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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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Unix & Linux SE — Don't Nest tmux in a Remote SSH Shell (mirror)

Metadata

Field	Value
Institute	Molodetz Institute — Research & Retrieval Division
Subject	shell-multiplexer-auto-attach
Document type	Source Dossier
Tier	1
Source title	dont nest tmux in a remote ssh shell
Source URL	https://kompas.wasmer.app/https_unix_stackexchange_com/questions/420733/dont-nest-tmux-in-a-remote-ssh-shell
Source publisher / author	Unix & Linux Stack Exchange (mirrored)
Source type	forum thread
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	Medium
Status	Active

Summary

Describes the specific real-world failure mode of SSH + auto-attach: $TMUX is a local environment variable and is never forwarded across an SSH connection, so a naive "attach if $TMUX unset" guard, applied to .bashrc on both the local and remote machine (e.g. a shared dotfiles setup), still ends up nesting a remote tmux session inside the local one — because the remote shell's $TMUX genuinely is unset, even while the user is already inside a local tmux pane that SSH'd out.

Key findings

$TMUX is a local process-tree fact, not a session fact — it does not and cannot know about multiplexing happening on a different machine up the SSH chain.
The fix requires detecting the SSH hop itself (e.g. $SSH_CONNECTION) and treating "I am the target of an incoming SSH connection" differently from "I am a plain local shell," rather than relying on $TMUX to carry information it structurally cannot carry.

Pros / strengths

Precisely names a failure mode that would otherwise only be discovered by a real user hitting "sessions should be nested with care" warnings in production.

Cons / limitations / caveats

Describes the problem and its cause clearly; does not by itself prescribe one canonical fix (several exist, with tradeoffs, per the Codegenes and Coderwall dossiers in this subject).

Relevance to tai

Critical for the proposal's auto-attach design: the guard logic must account for multi-hop SSH explicitly (checking $SSH_CONNECTION/$SSH_TTY, not just $TMUX), or a user SSHing from inside one tai-managed session into another host will get nested sessions despite the basic guard being "correct" on each host individually.

Changelog

Date	Change
2026-10-09	Initial dossier created.

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