- 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>
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2.1 KiB
Bash Check If Shell Is Interactive or Not (nixCraft / cyberciti.biz)
Metadata
| Field | Value |
|---|---|
| Institute | Molodetz Institute — Research & Retrieval Division |
| Subject | shell-multiplexer-auto-attach |
| Document type | Source Dossier |
| Tier | 1 |
| Source title | Bash Check If Shell Is Interactive or Not Under Linux / Unix Oses |
| Source URL | https://www.cyberciti.biz/faq/linux-unix-bash-check-interactive-shell/ |
| Source publisher / author | nixCraft (cyberciti.biz) |
| Source type | blog post |
| 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 practical guide recommending the $- special parameter (which contains the literal character i when the shell is interactive) as the preferred interactivity test, with the standard idiom case "$-" in *i*) ... ;; esac.
Key findings
$-is bash's own exposed flag string, set to includeiprecisely when the shell meets bash's formal interactive definition — it's reading bash's own self-assessment, not re-deriving it fromisatty()calls.- The canonical test form is a
casestatement matching*i*against$-.
Pros / strengths
- Simple, portable within bash, and directly backed by bash's own internal state rather than an external inference.
Cons / limitations / caveats
- Like any
isatty-adjacent signal,$-containingisays "bash thinks it's interactive," which — per the query E dossiers in this subject — a pty-backed automation tool or AI agent terminal can also satisfy. It answers "is bash interactive" correctly; it does not answer "is a human present."
Relevance to tai
This is the first-line check for the proposal's auto-attach guard (.bashrc should do nothing at all unless $- contains i), but per this subject's conclusion, it must be combined with other signals, not used alone, to approximate "a human is here."
Changelog
| Date | Change |
|---|---|
| 2026-10-09 | Initial dossier created. |