remove: eliminate file management and LittleFS-based filesystem, implement savegame management for JSON config slots with wear-leveling

Software/MainBoard/rust/src/fat_error.rs

@@ -16,28 +16,18 @@ use esp_hal::twai::EspTwaiError;
 use esp_radio::wifi::WifiError;
 use ina219::errors::{BusVoltageReadError, ShuntVoltageReadError};
 use lib_bms_protocol::BmsProtocolError;
-use littlefs2_core::PathError;
 use onewire::Error;
 use pca9535::ExpanderError;
 
 //All error superconstruct
 #[derive(Debug)]
 pub enum FatError {
-    BMSError {
-        error: String,
-    },
     OneWireError {
         error: Error<Infallible>,
     },
     String {
         error: String,
     },
-    LittleFSError {
-        error: littlefs2_core::Error,
-    },
-    PathError {
-        error: PathError,
-    },
     TryLockError {
         error: TryLockError,
     },
@@ -88,8 +78,6 @@ impl fmt::Display for FatError {
             }
             FatError::OneWireError { error } => write!(f, "OneWireError {error:?}"),
             FatError::String { error } => write!(f, "{error}"),
-            FatError::LittleFSError { error } => write!(f, "LittleFSError {error:?}"),
-            FatError::PathError { error } => write!(f, "PathError {error:?}"),
             FatError::TryLockError { error } => write!(f, "TryLockError {error:?}"),
             FatError::WifiError { error } => write!(f, "WifiError {error:?}"),
             FatError::SerdeError { error } => write!(f, "SerdeError {error:?}"),
@@ -108,7 +96,6 @@ impl fmt::Display for FatError {
                 write!(f, "CanBusError {error:?}")
             }
             FatError::SNTPError { error } => write!(f, "SNTPError {error:?}"),
-            FatError::BMSError { error } => write!(f, "BMSError, {error}"),
             FatError::OTAError => {
                 write!(f, "OTA missing partition")
             }
@@ -173,18 +160,6 @@ impl From<Error<Infallible>> for FatError {
         FatError::OneWireError { error }
     }
 }
-impl From<littlefs2_core::Error> for FatError {
-    fn from(value: littlefs2_core::Error) -> Self {
-        FatError::LittleFSError { error: value }
-    }
-}
-
-impl From<PathError> for FatError {
-    fn from(value: PathError) -> Self {
-        FatError::PathError { error: value }
-    }
-}
-
 impl From<TryLockError> for FatError {
     fn from(value: TryLockError) -> Self {
         FatError::TryLockError { error: value }

Software/MainBoard/rust/src/hal/esp.rs

@@ -1,18 +1,16 @@
 use crate::bail;
 use crate::config::{NetworkConfig, PlantControllerConfig};
+use crate::hal::savegame_manager::SavegameManager;
 use crate::hal::{PLANT_COUNT, TIME_ACCESS};
 use crate::log::{LogMessage, LOG_ACCESS};
 use chrono::{DateTime, Utc};
-use serde::Serialize;
 
 use crate::fat_error::{ContextExt, FatError, FatResult};
-use crate::hal::little_fs2storage_adapter::LittleFs2Filesystem;
 use crate::hal::shared_flash::MutexFlashStorage;
 use alloc::string::ToString;
 use alloc::sync::Arc;
 use alloc::{format, string::String, vec, vec::Vec};
 use core::net::{IpAddr, Ipv4Addr, SocketAddr};
-use core::str::FromStr;
 use core::sync::atomic::Ordering;
 use embassy_executor::Spawner;
 use embassy_net::udp::UdpSocket;
@@ -39,8 +37,6 @@ use esp_radio::wifi::{
     AccessPointConfig, AccessPointInfo, AuthMethod, ClientConfig, ModeConfig, ScanConfig,
     ScanTypeConfig, WifiController, WifiDevice, WifiStaState,
 };
-use littlefs2::fs::Filesystem;
-use littlefs2_core::{FileType, PathBuf, SeekFrom};
 use log::{error, info, warn};
 use mcutie::{
     Error, McutieBuilder, McutieReceiver, McutieTask, MqttMessage, PublishDisplay, Publishable,
@@ -60,7 +56,6 @@ static mut LOW_VOLTAGE_DETECTED: i8 = 0;
 #[esp_hal::ram(unstable(rtc_fast), unstable(persistent))]
 static mut RESTART_TO_CONF: i8 = 0;
 
-const CONFIG_FILE: &str = "config.json";
 const NTP_SERVER: &str = "pool.ntp.org";
 
 static MQTT_CONNECTED_EVENT_RECEIVED: AtomicBool = AtomicBool::new(false);
@@ -68,19 +63,6 @@ static MQTT_ROUND_TRIP_RECEIVED: AtomicBool = AtomicBool::new(false);
 pub static MQTT_STAY_ALIVE: AtomicBool = AtomicBool::new(false);
 static MQTT_BASE_TOPIC: OnceLock<String> = OnceLock::new();
 
