diff --git a/web_server.py b/web_server.py
index f4a897ce..cb869f23 100644
--- a/web_server.py
+++ b/web_server.py
@@ -21053,10 +21053,17 @@ def _get_source_playlist_states(states, error_label, info_log_label=None):
 def _submit_sync_task(sync_playlist_id, playlist_name, spotify_tracks, playlist_image_url):
     """Submit a sync to the shared executor (closes over sync_executor /
     _run_sync_task / get_current_profile_id so the lifted start_sync helper
-    stays free of those globals)."""
+    stays free of those globals).
+
+    Used by ALL per-source discovery syncs (Spotify-Public/Tidal/Deezer/Qobuz/
+    YouTube/iTunes-link/ListenBrainz/Beatport). These have no per-request mode
+    selector, so honor the configured default (Settings > Playlist sync mode) —
+    otherwise they always ran 'replace' regardless of the setting (#792)."""
+    from core.sync.playlist_edit import normalize_sync_mode
+    _mode = normalize_sync_mode(None, config_manager.get('playlist_sync.mode', 'replace'))
     return sync_executor.submit(
         _run_sync_task, sync_playlist_id, playlist_name, spotify_tracks,
-        None, get_current_profile_id(), playlist_image_url,
+        None, get_current_profile_id(), playlist_image_url, _mode,
     )