bootloader-debug

# Bootloader Debug ## Overview Use this skill to debug bootloader and application handoff problems without destroying recovery paths. Verify memory layout, image metadata, vector table, stack pointer, reset handler, validation, and rollback state before reflashing or erasing boot regions. ## When To Use Use this skill when: - A bootloader cannot start an application or jumps to the wrong image. - OTA/upgrade succeeds but the new firmware does not boot. - The issue involves image headers, checksums, signatures, slots, rollback, vector table relocation, or boot pins. - The user mentions MCUboot, U-Boot, vendor bootloader, IAP, DFU, app offset, or recovery mode. Do not use this skill for ordinary application crashes after a confirmed clean handoff; use `embedded-fault-debug`. For MCUboot-specific slot/signing/swap issues, use `mcuboot-integration`. For OTA delivery pipeline issues, use `ota-update-integration`. ## First Questions Ask for: - Chip/board and bootloader type. - Memory map: bootloader, app slot, scratch, config, NVM, and backup areas. - Image format and validation: raw binary, HEX, signed image, checksum, metadata header. - Upgrade state: active slot, pending, confirmed, rollback, recovery, or unknown. - Logs from bootloader and application if available. - Whether recovery access still works. ## Workflow 1. Protect recovery. Do not erase bootloader, recovery slot, calibration, or persistent upgrade state without explicit approval. 1. Confirm memory lay...