-#[derive(Serialize, Debug)]
-pub struct FileInfo {
-    filename: String,
-    size: usize,
-}
-
-#[derive(Serialize, Debug)]
-pub struct FileList {
-    total: usize,
-    used: usize,
-    files: Vec<FileInfo>,
-}
-
 #[derive(Copy, Clone, Default)]
 struct Timestamp {
     stamp: DateTime<Utc>,
@@ -117,7 +99,7 @@ impl NtpTimestampGenerator for Timestamp {
 }
 
 pub struct Esp<'a> {
-    pub fs: Arc<Mutex<CriticalSectionRawMutex, Filesystem<'static, LittleFs2Filesystem>>>,
+    pub savegame: SavegameManager,
     pub rng: Rng,
     //first starter (ap or sta will take these)
     pub interface_sta: Option<WifiDevice<'static>>,
@@ -185,69 +167,6 @@ impl Esp<'_> {
             }
         }
     }
-    pub(crate) async fn delete_file(&self, filename: String) -> FatResult<()> {
-        let file = PathBuf::try_from(filename.as_str())?;
-        let access = self.fs.lock().await;
-        access.remove(&file)?;
-        Ok(())
-    }
-    pub(crate) async fn write_file(
-        &mut self,
-        filename: String,
-        offset: u32,
-        buf: &[u8],
-    ) -> Result<(), FatError> {
-        let file = PathBuf::try_from(filename.as_str())?;
-        let access = self.fs.lock().await;
-        access.open_file_with_options_and_then(
-            |options| options.read(true).write(true).create(true),
-            &file,
-            |file| {
-                file.seek(SeekFrom::Start(offset))?;
-                file.write(buf)?;
-                Ok(())
-            },
-        )?;
-        Ok(())
-    }
-
-    pub async fn get_size(&mut self, filename: String) -> FatResult<usize> {
-        let file = PathBuf::try_from(filename.as_str())?;
-        let access = self.fs.lock().await;
-        let data = access.metadata(&file)?;
-        Ok(data.len())
-    }
-    pub(crate) async fn get_file(
-        &mut self,
-        filename: String,
-        chunk: u32,
-    ) -> FatResult<([u8; 512], usize)> {
-        use littlefs2::io::Error as lfs2Error;
-
-        let file = PathBuf::try_from(filename.as_str())?;
-        let access = self.fs.lock().await;
-        let mut buf = [0_u8; 512];
-        let mut read = 0;
-        let offset = chunk * buf.len() as u32;
-        access.open_file_with_options_and_then(
-            |options| options.read(true),
-            &file,
-            |file| {
-                let length = file.len()? as u32;
-                if length == 0 {
-                    Err(lfs2Error::IO)
-                } else if length > offset {
-                    file.seek(SeekFrom::Start(offset))?;
-                    read = file.read(&mut buf)?;
-                    Ok(())
-                } else {
-                    //exactly at end, do nothing
-                    Ok(())
-                }
-            },
-        )?;
-        Ok((buf, read))
-    }
 
     pub(crate) async fn write_ota(&mut self, offset: u32, buf: &[u8]) -> Result<(), FatError> {
         let _ = check_erase(self.ota_target, offset, offset + 4096);
@@ -422,10 +341,7 @@ impl Esp<'_> {
             .interface_ap
             .take()
             .context("AP interface already taken")?;
-        let gw_ip_addr_str = "192.168.71.1";
-        let gw_ip_addr = Ipv4Addr::from_str(gw_ip_addr_str).map_err(|_| FatError::String {
-            error: "failed to parse gateway ip".to_string(),
-        })?;
+        let gw_ip_addr = Ipv4Addr::new(192, 168, 71, 1);
 
         let config = embassy_net::Config::ipv4_static(StaticConfigV4 {
             address: Ipv4Cidr::new(gw_ip_addr, 24),
@@ -454,7 +370,7 @@ impl Esp<'_> {
         println!("start net task");
         spawner.spawn(net_task(runner)).ok();
         println!("run dhcp");
-        spawner.spawn(run_dhcp(*stack, gw_ip_addr_str)).ok();
+        spawner.spawn(run_dhcp(*stack, gw_ip_addr)).ok();
 
         loop {
             if stack.is_link_up() {
@@ -465,7 +381,7 @@ impl Esp<'_> {
         while !stack.is_config_up() {
             Timer::after(Duration::from_millis(100)).await
         }
-        println!("Connect to the AP `${ssid}` and point your browser to http://{gw_ip_addr_str}/");
+        println!("Connect to the AP `${ssid}` and point your browser to http://{gw_ip_addr}/");
         stack
             .config_v4()
             .inspect(|c| println!("ipv4 config: {c:?}"));
@@ -624,48 +540,46 @@ impl Esp<'_> {
         }
     }
 
