diff --git a/CHANGELOG.md b/CHANGELOG.md
index 68d0e08b..516d7906 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,7 @@
 - **ISO completion diagnostics** — strict per-packet validation now records a bounded snapshot of packet lengths, transfer slots, and the selected wire format on the first mismatch, without accepting packets more loosely. This is diagnostic groundwork for #354, not a compatibility workaround.
 
 ### Network & SMB
+- **SMB account formats and interrupted syncs** — usernames in `DOMAIN\user` or `user@domain` form now reach NTLM split into the account and domain a Windows client would send. If a library walk is interrupted, already-listed tracks are imported, stale rows are not purged, and the failure still surfaces so the next sync can finish the job.
 - **SMB sync resilience** — an unreadable or vanished child folder no longer aborts the whole library scan; directory loops are depth-capped and duplicate paths are skipped. Folder art larger than the server's single-READ limit now loads through the pipelined reader.
 - **SMB playback robustness** — a failing progress callback can no longer cancel a shared transfer or start a duplicate download, cache accounting failures no longer discard a completed file, a disappearing cache entry is treated as a miss, a changed remote file invalidates its cached bytes on resync, and a failed next-track download reports cleanly instead of throwing in the background.
 - **Atomic SMB downloads** — playback, next-track prefetch, and gapless preparation for the same file share one transfer. Downloads publish only after the native completion event, a consistent byte count, and a matching on-disk length; short, cancelled, and incomplete transfers delete their staging file and stay retryable.
diff --git a/docs/SMB_VALIDATION.md b/docs/SMB_VALIDATION.md
index 141d23f8..c5ced209 100644
--- a/docs/SMB_VALIDATION.md
+++ b/docs/SMB_VALIDATION.md
@@ -10,10 +10,15 @@ permission for every file or successful decoding/output.
 Library sync treats the configured root as mandatory but skips an unreadable or
 vanished child directory (common on Windows shares: `System Volume
 Information`, per-user folders, or a folder deleted mid-scan) instead of
-aborting the whole sync. Directory identities are de-duplicated and recursion is
-depth-capped so junction/DFS loops cannot run forever. Cover-art reads use the
-pipelined reader, so images larger than the server's single-READ limit still
-load.
+aborting the whole sync. If the walk is interrupted before it finishes, the
+entries already listed are imported, but stale rows are not purged and the scan
+still reports failure so the next attempt can complete it. Directory identities
+are de-duplicated and recursion is depth-capped so junction/DFS loops cannot
+run forever. Cover-art reads use the pipelined reader, so images larger than the
+server's single-READ limit still load.
+
+Username fields accept `DOMAIN\user` and `user@domain`; the native client
+receives the account and domain separately, matching a Windows client.
 
 Downloads use a same-directory hidden staging file, verify the server's byte
 count, then close and atomically rename it. Dart also requires the completion
@@ -70,6 +75,9 @@ posting addresses, share names or credentials.
 4. Interrupt Wi-Fi mid-download, restore it and retry **without clearing app
    data**. No partial file should play. Repeat with next-track prefetch running
    while manually selecting that track; both callers should use one transfer.
+   Also interrupt a library sync and confirm already-listed tracks stay while
+   the UI still reports the failure; a later successful sync must purge stale
+   rows normally.
 5. Upgrade from a build with a failed SMB transfer. The old cache file must not
    be reused. Check subsequent cache hits and cache-cap eviction.
 6. Fail file decoding/output deliberately; the playback banner should distinguish
diff --git a/lib/services/sources/smb_service.dart b/lib/services/sources/smb_service.dart
index 41d8b4ed..f5b74fc5 100644
--- a/lib/services/sources/smb_service.dart
+++ b/lib/services/sources/smb_service.dart
@@ -420,28 +420,40 @@ class SmbService implements NetworkSourceService {
     // cover/audio classification), yielding progress as the walk streams in.
     final byDir = <String, List<SmbEntry>>{};
     var totalEntries = 0;
-    await for (final entry in smbListShare(
-      host: s.host,
-      port: s.port,
-      share: s.share,
-      user: user,
-      pass: pass,
-      rootPath: s.rootPath,
-    )) {
-      totalEntries++;
-      if (!entry.isDir) {
-        final parent = _parentDir(entry.path);
-        (byDir[parent] ??= <SmbEntry>[]).add(entry);
-      }
-      if (totalEntries % 500 == 0) {
-        yield ScanProgress(
-          songsFound: 0,
-          totalFiles: totalEntries,
-          filesProcessed: totalEntries,
-          phase: 'Syncing ${server.label}',
-          currentFile: entry.name,
-        );
+    Object? walkError;
+    StackTrace? walkStackTrace;
+    try {
+      await for (final entry in smbListShare(
+        host: s.host,
+        port: s.port,
+        share: s.share,
+        user: user,
+        pass: pass,
+        rootPath: s.rootPath,
+      )) {
+        totalEntries++;
+        if (!entry.isDir) {
+          final parent = _parentDir(entry.path);
+          (byDir[parent] ??= <SmbEntry>[]).add(entry);
+        }
+        if (totalEntries % 500 == 0) {
+          yield ScanProgress(
+            songsFound: 0,
+            totalFiles: totalEntries,
+            filesProcessed: totalEntries,
+            phase: 'Syncing ${server.label}',
+            currentFile: entry.name,
+          );
+        }
       }
+    } catch (e, stackTrace) {
+      // A connection drop halfway through the tree must not throw away the
+      // entries already collected. Import them below, but never purge rows we
+      // simply did not reach, then surface the incomplete scan to the caller.
+      walkError = e;
+      walkStackTrace = stackTrace;
+      final failure = SmbFailure.from(e);
+      AppLog.instance.add('$failure result=partial entries=$totalEntries');
     }
 
