diff --git a/tests/integration/test_template_service_integration.py b/tests/integration/test_template_service_integration.py
new file mode 100644
index 00000000..ad1ce229
--- /dev/null
+++ b/tests/integration/test_template_service_integration.py
@@ -0,0 +1,202 @@
+"""
+Simplified integration tests for Template Service
+
+These tests verify the basic functionality of the template service
+without the full message queue infrastructure.
+"""
+
+import pytest
+import json
+from unittest.mock import AsyncMock, MagicMock
+
+from trustgraph.schema import PromptRequest, PromptResponse
+from trustgraph.template.prompt_manager import PromptManager
+
+
+@pytest.mark.integration 
+class TestTemplateServiceSimple:
+    """Simplified integration tests for Template Service components"""
+
+    @pytest.fixture
+    def sample_config(self):
+        """Sample configuration for testing"""
+        return {
+            "system": json.dumps("You are a helpful assistant."),
+            "template-index": json.dumps(["greeting", "json_test"]),
+            "template.greeting": json.dumps({
+                "prompt": "Hello {{ name }}, welcome to {{ system_name }}!",
+                "response-type": "text"
+            }),
+            "template.json_test": json.dumps({
+                "prompt": "Generate profile for {{ username }}",
+                "response-type": "json",
+                "schema": {
+                    "type": "object",
+                    "properties": {
+                        "name": {"type": "string"},
+                        "role": {"type": "string"}
+                    },
+                    "required": ["name", "role"]
+                }
+            })
+        }
+
+    @pytest.fixture
+    def prompt_manager(self, sample_config):
+        """Create a configured PromptManager"""
+        pm = PromptManager()
+        pm.load_config(sample_config)
+        pm.terms["system_name"] = "TrustGraph"
+        return pm
+
+    @pytest.mark.asyncio
+    async def test_prompt_manager_text_invocation(self, prompt_manager):
+        """Test PromptManager text response invocation"""
+        # Mock LLM function
+        async def mock_llm(system, prompt):
+            assert system == "You are a helpful assistant."
+            assert "Hello Alice, welcome to TrustGraph!" in prompt
+            return "Welcome message processed!"
+
+        result = await prompt_manager.invoke("greeting", {"name": "Alice"}, mock_llm)
+        
+        assert result == "Welcome message processed!"
+
+    @pytest.mark.asyncio
+    async def test_prompt_manager_json_invocation(self, prompt_manager):
+        """Test PromptManager JSON response invocation"""
+        # Mock LLM function
+        async def mock_llm(system, prompt):
+            assert "Generate profile for johndoe" in prompt
+            return '{"name": "John Doe", "role": "user"}'
+
+        result = await prompt_manager.invoke("json_test", {"username": "johndoe"}, mock_llm)
+        
+        assert isinstance(result, dict)
+        assert result["name"] == "John Doe"
+        assert result["role"] == "user"
+
+    @pytest.mark.asyncio
+    async def test_prompt_manager_json_validation_error(self, prompt_manager):
+        """Test JSON schema validation failure"""
+        # Mock LLM function that returns invalid JSON
+        async def mock_llm(system, prompt):
+            return '{"name": "John Doe"}'  # Missing required "role"
+
+        with pytest.raises(RuntimeError) as exc_info:
+            await prompt_manager.invoke("json_test", {"username": "johndoe"}, mock_llm)
+        
+        assert "Schema validation fail" in str(exc_info.value)
+
+    @pytest.mark.asyncio
+    async def test_prompt_manager_json_parse_error(self, prompt_manager):
+        """Test JSON parsing failure"""
+        # Mock LLM function that returns non-JSON
+        async def mock_llm(system, prompt):
+            return "This is not JSON at all"
+
+        with pytest.raises(RuntimeError) as exc_info:
+            await prompt_manager.invoke("json_test", {"username": "johndoe"}, mock_llm)
+        
+        assert "JSON parse fail" in str(exc_info.value)
+
+    @pytest.mark.asyncio
+    async def test_prompt_manager_unknown_prompt(self, prompt_manager):
+        """Test unknown prompt ID handling"""
