---
model: openai/gpt-5.6-sol
service: opencode
session: 76c5d31c-5a2f-4503-9b16-410ee7f4fab3
timestamp: 2026-08-19T23:48:24Z
git_ref: 557065d8
scope: code
substantive: true
raw_file: 20260819T234824Z_557065d8_prompt_io.raw.md
---

## Prompt

Investigate and fix PR #481's macOS TCP clustering and stream-overrun
failures without sacrificing IPC frame integrity or structured
concurrency.

## Response summary

Changed cancellation during `send_all()` from actor-wide stream closure
to shielded complete-frame publication followed by immediate pending
cancellation. Prevented failed overrun error shipment from promoting a
secondary transport closure over the context-local primary condition.

## Files changed

- `tractor/ipc/_transport.py` - complete in-flight frames before
  delivering sender cancellation.
- `tractor/_context.py` - absorb transport closure while reporting an
  overrun on an already-closing channel.
- `tests/ipc/test_each_tpt.py` - prove complete framing, cancellation
  delivery and channel reuse.
- `tests/test_context_stream_semantics.py` - prove overrun reporting
  tolerates a closed transport.

## Human edits

The human reported PR #481's red CI, asked for diagnosis and directed
the agent to proceed in the dedicated PR #481 worktree. During final
review, the human required preservation of the original far-end
cancellation rationale and fuller documentation of frame shielding,
shared-channel ownership and cancellation-delay tradeoffs. These were
human-directed agent edits; the human made no direct source-line edits.