# shellous — Async Processes and Pipelines

## Metadata

| Field | Value |
|---|---|
| Institute | Molodetz Institute — Research & Retrieval Division |
| Subject | async-pty-process-testing |
| Document type | Source Dossier |
| Tier | 1 |
| Source title | shellous: Async Processes and Pipelines |
| Source URL | https://pypi.org/project/shellous |
| Source publisher / author | shellous project (PyPI) |
| 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

shellous is an asyncio-native subprocess library. Its feature list includes running a program attached to a pseudo-terminal (pty, Unix-only) and `send()`/`expect()` methods for interactively driving a subprocess by pattern-matching its output — functionally the closest existing library to what `tai_test.py` ended up building itself.

## Key findings

- shellous explicitly supports pty-backed subprocess execution, and documents that this is Unix-only.
- It offers `send()`/`expect()` primitives, i.e. "write input, then wait for a pattern in the output" — the same shape as `tai_test.py`'s `ManagedProcess.send_line()` + `wait_for_pattern()`.
- It is built on asyncio, unlike pexpect (see `pypi-pexpect.md`), which is synchronous.

## Pros / strengths

- Proof that the exact combination `tai_test.py` needed — asyncio-native, pty-capable, expect-style interaction — is a real, previously-solved design space, not a one-off idea.
- Having `send()`/`expect()` as named primitives validates `tai_test.py`'s own `send_line()`/`wait_for_pattern()` naming and shape.

## Cons / limitations / caveats

- Only the top-level feature list was reviewed, not the actual implementation or its API stability/maturity; no version number, changelog, or usage examples were independently inspected.
- `tai_test.py` did not adopt shellous as a dependency — it is pure stdlib (`pty`, `asyncio`) by design, consistent with the `tai.py` project's own zero-dependency rule, so this source served as validation of the approach rather than as a library to use.

## Relevance to tai

Confirmed that building a pty-capable, asyncio-native, expect-style subprocess controller is a well-trodden pattern, which gave confidence in `tai_test.py`'s own from-scratch implementation (`ManagedProcess`) rather than needing to invent an unprecedented design.

## Changelog

| Date | Change |
|---|---|
| 2026-10-09 | Initial dossier created. |