+        async def mock_llm(system, prompt):
+            return "Response"
+
+        with pytest.raises(RuntimeError) as exc_info:
+            await prompt_manager.invoke("unknown_prompt", {}, mock_llm)
+        
+        assert "ID invalid" in str(exc_info.value)
+
+    @pytest.mark.asyncio
+    async def test_prompt_manager_term_merging(self, prompt_manager):
+        """Test proper term merging (global + prompt + input)"""
+        # Add prompt-specific terms
+        prompt_manager.prompts["greeting"].terms = {"greeting_prefix": "Hi"}
+        
+        async def mock_llm(system, prompt):
+            # Should have global term (system_name), input term (name), and any prompt terms
+            assert "TrustGraph" in prompt  # Global term
+            assert "Bob" in prompt  # Input term
+            return "Merged correctly"
+
+        result = await prompt_manager.invoke("greeting", {"name": "Bob"}, mock_llm)
+        assert result == "Merged correctly"
+
+    def test_prompt_manager_template_rendering(self, prompt_manager):
+        """Test direct template rendering"""
+        result = prompt_manager.render("greeting", {"name": "Charlie"})
+        
+        assert "Hello Charlie, welcome to TrustGraph!" == result.strip()
+
+    def test_prompt_manager_configuration_loading(self):
+        """Test configuration loading with various formats"""
+        pm = PromptManager()
+        
+        # Test empty configuration
+        pm.load_config({})
+        assert pm.config.system_template == "Be helpful."
+        assert len(pm.prompts) == 0
+        
+        # Test configuration with single prompt
+        config = {
+            "system": json.dumps("Test system"),
+            "template-index": json.dumps(["test"]),
+            "template.test": json.dumps({
+                "prompt": "Test {{ value }}",
+                "response-type": "text"
+            })
+        }
+        pm.load_config(config)
+        
+        assert pm.config.system_template == "Test system"
+        assert "test" in pm.prompts
+        assert pm.prompts["test"].response_type == "text"
+
+    @pytest.mark.asyncio
+    async def test_prompt_manager_json_with_markdown(self, prompt_manager):
+        """Test JSON extraction from markdown code blocks"""
+        async def mock_llm(system, prompt):
+            return '''
+            Here's the profile:
+            ```json
+            {"name": "Jane Smith", "role": "admin"}
+            ```
+            '''
+
+        result = await prompt_manager.invoke("json_test", {"username": "jane"}, mock_llm)
+        
+        assert isinstance(result, dict)
+        assert result["name"] == "Jane Smith"
+        assert result["role"] == "admin"
+
+    def test_prompt_manager_error_handling_in_templates(self, prompt_manager):
+        """Test error handling in template rendering"""
+        # Test with missing variable
+        with pytest.raises(Exception):  # ibis should raise on undefined variable
+            prompt_manager.render("greeting", {})  # Missing 'name'
+
+    @pytest.mark.asyncio
+    async def test_concurrent_prompt_invocations(self, prompt_manager):
+        """Test concurrent invocations"""
+        async def mock_llm(system, prompt):
+            # Extract name from prompt for response
+            if "Alice" in prompt:
+                return "Alice response"
+            elif "Bob" in prompt:
+                return "Bob response"
+            else:
+                return "Default response"
+
+        # Run concurrent invocations
+        import asyncio
+        results = await asyncio.gather(
+            prompt_manager.invoke("greeting", {"name": "Alice"}, mock_llm),
+            prompt_manager.invoke("greeting", {"name": "Bob"}, mock_llm),
+        )
+
+        assert "Alice response" in results
+        assert "Bob response" in results
\ No newline at end of file
diff --git a/tests/unit/test_prompt_manager.py b/tests/unit/test_prompt_manager.py
new file mode 100644
index 00000000..957586cf
--- /dev/null
+++ b/tests/unit/test_prompt_manager.py
@@ -0,0 +1,327 @@
+"""
+Unit tests for PromptManager
+
+These tests verify the functionality of the PromptManager class,
+including template rendering, term merging, JSON validation, and error handling.
