Scope ALSA get_state() to Playback channels on mixed Capture/Playback controls

[Copilot]

AlsaVolumeController.get_state() could parse the wrong value on mixer elements that expose both Capture and Playback channels, because amixer sget output was not constrained to Playback. This change makes get_state() explicitly read Playback state and locks that behavior with focused tests.

• Playback-only ALSA state read

  • Updated get_state() to call:
    • amixer -M -c <card> sget <element> playback
  • This aligns read-path behavior with set_state() (already using playback) and avoids capture-line ambiguity in mixed controls.

• Regression coverage for mixed-channel elements

  • Added a targeted test asserting get_state() invokes sget ... playback.
  • Updated existing command expectation in ALSA controller tests to include the playback qualifier.

proc = await asyncio.create_subprocess_exec(
    "amixer",
    "-M",
    "-c",
    self._card,
    "sget",
    self._element,
    "playback",
    stdout=asyncio.subprocess.PIPE,
    stderr=asyncio.subprocess.PIPE,
)

[Copilot]

Pull request overview

This PR fixes an ALSA parsing ambiguity by ensuring AlsaVolumeController.get_state() queries only Playback channels on mixer elements that expose both Capture and Playback, and adds regression tests to lock in the intended amixer invocation.

Changes:

• Update AlsaVolumeController.get_state() to call amixer ... sget <element> playback to avoid mixed-channel ambiguity.
• Add a focused test asserting get_state() includes the playback qualifier for mixed Capture/Playback controls.
• Update an existing ALSA controller test’s expected amixer sget arguments to include playback.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
sendspin/alsa_volume.py	Scopes get_state()’s amixer sget call to Playback channels by appending playback.
tests/test_alsa_volume.py	Adds/updates expectations to verify get_state() invokes amixer sget ... playback and remains correct on mixed controls.

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