mqtt-embedded-integration

# MQTT Embedded Integration ## Overview Use this skill for MCU MQTT clients by separating network link, TCP/TLS transport, MQTT session state, topic design, QoS, keepalive, and reconnect policy. MQTT success requires more than one successful publish. ## When To Use Use this skill when: - The user wants MQTT on an MCU or embedded device. - The task involves MQTT connect, publish, subscribe, keepalive, QoS, Last Will, retained messages, broker auth, TLS, reconnect, or offline buffering. - The issue is connection drops, no messages, duplicate messages, memory growth, TLS failure, or reconnect storms. Do not use this skill when basic IP connectivity is not working. Use `lwip-integration` or platform network debugging first. ## First Questions Ask for: - MQTT library/client and version. - Network stack, RTOS, transport, and whether TLS is used. - Broker address, port, auth method, and certificate model without asking for secrets. - Client ID, topics, QoS levels, keepalive, and reconnect policy. - Current logs, broker logs, packet capture, or error codes. - RAM budget and maximum payload size. ## Integration Checklist 1. Prove network first. Confirm DNS/IP, TCP connect, and broker reachability before MQTT debugging. 1. Configure identity. Client ID must be unique and stable enough for the product. 1. Bound payloads and buffers. Topic length, payload size, QoS queues, and offline buffers must fit RAM. 1. Set keepalive and reconnect policy. Avoid reconnect s...