+"""
+
+import pytest
+import json
+from unittest.mock import AsyncMock, MagicMock, patch
+
+from trustgraph.template.prompt_manager import PromptManager, PromptConfiguration, Prompt
+
+
+@pytest.mark.unit
+class TestPromptManager:
+    """Unit tests for PromptManager template functionality"""
+
+    @pytest.fixture
+    def sample_config(self):
+        """Sample configuration dict for PromptManager"""
+        return {
+            "system": json.dumps("You are a helpful assistant."),
+            "template-index": json.dumps(["simple_text", "json_response", "complex_template"]),
+            "template.simple_text": json.dumps({
+                "prompt": "Hello {{ name }}, welcome to {{ system_name }}!",
+                "response-type": "text"
+            }),
+            "template.json_response": json.dumps({
+                "prompt": "Generate a user profile for {{ username }}",
+                "response-type": "json",
+                "schema": {
+                    "type": "object",
+                    "properties": {
+                        "name": {"type": "string"},
+                        "age": {"type": "number"}
+                    },
+                    "required": ["name", "age"]
+                }
+            }),
+            "template.complex_template": json.dumps({
+                "prompt": """
+                {% for item in items %}
+                - {{ item.name }}: {{ item.value }}
+                {% endfor %}
+                Total: {{ items|length }}
+                """,
+                "response-type": "text"
+            })
+        }
+
+    @pytest.fixture
+    def prompt_manager(self, sample_config):
+        """Create a PromptManager with sample configuration"""
+        pm = PromptManager()
+        pm.load_config(sample_config)
+        # Add global terms manually since load_config doesn't handle them
+        pm.terms["system_name"] = "TrustGraph"
+        pm.terms["version"] = "1.0"
+        return pm
+
+    def test_prompt_manager_initialization(self, prompt_manager, sample_config):
+        """Test PromptManager initialization with configuration"""
+        assert prompt_manager.config.system_template == "You are a helpful assistant."
+        assert len(prompt_manager.prompts) == 3
+        assert "simple_text" in prompt_manager.prompts
+
+    def test_simple_text_template_rendering(self, prompt_manager):
+        """Test basic template rendering with text response"""
+        terms = {"name": "Alice"}
+        
+        rendered = prompt_manager.render("simple_text", terms)
+        
+        assert rendered == "Hello Alice, welcome to TrustGraph!"
+
+    def test_global_terms_merging(self, prompt_manager):
+        """Test that global terms are properly merged"""
+        terms = {"name": "Bob"}
+        
+        # Global terms should be available in template
+        rendered = prompt_manager.render("simple_text", terms)
+        
+        assert "TrustGraph" in rendered  # From global terms
+        assert "Bob" in rendered  # From input terms
+
+    def test_term_override_priority(self, prompt_manager):
+        """Test term override priority: input > prompt > global"""
+        # Add a test prompt with overlapping terms
+        test_config = {
+            "template.test": json.dumps({
+                "prompt": "Value is: {{ value }}",
+                "response-type": "text"
+            })
+        }
+        prompt_manager.load_config({**prompt_manager.config.__dict__, **test_config})
+        prompt_manager.terms["value"] = "global"
+        prompt_manager.prompts["test"].terms["value"] = "prompt"
+        
+        # Test with no input override
+        rendered = prompt_manager.render("test", {})
+        assert rendered == "Value is: prompt"  # Prompt terms override global
+        
+        # Test with input override
+        rendered = prompt_manager.render("test", {"value": "input"})
+        assert rendered == "Value is: input"  # Input terms override all
+
+    def test_complex_template_rendering(self, prompt_manager):
+        """Test complex template with loops and filters"""
+        terms = {
+            "items": [
+                {"name": "Item1", "value": 10},
+                {"name": "Item2", "value": 20},
+                {"name": "Item3", "value": 30}
+            ]
+        }
+        
+        rendered = prompt_manager.render("complex_template", terms)
+        
+        assert "Item1: 10" in rendered
+        assert "Item2: 20" in rendered
+        assert "Item3: 30" in rendered
+        assert "Total: 3" in rendered
+
+    @pytest.mark.asyncio
+    async def test_invoke_text_response(self, prompt_manager):
+        """Test invoking a prompt with text response"""
+        mock_llm = AsyncMock()
+        mock_llm.return_value = "Welcome Alice to TrustGraph!"
