Expand active project wave and serialize refreshes

src/atocore/ingestion/pipeline.py

@@ -2,8 +2,10 @@
 
 import hashlib
 import json
+import threading
 import time
 import uuid
+from contextlib import contextmanager
 from pathlib import Path
 
 import atocore.config as _config
@@ -17,6 +19,17 @@ log = get_logger("ingestion")
 
 # Encodings to try when reading markdown files
 _ENCODINGS = ["utf-8", "utf-8-sig", "latin-1", "cp1252"]
+_INGESTION_LOCK = threading.Lock()
+
+
+@contextmanager
+def exclusive_ingestion():
+    """Serialize long-running ingestion operations across API requests."""
+    _INGESTION_LOCK.acquire()
+    try:
+        yield
+    finally:
+        _INGESTION_LOCK.release()
 
 
 def ingest_file(file_path: Path) -> dict: