enable sqlite wal mode for file databases

app/database.py

@@ -45,6 +45,15 @@ def _get_connection_string(db_path) -> tuple[str, dict]:
     return db_path, {}
 
 
+def _is_file_database(db_path) -> bool:
+    """Check if database path refers to a file (not in-memory)."""
+    if isinstance(db_path, Path):
+        return True
+    if isinstance(db_path, str) and db_path not in (":memory:", ""):
+        return not db_path.startswith("file::memory:")
+    return False
+
+
 def get_db() -> sqlite3.Connection:
     """Get database connection for current request context."""
     if "db" not in g:
@@ -53,8 +62,10 @@ def get_db() -> sqlite3.Connection:
         g.db = sqlite3.connect(conn_str, **kwargs)
         g.db.row_factory = sqlite3.Row
         g.db.execute("PRAGMA foreign_keys = ON")
-        if isinstance(db_path, Path):
-            g.db.execute("PRAGMA journal_mode = WAL")
+        if _is_file_database(db_path):
+            # WAL mode set in init_db; these optimize per-connection behavior
+            g.db.execute("PRAGMA busy_timeout = 5000")
+            g.db.execute("PRAGMA synchronous = NORMAL")
     return g.db
 
 
@@ -79,6 +90,9 @@ def init_db() -> None:
         _memory_db_holder.commit()
     else:
         db = get_db()
+        # Enable WAL mode for file databases (persists with database)
+        if _is_file_database(db_path):
+            db.execute("PRAGMA journal_mode = WAL")
         db.executescript(SCHEMA)
         db.commit()