+        
+        result = await prompt_manager.invoke(
+            "simple_text",
+            {"name": "Alice"},
+            mock_llm
+        )
+        
+        assert result == "Welcome Alice to TrustGraph!"
+        
+        # Verify LLM was called with correct prompts
+        mock_llm.assert_called_once()
+        call_args = mock_llm.call_args[1]
+        assert call_args["system"] == "You are a helpful assistant."
+        assert "Hello Alice, welcome to TrustGraph!" in call_args["prompt"]
+
+    @pytest.mark.asyncio
+    async def test_invoke_json_response_valid(self, prompt_manager):
+        """Test invoking a prompt with valid JSON response"""
+        mock_llm = AsyncMock()
+        mock_llm.return_value = '{"name": "John Doe", "age": 30}'
+        
+        result = await prompt_manager.invoke(
+            "json_response",
+            {"username": "johndoe"},
+            mock_llm
+        )
+        
+        assert isinstance(result, dict)
+        assert result["name"] == "John Doe"
+        assert result["age"] == 30
+
+    @pytest.mark.asyncio
+    async def test_invoke_json_response_with_markdown(self, prompt_manager):
+        """Test JSON extraction from markdown code blocks"""
+        mock_llm = AsyncMock()
+        mock_llm.return_value = """
+        Here is the user profile:
+        
+        ```json
+        {
+            "name": "Jane Smith",
+            "age": 25
+        }
+        ```
+        
+        This is a valid profile.
+        """
+        
+        result = await prompt_manager.invoke(
+            "json_response",
+            {"username": "janesmith"},
+            mock_llm
+        )
+        
+        assert isinstance(result, dict)
+        assert result["name"] == "Jane Smith"
+        assert result["age"] == 25
+
+    @pytest.mark.asyncio
+    async def test_invoke_json_validation_failure(self, prompt_manager):
+        """Test JSON schema validation failure"""
+        mock_llm = AsyncMock()
+        # Missing required 'age' field
+        mock_llm.return_value = '{"name": "Invalid User"}'
+        
+        with pytest.raises(ValueError) as exc_info:
+            await prompt_manager.invoke(
+                "json_response",
+                {"username": "invalid"},
+                mock_llm
+            )
+        
+        assert "JSON schema validation failed" in str(exc_info.value)
+
+    @pytest.mark.asyncio
+    async def test_invoke_json_parse_failure(self, prompt_manager):
+        """Test invalid JSON parsing"""
+        mock_llm = AsyncMock()
+        mock_llm.return_value = "This is not JSON at all"
+        
+        with pytest.raises(ValueError) as exc_info:
+            await prompt_manager.invoke(
+                "json_response",
+                {"username": "test"},
+                mock_llm
+            )
+        
+        assert "No JSON found in response" in str(exc_info.value)
+
+    @pytest.mark.asyncio
+    async def test_invoke_unknown_prompt(self, prompt_manager):
+        """Test invoking an unknown prompt ID"""
+        mock_llm = AsyncMock()
+        
+        with pytest.raises(KeyError):
+            await prompt_manager.invoke(
+                "nonexistent_prompt",
+                {},
+                mock_llm
+            )
+
+    def test_template_rendering_with_undefined_variable(self, prompt_manager):
+        """Test template rendering with undefined variables"""
+        terms = {}  # Missing 'name' variable
+        
+        # This should raise an error or use empty string depending on config
+        with pytest.raises(Exception):  # ibis/Jinja2 will raise on undefined
+            prompt_manager.render("simple_text", terms)
+
+    @pytest.mark.asyncio
+    async def test_json_response_without_schema(self):
