A Bluetooth desk pet that lives off Claude approval prompts

What it does

Anthropic open-sourced the firmware for a small ESP32 desk companion that pairs with Claude Desktop over BLE. The device mirrors Claude’s state—sleeping when idle, sweating during active sessions, and flashing an LED when a permission prompt needs your answer. You can scroll recent messages, cycle through eighteen ASCII pets, or drag custom GIF character packs onto the desktop app to stream them live to the device.

The interesting bit

The project is really two things: a complete M5StickC Plus firmware with seven emotional states, and a documented wire protocol (Nordic UART Service, JSON schemas, folder-push transport) so makers can build entirely different hardware without touching this codebase. The GIF pipeline is charmingly constrained—96 pixels wide, under 1.8 MB total, streamed over Bluetooth like it’s 1999 but in a good way.

Key highlights

• 18 built-in ASCII pets, each with 7 animations (sleep, idle, busy, attention, celebrate, dizzy, heart)
• Custom GIF characters via drag-and-drop folder push over BLE, with a Python prep tool to normalize source art
• Physical approve/deny buttons for Claude permission prompts right on the device
• Seven emotional states mapped to real Claude Desktop events, including a celebrate level-up every 50K tokens
• Wire protocol spec in REFERENCE.md for building your own hardware from scratch

Caveats

• BLE API requires enabling Developer Mode in Claude Desktop and is explicitly not an officially supported product feature
• Firmware is tightly coupled to the M5StickC Plus Arduino libraries; porting to other ESP32 boards means rewriting display, IMU, and button drivers
• Custom GIF packs must stay under 1.8 MB and fit a 135×240 portrait screen

Verdict

Makers and Claude power users who want a tangible, glanceable presence for their AI assistant will find this a fun starting point. If you don’t own an ESP32 dev board or don’t live in Claude Desktop’s developer mode, this is a curiosity, not a tool.