perf: reduce unnecessary deepcopies in Agent

haystack/components/agents/agent.py

@@ -28,7 +28,6 @@
     _should_trigger_tool_invoker_breakpoint,
     _validate_tool_breakpoint_is_valid,
 )
-from haystack.core.pipeline.utils import _deepcopy_with_exceptions
 from haystack.core.serialization import component_to_dict, default_from_dict, default_to_dict
 from haystack.dataclasses import (
     AgentBreakpoint,
@@ -290,7 +289,8 @@ def __init__(
         self._state_schema = state_schema or {}
 
         # Initialize state schema
-        resolved_state_schema = _deepcopy_with_exceptions(self._state_schema)
+        # shallow copy is sufficient: we only add a top-level "messages" key, never mutate nested values
+        resolved_state_schema = dict(self._state_schema)
         if resolved_state_schema.get("messages") is None:
             resolved_state_schema["messages"] = {"type": list[ChatMessage], "handler": merge_lists}
         self.state_schema = resolved_state_schema
@@ -750,7 +750,8 @@ def run(  # noqa: PLR0915
             )
 
         with self._create_agent_span() as span:
-            span.set_content_tag("haystack.agent.input", _deepcopy_with_exceptions(agent_inputs))
+            # agent_inputs is local and not used after this point, so we avoid deepcopying it
+            span.set_content_tag("haystack.agent.input", agent_inputs)
 
             while exe_context.counter < self.max_agent_steps:
                 # We skip the chat generator when restarting from a snapshot from a ToolBreakpoint
@@ -983,7 +984,8 @@ async def run_async(  # noqa: PLR0915
             )
 
         with self._create_agent_span() as span:
-            span.set_content_tag("haystack.agent.input", _deepcopy_with_exceptions(agent_inputs))
+            # agent_inputs is local and not used after this point, so we avoid deepcopying it
+            span.set_content_tag("haystack.agent.input", agent_inputs)
 
             while exe_context.counter < self.max_agent_steps:
                 # We skip the chat generator when restarting from a snapshot from a ToolBreakpoint

releasenotes/notes/reduce-agent-deepcopies-2fc601301180d190.yaml

@@ -0,0 +1,7 @@
+---
+enhancements:
+  - |
+    Reduced unnecessary deepcopies in Agent for improved performance.
+    Replaced deepcopy of ``state_schema`` with a shallow dict copy since only top-level keys are modified,
+    and removed deepcopy of ``agent_inputs`` for span tags since the dict is freshly created and only used
+    for tracing.