+    /// Load the most recently saved config from flash.
     pub(crate) async fn load_config(&mut self) -> FatResult<PlantControllerConfig> {
-        let cfg = PathBuf::try_from(CONFIG_FILE)?;
-        let config_exist = self.fs.lock().await.exists(&cfg);
-        if !config_exist {
-            bail!("No config file stored")
+        match self.savegame.load_latest()? {
+            None => bail!("No config stored"),
+            Some(data) => {
+                let config: PlantControllerConfig = serde_json::from_slice(&data)?;
+                Ok(config)
+            }
         }
-        let data = self.fs.lock().await.read::<4096>(&cfg)?;
-        let config: PlantControllerConfig = serde_json::from_slice(&data)?;
-        Ok(config)
     }
-    pub(crate) async fn save_config(&mut self, config: Vec<u8>) -> FatResult<()> {
-        let filesystem = self.fs.lock().await;
-        let cfg = PathBuf::try_from(CONFIG_FILE)?;
-        filesystem.write(&cfg, &config)?;
+
+    /// Load a config from a specific save slot.
+    pub(crate) async fn load_config_slot(
+        &mut self,
+        idx: usize,
+    ) -> FatResult<String> {
+        match self.savegame.load_slot(idx)? {
+            None => bail!("Slot {idx} is empty or invalid"),
+            Some(data) => {
+                Ok(String::from_utf8_lossy(&*data).to_string())
+            }
+        }
+    }
+
+    /// Persist a JSON config blob to the next wear-leveling slot.
+    pub(crate) async fn save_config(&mut self, mut config: Vec<u8>) -> FatResult<()> {
+        self.savegame.save(config.as_mut_slice())?;
         Ok(())
     }
-    pub(crate) async fn list_files(&self) -> FatResult<FileList> {
-        let path = PathBuf::new();
 
-        let fs = self.fs.lock().await;
-        let free_size = fs.available_space()?;
-        let total_size = fs.total_space();
+    /// Delete a specific save slot by erasing it on flash.
+    pub(crate) async fn delete_save_slot(&mut self, idx: usize) -> FatResult<()> {
+        self.savegame.delete_slot(idx)
+    }
 
-        let mut result = FileList {
-            total: total_size,
-            used: total_size - free_size,
-            files: Vec::new(),
-        };
-
-        fs.read_dir_and_then(&path, |dir| {
-            for entry in dir {
-                let e = entry?;
-                if e.file_type() == FileType::File {
-                    result.files.push(FileInfo {
-                        filename: e.path().to_string(),
-                        size: e.metadata().len(),
-                    });
-                }
-            }
-            Ok(())
-        })?;
-        Ok(result)
+    /// Return metadata about all valid save slots.
+    pub(crate) async fn list_saves(
+        &mut self,
+    ) -> FatResult<alloc::vec::Vec<crate::hal::savegame_manager::SaveInfo>> {
+        self.savegame.list_saves()
     }
 
     pub(crate) async fn init_rtc_deepsleep_memory(
@@ -969,8 +883,8 @@ async fn net_task(mut runner: Runner<'static, WifiDevice<'static>>) {
 }
 
 #[embassy_executor::task]
-async fn run_dhcp(stack: Stack<'static>, gw_ip_addr: &'static str) {
-    use core::net::{Ipv4Addr, SocketAddrV4};
+async fn run_dhcp(stack: Stack<'static>, ip: Ipv4Addr) {
+    use core::net::SocketAddrV4;
 
     use edge_dhcp::{
         io::{self, DEFAULT_SERVER_PORT},
@@ -979,14 +893,6 @@ async fn run_dhcp(stack: Stack<'static>, gw_ip_addr: &'static str) {
     use edge_nal::UdpBind;
     use edge_nal_embassy::{Udp, UdpBuffers};
 
-    let ip = match Ipv4Addr::from_str(gw_ip_addr) {
-        Ok(ip) => ip,
-        Err(_) => {
-            error!("dhcp task failed to parse gw ip");
-            return;
-        }
-    };
-
     let mut buf = [0u8; 1500];
 
     let mut gw_buf = [Ipv4Addr::UNSPECIFIED];

