---
model: openai/gpt-5.6-sol
service: opencode
session: ses_3e4c90d3eafeqHEtRYSIHgHhpA
timestamp: 2026-08-18T19:30:01Z
git_ref: bf06b4f8
scope: code
substantive: true
raw_file: 20260818T193001Z_bf06b4f8_prompt_io.raw.md
---

## Prompt

Fix cancellation during an indeterminate transport write without
allowing a second RPC msg to corrupt the stream. Keep the transport
fix separate from the higher-level `to_actor` remediation and explain
the length-prefixed protocol rather than using unexplained "framed
send" terminology.

## Response summary

Close a msgpack transport stream when cancellation interrupts its
length-prefixed `send_all()` operation. The stream can no longer be
safely reused because Trio cannot report how many bytes were written.

## Files changed

- `tractor/ipc/_transport.py` - close an interrupted send stream.
- `tests/ipc/test_each_tpt.py` - cover cancellation during the write.

## Human edits

The human required this transport edge-case fix to land as its own
behavioral commit with a detailed message. During staged review, the
human also rejected the unexplained "framed send" wording and asked
for terminology tied directly to the actual transport operation.