Async Stewart Filmscreen CVM client for long-running integrations (Home Assistant primary target).

This is a clean implementation focused on reliability, explicit typing, and deterministic parsing.

Protocol reference used:

• https://www.stewartfilmscreen.com/Files/files/Support%20Material/Controls/CVM.pdf

Design boundary:

• This library owns protocol parsing, transport behavior, reconnect behavior, and safe command pacing.
• Integrations built on top of it should focus on product-specific entity mapping and UX, not duplicate queueing or protocol safety rules.

pip install stewart-filmscreen

import asyncio

from stewart_filmscreen.client import StewartFilmscreenClient


async def main() -> None:
    client = StewartFilmscreenClient(
        host="192.168.1.50",
        username="your_username",
        password="your_password",
    )

    try:
        await client.start()
        await client.wait_authenticated(timeout=10)

        await client.move_down("1.1.1.MOTOR")
        await client.stop("1.1.1.MOTOR")
        await client.recall_preset(3)
    finally:
        await client.stop_client()


asyncio.run(main())

By default, commands are paced with a conservative 1.0s inter-command delay because some CVM controllers become unreliable when requests are sent too rapidly. Override command_throttle_seconds only if you have verified your controller tolerates a lower value.

Preset commands are validated against the documented CVM slot range of 1-24.

uv sync --group dev
uv run ruff check .
uv run ruff format --check .
uv run ty check stewart_filmscreen
uv run pytest -v

The test suite includes a manual, read-only integration tier for validating behavior against a real CVM.

• Marker: integration_real
• Opt-in gate: STEWART_ITEST=1
• Target host: STEWART_HOST=<ip-or-hostname>
• Optional port override: STEWART_PORT=23
• Credentials: STEWART_USERNAME, STEWART_PASSWORD
• Optional metadata: STEWART_MAC
• If the device is offline/unreachable, tests are skipped.

Set up local env:

cp .env.example .env

Run the real-device tests:

set -a && source .env && set +a && uv run pytest -v -m integration_real