Firmware

ESP32-S3 firmware (ESP-IDF / FreeRTOS). It will implement protocol v1 and mirror the handset state machine in packages/core/src/device.ts, using the browser emulator (apps/device-web) as its reference implementation and test peer.

Requirements already decided

USB power source policy (hardware/DESIGN.md §9.2a)

Read the USB-C Rp advertisement on CC1/CC2 (GPIO1/GPIO2, ADC1; 5.1 kΩ Rd fitted): < 0.66 V = Default (500 mA, also every USB-A→C cable), 0.66–1.23 V = 1.5 A, > 1.23 V = 3 A. Use the higher of the two pins (only the connected one carries Rp). Re-read on attach and every few seconds.
Kids: full features on any source.
Lounge on a Default source → reduced mode: keep the radar powered off (LD_PWR_EN low), LEDs ≤ 10 %, ringer ≤ 0.5 W, charging off (CHG_CE high); presence falls back to hook + NFC. Status display: USE 1.5A CHARGER.
Always cap LEDs ≤ 30 % and amp level per hardware/schematic/power_budget.yaml.
Report it in status: power: { source: "default" | "1.5A" | "3A", reduced: boolean }.