---
model: openai/gpt-5.6-sol
service: opencode
timestamp: 2026-08-20T14:38:50Z
git_ref: 559fd0f1
diff_cmd: git diff HEAD~1..HEAD
---

Continue preparing PR #481 after pushing the macOS debugger skip fix.
Follow the replacement CI run and address any remaining PR-specific
failure.

> `git diff HEAD~1..HEAD -- tractor/ipc/_transport.py`

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

macOS UDS failed `test_reqresp_ontopof_streaming` when its two-second
`move_on_after()` scope cancelled during `stream.send('ping')`. Commit
`88a23449` shields framed `send_all()` and checks pending cancellation only
after a successful write. Concurrent transport teardown instead closed the
socket, causing `ClosedResourceError` to escape as `TransportClosed` before
the pending cancellation could be delivered.

Preserve structured cancellation precedence on the shielded send's
transport-error path, and add a deterministic regression that cancels the
sender before making the fake stream raise `ClosedResourceError`.