---
model: gpt-5.6-sol
service: opencode
session: trio-bindspace-fd-transport
timestamp: 2026-08-28T17:29:43Z
git_ref: 2ca8c570
scope: code
substantive: true
raw_file: 20260828T172943Z_2ca8c570_prompt_io.raw.md
---

## Prompt

After committing generic pre-handshake child-death detection, the human
approved the proposed next Layer C slice: transport a live bindspace
capability through the Trio spawn backend.

## Response summary

Plumb an optional process-local `Bindspace` through actor spawn APIs.
Give a Trio exec child its own inherited namespace descriptor, preserve
existing caller `pass_fds`, transport the FD/inode pair through the CLI,
and close the temporary parent descriptor on every open-process outcome.
Reject unsupported multiprocessing transport explicitly. Exercise the
complete Trio path with a real actor that enters a distinct network
namespace and reports its namespace and inherited-FD inodes over RPC.

## Files changed

- `tractor/runtime/_supervise.py` - accept and relay a child bindspace.
- `tractor/to_actor/_api.py` - expose bindspace spawn configuration.
- `tractor/spawn/_spawn.py` - relay the bindspace to spawn backends.
- `tractor/spawn/_trio.py` - duplicate, transfer, and close the FD.
- `tractor/spawn/_mp.py` - reject unsupported MP transport.
- `tractor/_child.py` - parse and forward the atomic CLI capability.
- `tests/test_netns_spawn.py` - cover transport and cleanup schedules.

## Human edits

The human approved the Trio-first transport boundary after reviewing
the proposed dependency order, then supplied staged-diff comments across
multiple review passes. Human-directed revisions replaced abstract
ownership wording with concrete FD and process terminology, clarified
descriptor cleanup, preserved existing `pass_fds` explicitly, and
replaced the mocked success-path test with a real child actor, real
`setns()`, handshake, and RPC round trip inside unprivileged user/network
namespaces. Follow-up review added direct parent FD-table verification
that the temporary child-bound duplicate is closed after successful
spawn.

Multiprocessing FD reduction and root-process namespace entry remain
separate follow-up slices. No direct manual source edits were observed;
the review-driven source revisions were applied by the agent.