+        """Test JSON response without schema validation"""
+        pm = PromptManager()
+        config = {
+            "system": json.dumps("Test"),
+            "template-index": json.dumps(["no_schema"]),
+            "template.no_schema": json.dumps({
+                "prompt": "Generate any JSON",
+                "response-type": "json"
+                # No schema defined
+            })
+        }
+        pm.load_config(config)
+        
+        mock_llm = AsyncMock()
+        mock_llm.return_value = '{"any": "json", "is": "valid"}'
+        
+        result = await pm.invoke("no_schema", {}, mock_llm)
+        
+        assert result == {"any": "json", "is": "valid"}
+
+    def test_prompt_configuration_validation(self):
+        """Test PromptConfiguration validation"""
+        # Valid configuration
+        config = PromptConfiguration(
+            system_template="Test system",
+            prompts={
+                "test": Prompt(
+                    template="Hello {{ name }}",
+                    response_type="text"
+                )
+            }
+        )
+        assert config.system_template == "Test system"
+        assert len(config.prompts) == 1
+
+    def test_nested_template_includes(self, prompt_manager):
+        """Test templates with nested variable references"""
+        # Add global terms
+        prompt_manager.terms["company"] = "TrustGraph"
+        prompt_manager.terms["year"] = 2024
+        
+        # Add a nested template
+        config = {
+            "template.nested": json.dumps({
+                "prompt": "{{ greeting }} from {{ company }} in {{ year }}!",
+                "response-type": "text"
+            })
+        }
+        prompt_manager.load_config({**prompt_manager.config.__dict__, **config})
+        prompt_manager.prompts["nested"].terms = {"greeting": "Welcome"}
+        
+        rendered = prompt_manager.render("nested", {"user": "Alice"})
+        
+        # Should contain company and year from global terms
+        assert "TrustGraph" in rendered
+        assert "2024" in rendered
+
+    @pytest.mark.asyncio
+    async def test_concurrent_invocations(self, prompt_manager):
+        """Test concurrent prompt invocations"""
+        mock_llm = AsyncMock()
+        mock_llm.side_effect = [
+            "Response for Alice",
+            "Response for Bob",
+            "Response for Charlie"
+        ]
+        
+        # Simulate concurrent invocations
+        import asyncio
+        results = await asyncio.gather(
+            prompt_manager.invoke("simple_text", {"name": "Alice"}, mock_llm),
+            prompt_manager.invoke("simple_text", {"name": "Bob"}, mock_llm),
+            prompt_manager.invoke("simple_text", {"name": "Charlie"}, mock_llm)
+        )
+        
+        assert len(results) == 3
+        assert "Alice" in results[0]
+        assert "Bob" in results[1]
+        assert "Charlie" in results[2]
+
+    def test_empty_configuration(self):
+        """Test PromptManager with minimal configuration"""
+        pm = PromptManager()
+        pm.load_config({})  # Empty config
+        
+        assert pm.config.system_template == "Be helpful."  # Default system
+        assert pm.terms == {}  # Default empty terms
+        assert len(pm.prompts) == 0
\ No newline at end of file
diff --git a/tests/unit/test_prompt_manager_edge_cases.py b/tests/unit/test_prompt_manager_edge_cases.py
new file mode 100644
index 00000000..7b8a81e6
--- /dev/null
+++ b/tests/unit/test_prompt_manager_edge_cases.py
@@ -0,0 +1,428 @@
+"""
+Edge case and error handling tests for PromptManager
+
+These tests focus on boundary conditions, error scenarios, and 
+unusual but valid use cases for the PromptManager.
