fix: support instructions provider for agents

Author: evgeny-l

typescript-sdk/integrations/adk-middleware/src/adk_middleware/adk_agent.py

@@ -701,18 +701,27 @@ async def _start_background_execution(
         if input.messages and isinstance(input.messages[0], SystemMessage):
             system_content = input.messages[0].content
             if system_content:
-                # Get existing instruction (may be None or empty)
                 current_instruction = getattr(adk_agent, 'instruction', '') or ''
-                
-                # Append SystemMessage content to existing instructions
-                if current_instruction:
-                    new_instruction = f"{current_instruction}\n\n{system_content}"
+
+                if callable(current_instruction):
+                    # Handle instructions provider
+                    async def instruction_provider_wrapper(*args, **kwargs):
+                        original_instructions = await current_instruction(*args, **kwargs)
+                        return f"{original_instructions}\n\n{system_content}"
+
+                    new_instruction = instruction_provider_wrapper
+                    logger.debug(
+                        f"Will wrap callable InstructionProvider and append SystemMessage: '{system_content[:100]}...'")
                 else:
-                    new_instruction = system_content
-                
+                    # Handle string instructions
+                    if current_instruction:
+                        new_instruction = f"{current_instruction}\n\n{system_content}"
+                    else:
+                        new_instruction = system_content
+                    logger.debug(f"Will append SystemMessage to string instructions: '{system_content[:100]}...'")
+
                 agent_updates['instruction'] = new_instruction
-                logger.debug(f"Will append SystemMessage to agent instructions: '{system_content[:100]}...'")
-        
+
         # Create dynamic toolset if tools provided and prepare tool updates
         toolset = None
         if input.tools:

typescript-sdk/integrations/adk-middleware/tests/test_adk_agent.py

@@ -239,6 +239,67 @@ async def mock_run_background(input, adk_agent, user_id, app_name, event_queue):
         expected_instruction = "You are a helpful assistant.\n\nBe very concise in responses."
         assert captured_agent.instruction == expected_instruction
 
+    @pytest.mark.asyncio
+    async def test_system_message_appended_to_instruction_provider(self):
+        """Test that SystemMessage as first message gets appended to agent instructions
+        when they are set via instruction provider."""
+        # Create an agent with initial instructions
+        received_context = None
+        
+        async def instruction_provider(context) -> str:
+            nonlocal received_context
+            received_context = context
+            return "You are a helpful assistant."
+
+        mock_agent = Agent(
+            name="test_agent",
+            instruction=instruction_provider
+        )
+
+        adk_agent = ADKAgent(adk_agent=mock_agent, app_name="test_app", user_id="test_user")
+
+        # Create input with SystemMessage as first message
+        system_input = RunAgentInput(
+            thread_id="test_thread",
+            run_id="test_run",
+            messages=[
+                SystemMessage(id="sys_1", role="system", content="Be very concise in responses."),
+                UserMessage(id="msg_1", role="user", content="Hello")
+            ],
+            context=[],
+            state={},
+            tools=[],
+            forwarded_props={}
+        )
+
+        # Mock the background execution to capture the modified agent
+        captured_agent = None
+        original_run_background = adk_agent._run_adk_in_background
+
+        async def mock_run_background(input, adk_agent, user_id, app_name, event_queue):
+            nonlocal captured_agent
+            captured_agent = adk_agent
+            # Just put a completion event in the queue and return
+            await event_queue.put(None)
+
+        with patch.object(adk_agent, '_run_adk_in_background', side_effect=mock_run_background):
+            # Start execution to trigger agent modification
+            execution = await adk_agent._start_background_execution(system_input)
+
+            # Wait briefly for the background task to start
+            await asyncio.sleep(0.01)
+
+        # Verify the agent's instruction was wrapped correctly
+        assert captured_agent is not None
+        assert callable(captured_agent.instruction) is True
+
+        # Test that the context object received in instruction provider is the same
+        test_context = {"test": "value"}
+        expected_instruction = "You are a helpful assistant.\n\nBe very concise in responses."
+        agent_instruction = await captured_agent.instruction(test_context)
+        assert agent_instruction == expected_instruction
+        assert received_context is test_context
+
     @pytest.mark.asyncio
     async def test_system_message_not_first_ignored(self):
         """Test that SystemMessage not as first message is ignored."""