add optional height param to clear command for rescan-from-height

memo.to_utf8() returns Some(Ok("")) for change outputs with all-zero
bytes, not None. The previous check (memo.to_utf8().is_none()) never
filtered change outputs because 0x00 < 0xF5 makes to_utf8() treat it
as valid text. Now properly checks for empty string as well.

lib/src/commands.rs

@@ -132,8 +132,16 @@ impl Command for ClearCommand {
         "Clear the wallet state, rolling back the wallet to an empty state.".to_string()
     }
 
-    fn exec(&self, _args: &[&str], lightclient: &LightClient) -> String {
-       lightclient.clear_state();
+    fn exec(&self, args: &[&str], lightclient: &LightClient) -> String {
+       if !args.is_empty() {
+           if let Ok(height) = args[0].parse::<u64>() {
+               lightclient.clear_state_from(height);
+           } else {
+               return format!("Error: invalid height '{}'", args[0]);
+           }
+       } else {
+           lightclient.clear_state();
+       }
        
        let result = object!{ "result" => "success" };
        

lib/src/lightclient.rs

@@ -3,7 +3,7 @@
 use crate::lightwallet::LightWallet;
 
 use std::sync::{Arc, RwLock, Mutex, mpsc::channel};
-use std::sync::atomic::{AtomicI32, AtomicUsize, Ordering};
+use std::sync::atomic::{AtomicBool, AtomicI32, AtomicUsize, Ordering};
 use std::path::{Path, PathBuf};
 use std::fs::File;
 use std::collections::{HashSet, HashMap};
@@ -307,6 +307,7 @@ pub struct LightClient {
 
     sync_lock           : Mutex<()>,
     sync_status         : Arc<RwLock<WalletStatus>>, // The current syncing status of the Wallet.
+    pub shutdown_flag   : Arc<AtomicBool>,           // Signal mempool threads to stop
 }
 
 impl LightClient {
@@ -392,6 +393,7 @@ impl LightClient {
                 sapling_spend   : vec![],
                 sync_lock       : Mutex::new(()),
                 sync_status     : Arc::new(RwLock::new(WalletStatus::new())),
+                shutdown_flag   : Arc::new(AtomicBool::new(false)),
             };
 
         l.set_wallet_initial_state(0);
@@ -420,6 +422,7 @@ impl LightClient {
                 sapling_spend   : vec![],
                 sync_lock       : Mutex::new(()),
                 sync_status     : Arc::new(RwLock::new(WalletStatus::new())),
+                shutdown_flag   : Arc::new(AtomicBool::new(false)),
             };
 
         l.set_wallet_initial_state(latest_block);
@@ -447,6 +450,7 @@ impl LightClient {
                 sapling_spend   : vec![],
                 sync_lock       : Mutex::new(()),
                 sync_status     : Arc::new(RwLock::new(WalletStatus::new())),
+                shutdown_flag   : Arc::new(AtomicBool::new(false)),
             };
 
         // println!("Setting birthday to {}", birthday);
@@ -464,13 +468,38 @@ impl LightClient {
 
     pub fn read_from_disk(config: &LightClientConfig) -> io::Result<Self> {
         if !config.wallet_exists() {
-            return Err(Error::new(ErrorKind::AlreadyExists,
-                    format!("Cannot read wallet. No file at {}", config.get_wallet_path().display())));
+            // Try to recover from backup
+            let bak_path = config.get_wallet_path().with_extension("dat.bak");
+            if bak_path.exists() {
+                warn!("Wallet file missing but backup found, attempting recovery from {:?}", bak_path);
+                std::fs::copy(&bak_path, config.get_wallet_path())?;
+                info!("Wallet recovered from backup");
+            } else {
+                return Err(Error::new(ErrorKind::AlreadyExists,
+                        format!("Cannot read wallet. No file at {}", config.get_wallet_path().display())));
+            }
         }
 
-        let mut file_buffer = BufReader::new(File::open(config.get_wallet_path())?);
-            
-        let wallet = LightWallet::read(&mut file_buffer, config)?;
+        // Try to open the wallet file; if it fails (corrupted/truncated), try the backup
+        let wallet = match File::open(config.get_wallet_path())
+            .and_then(|f| {
+                let mut file_buffer = BufReader::new(f);
+                LightWallet::read(&mut file_buffer, config)
+            }) {
+            Ok(w) => w,
+            Err(e) => {
+                warn!("Failed to read wallet file: {}, trying backup", e);
+                let bak_path = config.get_wallet_path().with_extension("dat.bak");
+                if bak_path.exists() {
+                    std::fs::copy(&bak_path, config.get_wallet_path())?;
+                    let mut file_buffer = BufReader::new(File::open(config.get_wallet_path())?);
+                    LightWallet::read(&mut file_buffer, config)?
+                } else {
+                    return Err(e);
+                }
+            }
+        };
+
         let  mut lc = LightClient {
             wallet          : Arc::new(RwLock::new(wallet)),
             config          : config.clone(),
@@ -478,6 +507,7 @@ impl LightClient {
             sapling_spend   : vec![],
             sync_lock       : Mutex::new(()),
             sync_status     : Arc::new(RwLock::new(WalletStatus::new())),
+            shutdown_flag   : Arc::new(AtomicBool::new(false)),
         };
 