+"""
+
+import pytest
+import json
+import asyncio
+from unittest.mock import AsyncMock
+
+from trustgraph.template.prompt_manager import PromptManager, PromptConfiguration, Prompt
+
+
+@pytest.mark.unit
+class TestPromptManagerEdgeCases:
+    """Edge case tests for PromptManager"""
+
+    @pytest.mark.asyncio
+    async def test_very_large_json_response(self):
+        """Test handling of very large JSON responses"""
+        pm = PromptManager()
+        config = {
+            "system": json.dumps("Test"),
+            "template-index": json.dumps(["large_json"]),
+            "template.large_json": json.dumps({
+                "prompt": "Generate large dataset",
+                "response-type": "json"
+            })
+        }
+        pm.load_config(config)
+        
+        # Create a large JSON structure
+        large_data = {
+            f"item_{i}": {
+                "name": f"Item {i}",
+                "data": list(range(100)),
+                "nested": {
+                    "level1": {
+                        "level2": f"Deep value {i}"
+                    }
+                }
+            }
+            for i in range(100)
+        }
+        
+        mock_llm = AsyncMock()
+        mock_llm.return_value = json.dumps(large_data)
+        
+        result = await pm.invoke("large_json", {}, mock_llm)
+        
+        assert isinstance(result, dict)
+        assert len(result) == 100
+        assert "item_50" in result
+
+    @pytest.mark.asyncio
+    async def test_unicode_and_special_characters(self):
+        """Test handling of unicode and special characters"""
+        pm = PromptManager()
+        config = {
+            "system": json.dumps("Test"),
+            "template-index": json.dumps(["unicode"]),
+            "template.unicode": json.dumps({
+                "prompt": "Process text: {{ text }}",
+                "response-type": "text"
+            })
+        }
+        pm.load_config(config)
+        
+        special_text = "Hello 世界! 🌍 Привет мир! مرحبا بالعالم"
+        
+        mock_llm = AsyncMock()
+        mock_llm.return_value = f"Processed: {special_text}"
+        
+        result = await pm.invoke("unicode", {"text": special_text}, mock_llm)
+        
+        assert special_text in result
+        assert "🌍" in result
+        assert "世界" in result
+
+    @pytest.mark.asyncio
+    async def test_nested_json_in_text_response(self):
+        """Test text response containing JSON-like structures"""
+        pm = PromptManager()
+        config = {
+            "system": json.dumps("Test"),
+            "template-index": json.dumps(["text_with_json"]),
+            "template.text_with_json": json.dumps({
+                "prompt": "Explain this data",
+                "response-type": "text"  # Text response, not JSON
+            })
+        }
+        pm.load_config(config)
+        
+        mock_llm = AsyncMock()
+        mock_llm.return_value = """
+        The data structure is:
+        {
+            "key": "value",
+            "nested": {
+                "array": [1, 2, 3]
+            }
+        }
+        This represents a nested object.
+        """
+        
+        result = await pm.invoke("text_with_json", {}, mock_llm)
+        
+        assert isinstance(result, str)  # Should remain as text
+        assert '"key": "value"' in result
+
+    @pytest.mark.asyncio
+    async def test_multiple_json_blocks_in_response(self):
+        """Test response with multiple JSON blocks"""
+        pm = PromptManager()
+        config = {
+            "system": json.dumps("Test"),
+            "template-index": json.dumps(["multi_json"]),
+            "template.multi_json": json.dumps({
+                "prompt": "Generate examples",
+                "response-type": "json"
+            })
+        }
+        pm.load_config(config)
+        
+        mock_llm = AsyncMock()
+        mock_llm.return_value = """
+        Here's the first example:
+        ```json
+        {"first": true, "value": 1}
+        ```
+        
+        And here's another:
+        ```json
+        {"second": true, "value": 2}
+        ```
+        """
+        
+        # Should extract the first valid JSON block
+        result = await pm.invoke("multi_json", {}, mock_llm)
+        
+        assert result == {"first": True, "value": 1}
+
+    @pytest.mark.asyncio
+    async def test_json_with_comments(self):
+        """Test JSON response with comment-like content"""
+        pm = PromptManager()
+        config = {
+            "system": json.dumps("Test"),
+            "template-index": json.dumps(["json_comments"]),
+            "template.json_comments": json.dumps({
+                "prompt": "Generate config",
+                "response-type": "json"
+            })
+        }
