embedded-state-machine-libs

# Embedded State Machine Libs ## Overview Use this skill for embedded state machine libraries and hand-written finite state machines. The core is to make states, events, transitions, side effects, and invalid transitions explicit and verifiable. ## When To Use Use this skill when: - The user wants to add or debug a StateMachine library or event-driven MCU workflow. - The issue involves wrong transitions, stuck states, reentrancy, event loss, timeout handling, or unclear state ownership. - Firmware has modes such as idle, init, run, error, recovery, upgrade, sleep, or calibration. Do not use this skill for RTOS scheduling issues unless the state machine is the primary abstraction. ## First Questions Ask for: - State machine library or custom implementation. - State list, event list, and current failing transition. - Whether transitions run in ISR, task, main loop, or callback context. - Whether timeouts, retries, or external interrupts drive events. - Expected behavior for invalid events. ## Integration Checklist 1. Define states and events. Names should reflect system meaning, not implementation steps. 1. Separate transition from action. Make it clear what changes state and what side effects run because of the transition. 1. Define invalid event behavior. Ignore, log, assert, error transition, or recovery must be explicit. 1. Guard reentrancy. Avoid nested transitions unless the library explicitly supports them. 1. Add observability. Log state tr...