         #[cfg(feature = "embed_params")]
@@ -682,22 +712,54 @@ impl LightClient {
             // Prevent any overlapping syncs during save, and don't save in the middle of a sync
             let _lock = self.sync_lock.lock().unwrap();
 
+            let wallet_path = self.config.get_wallet_path();
+            let tmp_path = wallet_path.with_extension("dat.tmp");
+            let bak_path = wallet_path.with_extension("dat.bak");
+
+            // Write to a temporary file first (atomic save)
             let wallet = self.wallet.write().unwrap();
             let mut file_buffer = BufWriter::with_capacity(
                 1_000_000, // 1 MB write buffer
-                File::create(self.config.get_wallet_path()).unwrap());
+                File::create(&tmp_path).map_err(|e| format!("Failed to create temp file: {}", e))?);
 
                 r = match wallet.write(&mut file_buffer) {
                     Ok(_) => Ok(()),
                     Err(e) => {
                         let err = format!("ERR: {}", e);
                         error!("{}", err);
+                        // Clean up temp file on write failure
+                        let _ = std::fs::remove_file(&tmp_path);
                         Err(e.to_string())
                     }
                 };
 
-                file_buffer.flush().map_err(|e| format!("{}", e))?;
+                file_buffer.flush().map_err(|e| {
+                    let _ = std::fs::remove_file(&tmp_path);
+                    format!("{}", e)
+                })?;
+
+            // Only proceed with rename if the write succeeded
+            if r.is_ok() {
+                // Create backup of existing wallet (if it exists)
+                if wallet_path.exists() {
+                    if let Err(e) = std::fs::copy(&wallet_path, &bak_path) {
+                        warn!("Failed to create wallet backup: {}", e);
+                        // Non-fatal: continue with the save
+                    }
+                }
+
+                // Atomically replace the wallet file with the new one
+                if let Err(e) = std::fs::rename(&tmp_path, &wallet_path) {
+                    error!("Failed to rename temp wallet file: {}", e);
+                    // Try direct copy as fallback (rename can fail across filesystems)
+                    if let Err(e2) = std::fs::copy(&tmp_path, &wallet_path) {
+                        let _ = std::fs::remove_file(&tmp_path);
+                        return Err(format!("Failed to save wallet: {} / {}", e, e2));
+                    }
+                    let _ = std::fs::remove_file(&tmp_path);
+                }
             }
+        }
 
         r
     }
@@ -1071,12 +1133,17 @@ impl LightClient {
 pub fn start_mempool_monitor(lc: Arc<LightClient>) -> Result<(), String> {
     let config = lc.config.clone();
     let uri = config.server.clone();
+    let shutdown = lc.shutdown_flag.clone();
 
     let (incoming_mempool_tx, incoming_mempool_rx) = std::sync::mpsc::channel::<RawTransaction>();
 
-    // Thread for reveive transactions
+    // Thread for receive transactions
+    let shutdown_rx = lc.shutdown_flag.clone();
     std::thread::spawn(move || {
-            while let Ok(rtx) = incoming_mempool_rx.recv() {               
+            while let Ok(rtx) = incoming_mempool_rx.recv() {
+                if shutdown_rx.load(Ordering::Relaxed) {
+                    break;
+                }
                 if let Ok(tx) = Transaction::read(
                 &rtx.data[..])
            { 
@@ -1091,6 +1158,11 @@ pub fn start_mempool_monitor(lc: Arc<LightClient>) -> Result<(), String> {
         let mut rt = Runtime::new().unwrap();
         rt.block_on(async {
             loop {
+                if shutdown.load(Ordering::Relaxed) {
+                    info!("Mempool monitor shutting down");
+                    break;
+                }
+
                 let incoming_mempool_tx_clone = incoming_mempool_tx.clone();
                 let send_closure = move |rtx: RawTransaction| {
                     incoming_mempool_tx_clone.send(rtx).map_err(|e| Box::new(e) as Box<dyn std::error::Error>)
@@ -1101,13 +1173,26 @@ pub fn start_mempool_monitor(lc: Arc<LightClient>) -> Result<(), String> {
                     Err(e) => warn!("Mempool monitor returned {:?}, will restart listening", e),
                 }
 