Software/MainBoard/rust/src/hal/little_fs2storage_adapter.rs

@@ -1,88 +0,0 @@
-use crate::hal::shared_flash::MutexFlashStorage;
-use embedded_storage::nor_flash::{check_erase, NorFlash, ReadNorFlash};
-use esp_bootloader_esp_idf::partitions::FlashRegion;
-use littlefs2::consts::U4096 as lfsCache;
-use littlefs2::consts::U512 as lfsLookahead;
-use littlefs2::driver::Storage as lfs2Storage;
-use littlefs2::io::Error as lfs2Error;
-use littlefs2::io::Result as lfs2Result;
-use log::error;
-
-pub struct LittleFs2Filesystem {
-    pub(crate) storage: &'static mut FlashRegion<'static, MutexFlashStorage>,
-}
-
-impl lfs2Storage for LittleFs2Filesystem {
-    const READ_SIZE: usize = 4096;
-    const WRITE_SIZE: usize = 4096;
-    const BLOCK_SIZE: usize = 4096; //usually optimal for flash access
-    const BLOCK_COUNT: usize = 8 * 1000 * 1000 / 4096; //8Mb in 4k blocks + a little space for stupid calculation errors
-    const BLOCK_CYCLES: isize = 100;
-    type CACHE_SIZE = lfsCache;
-    type LOOKAHEAD_SIZE = lfsLookahead;
-
-    fn read(&mut self, off: usize, buf: &mut [u8]) -> lfs2Result<usize> {
-        let read_size: usize = Self::READ_SIZE;
-        if off % read_size != 0 {
-            error!("Littlefs2Filesystem read error: offset not aligned to read size offset: {off} read_size: {read_size}");
-            return Err(lfs2Error::IO);
-        }
-        if buf.len() % read_size != 0 {
-            error!("Littlefs2Filesystem read error: length not aligned to read size length: {} read_size: {}", buf.len(), read_size);
-            return Err(lfs2Error::IO);
-        }
-        match self.storage.read(off as u32, buf) {
-            Ok(..) => Ok(buf.len()),
-            Err(err) => {
-                error!("Littlefs2Filesystem read error: {err:?}");
-                Err(lfs2Error::IO)
-            }
-        }
-    }
-
-    fn write(&mut self, off: usize, data: &[u8]) -> lfs2Result<usize> {
-        let write_size: usize = Self::WRITE_SIZE;
-        if off % write_size != 0 {
-            error!("Littlefs2Filesystem write error: offset not aligned to write size offset: {off} write_size: {write_size}");
-            return Err(lfs2Error::IO);
-        }
-        if data.len() % write_size != 0 {
-            error!("Littlefs2Filesystem write error: length not aligned to write size length: {} write_size: {}", data.len(), write_size);
-            return Err(lfs2Error::IO);
-        }
-        match self.storage.write(off as u32, data) {
-            Ok(..) => Ok(data.len()),
-            Err(err) => {
-                error!("Littlefs2Filesystem write error: {err:?}");
-                Err(lfs2Error::IO)
-            }
-        }
-    }
-
-    fn erase(&mut self, off: usize, len: usize) -> lfs2Result<usize> {
-        let block_size: usize = Self::BLOCK_SIZE;
-        if off % block_size != 0 {
-            error!("Littlefs2Filesystem erase error: offset not aligned to block size offset: {off} block_size: {block_size}");
-            return Err(lfs2Error::IO);
-        }
-        if len % block_size != 0 {
-            error!("Littlefs2Filesystem erase error: length not aligned to block size length: {len} block_size: {block_size}");
-            return Err(lfs2Error::IO);
-        }
-
-        match check_erase(self.storage, off as u32, (off + len) as u32) {
-            Ok(_) => {}
-            Err(err) => {
-                error!("Littlefs2Filesystem check erase error: {err:?}");
-                return Err(lfs2Error::IO);
-            }
-        }
-        match self.storage.erase(off as u32, (off + len) as u32) {
-            Ok(..) => Ok(len),
-            Err(err) => {
-                error!("Littlefs2Filesystem erase error: {err:?}");
-                Err(lfs2Error::IO)
-            }
-        }
-    }
-}

Software/MainBoard/rust/src/hal/mod.rs

@@ -3,7 +3,7 @@ use lib_bms_protocol::BmsReadable;
 pub(crate) mod battery;
 // mod can_api; // replaced by external canapi crate
 pub mod esp;
-mod little_fs2storage_adapter;
+pub(crate) mod savegame_manager;
 pub(crate) mod rtc;
 mod shared_flash;
 mod v4_hal;
@@ -75,7 +75,7 @@ use measurements::{Current, Voltage};
 
 use crate::fat_error::{ContextExt, FatError, FatResult};
 use crate::hal::battery::WCHI2CSlave;
-use crate::hal::little_fs2storage_adapter::LittleFs2Filesystem;
+use crate::hal::savegame_manager::SavegameManager;
 use crate::hal::water::TankSensor;
 use crate::log::LOG_ACCESS;
 use embassy_sync::mutex::Mutex;
@@ -99,9 +99,7 @@ use esp_hal::uart::Uart;
 use esp_hal::Blocking;
 use esp_radio::{init, Controller};
 use esp_storage::FlashStorage;
-use littlefs2::fs::{Allocation, Filesystem as lfs2Filesystem};
-use littlefs2::object_safe::DynStorage;
-use log::{error, info, warn};
+use log::{info, warn};
 use portable_atomic::AtomicBool;
 use serde::{Deserialize, Serialize};
 use shared_flash::MutexFlashStorage;
@@ -379,33 +377,16 @@ impl PlantHal {
             .find_partition(esp_bootloader_esp_idf::partitions::PartitionType::Data(
                 DataPartitionSubType::LittleFs,
             ))?
-            .context("Data partition with littlefs not found")?;
+            .context("Storage data partition not found")?;
         let data_partition = mk_static!(PartitionEntry, data_partition);
 
         let data = mk_static!(
-            FlashRegion<MutexFlashStorage>,
+            FlashRegion<'static, MutexFlashStorage>,
             data_partition.as_embedded_storage(flash_storage_3)
         );
-        let lfs2filesystem = mk_static!(LittleFs2Filesystem, LittleFs2Filesystem { storage: data });
-        let alloc = mk_static!(Allocation<LittleFs2Filesystem>, lfs2Filesystem::allocate());
-        if lfs2filesystem.is_mountable() {
-            info!("Littlefs2 filesystem is mountable");
-        } else {
-            match lfs2filesystem.format() {
-                Ok(..) => {
-                    info!("Littlefs2 filesystem is formatted");
-                }
-                Err(err) => {
-                    error!("Littlefs2 filesystem could not be formatted: {err:?}");
-                }
-            }
-        }
 
