fix(memory): escape delimiters when building the session scope key (#6892)

mem0/memory/main.py

@@ -404,13 +404,18 @@ def _build_filters_and_metadata(
     return base_metadata_template, effective_query_filters
 
 
+def _escape_scope_value(val: Any) -> str:
+    """Escape the structural delimiters of the session scope key."""
+    return str(val).replace("%", "%25").replace("&", "%26").replace("=", "%3D")
+
+
 def _build_session_scope(filters):
     """Build deterministic session scope string from entity IDs."""
     parts = []
     for key in sorted(["user_id", "agent_id", "run_id"]):
         val = filters.get(key)
         if val:
-            parts.append(f"{key}={val}")
+            parts.append(f"{key}={_escape_scope_value(val)}")
     return "&".join(parts)