+        pm.load_config(config)
+        
+        mock_llm = AsyncMock()
+        # JSON with comment-like content that should be extracted
+        mock_llm.return_value = """
+        // This is a configuration file
+        {
+            "setting": "value",  // Important setting
+            "number": 42
+        }
+        /* End of config */
+        """
+        
+        # Standard JSON parser won't handle comments
+        with pytest.raises(ValueError):
+            await pm.invoke("json_comments", {}, mock_llm)
+
+    def test_template_with_raw_blocks(self):
+        """Test template with raw blocks that shouldn't be processed"""
+        pm = PromptManager()
+        config = {
+            "system": json.dumps("Test"),
+            "template-index": json.dumps(["raw_template"]),
+            "template.raw_template": json.dumps({
+                "prompt": """
+                    Normal: {{ variable }}
+                    {% raw %}
+                    Raw block: {{ this_should_not_be_processed }}
+                    {% endraw %}
+                    Normal again: {{ another }}
+                    """,
+                "response-type": "text"
+            })
+        }
+        pm.load_config(config)
+        
+        result = pm.render(
+            "raw_template",
+            {"variable": "processed", "another": "also processed"}
+        )
+        
+        assert "processed" in result
+        assert "{{ this_should_not_be_processed }}" in result  # Should remain as-is
+        assert "also processed" in result
+
+    @pytest.mark.asyncio
+    async def test_empty_json_response_variations(self):
+        """Test various empty JSON response formats"""
+        pm = PromptManager()
+        config = {
+            "system": json.dumps("Test"),
+            "template-index": json.dumps(["empty_json"]),
+            "template.empty_json": json.dumps({
+                "prompt": "Generate empty data",
+                "response-type": "json"
+            })
+        }
+        pm.load_config(config)
+        
+        empty_variations = [
+            "{}",
+            "[]",
+            "null",
+            '""',
+            "0",
+            "false"
+        ]
+        
+        for empty_value in empty_variations:
+            mock_llm = AsyncMock()
+            mock_llm.return_value = empty_value
+            
+            result = await pm.invoke("empty_json", {}, mock_llm)
+            assert result == json.loads(empty_value)
+
+    @pytest.mark.asyncio
+    async def test_malformed_json_recovery(self):
+        """Test recovery from slightly malformed JSON"""
+        pm = PromptManager()
+        config = {
+            "system": json.dumps("Test"),
+            "template-index": json.dumps(["malformed"]),
+            "template.malformed": json.dumps({
+                "prompt": "Generate data",
+                "response-type": "json"
+            })
+        }
+        pm.load_config(config)
+        
+        # Missing closing brace - should fail
+        mock_llm = AsyncMock()
+        mock_llm.return_value = '{"key": "value"'
+        
+        with pytest.raises(RuntimeError) as exc_info:
+            await pm.invoke("malformed", {}, mock_llm)
+        
+        assert "JSON parse fail" in str(exc_info.value)
+
+    def test_template_infinite_loop_protection(self):
+        """Test protection against infinite template loops"""
+        pm = PromptManager()
+        config = {
+            "system": json.dumps("Test"),
+            "template-index": json.dumps(["recursive"]),
+            "template.recursive": json.dumps({
+                "prompt": "{{ recursive_var }}",
+                "response-type": "text"
+            })
+        }
+        pm.load_config(config)
+        pm.prompts["recursive"].terms = {"recursive_var": "This includes {{ recursive_var }}"}
+        
+        # This should not cause infinite recursion
+        result = pm.render("recursive", {})
+        
+        # The exact behavior depends on the template engine
+        assert isinstance(result, str)
+
+    @pytest.mark.asyncio
+    async def test_extremely_long_template(self):
+        """Test handling of extremely long templates"""
+        # Create a very long template
+        long_template = "Start\n" + "\n".join([
+            f"Line {i}: " + "{{ var_" + str(i) + " }}"
+            for i in range(1000)
+        ]) + "\nEnd"
+        
+        pm = PromptManager()
+        config = {
+            "system": json.dumps("Test"),
+            "template-index": json.dumps(["long"]),
+            "template.long": json.dumps({
+                "prompt": long_template,
+                "response-type": "text"
+            })
+        }
+        pm.load_config(config)
+        
+        # Create corresponding variables
