Six public API functions had no callers anywhere in the firmware:
splash_prev, splash_set_active, splash_current_name, splash_count,
ble_is_connected, imu_set_rotation, power_is_usb_connected,
power_usb_changed. Trimming them lets power.cpp drop the VBUS state
machine (cached_usb, usb_changed_flag, last_vbus_ms,
enableVbusVoltageMeasure). usage_rate_reset becomes file-static since
the only caller is in usage_rate.cpp itself. Montserrat font flags in
platformio.ini were enabled but never referenced.
Group splash animations into four moods (idle/normal/active/heavy) and pick
which group plays based on a 5-min sliding rate of session_pct. Thresholds
sit at 0.10/0.20/0.33 %/min so Heavy fires when usage matches or beats the
5-hour session reset pace. Splash auto-rotates within the current group
every 20s; group recomputes on every BLE poll and the splash re-picks
immediately if it changes mid-display. 4-min minimum window prevents
single-sample bumps after boot from falsely landing in Heavy.
Hermann Björgvin Haraldsson