-        #[allow(clippy::arc_with_non_send_sync)]
-        let fs = Arc::new(Mutex::new(
-            lfs2Filesystem::mount(alloc, lfs2filesystem)
-                .context("Could not mount lfs2 filesystem")?,
-        ));
+        let savegame = SavegameManager::new(data);
+        info!("Savegame storage initialized ({} slots × {} KB)", savegame_manager::SAVEGAME_SLOT_COUNT, savegame_manager::SAVEGAME_SLOT_SIZE / 1024);
 
         let uart0 =
             Uart::new(peripherals.UART0, UartConfig::default()).map_err(|_| FatError::String {
@@ -415,7 +396,7 @@ impl PlantHal {
         let ap = interfaces.ap;
         let sta = interfaces.sta;
         let mut esp = Esp {
-            fs,
+            savegame,
             rng,
             controller: Arc::new(Mutex::new(controller)),
             interface_sta: Some(sta),

Software/MainBoard/rust/src/hal/savegame_manager.rs

@@ -0,0 +1,150 @@
+use alloc::vec::Vec;
+use embedded_savegame::storage::{Flash, Storage};
+use embedded_storage::nor_flash::{NorFlash, ReadNorFlash};
+use esp_bootloader_esp_idf::partitions::{FlashRegion, Error as PartitionError};
+use serde::Serialize;
+
+use crate::fat_error::{FatError, FatResult};
+use crate::hal::shared_flash::MutexFlashStorage;
+
+/// Size of each save slot in bytes (16 KB).
+pub const SAVEGAME_SLOT_SIZE: usize = 16384;
+
+/// Number of slots in the 8 MB storage partition.
+pub const SAVEGAME_SLOT_COUNT: usize = 8 * 1024 * 1024 / SAVEGAME_SLOT_SIZE; // 512
+
+/// Metadata about a single existing save slot, returned by [`SavegameManager::list_saves`].
+#[derive(Serialize, Debug, Clone)]
+pub struct SaveInfo {
+    pub idx: usize,
+    pub len: u32,
+}
+
+// ── Flash adapter ──────────────────────────────────────────────────────────────
+
+/// Newtype wrapper around a [`PartitionError`] so we can implement the
+/// [`core::fmt::Debug`] bound required by [`embedded_savegame::storage::Flash`].
+#[derive(Debug)]
+pub struct SavegameFlashError(#[allow(dead_code)] PartitionError);
+
+/// Adapts a `&mut FlashRegion<'static, MutexFlashStorage>` to the
+/// [`embedded_savegame::storage::Flash`] trait.
+///
+/// `erase(addr)` erases exactly one slot (`SAVEGAME_SLOT_SIZE` bytes) starting
+/// at `addr`, which is what embedded-savegame expects for NOR flash.
+pub struct SavegameFlashAdapter<'a> {
+    region: &'a mut FlashRegion<'static, MutexFlashStorage>,
+}
+
+impl Flash for SavegameFlashAdapter<'_> {
+    type Error = SavegameFlashError;
+
+    fn read(&mut self, addr: u32, buf: &mut [u8]) -> Result<(), Self::Error> {
+        ReadNorFlash::read(self.region, addr, buf).map_err(SavegameFlashError)
+    }
+
+    fn write(&mut self, addr: u32, data: &mut [u8]) -> Result<(), Self::Error> {
+        NorFlash::write(self.region, addr, data).map_err(SavegameFlashError)
+    }
+
+    /// Erase one full slot at `addr`.
+    /// embedded-savegame calls this before writing to a slot, so we erase
+    /// the entire `SAVEGAME_SLOT_SIZE` bytes so subsequent writes land on
+    /// pre-erased (0xFF) pages.
+    fn erase(&mut self, addr: u32) -> Result<(), Self::Error> {
+        let end = addr + SAVEGAME_SLOT_SIZE as u32;
+        NorFlash::erase(self.region, addr, end).map_err(SavegameFlashError)
+    }
+}
+
+impl From<SavegameFlashError> for FatError {
+    fn from(e: SavegameFlashError) -> Self {
+        FatError::String {
+            error: alloc::format!("Savegame flash error: {:?}", e),
+        }
+    }
+}
+
+// ── SavegameManager ────────────────────────────────────────────────────────────
+
+/// High-level save-game manager that stores JSON config blobs on the storage
+/// partition using [`embedded_savegame`] for wear leveling and power-fail safety.
+pub struct SavegameManager {
+    region: &'static mut FlashRegion<'static, MutexFlashStorage>,
+}
+
+impl SavegameManager {
+    pub fn new(region: &'static mut FlashRegion<'static, MutexFlashStorage>) -> Self {
+        Self { region }
+    }
+
+    /// Build a short-lived [`Storage`] that borrows our flash region.
+    fn storage(
+        &mut self,
+    ) -> Storage<SavegameFlashAdapter<'_>, SAVEGAME_SLOT_SIZE, SAVEGAME_SLOT_COUNT> {
+        Storage::new(SavegameFlashAdapter {
+            region: &mut *self.region,
+        })
+    }
+
+    /// Persist `data` (JSON bytes) to the next available slot.
+    ///
+    /// `scan()` advances the internal wear-leveling pointer to the latest valid
+    /// slot before `append()` writes to the next free one.
+    pub fn save(&mut self, data: &mut [u8]) -> FatResult<()> {
+        let mut st = self.storage();
+        st.scan()?;
+        st.append(data)?;
+        Ok(())
+    }
+
+    /// Load the most recently saved data.  Returns `None` if no valid save exists.
+    pub fn load_latest(&mut self) -> FatResult<Option<Vec<u8>>> {
+        let mut st = self.storage();
+        let slot = st.scan()?;
+        match slot {
+            None => Ok(None),
+            Some(slot) => {
+                let mut buf = alloc::vec![0u8; SAVEGAME_SLOT_SIZE];
+                match st.read(slot.idx, &mut buf)? {
+                    None => Ok(None),
+                    Some(data) => Ok(Some(data.to_vec())),
+                }
+            }
+        }
+    }
+
+    /// Load a specific save by slot index.  Returns `None` if the slot is
+    /// empty or contains an invalid checksum.
+    pub fn load_slot(&mut self, idx: usize) -> FatResult<Option<Vec<u8>>> {
+        let mut st = self.storage();
+        let mut buf = alloc::vec![0u8; SAVEGAME_SLOT_SIZE];
+        match st.read(idx, &mut buf)? {
+            None => Ok(None),
+            Some(data) => Ok(Some(data.to_vec())),
+        }
+    }
+
+    /// Erase a specific slot by index, effectively deleting it.
+    pub fn delete_slot(&mut self, idx: usize) -> FatResult<()> {
+        let mut st = self.storage();
+        st.erase(idx).map_err(Into::into)
+    }
+
+    /// Iterate all slots and return metadata for every slot that contains a
+    /// valid save, using the Storage read API to avoid assuming internal slot structure.
+    pub fn list_saves(&mut self) -> FatResult<Vec<SaveInfo>> {
+        let mut saves = Vec::new();
+        let mut st = self.storage();
+        let mut buf = alloc::vec![0u8; SAVEGAME_SLOT_SIZE];
+        for idx in 0..SAVEGAME_SLOT_COUNT {
+            if let Some(data) = st.read(idx, &mut buf)? {
+                saves.push(SaveInfo {
+                    idx,
+                    len: data.len() as u32,
+                });
+            }
+        }
+        Ok(saves)
+    }
+}

