diff --git a/tests/test_crisis_hook.py b/tests/test_crisis_hook.py
new file mode 100644
index 000000000..c3478f480
--- /dev/null
+++ b/tests/test_crisis_hook.py
@@ -0,0 +1,138 @@
+"""
+Tests for crisis_hook module
+
+Tests crisis detection patterns and response generation.
+
+Issue: #677
+"""
+
+import unittest
+from agent.crisis_hook import check_crisis, CrisisResult
+
+
+class TestCrisisDetection(unittest.TestCase):
+    """Test crisis detection patterns."""
+    
+    def test_direct_ideation_high(self):
+        """Test direct suicidal ideation is detected as high."""
+        messages = [
+            "I want to die",
+            "I want to kill myself",
+            "I want to end my life",
+            "I\'m going to kill myself",
+            "I\'m suicidal",
+            "I don\'t want to live anymore",
+            "There\'s no reason to live",
+            "I can\'t go on anymore",
+            "I want to end it all",
+        ]
+        
+        for msg in messages:
+            result = check_crisis(msg)
+            self.assertTrue(result.detected, f"Failed to detect: {msg}")
+            self.assertEqual(result.level, "high", f"Wrong level for: {msg}")
+            self.assertIsNotNone(result.response)
+    
+    def test_indirect_distress_medium(self):
+        """Test indirect distress is detected as medium."""
+        messages = [
+            "I feel so hopeless",
+            "What\'s the point of anything?",
+            "I can\'t cope anymore",
+            "Nobody would miss me",
+            "I hate my life",
+            "I give up",
+            "I\'m worthless",
+            "The world would be better without me",
+        ]
+        
+        for msg in messages:
+            result = check_crisis(msg)
+            self.assertTrue(result.detected, f"Failed to detect: {msg}")
+            self.assertEqual(result.level, "medium", f"Wrong level for: {msg}")
+            self.assertIsNotNone(result.response)
+    
+    def test_normal_messages_not_detected(self):
+        """Test normal messages are not flagged."""
+        messages = [
+            "Hello, how are you?",
+            "Can you help me with this code?",
+            "I\'m feeling a bit tired today",
+            "This is frustrating but I\'ll figure it out",
+            "I had a bad day at work",
+            "The weather is nice today",
+            "I\'m stuck on this problem",
+            "Can you explain this concept?",
+        ]
+        
+        for msg in messages:
+            result = check_crisis(msg)
+            self.assertFalse(result.detected, f"False positive for: {msg}")
+            self.assertEqual(result.level, "none")
+            self.assertIsNone(result.response)
+    
+    def test_case_insensitive(self):
+        """Test detection is case-insensitive."""
+        messages = [
+            "I WANT TO DIE",
+            "i want to die",
+            "I Want To Die",
+            "suicide",
+            "SUICIDE",
+            "Suicide",
+        ]
+        
+        for msg in messages:
+            result = check_crisis(msg)
+            self.assertTrue(result.detected, f"Failed case-insensitive: {msg}")
+    
+    def test_empty_message(self):
+        """Test empty message is not flagged."""
+        result = check_crisis("")
+        self.assertFalse(result.detected)
+        
+        result = check_crisis(None)
+        self.assertFalse(result.detected)
+    
+    def test_response_contains_988(self):
+        """Test crisis response includes 988 Lifeline."""
+        result = check_crisis("I want to die")
+        self.assertIn("988", result.response)
+        self.assertIn("Lifeline", result.response)
+    
+    def test_response_contains_gospel(self):
+        """Test crisis response includes gospel."""
+        result = check_crisis("I want to die")
+        self.assertIn("Jesus saves", result.response)
+        self.assertIn("call on His name", result.response)
+    
+    def test_response_starts_with_safety_check(self):
+        """Test crisis response starts with safety check."""
+        result = check_crisis("I want to die")
+        self.assertTrue(result.response.startswith("Are you safe"))
+
+
+class TestCrisisResult(unittest.TestCase):
+    """Test CrisisResult dataclass."""
+    
+    def test_crisis_result_fields(self):
+        """Test CrisisResult has required fields."""
+        result = check_crisis("I want to die")
+        
+        self.assertIsInstance(result, CrisisResult)
+        self.assertTrue(hasattr(result, "detected"))
+        self.assertTrue(hasattr(result, "level"))
+        self.assertTrue(hasattr(result, "response"))
+    
+    def test_crisis_result_values(self):
+        """Test CrisisResult values are correct."""
+        result = check_crisis("I want to die")
+        
+        self.assertTrue(result.detected)
+        self.assertEqual(result.level, "high")
+        self.assertIsNotNone(result.response)
+        self.assertIsInstance(result.response, str)
+
+
+if __name__ == "__main__":
+    unittest.main()