---
model: openai/gpt-5.6-sol
service: opencode
timestamp: 2026-08-18T19:30:01Z
git_ref: bf06b4f8
diff_cmd: git diff HEAD~1..HEAD
---

Prospective review found that cancellation can interrupt
`MsgpackTransport.send()` after `send_all()` writes only part of its
length-prefixed msg. Sending a cancellation request afterward can
append another msg to the indeterminate stream and desynchronize the
peer decoder.

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

Close the stream under a cancellation shield when `send_all()` is
cancelled. Cover the behavior with a fake stream that checkpoints
inside the write and records forced closure.