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tai/research/shell-multiplexer-auto-attach/libtmux-pane-interaction.md
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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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Markdown

# Pane Interaction — libtmux docs
## Metadata
| Field | Value |
|---|---|
| Institute | Molodetz Institute — Research & Retrieval Division |
| Subject | shell-multiplexer-auto-attach |
| Document type | Source Dossier |
| Tier | 1 |
| Source title | Pane Interaction - libtmux 0.53.0 documentation |
| Source URL | https://libtmux.git-pull.com/topics/pane_interaction.html |
| Source publisher / author | libtmux project |
| Source type | vendor docs |
| 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
libtmux's own documentation for the send-keys/capture-pane automation pattern: spawn or attach a session, send keystrokes with `send_keys`, read the rendered screen back with `capture_pane` (optionally the full scrollback via `-S -`), and loop until the expected state appears.
## Key findings
- The canonical "drive and poll" loop: `send_keys()` then `capture_pane()`, waiting briefly for output to catch up before reading.
- A documented, easy-to-miss gotcha: a command is **not executed** unless `Enter` is sent as its own, separate key event — typing the text alone leaves it sitting unexecuted in the prompt.
- Output can lag behind the command that produced it, so libtmux's own examples add short sleeps before capturing.
## Pros / strengths
- Comes from a maintained Python wrapper library that has clearly hit these exact gotchas in practice — the Enter-must-be-separate warning in particular is the kind of thing that silently breaks automation until someone documents it.
## Cons / limitations / caveats
- The send+capture+sleep loop is inherently a polling approach with a race condition (how long is "briefly"?) — it's not real event-driven I/O the way control-mode notifications are.
## Relevance to tai
This is the baseline implementation for the proposal's "write/type at a position" and "read pane content" commands when NOT using control mode — and the Enter-as-separate-key gotcha must be built into the design from day one, not discovered via a bug report later.
## Changelog
| Date | Change |
|---|---|
| 2026-10-09 | Initial dossier created. |