Add advanced search engine with inverted index, thread pool execution, configuration API, and comprehensive diagnostics

backend/indexer.py

@@ -22,6 +22,10 @@ vault_config: Dict[str, Dict[str, Any]] = {}
 # Thread-safe lock for index updates
 _index_lock = threading.Lock()
 
+# Generation counter — incremented on each index rebuild so consumers
+# (e.g. the inverted index in search.py) can detect staleness.
+_index_generation: int = 0
+
 # O(1) lookup table for wikilink resolution: {filename_lower: [{vault, path}, ...]}
 _file_lookup: Dict[str, List[Dict[str, str]]] = {}
 
@@ -318,6 +322,7 @@ async def build_index() -> None:
         new_path_index[vname] = vdata.get("paths", [])
     
     # Atomic swap under lock for thread safety during concurrent reads
+    global _index_generation
     with _index_lock:
         index.clear()
         index.update(new_index)
@@ -325,6 +330,7 @@ async def build_index() -> None:
         _file_lookup.update(new_lookup)
         path_index.clear()
         path_index.update(new_path_index)
+        _index_generation += 1
 
     total_files = sum(len(v["files"]) for v in index.values())
     logger.info(f"Index built: {len(index)} vaults, {total_files} total files")