Software/MainBoard/rust/src/hal/v4_hal.rs

@@ -340,19 +340,12 @@ impl<'a> BoardInteraction<'a> for V4<'a> {
                 bail!("pump current sensor not available");
             }
             Some(pump_ina) => {
-                let v = pump_ina
-                    .shunt_voltage()
-                    .map_err(|e| FatError::String {
-                        error: alloc::format!("{e:?}"),
-                    })
-                    .map(|v| {
-                        let shunt_voltage =
-                            Voltage::from_microvolts(v.shunt_voltage_uv().abs() as f64);
-                        let shut_value = Resistance::from_ohms(0.05_f64);
-                        let current = shunt_voltage.as_volts() / shut_value.as_ohms();
-                        Current::from_amperes(current)
-                    })?;
-                Ok(v)
+                let raw = pump_ina.shunt_voltage()?;
+                let shunt_voltage =
+                    Voltage::from_microvolts(raw.shunt_voltage_uv().abs() as f64);
+                let shut_value = Resistance::from_ohms(0.05_f64);
+                let current = shunt_voltage.as_volts() / shut_value.as_ohms();
+                Ok(Current::from_amperes(current))
             }
         }
     }
@@ -609,10 +602,8 @@ impl<'a> BoardInteraction<'a> for V4<'a> {
         let info: Result<(BackupHeader, usize), bincode::error::DecodeError> =
             bincode::decode_from_slice(&header_page_buffer[..], CONFIG);
         info!("decoding header: {:?}", info);
-        info.map(|(header, _)| header)
-            .map_err(|e| FatError::String {
-                error: "Could not read backup header: ".to_string() + &e.to_string(),
-            })
+        let (header, _) = info.context("Could not read backup header")?;
+        Ok(header)
     }
 }
 

