Changelog

0.3.0

Dual debug backend and AI-facing crash diagnosis.

Dual backend behind a single DebugBackend trait, selected at connect:
- probe-rs (default) — native probe-rs; full flash and RTT support.
- openocd (experimental) — talks to an already-running openocd over the GDB Remote Serial Protocol (openocd_address, default 127.0.0.1:3333). The AI uses the same tool set for both; only connect differs.
diagnose_fault — reads the Cortex-M SCB fault registers (CFSR/HFSR/MMFAR/BFAR/SHCSR/CPUID) plus PC/SP/LR in one call and returns a compact structured evidence bundle with the set fault bits. Reports raw evidence; it does not assert a root cause.
unwind_exception — maps a crash to source lines. On the probe-rs backend it returns a full DWARF backtrace via probe-rs's own unwinder; on the OpenOCD backend it reads the Cortex-M exception stack frame and maps the faulting PC/caller LR. Requires an elf_path built with debug info.
24 MCP tools total (added diagnose_fault, unwind_exception).

OpenOCD backend verified end-to-end on a real ESP32-S3 (openocd-esp32): connect, memory read/write, halt/run/step/reset, and register reads (PC/SP/LR) are correct.

OpenOCD register reads use monitor reg <name> (openocd resolves names per architecture), so PC/SP/LR work across ARM/Xtensa/RISC-V. Start openocd with gdb_memory_map disable or it may reject the GDB connection.
diagnose_fault and unwind_exception are Cortex-M specific and do not apply to Xtensa (ESP32) targets. Their probe-rs paths delegate to probe-rs's tested DWARF/register code; they are unit-tested but not yet exercised on a physical Cortex-M crash.

Initial MCP server for embedded debugging via probe-rs (probe discovery, target sessions, memory, breakpoints, flash, RTT), CLI, and bundled skill.