Files
tai/research/shell-multiplexer-auto-attach/github-vscode-issue-253265.md
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

2.3 KiB

VS Code Issue #253265 — Agent/Chat Extension Cannot See Terminal Command Output

Metadata

Field Value
Institute Molodetz Institute — Research & Retrieval Division
Subject shell-multiplexer-auto-attach
Document type Source Dossier
Tier 1
Source title Agent/Chat extension cannot see terminal command output, but shows normally in terminal
Source URL https://github.com/microsoft/vscode/issues/253265
Source publisher / author Microsoft (vscode repository)
Source type repository
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

A filed VS Code bug where an agent extension's view of a terminal diverges from what a human actually sees rendered in the same terminal — the agent and the human are, in effect, looking at two different realities of the "same" shell session.

Key findings

  • Terminal output visible to a human is not guaranteed to be visible, in the same form, to a program also attached to that terminal — buffering, rendering, and capture paths can diverge.
  • This is a second concrete example (alongside #161238) of VS Code's own first-party integration hitting a reliability gap in terminal introspection.

Pros / strengths

  • A specific, filed, reproducible bug report rather than a vague generalization — adds concrete weight to the pattern already established by the other VS Code dossier in this subject.

Cons / limitations / caveats

  • A single bug report; doesn't establish how common or how severe the general class of issue is across tools, just that it occurs in a major one.

Relevance to tai

Reinforces the same "design for graceful degradation, not perfect detection/capture" principle for the proposal: if a tai control layer captures pane content for its own grep/read commands, it should not assume its view will always exactly match whatever VS Code, another tool, or the human sees rendered — and should log/flag divergence rather than silently trusting a possibly-stale capture.

Changelog

Date Change
2026-10-09 Initial dossier created.