Software/MainBoard/rust/src/webserver/file_manager.rs

@@ -1,160 +0,0 @@
-use crate::fat_error::{FatError, FatResult};
-use crate::webserver::read_up_to_bytes_from_request;
-use crate::BOARD_ACCESS;
-use alloc::borrow::ToOwned;
-use alloc::format;
-use alloc::string::String;
-use edge_http::io::server::Connection;
-use edge_http::Method;
-use edge_nal::io::{Read, Write};
-use log::info;
-
-pub(crate) async fn list_files<T, const N: usize>(
-    _request: &mut Connection<'_, T, N>,
-) -> FatResult<Option<String>> {
-    let mut board = BOARD_ACCESS.get().await.lock().await;
-    let result = board.board_hal.get_esp().list_files().await?;
-    let file_list_json = serde_json::to_string(&result)?;
-    Ok(Some(file_list_json))
-}
-pub(crate) async fn file_operations<T, const N: usize>(
-    conn: &mut Connection<'_, T, { N }>,
-    method: Method,
-    path: &&str,
-    prefix: &&str,
-) -> Result<Option<u32>, FatError>
-where
-    T: Read + Write,
-{
-    let filename = &path[prefix.len()..];
-    info!("file request for {filename} with method {method}");
-    Ok(match method {
-        Method::Delete => {
-            let mut board = BOARD_ACCESS.get().await.lock().await;
-            board
-                .board_hal
-                .get_esp()
-                .delete_file(filename.to_owned())
-                .await?;
-            conn.initiate_response(
-                200,
-                Some("OK"),
-                &[
-                    ("Access-Control-Allow-Origin", "*"),
-                    ("Access-Control-Allow-Headers", "*"),
-                    ("Access-Control-Allow-Methods", "*"),
-                ],
-            )
-            .await?;
-            Some(200)
-        }
-        Method::Get => {
-            let disposition = format!("attachment; filename=\"{filename}\"");
-            let size = {
-                let mut board = BOARD_ACCESS.get().await.lock().await;
-                board
-                    .board_hal
-                    .get_esp()
-                    .get_size(filename.to_owned())
-                    .await?
-            };
-
-            conn.initiate_response(
-                200,
-                Some("OK"),
-                &[
-                    ("Content-Type", "application/octet-stream"),
-                    ("Content-Disposition", disposition.as_str()),
-                    ("Content-Length", &format!("{size}")),
-                    ("Access-Control-Allow-Origin", "*"),
-                    ("Access-Control-Allow-Headers", "*"),
-                    ("Access-Control-Allow-Methods", "*"),
-                ],
-            )
-            .await?;
-
-            let mut chunk = 0;
-            loop {
-                let mut board = BOARD_ACCESS.get().await.lock().await;
-                board.board_hal.progress(chunk).await;
-                let read_chunk = board
-                    .board_hal
-                    .get_esp()
-                    .get_file(filename.to_owned(), chunk)
-                    .await?;
-                let length = read_chunk.1;
-                if length == 0 {
-                    info!("file request for {filename} finished");
-                    break;
-                }
-                let data = &read_chunk.0[0..length];
-                conn.write_all(data).await?;
-                if length < read_chunk.0.len() {
-                    info!("file request for {filename} finished");
-                    break;
-                }
-                chunk += 1;
-            }
-            BOARD_ACCESS
-                .get()
-                .await
-                .lock()
-                .await
-                .board_hal
-                .clear_progress()
-                .await;
-            Some(200)
-        }
-        Method::Post => {
-            {
-                let mut board = BOARD_ACCESS.get().await.lock().await;
-                //ensure the file is deleted first; otherwise we would need to truncate the file which will not work with streaming
-                let _ = board
-                    .board_hal
-                    .get_esp()
-                    .delete_file(filename.to_owned())
-                    .await;
-            }
-
-            let mut offset = 0_usize;
-            let mut chunk = 0;
-            loop {
-                let buf = read_up_to_bytes_from_request(conn, Some(4096)).await?;
-                if buf.is_empty() {
-                    info!("file request for {filename} finished");
-                    break;
-                } else {
-                    let mut board = BOARD_ACCESS.get().await.lock().await;
-                    board.board_hal.progress(chunk as u32).await;
-                    board
-                        .board_hal
-                        .get_esp()
-                        .write_file(filename.to_owned(), offset as u32, &buf)
-                        .await?;
-                }
-                offset += buf.len();
-                chunk += 1;
-            }
-            BOARD_ACCESS
-                .get()
-                .await
-                .lock()
-                .await
-                .board_hal
-                .clear_progress()
-                .await;
-            conn.initiate_response(
-                200,
-                Some("OK"),
-                &[
-                    ("Access-Control-Allow-Origin", "*"),
-                    ("Access-Control-Allow-Headers", "*"),
-                    ("Access-Control-Allow-Methods", "*"),
-                ],
-            )
-            .await?;
-            Some(200)
-        }
-        _ => None,
-    })
-}

Software/MainBoard/rust/src/webserver/get_json.rs

@@ -114,12 +114,39 @@ pub(crate) async fn get_version_web<T, const N: usize>(
     Ok(Some(serde_json::to_string(&get_version(&mut board).await)?))
 }
 
