test: strengthen assertions across 3 more test files (batch 2)

test_run_agent.py (2 weak → 0, +13 assertions):
  - Session ID validated against actual YYYYMMDD_HHMMSS_hex format
  - API failure verifies error message propagation
  - Invalid JSON args verifies empty dict fallback + message structure
  - Context compression verifies final_response + completed flag
  - Invalid tool name retry verifies api_calls count
  - Invalid response verifies completed/failed/error structure

test_model_tools.py (3 weak → 0):
  - Unknown tool error includes tool name in message
  - Exception returns dict with 'error' key + non-empty message
  - get_all_tool_names verifies both web_search AND terminal present

test_approval.py (1 weak → 0, assert ratio 1.1 → 2.2):
  - Dangerous commands verify description content (delete, shell, drop, etc.)
  - Safe commands explicitly assert key AND desc are None
  - Pre/post condition checks for state management

tests/test_model_tools.py

@@ -27,12 +27,16 @@ class TestHandleFunctionCall:
     def test_unknown_tool_returns_error(self):
         result = json.loads(handle_function_call("totally_fake_tool_xyz", {}))
         assert "error" in result
+        assert "totally_fake_tool_xyz" in result["error"]
 
     def test_exception_returns_json_error(self):
         # Even if something goes wrong, should return valid JSON
         result = handle_function_call("web_search", None)  # None args may cause issues
         parsed = json.loads(result)
         assert isinstance(parsed, dict)
+        assert "error" in parsed
+        assert len(parsed["error"]) > 0
+        assert "error" in parsed["error"].lower() or "failed" in parsed["error"].lower()
 
 
 # =========================================================================
@@ -82,7 +86,8 @@ class TestBackwardCompat:
         assert isinstance(names, list)
         assert len(names) > 0
         # Should contain well-known tools
-        assert "web_search" in names or "terminal" in names
+        assert "web_search" in names
+        assert "terminal" in names
 
     def test_get_toolset_for_tool(self):
         result = get_toolset_for_tool("web_search")