Files
tai/research/async-pty-process-testing/python-asyncio-issue499-add-reader-eof.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

2.4 KiB

loop.add_reader and <<EOF · Issue #499 · python/asyncio

Metadata

Field Value
Institute Molodetz Institute — Research & Retrieval Division
Subject async-pty-process-testing
Document type Source Dossier
Tier 1
Source title loop.add_reader and <<EOF · Issue #499
Source URL https://github.com/python/asyncio/issues/499
Source publisher / author python/asyncio project (GitHub)
Source type repository (issue)
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

An upstream issue in the (now-archived, pre-stdlib-merge) python/asyncio project discussing edge cases of loop.add_reader combined with shell here-document (<<EOF) input and EOF handling on stdin.

Key findings

  • add_reader/stdin EOF handling is treated as a known rough edge in asyncio's own issue tracker, not a fully solved, documented-everywhere corner of the API.
  • The issue's existence itself is evidence that different stdin-feeding mechanisms (interactive shell vs. here-doc vs. piped file) can surface different edge-case behavior with add_reader.

Pros / strengths

  • Primary-source confirmation (from the asyncio project itself) that this is a genuinely tricky area, not something tai_test.py's own testing was wrong to be cautious about.

Cons / limitations / caveats

  • This dossier is based on a web-search synthesis of the issue's existence and general topic, not a full read of the issue thread's technical discussion or resolution — the specific EOF-handling edge case it describes was not independently verified against tai_test.py's own StdinBridge implementation.
  • The issue predates asyncio's merge into the stdlib and may reference an older API surface.

Relevance to tai

Reinforced the decision to keep StdinBridge.start() defensive: it returns False (no-op) when sys.stdin.isatty() is false, rather than attempting add_reader against every possible stdin configuration (pipes, here-docs, redirected files) and hoping EOF behaves consistently. tai_test.py only ever activates the live-stdin bridge when a real interactive terminal is confirmed present.

Changelog

Date Change
2026-10-09 Initial dossier created.