Use configuration system for max_input_tokens

- Remove max_input_tokens parameter from AgentController constructor
- Use LLM configuration system to set max_input_tokens through config.toml or environment variables
- Update test to set max_input_tokens directly in LLM config

Users can now set max_input_tokens in two ways:
1. Through config.toml:
   [llm]
   max_input_tokens = 20000

2. Through environment variables:
   export LLM_MAX_INPUT_TOKENS=20000

openhands/controller/agent_controller.py

@@ -89,7 +89,6 @@ def __init__(
         is_delegate: bool = False,
         headless_mode: bool = True,
         status_callback: Callable | None = None,
-        max_input_tokens: int | None = None,
     ):
         """Initializes a new instance of the AgentController class.
 
@@ -112,10 +111,6 @@ def __init__(
         self.agent = agent
         self.headless_mode = headless_mode
 
-        # Set max input tokens if provided
-        if max_input_tokens is not None:
-            self.agent.llm.config.max_input_tokens = max_input_tokens
-
         # subscribe to the event stream
         self.event_stream = event_stream
         self.event_stream.subscribe(

tests/unit/test_truncation.py

@@ -190,16 +190,18 @@ def test_history_restoration_after_truncation(self, mock_event_stream, mock_agen
     def test_context_window_parameter_truncation(self, mock_event_stream, mock_agent):
         # Configure mock agent's LLM to return specific token counts
         mock_agent.llm.get_token_count.return_value = 100
+
+        # Set max_input_tokens in LLM config
+        mock_agent.llm.config.max_input_tokens = 80
 
-        # Create controller with context window of 80 tokens
+        # Create controller
         controller = AgentController(
             agent=mock_agent,
             event_stream=mock_event_stream,
             max_iterations=10,
             sid='test_truncation',
             confirmation_mode=False,
             headless_mode=True,
-            max_input_tokens=80,
         )
 
         # Create initial events