What changed

A new Press Controls screen under Device Settings consolidates every press-related setting into one place: press speed, press & hold duration, call-button mapping, and (for stemmed AirPods) custom single / double / triple / long press actions. Previously these were scattered across the Controls card and a separate "Stem Actions" screen.

Stem action mappings are now per-device. If you own more than one pair of AirPods you can set different mappings on each one.

A Pro badge appears on the Press Mappings section header so you can see upfront that assigning custom actions requires an upgrade, rather than finding out only after tapping a dropdown.

The screen name was chosen to fit both stemmed AirPods and the AirPods Max (Digital Crown / noise control button).

Technical Context

• Mappings moved from a global DataStore (StemActionSettings) onto a new stemActions: StemActionsConfig field on AppleDeviceProfile. No migration path — feature was beta / unreleased, so accepting the data loss was simpler than per-profile bootstrapping. Beta users with custom mappings will see them reset on update.
• Pro gate moved from screen-entry (navToPressControls()) to per-mapping setter. Each setter checks, in order: (1) no-op short-circuit if action == current, (2) free-clear allowance if action == NONE, (3) Pro check — otherwise navigate to Upgrade. Rule (2) prevents lapsed-Pro users from being trapped with old mappings.
• StemPressReaction now resolves the event address to a profile before looking up the mapped action. StemConfigSender computes a per-profile mask instead of broadcasting one shared mask, so a device with no custom mappings gets 0x00 and won't intercept presses at all.
• StemAction enum and the AAP protocol classes (StemPressEvent, StemPressReaction, StemConfigSender) keep their names intentionally — they describe Apple's on-wire protocol, not the UI.
• PressMappingsCard was extracted into its own file so it has self-contained Compose previews for Pro and non-Pro states; the screen itself also has Pro / non-Pro / press-only-device previews.
• Nav key change from data object StemActionConfig to data class PressControls(profileId) — saved back-stack state from before the change won't deserialise cleanly, which is acceptable since the screen was beta.

Review checklist

• Device Settings → Controls card shows only the Press Controls nav link plus Volume Swipe toggle and wait time
• Tap Press Controls → timing / call sections render first, then the Press Mappings card with an Upgrade badge (free) or without it (Pro)
• Free user picking a non-NONE mapping navigates to Upgrade without persisting; clearing to NONE always works
• Two profiles with different mappings trigger different actions on their respective devices
• Press-only device (press timing / call controls but no hasStemConfig) shows the nav link and opens the screen with timing / call sections only — no mapping rows, no reset button, no ANC info box