After updates

config.yaml

@@ -70,12 +70,18 @@ model:
 # -----------------------------------------------------
 # Directory Scanner
 # -----------------------------------------------------
+# Scans the permanent storage location in place (no staging/copy step).
+# The corpus is large (~163k files / ~41TB), so the default interval is 2 hours.
+# A single-instance guard (in-process lock + DB lock with a lease) ensures a
+# long-running scan never overlaps another scan, even across replicas.
 scanner:
-  scan_interval_seconds: 60
+  scan_interval_seconds: 7200   # 2 hours (adaptive: raise for very large corpora)
   walker_threads: 8
   ffprobe_timeout_seconds: 10
   hash_algorithm: sha256
   hash_chunk_size_mb: 1
+  lock_lease_seconds: 21600     # 6 hours: max time a scan may hold the lock before it is considered stale
+  heartbeat_interval_files: 500 # refresh the lock lease every N files processed
 
 # -----------------------------------------------------
 # Codec Validation