
non-owner test places two peers behind an active source read, closes one and
proves only that peer exits while the shared event stays unset. The owner test
closes a source owner whose receive shields cancellation and parameterizes a
returned value, `RuntimeError`, and `EndOfChannel`; each discarded outcome
hands the next source receive to the waiting root without terminal-state or
EOC publication.

Verification output:

```text
.................                                                        [100%]
17 passed in 5.84s
```

Python compilation and `git diff --check` passed. Iterative adversarial review
caught a waiting non-owner hang, cancellation-shielded source returns, and
shielded source exceptions. All were fixed. Final review found no actionable
issues.