+        variables = {f"var_{i}": f"value_{i}" for i in range(1000)}
+        
+        mock_llm = AsyncMock()
+        mock_llm.return_value = "Processed long template"
+        
+        result = await pm.invoke("long", variables, mock_llm)
+        
+        assert result == "Processed long template"
+        
+        # Check that template was rendered correctly
+        call_args = mock_llm.call_args[1]
+        rendered = call_args["prompt"]
+        assert "Line 500: value_500" in rendered
+
+    @pytest.mark.asyncio
+    async def test_json_schema_with_additional_properties(self):
+        """Test JSON schema validation with additional properties"""
+        pm = PromptManager()
+        config = {
+            "system": json.dumps("Test"),
+            "template-index": json.dumps(["strict_schema"]),
+            "template.strict_schema": json.dumps({
+                "prompt": "Generate user",
+                "response-type": "json",
+                "schema": {
+                    "type": "object",
+                    "properties": {
+                        "name": {"type": "string"}
+                    },
+                    "required": ["name"],
+                    "additionalProperties": False
+                }
+            })
+        }
+        pm.load_config(config)
+        
+        mock_llm = AsyncMock()
+        # Response with extra property
+        mock_llm.return_value = '{"name": "John", "age": 30}'
+        
+        # Should fail validation due to additionalProperties: false
+        with pytest.raises(RuntimeError) as exc_info:
+            await pm.invoke("strict_schema", {}, mock_llm)
+        
+        assert "Schema validation fail" in str(exc_info.value)
+
+    @pytest.mark.asyncio
+    async def test_llm_timeout_handling(self):
+        """Test handling of LLM timeouts"""
+        pm = PromptManager()
+        config = {
+            "system": json.dumps("Test"),
+            "template-index": json.dumps(["timeout_test"]),
+            "template.timeout_test": json.dumps({
+                "prompt": "Test prompt",
+                "response-type": "text"
+            })
+        }
+        pm.load_config(config)
+        
+        mock_llm = AsyncMock()
+        mock_llm.side_effect = asyncio.TimeoutError("LLM request timed out")
+        
+        with pytest.raises(asyncio.TimeoutError):
+            await pm.invoke("timeout_test", {}, mock_llm)
+
+    def test_template_with_filters_and_tests(self):
+        """Test template with Jinja2 filters and tests"""
+        pm = PromptManager()
+        config = {
+            "system": json.dumps("Test"),
+            "template-index": json.dumps(["filters"]),
+            "template.filters": json.dumps({
+                "prompt": """
+                    {% if items %}
+                    Items ({{ items|length }}):
+                    {% for item in items|sort %}
+                    - {{ item|upper }}
+                    {% endfor %}
+                    {% else %}
+                    No items
+                    {% endif %}
+                    """,
+                "response-type": "text"
+            })
+        }
+        pm.load_config(config)
+        
+        # Test with items
+        result = pm.render(
+            "filters",
+            {"items": ["banana", "apple", "cherry"]}
+        )
+        
+        assert "Items (3)" in result
+        assert "- APPLE" in result
+        assert "- BANANA" in result
+        assert "- CHERRY" in result
+        
+        # Test without items
+        result = pm.render("filters", {"items": []})
+        assert "No items" in result
+
+    @pytest.mark.asyncio
+    async def test_concurrent_template_modifications(self):
+        """Test thread safety of template operations"""
+        pm = PromptManager()
+        config = {
+            "system": json.dumps("Test"),
+            "template-index": json.dumps(["concurrent"]),
+            "template.concurrent": json.dumps({
+                "prompt": "User: {{ user }}",
+                "response-type": "text"
+            })
+        }
+        pm.load_config(config)
+        
+        mock_llm = AsyncMock()
+        mock_llm.side_effect = lambda **kwargs: f"Response for {kwargs['prompt'].split()[1]}"
+        
+        # Simulate concurrent invocations with different users
+        import asyncio
+        tasks = []
+        for i in range(10):
+            tasks.append(
+                pm.invoke("concurrent", {"user": f"User{i}"}, mock_llm)
+            )
+        
+        results = await asyncio.gather(*tasks)
+        
+        # Each result should correspond to its user
+        for i, result in enumerate(results):
+            assert f"User{i}" in result
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