diff --git a/tests/test_core.py b/tests/test_core.py
index 98ba4bd..be2c3cc 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -103,8 +103,18 @@ def test_start_ssh_agent_reuse(ssh_manager, mocker):
     mock_load_agent = mocker.patch.object(ssh_manager, "_load_agent_info")
     mock_verify_key = mocker.patch.object(ssh_manager, "_verify_loaded_key")
     mock_run_command = mocker.patch.object(ssh_manager, "run_command")
+    mock_add_key = mocker.patch.object(ssh_manager, "_add_ssh_key")
     mock_logger = mocker.patch("persistent_ssh_agent.core.logger")
 
+    # Mock run_command to return a successful result with proper stdout
+    class MockResult:
+        returncode = 0
+        stdout = "SSH_AUTH_SOCK=/tmp/ssh-XXX/agent.123; export SSH_AUTH_SOCK;\nSSH_AGENT_PID=123; export SSH_AGENT_PID;"
+    mock_run_command.return_value = MockResult()
+
+    # Mock successful key operations
+    mock_add_key.return_value = True
+
     # Test case 1: Successfully reuse existing agent
     mock_load_agent.return_value = True
     mock_verify_key.return_value = True
@@ -112,34 +122,58 @@ def test_start_ssh_agent_reuse(ssh_manager, mocker):
 
     assert ssh_manager._start_ssh_agent(identity_file) is True
     mock_logger.debug.assert_called_with("Using existing agent with loaded key: %s", identity_file)
-    mock_run_command.assert_not_called()
 
     # Test case 2: Found agent but key not loaded
     mock_verify_key.return_value = False
+    mock_logger.debug.reset_mock()  # Reset mock to clear previous calls
+
     assert ssh_manager._start_ssh_agent(identity_file) is True
-    mock_logger.debug.assert_called_with("Existing agent found but key not loaded")
+    mock_logger.debug.assert_has_calls([
+        mocker.call("Existing agent found but key not loaded"),
+        mocker.call("Saved agent info to: %s", ssh_manager._agent_info_file),
+        mocker.call("Adding key to agent: %s", identity_file)
+    ], any_order=False)
 
     # Test case 3: No valid agent found
     mock_load_agent.return_value = False
+    mock_logger.debug.reset_mock()
+
     assert ssh_manager._start_ssh_agent(identity_file) is True
-    mock_logger.debug.assert_called_with("No valid existing agent found")
+    mock_logger.debug.assert_has_calls([
+        mocker.call("No valid existing agent found"),
+        mocker.call("Saved agent info to: %s", ssh_manager._agent_info_file),
+        mocker.call("Adding key to agent: %s", identity_file)
+    ], any_order=False)
 
     # Test case 4: Agent reuse disabled
     ssh_manager._reuse_agent = False
+    mock_logger.debug.reset_mock()
+
     assert ssh_manager._start_ssh_agent(identity_file) is True
-    mock_logger.debug.assert_called_with("Agent reuse disabled, starting new agent")
+    mock_logger.debug.assert_has_calls([
+        mocker.call("Agent reuse disabled, starting new agent"),
+        mocker.call("Saved agent info to: %s", ssh_manager._agent_info_file),
+        mocker.call("Adding key to agent: %s", identity_file)
+    ], any_order=False)
 
 
 def test_start_ssh_agent_platform_specific(ssh_manager, mocker):
     """Test platform-specific SSH agent startup."""
     mock_run_command = mocker.patch.object(ssh_manager, "run_command")
     mock_os = mocker.patch("persistent_ssh_agent.core.os")
+    mock_verify_key = mocker.patch.object(ssh_manager, "_verify_loaded_key")
+    mock_add_key = mocker.patch.object(ssh_manager, "_add_ssh_key")
 
-    # Mock run_command to return a successful result
+    # Mock run_command to return a successful result with proper stdout
     class MockResult:
         returncode = 0
+        stdout = "SSH_AUTH_SOCK=/tmp/ssh-XXX/agent.123; export SSH_AUTH_SOCK;\nSSH_AGENT_PID=123; export SSH_AGENT_PID;"
     mock_run_command.return_value = MockResult()
 
+    # Mock successful key operations
+    mock_verify_key.return_value = False  # Key not loaded initially
+    mock_add_key.return_value = True  # Key added successfully
+
     # Test Windows (nt) platform
     mock_os.name = "nt"
     ssh_manager._reuse_agent = False  # Disable reuse to test agent startup
diff --git a/tests/test_core_coverage.py b/tests/test_core_coverage.py
index 5a93323..849ded7 100644
--- a/tests/test_core_coverage.py
+++ b/tests/test_core_coverage.py
@@ -755,7 +755,8 @@ def test_error_handling_edge_cases(ssh_manager):
     with patch.object(ssh_manager, "run_command") as mock_run, \
          patch("builtins.open", mock_open()) as mock_file, \
          patch("os.path.exists") as mock_exists, \
-         patch("json.load") as mock_load:
+         patch("json.load") as mock_load, \
+         patch("os.name", "nt"):  # Mock Windows platform for consistent testing
 
         # Test file read error with permission denied
         mock_exists.return_value = True
@@ -773,14 +774,23 @@ def test_error_handling_edge_cases(ssh_manager):
             "timestamp": time.time(),
             "SSH_AUTH_SOCK": "test_sock",
             "SSH_AGENT_PID": "test_pid",
-            "platform": "wrong_platform"  # Use wrong platform to trigger error
+            "platform": "nt"  # Match the mocked Windows platform
         }
         mock_run.return_value = subprocess.CompletedProcess(
-            args=[], returncode=0, stdout=b"", stderr=b""
+            args=[], returncode=2, stdout=b"", stderr=b""  # Return code 2 indicates agent not running
         )
         with patch.dict(os.environ, {}, clear=True):
             assert not ssh_manager._load_agent_info()
 
+        # Test platform mismatch error
+        mock_load.return_value = {
+            "timestamp": time.time(),
+            "SSH_AUTH_SOCK": "test_sock",
+            "SSH_AGENT_PID": "test_pid",
+            "platform": "posix"  # Mismatch with Windows platform
+        }
+        assert not ssh_manager._load_agent_info()
+
 
 def test_ssh_config_advanced_parsing(ssh_manager):
     """Test advanced SSH config parsing scenarios."""