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retoorandClaude Sonnet 5 9dbd1fe667 Add plexer subsystem, container test infra, and last-resort opencode box backend

- Plexer: always-active terminal multiplexing. NativePlexerController/
  TmuxPlexerController share one interface, chosen by which env var is
  already set (TAI_PLEXER_SOCKET vs TMUX_PANE); NativePlexerBackend is
  the pty.fork()-based wrapper (raw mode, SIGWINCH resize forwarding,
  a Unix-socket control protocol, continuous session logging, a
  Ctrl+A prefix key distinct from tmux's own Ctrl+B). Auto-wraps new
  interactive shells via a .bashrc hook mirroring the existing
  command-not-found install pattern, gated on $TMUX/$TAI_PLEXER_ACTIVE/
  a $HOME/.tai-no-plexer bypass. New plexer_send/read/type/status
  tools, env-gated on a detected controller.
- tests/container.py + docker-compose.yml + tests/docker/Dockerfile:
  a disposable podman/docker image for the tests that must never touch
  a real machine (installing the plexer hook into a real ~/.bashrc, a
  live tmux session). Required suite (test_seal.py, test_tai.py,
  tests/plexer.py, tests/bashrc.py) gates the result; tests/rag.py
  runs as best-effort since its real-LLM dependency can't be satisfied
  inside a disposable container with no nested engine.
- tests/bashrc.py: real end-to-end hook install + bash -i auto-wrap,
  anti-recursion, tmux-active skip, non-interactive skip, a live
  TmuxPlexerController test, and an install/uninstall round-trip.
- tests/plexer.py: NativePlexerBackend under a real pty, plus a
  dedicated robustness pass (file permissions, >64KB payload framing,
  a malformed control request, a genuine self-deadlock fix in the
  write-to-child path).
- tai_test.py: the shared async process-driving framework (pipe/pty
  transport, group-wide kill-and-reap, a StdinBridge for --interactive)
  both test files build on.
- ChatClient last-resort backend: when there's no local opencode CLI
  but the sandbox box is already running, install opencode into it
  (official Node tarball, not apt -- apt's nodejs/npm pull in
  webpack/babel/jest as transitive deps) and route through it instead
  of giving up. Only reachable after the first retry round already
  failed everything else; never creates the box itself. TmuxPlexerController.status()
  fixed to use `list-panes` instead of `display-message -p`, which
  silently fell back to the default pane instead of erroring against
  a dead target.
- Fix 4 pre-existing test_tai.py bugs surfaced by running it in a
  clean environment for the first time: two stale mock signatures
  (subprocess.run's stdout= kwarg, Chat.complete's deadline= kwarg),
  one $TMUX-dependent catalog assertion, one tty-dependent color
  assertion.
- research/: a sourced research archive (Source Dossier/Citation
  Card/Conclusion tiers) backing the above design decisions, with its
  own audit.py consistency checker.
- .gitignore: fix a blanket *.md rule that was about to silently drop
  the entire research/ archive from version control; add __pycache__/
  and the one-off debug transcript this session started from.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

2026-10-10 04:36:05 +02:00

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Subprocesses — Python 3 documentation (asyncio.subprocess)

Metadata

Field	Value
Institute	Molodetz Institute — Research & Retrieval Division
Subject	async-pty-process-testing
Document type	Source Dossier
Tier	1
Source title	Subprocesses — Python 3.14 documentation
Source URL	https://docs.python.org/3/library/asyncio-subprocess.html
Source publisher / author	Python Software Foundation
Source type	standard (official stdlib documentation)
Source date (published)	Unknown — not stated (continuously updated)
Date researched	2026-10-09
Researched by	tai (agent), model: Claude Sonnet 5, on behalf of retoor
Research method	web search synthesis
Confidence	High
Status	Active

Summary

The canonical stdlib reference for asyncio.subprocess, confirming the exact semantics of terminate()/kill(), how Process.stdout/Process.stderr expose StreamReader instances when PIPE is used, and the deadlock risk of reading those streams manually instead of via communicate().

Key findings

On POSIX, Process.terminate() sends SIGTERM to the child; Process.kill() sends SIGKILL. On Windows, terminate() calls the Win32 TerminateProcess API; there is no separate POSIX-signal distinction.
When stdout=PIPE or stderr=PIPE is passed, Process.stdout/Process.stderr are asyncio.StreamReader instances — the same abstraction tai_test.py wraps a pty master fd into via loop.connect_read_pipe, for a uniform interface across both transports.
The docs warn that reading those streams manually (rather than via communicate()) can deadlock, because the child can block on a full pipe buffer if its output isn't drained quickly enough while it's also waiting on something else.

Pros / strengths

Authoritative, primary-source documentation — the single most load-bearing source in this entire subject for API semantics.

Cons / limitations / caveats

Documents stdlib behavior as of whatever version was fetched; does not itself discuss process-group-wide termination (killpg) or the controlling-terminal/pty nuances this subject's other sources cover — those required separate sources.

Relevance to tai

The definitive basis for tai_test.py's choice of terminate() (SIGTERM) before escalating to kill() (SIGKILL) in ManagedProcess.terminate()'s escalation loop, and for exposing Process.stdout/Process.stderr as the pipe-mode reader rather than hand-rolling a reader over raw fds in that transport. The deadlock warning is why ManagedProcess.drain_until_eof() continuously reads in a loop until EOF rather than attempting a single large read.

Changelog

Date	Change
2026-10-09	Initial dossier created.

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