IR remote: power key switches the screen; count irserver's repeats

KEY_POWER emits ToggleScreenRequested, which a new ScreenService turns into the
optional general.screen.toggle_command (musicdolphin: ansible's kiosk-screen). It is
a service, not a reaction, so the subprocess runs in its own task instead of holding
the bus; a press while one is still running is dropped, and failures, hangs and a
missing command are only logged.

irserver reports every line of a held button as repeat 00, so a slightly long press
on Next skipped several tracks and Power would switch the screen off and on again.
A line of the same button within 0.25s of the previous one now counts as a repeat.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

python-backend/tests/test_screen.py

@@ -0,0 +1,110 @@
+"""The screen service: runs the configured command per toggle, and never takes the bus down."""
+
+from __future__ import annotations
+
+import asyncio
+import shlex
+import sys
+from collections.abc import AsyncIterator
+from pathlib import Path
+
+import pytest
+
+from musicmouse.bus import EventBus
+from musicmouse.config import ScreenConfig
+from musicmouse.events import ToggleScreenRequested
+from musicmouse.services.screen import ScreenService
+
+
+def _python(code: str) -> str:
+    return f"{shlex.quote(sys.executable)} -c {shlex.quote(code)}"
+
+
+def _appending(log: Path, *, then: str = "") -> str:
+    """A command that appends a line to ``log`` each time it runs."""
+    return _python(f"open({str(log)!r}, 'a').write('ran\\n'); {then}")
+
+
+@pytest.fixture
+async def bus() -> AsyncIterator[EventBus]:
+    async with EventBus() as bus:
+        yield bus
+
+
+async def _settle(service: ScreenService) -> None:
+    while service._running is not None and not service._running.done():
+        await asyncio.sleep(0.01)
+
+
+async def _started(bus: EventBus, config: ScreenConfig) -> tuple[ScreenService, asyncio.Task[None]]:
+    service = ScreenService(bus, config)
+    task = asyncio.create_task(service.run())
+    await asyncio.sleep(0)  # let it subscribe
+    return service, task
+
+
+async def test_each_press_runs_the_command(bus: EventBus, tmp_path: Path) -> None:
+    log = tmp_path / "ran"
+    service, task = await _started(bus, ScreenConfig(toggle_command=_appending(log)))
+    try:
+        for _ in range(2):
+            await bus.emit_and_wait(ToggleScreenRequested(source="lirc"))
+            await _settle(service)
+    finally:
+        task.cancel()
+
+    assert log.read_text() == "ran\nran\n"
+
+
+async def test_a_press_while_the_command_runs_is_ignored(bus: EventBus, tmp_path: Path) -> None:
+    log = tmp_path / "ran"
+    command = _appending(log, then="import time; time.sleep(0.3)")
+    service, task = await _started(bus, ScreenConfig(toggle_command=command))
+    try:
+        await bus.emit_and_wait(ToggleScreenRequested(source="lirc"))
+        await bus.emit_and_wait(ToggleScreenRequested(source="lirc"))
+        await _settle(service)
+    finally:
+        task.cancel()
+
+    assert log.read_text() == "ran\n"
+
+
+async def test_a_failing_command_is_logged(bus: EventBus, caplog: pytest.LogCaptureFixture) -> None:
+    command = _python("import sys; print('no display'); sys.exit(3)")
+    service, task = await _started(bus, ScreenConfig(toggle_command=command))
+    try:
+        await bus.emit_and_wait(ToggleScreenRequested(source="lirc"))
+        await _settle(service)
+    finally:
+        task.cancel()
+
+    assert "exit 3" in caplog.text
+    assert "no display" in caplog.text
+
+
+async def test_a_missing_command_is_logged(
+    bus: EventBus, caplog: pytest.LogCaptureFixture, tmp_path: Path
+) -> None:
+    service, task = await _started(
+        bus, ScreenConfig(toggle_command=str(tmp_path / "no-such-command"))
+    )
+    try:
+        await bus.emit_and_wait(ToggleScreenRequested(source="lirc"))
+        await _settle(service)
+    finally:
+        task.cancel()
+
+    assert "could not start" in caplog.text
+
+
+async def test_a_hung_command_is_killed(bus: EventBus, caplog: pytest.LogCaptureFixture) -> None:
+    command = _python("import time; time.sleep(30)")
+    service, task = await _started(bus, ScreenConfig(toggle_command=command, timeout=0.2))
+    try:
+        await bus.emit_and_wait(ToggleScreenRequested(source="lirc"))
+        await asyncio.wait_for(_settle(service), 5)
+    finally:
+        task.cancel()
+
+    assert "killed" in caplog.text