retoorandClaude Sonnet 5
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- 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>
48 lines
2.6 KiB
Markdown
48 lines
2.6 KiB
Markdown
# Checking for Interactive Shell in a Python Script (pythontutorials.net)
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## Metadata
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| Field | Value |
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| Institute | Molodetz Institute — Research & Retrieval Division |
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| Subject | shell-multiplexer-auto-attach |
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| Document type | Source Dossier |
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| Tier | 1 |
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| Source title | How to Check if a Shell is Interactive in a Python Script: Preferred Methods Explained |
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| Source URL | https://www.pythontutorials.net/blog/checking-for-interactive-shell-in-a-python-script/ |
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| Source publisher / author | pythontutorials.net |
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| Source type | blog post |
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| Source date (published) | Unknown — not stated |
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| Date researched | 2026-10-09 |
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| Researched by | tai (agent), model: Claude Sonnet 5, on behalf of retoor |
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| Research method | web search synthesis |
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| Confidence | Medium |
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| Status | Active |
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## Summary
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Suggests checking whether `PS1` exists in a Python script's environment as a proxy for shell interactivity — flagged independently (not by this source, but by general knowledge noted in the search synthesis) as unreliable, since `PS1` is normally a shell variable that is not exported to child processes.
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## Key findings
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- `PS1`, unless explicitly `export`ed, is invisible to any child process (including a Python script, or tai itself if written in Python) inspecting its own environment — `os.environ.get("PS1")` will typically be empty even in a genuinely interactive parent shell.
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- This caveat is a real correctness bug if a tai component written in Python ever tried to re-derive "is the parent shell interactive" from its own `os.environ`.
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## Pros / strengths
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- Surfaces a specific, concrete correctness trap for exactly the kind of cross-language (bash-to-Python) interactivity check the proposal would otherwise be tempted to write.
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## Cons / limitations / caveats
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- The source itself suggests the `PS1`-in-environment check as a *method*; the caveat about its unreliability from a child process comes from general knowledge noted alongside the search synthesis, not from the source's own text — treat the caveat as independently well-established (PS1 export behavior is standard shell semantics), but attribute it honestly as outside this specific article.
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## Relevance to tai
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A hard "don't do this" for the proposal: any Python-side component of tai must never try to detect shell interactivity by reading `PS1` from `os.environ` — it won't be there even when the parent genuinely is interactive. Detection has to happen in the shell (`.bashrc`, via `$-`) and be passed to tai explicitly (an env var, an argument), not re-derived downstream.
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## Changelog
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| Date | Change |
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| 2026-10-09 | Initial dossier created. |
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