Calendink/Provider/AgentTasks/epic2_sd_card_storage.md

Epic 2: Provider Persistent Storage (SD Card)

Goal

Ensure Users, Tasks, and Settings survive device reboots on the ESP32-S3 Provider.

Context

Currently, the Provider's state (Todo tasks, Registered Devices, and User objects) resides in static BSS arrays like g_Tasks[32]. This means the state is lost on every reset. The ESP32-S3 board has an onboard 3GB SD Card reader. This Epic focuses on migrating the data layer to utilize this SD Card.

Scope & Technologies to Investigate

1. Hardware Pinout:
   • Determine the exact physical pins the SD Card reader is using on the specific ESP32-S3 board.
   • Investigate if it is wired for standard SPI (sdspi) or native SDMMC (1-bit or 4-bit mode).
2. ESP-IDF Storage Drivers:
   • Mount a FATFS partition using the esp_vfs_fat_sdmmc / esp_vfs_fat_sdspi components.
3. Data Model:
   • Decide between compiling SQLite for ESP-IDF (better querying, harder setup) or relying on flat .json files parsed via cJSON (easier setup, sufficient for MVP limits like 4 users and 32 tasks).

Next Steps to Start

1. Create a tdd/sd_card_persistence.md.
2. Find the board schematic or test GPIO configurations to successfully mount the SD Card.
3. Abstract the storage functionality into a generic store.hpp/cpp interface so the manage.cpp and API handlers don't need to be rewritten.
4. Update seed_users() and seed_tasks() routines to populate initial .json files if the SD Card is empty.