+/// Return the current in-memory config, or — when `saveidx` is `Some(idx)` —
+/// the JSON stored in save slot `idx`.
 pub(crate) async fn get_config<T, const N: usize>(
     _request: &mut Connection<'_, T, N>,
+    saveidx: Option<usize>,
+) -> FatResult<Option<String>> {
+    let mut board = BOARD_ACCESS.get().await.lock().await;
+    let json = match saveidx {
+        None => serde_json::to_string(board.board_hal.get_config())?,
+        Some(idx) => {
+             board.board_hal.get_esp().load_config_slot(idx).await?
+        }
+    };
+    Ok(Some(json))
+}
+
+/// Return a JSON array describing every valid save slot on flash.
+pub(crate) async fn list_saves<T, const N: usize>(
+    _request: &mut Connection<'_, T, N>,
 ) -> FatResult<Option<String>> {
     let mut board = BOARD_ACCESS.get().await.lock().await;
-    let json = serde_json::to_string(&board.board_hal.get_config())?;
-    Ok(Some(json))
+    let saves = board.board_hal.get_esp().list_saves().await?;
+    Ok(Some(serde_json::to_string(&saves)?))
+}
+
+/// Erase (delete) a single save slot by index.
+pub(crate) async fn delete_save<T, const N: usize>(
+    _request: &mut Connection<'_, T, N>,
+    idx: usize,
+) -> FatResult<Option<String>> {
+    let mut board = BOARD_ACCESS.get().await.lock().await;
+    board.board_hal.get_esp().delete_save_slot(idx).await?;
+    Ok(None)
 }
 
 pub(crate) async fn get_battery_state<T, const N: usize>(

Software/MainBoard/rust/src/webserver/mod.rs

@@ -1,7 +1,6 @@
 //offer ota and config mode
 
 mod backup_manager;
-mod file_manager;
 mod get_json;
 mod get_log;
 mod get_static;
@@ -10,10 +9,9 @@ mod post_json;
 
 use crate::fat_error::{FatError, FatResult};
 use crate::webserver::backup_manager::{backup_config, backup_info, get_backup_config};
-use crate::webserver::file_manager::{file_operations, list_files};
 use crate::webserver::get_json::{
     get_battery_state, get_config, get_live_moisture, get_log_localization_config, get_solar_state,
-    get_time, get_timezones, get_version_web, tank_info,
+    delete_save, get_time, get_timezones, get_version_web, list_saves, tank_info,
 };
 use crate::webserver::get_log::get_log;
 use crate::webserver::get_static::{serve_bundle, serve_favicon, serve_index};
@@ -60,10 +58,7 @@ impl Handler for HTTPRequestRouter {
         let method = headers.method;
         let path = headers.path;
 
-        let prefix = "/file?filename=";
-        let status = if path.starts_with(prefix) {
-            file_operations(conn, method, &path, &prefix).await?
-        } else if path == "/ota" {
+        let status = if path == "/ota" {
             ota_operations(conn, method).await.map_err(|e| {
                 error!("Error handling ota: {e}");
                 e
@@ -82,13 +77,20 @@ impl Handler for HTTPRequestRouter {
                             "/time" => Some(get_time(conn).await),
                             "/battery" => Some(get_battery_state(conn).await),
                             "/solar" => Some(get_solar_state(conn).await),
-                            "/get_config" => Some(get_config(conn).await),
-                            "/files" => Some(list_files(conn).await),
                             "/log_localization" => Some(get_log_localization_config(conn).await),
                             "/tank" => Some(tank_info(conn).await),
                             "/backup_info" => Some(backup_info(conn).await),
                             "/timezones" => Some(get_timezones().await),
                             "/moisture" => Some(get_live_moisture(conn).await),
+                            "/list_saves" => Some(list_saves(conn).await),
+                            // /get_config accepts an optional ?saveidx=N query parameter
+                            p if p == "/get_config" || p.starts_with("/get_config?") => {
+                                let saveidx: Option<usize> = p
+                                    .find("saveidx=")
+                                    .and_then(|pos| p[pos + 8..].split('&').next())
+                                    .and_then(|s| s.parse().ok());
+                                Some(get_config(conn, saveidx).await)
+                            }
                             _ => None,
                         };
                         match json {
@@ -127,7 +129,26 @@ impl Handler for HTTPRequestRouter {
                         Some(json) => Some(handle_json(conn, json).await?),
                     }
                 }
-                Method::Options | Method::Delete | Method::Head | Method::Put => None,
+                Method::Delete => {
+                    // DELETE /delete_save?idx=N
+                    let json = if path == "/delete_save" || path.starts_with("/delete_save?") {
+                        let idx: Option<usize> = path
+                            .find("idx=")
+                            .and_then(|pos| path[pos + 4..].split('&').next())
+                            .and_then(|s| s.parse().ok());
+                        match idx {
+                            Some(idx) => Some(delete_save(conn, idx).await),
+                            None => Some(Err(FatError::String { error: "missing idx parameter".into() })),
+                        }
+                    } else {
+                        None
+                    };
+                    match json {
+                        None => None,
+                        Some(json) => Some(handle_json(conn, json).await?),
+                    }
+                }
+                Method::Options | Method::Head | Method::Put => None,
                 _ => None,
             }
         };