retoorandClaude Sonnet 5
9dbd1fe667
- 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>
50 lines
3.4 KiB
Markdown
50 lines
3.4 KiB
Markdown
# sync: interactive launches strip the harness of its controlling terminal (start_new_session=True) · Issue #1 · anntnzrb/agents
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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 | async-pty-process-testing |
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| Document type | Source Dossier |
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| Tier | 1 |
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| Source title | sync: interactive launches strip the harness of its controlling terminal (start_new_session=True) |
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| Source URL | https://github.com/anntnzrb/agents/issues/1 |
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| Source publisher / author | GitHub user anntnzrb |
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| Source type | repository (issue) |
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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 | High |
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| Status | Active |
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## Summary
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A GitHub issue documenting a real, encountered bug: a test/automation harness launched an interactive child process with `start_new_session=True`, which left the harness without a controlling terminal and broke window-resize and Ctrl-C handling for the child. The issue includes a small probe script for diagnosing whether a child process actually has a controlling terminal.
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## Key findings
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- `start_new_session=True` makes the child a new session leader; if that child is then given a pty as stdin/stdout/stderr, whether the pty becomes its *controlling* terminal (in the POSIX job-control sense) is not automatic — the issue describes a concrete case where it did not, breaking SIGWINCH-based resize and tty-line-discipline Ctrl-C-as-SIGINT.
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- The reporter's diagnostic approach: a probe script that checks `os.isatty(0)`, `os.tcgetpgrp(0)`, and whether `/dev/tty` can be opened, to confirm a child process actually has a controlling terminal rather than just an open pty fd.
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## Pros / strengths
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- A real, lived-through failure report rather than theoretical speculation — exactly the kind of pitfall that's easy to get subtly wrong when combining `start_new_session=True` (needed for safe process-group-wide `killpg` cleanup) with pty-based spawning (needed for `isatty()`-correct interactive behavior).
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- The diagnostic probe script is a concrete, reusable technique for anyone needing to verify controlling-terminal status.
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## Cons / limitations / caveats
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- A single GitHub issue report, not a kernel/POSIX specification — the exact conditions under which a session leader's first terminal open becomes its controlling terminal can depend on how the fd was obtained (opened directly by the child vs. inherited already-open from the parent), and this issue doesn't fully disambiguate that for the inherited-fd case `tai_test.py` actually uses.
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- No resolution/fix is confirmed as verified in this research pass (the issue's eventual outcome was not reviewed).
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## Relevance to tai
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Directly shaped `tai_test.py`'s documented, accepted limitation: its pty mode does not explicitly call `ioctl(TIOCSCTTY)`, so controlling-terminal/job-control semantics (SIGWINCH forwarding, Ctrl-C-as-SIGINT from the tty line discipline) are not guaranteed. This was judged acceptable because `tai.py`'s own code only checks `sys.stdin.isatty()` (a property of the fd itself, unaffected by session/controlling-terminal status) and `tai_test.py`'s tests only script line-based input/output, never relying on resize or terminal-generated signals.
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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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