     final syncedRemoteIds = <String>{};
@@ -492,6 +504,12 @@ class SmbService implements NetworkSourceService {
       songsFound += entities.length;
     }
 
+    if (walkError != null) {
+      // Imported rows stay; no purge or lastSyncedAt stamp for an incomplete
+      // walk, because unseen files are not stale.
+      Error.throwWithStackTrace(walkError, walkStackTrace!);
+    }
+
     await purgeAndStampNetworkSync(server, syncedRemoteIds);
 
     yield ScanProgress(
diff --git a/rust/src/api/smb_api.rs b/rust/src/api/smb_api.rs
index 7ac42dda..acb83c3b 100644
--- a/rust/src/api/smb_api.rs
+++ b/rust/src/api/smb_api.rs
@@ -51,14 +51,34 @@ fn failure(stage: &str, error: smb2::Error) -> anyhow::Error {
     anyhow::anyhow!("SMB stage={} code={}", stage, error_code(&error))
 }
 
+/// `smb2` takes the account name and domain separately. Users commonly type
+/// `DOMAIN\user` or `user@domain` into the single username field; split those
+/// forms so NTLM receives the pieces a Windows client would send. Plain local
+/// accounts pass through unchanged.
+fn split_account(user: &str) -> (&str, &str) {
+    if let Some((domain, account)) = user.split_once('\\') {
+        if !domain.is_empty() && !account.is_empty() {
+            return (account, domain);
+        }
+    }
+    if let Some((account, domain)) = user.split_once('@') {
+        if !account.is_empty() && !domain.is_empty() {
+            return (account, domain);
+        }
+    }
+    (user, "")
+}
+
 /// Shared client configuration. `smb2::connect`'s shorthand is a five-second,
 /// no-reconnect client; a share on a waking NAS, or a Wi-Fi roam between
 /// tracks, should recover in place instead of failing the whole transfer.
 fn client_config(host: &str, port: u16, user: &str, pass: &str) -> smb2::ClientConfig {
+    let (account, domain) = split_account(user);
     smb2::ClientConfig {
         addr: addr(host, port),
-        username: user.to_string(),
+        username: account.to_string(),
         password: pass.to_string(),
+        domain: domain.to_string(),
         timeout: Duration::from_secs(15),
         auto_reconnect: true,
         ..Default::default()
@@ -334,7 +354,7 @@ pub async fn smb_download_file(
 mod tests {
     use super::{
         addr, client_config, failure, should_skip_directory_error, skippable_subdirectory_error,
-        PendingDownload,
+        split_account, PendingDownload,
     };
     use std::io::Write;
     use std::path::PathBuf;
@@ -466,7 +486,25 @@ mod tests {
         assert_eq!(config.addr, "nas.local:1445");
         assert_eq!(config.username, "user");
         assert_eq!(config.password, "pass");
+        assert_eq!(config.domain, "");
         assert!(config.auto_reconnect);
         assert_eq!(config.timeout, Duration::from_secs(15));
     }
+
+    #[test]
+    fn account_formats_split_domain_and_user() {
+        assert_eq!(split_account("alice"), ("alice", ""));
+        assert_eq!(split_account(r"CORP\alice"), ("alice", "CORP"));
+        assert_eq!(
+            split_account("alice@corp.example"),
+            ("alice", "corp.example")
+        );
+        assert_eq!(split_account(""), ("", ""));
+        assert_eq!(split_account(r"DOMAIN\"), (r"DOMAIN\", ""));
+        assert_eq!(split_account(r"\alice"), (r"\alice", ""));
+
+        let config = client_config("nas.local", 445, r"CORP\alice", "pass");
+        assert_eq!(config.username, "alice");
+        assert_eq!(config.domain, "CORP");
+    }
 }