[dianjixz]

The volume shortcut re-read the mixer on every press while Settings -> Speaker rendered whatever its own asynchronous read returned, so the two could show different values for the same mixer state.

Read the mixer once at launcher startup on a worker thread. The reader waits for two consecutive equal readings before publishing, because WirePlumber applies the card's stored volume while it comes up, and falls back to the last valid reading if the value never settles. Shortcuts now step from the cached value instead of issuing another read, and every volume write updates the cache.

Settings -> Speaker seeds its first frame from the same cache and pushes mixer results (read, preview and commit) back into it, so leaving the page cannot expose a stale value. The persisted config key remains only a fallback for a page opened before the startup read finished.

Launcher teardown joins the startup reader, and the test build now links pthread for the worker thread.