Add Laminar tracing support for ACPAgent

- Initialize Laminar when ACPAgent module loads (maybe_init_laminar)
- Add @observe decorator to step() method for tracing ACP agent calls
- Consistent with regular Agent's Laminar integration

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: simonrosenberg

openhands-sdk/openhands/sdk/agent/acp_agent.py

@@ -47,9 +47,14 @@
 from openhands.sdk.llm import LLM, Message, MessageToolCall, TextContent
 from openhands.sdk.tool.builtins.finish import FinishAction, FinishObservation
 from openhands.sdk.logger import get_logger
+from openhands.sdk.observability.laminar import maybe_init_laminar, observe
 from openhands.sdk.tool import Tool  # noqa: TC002
 
 
+logger = get_logger(__name__)
+maybe_init_laminar()
+
+
 if TYPE_CHECKING:
     from openhands.sdk.conversation import (
         ConversationCallbackType,
@@ -59,8 +64,6 @@
     )
 
 
-logger = get_logger(__name__)
-
 # Seconds to wait after prompt() for pending session_update notifications
 # to be processed.  This is a best-effort workaround: the ACP protocol does
 # not currently signal when all notifications for a turn have been delivered,
@@ -636,6 +639,7 @@ async def _init() -> tuple[Any, Any, Any, str, str, str]:
         self._conn, self._process, self._filtered_reader, self._session_id, self._agent_name, self._agent_version = result
         self._working_dir = working_dir
 
+    @observe(name="acp_agent.step", ignore_inputs=["conversation", "on_event"])
     def step(
         self,
         conversation: LocalConversation,