fix(session_search): coerce limit to int to prevent TypeError with non-int values (#10522)

Models (especially open-source like qwen3.5-plus) may send non-int values
for the limit parameter — None (JSON null), string, or even a type object.
This caused TypeError: '<=' not supported between instances of 'int' and
'type' when the value reached min()/comparison operations.

Changes:
- Add defensive int coercion at session_search() entry with fallback to 3
- Clamp limit to [1, 5] range (was only capped at 5, not floored)
- Add tests for None, type object, string, negative, and zero limit values

Reported by community user ludoSifu via Discord.

tests/tools/test_session_search.py

@@ -290,6 +290,63 @@ class TestSessionSearch:
         assert result["results"] == []
         assert result["sessions_searched"] == 0
 
+    def test_limit_none_coerced_to_default(self):
+        """Model sends limit=null → should fall back to 3, not TypeError."""
+        from unittest.mock import MagicMock
+        from tools.session_search_tool import session_search
+
+        mock_db = MagicMock()
+        mock_db.search_messages.return_value = []
+
+        result = json.loads(session_search(
+            query="test", db=mock_db, limit=None,
+        ))
+        assert result["success"] is True
+
+    def test_limit_type_object_coerced_to_default(self):
+        """Model sends limit as a type object → should fall back to 3, not TypeError."""
+        from unittest.mock import MagicMock
+        from tools.session_search_tool import session_search
+
+        mock_db = MagicMock()
+        mock_db.search_messages.return_value = []
+
+        result = json.loads(session_search(
+            query="test", db=mock_db, limit=int,
+        ))
+        assert result["success"] is True
+
+    def test_limit_string_coerced(self):
+        """Model sends limit as string '2' → should coerce to int."""
+        from unittest.mock import MagicMock
+        from tools.session_search_tool import session_search
+
+        mock_db = MagicMock()
+        mock_db.search_messages.return_value = []
+
+        result = json.loads(session_search(
+            query="test", db=mock_db, limit="2",
+        ))
+        assert result["success"] is True
+
+    def test_limit_clamped_to_range(self):
+        """Negative or zero limit should be clamped to 1."""
+        from unittest.mock import MagicMock
+        from tools.session_search_tool import session_search
+
+        mock_db = MagicMock()
+        mock_db.search_messages.return_value = []
+
+        result = json.loads(session_search(
+            query="test", db=mock_db, limit=-5,
+        ))
+        assert result["success"] is True
+
+        result = json.loads(session_search(
+            query="test", db=mock_db, limit=0,
+        ))
+        assert result["success"] is True
+
     def test_current_root_session_excludes_child_lineage(self):
         """Delegation child hits should be excluded when they resolve to the current root session."""
         from unittest.mock import MagicMock

tools/session_search_tool.py

@@ -310,7 +310,15 @@ def session_search(
     if db is None:
         return tool_error("Session database not available.", success=False)
 
-    limit = min(limit, 5)  # Cap at 5 sessions to avoid excessive LLM calls
+    # Defensive: models (especially open-source) may send non-int limit values
+    # (None when JSON null, string "int", or even a type object).  Coerce to a
+    # safe integer before any arithmetic/comparison to prevent TypeError.
+    if not isinstance(limit, int):
+        try:
+            limit = int(limit)
+        except (TypeError, ValueError):
+            limit = 3
+    limit = max(1, min(limit, 5))  # Clamp to [1, 5]
 
     # Recent sessions mode: when query is empty, return metadata for recent sessions.
     # No LLM calls — just DB queries for titles, previews, timestamps.