littlefs-integration

# littlefs Integration ## Overview Use this skill to integrate littlefs safely on embedded block devices. The core task is to make the `lfs_config` match the real storage geometry and prove mount, format, write, sync, power-loss, and remount behavior. ## When To Use Use this skill when: - The user wants to add or debug littlefs on MCU internal flash, external SPI/QSPI NOR, NAND-like storage, EEPROM emulation, SD-backed block devices, or RTOS storage. - The issue involves mount failures, `LFS_ERR_CORRUPT`, read/write errors, wear leveling, block geometry, formatting, or data loss after reboot. - The project uses `lfs.h`, `lfs_file_*`, `lfs_dir_*`, or `struct lfs_config`. Do not use this skill for generic flash programming failures before the block device driver works. Use `mcu-flashing-debug` first. ## First Questions Ask for: - Storage type, size, erase block size, program size, read size, and erase value. - Whether storage is internal flash, external NOR/NAND, SD card, RAM disk, or simulator. - Existing `lfs_config`, block device read/prog/erase/sync functions, and error codes. - RTOS or bare-metal environment, locking needs, and whether dynamic allocation is allowed. - Whether formatting is allowed. Formatting can destroy existing data. - Current symptom and exact littlefs error code. ## Integration Checklist 1. Confirm block geometry. Set `read_size`, `prog_size`, `block_size`, `block_count`, `cache_size`, `lookahead_size`, and `block_cycles` from the real st...