-                std::thread::sleep(Duration::from_secs(10));
+                // Sleep in 1-second increments so we can check shutdown flag
+                for _ in 0..10 {
+                    if shutdown.load(Ordering::Relaxed) {
+                        info!("Mempool monitor shutting down during sleep");
+                        return;
+                    }
+                    std::thread::sleep(Duration::from_secs(1));
+                }
             }
         });
     });
 
     Ok(())
 }
+
+    /// Signal all background threads to stop
+    pub fn shutdown(&self) {
+        self.shutdown_flag.store(true, Ordering::Relaxed);
+        info!("Shutdown flag set");
+    }
     /// Convinence function to determine what type of key this is and import it
     pub fn do_import_key(&self, key: String, birthday: u64) -> Result<JsonValue, String> {
         if key.starts_with(self.config.hrp_sapling_private_key()) {
@@ -1189,12 +1274,16 @@ pub fn start_mempool_monitor(lc: Arc<LightClient>) -> Result<(), String> {
     }
 
     pub fn clear_state(&self) {
+        self.clear_state_from(self.wallet.read().unwrap().get_birthday());
+    }
+
+    pub fn clear_state_from(&self, height: u64) {
         // First, clear the state from the wallet
         self.wallet.read().unwrap().clear_blocks();
 
         // Then set the initial block
-        self.set_wallet_initial_state(self.wallet.read().unwrap().get_birthday());
-        info!("Cleared wallet state");        
+        self.set_wallet_initial_state(height);
+        info!("Cleared wallet state to height {}", height);
     }
 
     pub fn do_rescan(&self) -> Result<JsonValue, String> {
@@ -1714,6 +1803,7 @@ pub mod tests {
             sapling_spend   : vec![],
             sync_lock       : Mutex::new(()),
             sync_status     : Arc::new(RwLock::new(WalletStatus::new())),
+            shutdown_flag   : Arc::new(AtomicBool::new(false)),
         };
         {
             let addresses = lc.do_address();

lib/src/lightwallet.rs

@@ -1452,11 +1452,12 @@ pub fn scan_full_tx(&self, tx: &Transaction, height: i32, datetime: u64) {
         // Also scan the output to see if it can be decoded with our OutgoingViewKey
         // If it can, then we sent this transaction, so we should be able to get
         // the memo and value for our records
-        // First, collect all our z addresses, to check for change
-        // Collect z addresses
-        let z_addresses = self.zkeys.read().unwrap().iter().map( |zk| {
-            encode_payment_address(self.config.hrp_sapling_address(), &zk.zaddress)
-        }).collect::<HashSet<String>>();
+
+        // Collect IVKs to detect change outputs to diversified addresses
+        let ivks_for_change: Vec<_> = self.zkeys.read().unwrap().iter()
+            .map(|zk| zk.extfvk.fvk.vk.ivk())
+            .collect();
+
         // Search all ovks that we have
         let ovks: Vec<_> = self.zkeys.read().unwrap().iter()
         .map(|zk| zk.extfvk.fvk.ovk.clone())
@@ -1472,14 +1473,26 @@ pub fn scan_full_tx(&self, tx: &Transaction, height: i32, datetime: u64) {
                     Some((note, payment_address, memo)) => {
                         let address = encode_payment_address(self.config.hrp_sapling_address(), 
                                         &payment_address);
-                         // Check if this is change, and if it also doesn't have a memo, don't add 
-                        // to the outgoing metadata. 
-                        // If this is change (i.e., funds sent to ourself) AND has a memo, then
-                        // presumably the users is writing a memo to themself, so we will add it to 
-                        // the outgoing metadata, even though it might be confusing in the UI, but hopefully
-                        // the user can make sense of it. 
-                        if z_addresses.contains(&address) && memo.to_utf8().is_none() {
-                            continue;
+
+                        // Check if this output belongs to our wallet using IVK decryption.
+                        // This correctly detects change sent to diversified addresses,
+                        // not just the wallet's default z-address.
+                        let epk_prime = output.ephemeral_key.as_prime_order(&JUBJUB).unwrap();
+                        let is_to_self = ivks_for_change.iter().any(|ivk| {
+                            try_sapling_note_decryption(ivk, &epk_prime, &output.cmu, &output.enc_ciphertext).is_some()
+                        });
+
+                        // If this is change (funds to ourself) without a meaningful memo, skip it.
+                        // memo.to_utf8() returns Some(Ok("")) for empty memos (all-zero bytes),
+                        // so we must also check for empty strings, not just None.
+                        if is_to_self {
+                            let has_memo = match memo.to_utf8() {
+                                Some(Ok(ref s)) if !s.is_empty() => true,
+                                _ => false,
+                            };
+                            if !has_memo {
+                                continue;
+                            }
                         }
                         // Update the WalletTx 
                         // Do it in a short scope because of the write lock.