Summary

This changeset makes StreamController use the Stream Deck+ touchscreen API more effectively and removes a large amount of redundant UI-preview work.

On the hardware side, touchscreen updates now use partial-region scheduling instead of always treating the strip like a full-frame surface. On the UI side, preview updates are coalesced so rapid meter or volume changes do not flood GTK with stale thumbnail work.

What changed

• Added BetterDeck context manager support in BetterDeck.py so StreamController can batch writes under the hardware library’s update lock.
• Reworked the media-player flush path in DeckController.py:
  • batch key and touchscreen writes under one deck lock
  • queue touchscreen work as region images instead of pre-encoded full-strip payloads
  • support partial touchscreen region uploads for dial updates
  • merge adjacent touchscreen regions before flushing
  • dedupe key and touchscreen writes by content hash
  • drop stale page writes instead of flushing them later
  • temporarily boost priority for real user interactions so volume/mute feedback wins over meter churn
• Added cached touchscreen base/current composition in DeckController.py so dial updates can replace only their own strip region.
• Fixed stale transparent pixels when no background is present by replacing the full dial slot during partial updates instead of alpha-pasting it back into the cached strip.
• Coalesced touchscreen preview updates before sending them into GTK in DeckController.py.

Why

Before this change:

• live meters could crowd out more important strip updates
• dial updates rebuilt and resent more strip data than necessary
• transparent updates could leave stale pixels behind when no background was present
• the GTK preview path generated frequent stale-task abort logs during normal operation

After this change:

• interaction-driven updates are prioritized
• the Stream Deck+ strip uses partial-region writes
• redundant writes are skipped
• preview churn is reduced and the stale-task logs are gone