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T

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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sync: interactive launches strip the harness of its controlling terminal (start_new_session=True) · Issue #1 · anntnzrb/agents

Metadata

Field	Value
Institute	Molodetz Institute — Research & Retrieval Division
Subject	async-pty-process-testing
Document type	Source Dossier
Tier	1
Source title	sync: interactive launches strip the harness of its controlling terminal (start_new_session=True)
Source URL	https://github.com/anntnzrb/agents/issues/1
Source publisher / author	GitHub user anntnzrb
Source type	repository (issue)
Source date (published)	Unknown — not stated
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

A GitHub issue documenting a real, encountered bug: a test/automation harness launched an interactive child process with start_new_session=True, which left the harness without a controlling terminal and broke window-resize and Ctrl-C handling for the child. The issue includes a small probe script for diagnosing whether a child process actually has a controlling terminal.

Key findings

start_new_session=True makes the child a new session leader; if that child is then given a pty as stdin/stdout/stderr, whether the pty becomes its controlling terminal (in the POSIX job-control sense) is not automatic — the issue describes a concrete case where it did not, breaking SIGWINCH-based resize and tty-line-discipline Ctrl-C-as-SIGINT.
The reporter's diagnostic approach: a probe script that checks os.isatty(0), os.tcgetpgrp(0), and whether /dev/tty can be opened, to confirm a child process actually has a controlling terminal rather than just an open pty fd.

Pros / strengths

A real, lived-through failure report rather than theoretical speculation — exactly the kind of pitfall that's easy to get subtly wrong when combining start_new_session=True (needed for safe process-group-wide killpg cleanup) with pty-based spawning (needed for isatty()-correct interactive behavior).
The diagnostic probe script is a concrete, reusable technique for anyone needing to verify controlling-terminal status.

Cons / limitations / caveats

A single GitHub issue report, not a kernel/POSIX specification — the exact conditions under which a session leader's first terminal open becomes its controlling terminal can depend on how the fd was obtained (opened directly by the child vs. inherited already-open from the parent), and this issue doesn't fully disambiguate that for the inherited-fd case tai_test.py actually uses.
No resolution/fix is confirmed as verified in this research pass (the issue's eventual outcome was not reviewed).

Relevance to tai

Directly shaped tai_test.py's documented, accepted limitation: its pty mode does not explicitly call ioctl(TIOCSCTTY), so controlling-terminal/job-control semantics (SIGWINCH forwarding, Ctrl-C-as-SIGINT from the tty line discipline) are not guaranteed. This was judged acceptable because tai.py's own code only checks sys.stdin.isatty() (a property of the fd itself, unaffected by session/controlling-terminal status) and tai_test.py's tests only script line-based input/output, never relying on resize or terminal-generated signals.

Changelog

Date	Change
2026-10-09	Initial dossier created.

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