---
model: openai/gpt-5.6-sol
service: opencode
timestamp: 2026-08-19T23:48:24Z
git_ref: 557065d8
diff_cmd: git diff HEAD~1..HEAD
---

Fix the macOS TCP regressions where cancellation during a framed send
closed the actor-wide channel and replaced primary stream errors with
secondary `TransportClosed` failures.

> `git diff HEAD~1..HEAD -- tractor/ipc/_transport.py tractor/_context.py tests/ipc/test_each_tpt.py tests/test_context_stream_semantics.py`

Shield complete frame publication, then deliver pending cancellation
immediately after leaving the shield. Preserve channel reuse instead of
closing the multiplexed socket from a context-local sender. Treat
`TransportClosed` while shipping `StreamOverrun` as failed delivery so
the secondary error can not crash the actor-wide RPC loop.

Add deterministic unit regressions for cancellation in the middle of a
frame and overrun reporting after transport closure.

Verification:

- transport/context unit regressions: `3 passed`
- exact TCP and UDS CI-node batches: `11 passed, 1 skipped`
- transport/context/clustering/RPC TCP: `88 passed`
- transport/context/clustering/RPC UDS: `86 passed, 2 skipped`
- full TCP suite: `478 passed, 9 skipped, 7 xfailed, 3 xpassed`
- full UDS rerun: `476 passed, 11 skipped, 8 xfailed, 2 xpassed`
