diff --git a/trpc_agent_sdk/agents/_base_agent.py b/trpc_agent_sdk/agents/_base_agent.py
index 930cd896..7b16cc16 100644
--- a/trpc_agent_sdk/agents/_base_agent.py
+++ b/trpc_agent_sdk/agents/_base_agent.py
@@ -260,9 +260,18 @@ async def run_async(
         from trpc_agent_sdk.telemetry._trace import tracer
         from trpc_agent_sdk.telemetry._trace import trace_agent
 
-        # Avoid start_as_current_span in async generators; cancellation may close
-        # the generator from another context and trigger detach token errors.
+        # Manually propagate span context using attach/detach instead of
+        # start_as_current_span. This ensures child spans (call_llm, execute_tool,
+        # etc.) can correctly resolve their parent.
+        # We use start_span + attach/detach rather than start_as_current_span
+        # because __aexit__ of the context manager is not guaranteed to run when
+        # an async generator is cancelled, but try/finally always executes
+        # even under CancelledError (PEP 492).
+        from opentelemetry import context as context_api
+        from opentelemetry.trace import set_span_in_context
+
         span = tracer.start_span(f"agent_run [{self.name}]")
+        _ctx_token = context_api.attach(set_span_in_context(span, context_api.get_current()))
         try:
             ctx = self._create_invocation_context(parent_context)
             if ctx.agent_context is None:
@@ -325,6 +334,7 @@ async def run_async(
                 # avoid memory leak
                 reset_invocation_ctx(token)
         finally:
+            context_api.detach(_ctx_token)
             span.end()
 
     @abstractmethod
diff --git a/trpc_agent_sdk/runners.py b/trpc_agent_sdk/runners.py
index 9c292a84..7173886d 100644
--- a/trpc_agent_sdk/runners.py
+++ b/trpc_agent_sdk/runners.py
@@ -380,9 +380,18 @@ async def run_async(
         Yields:
             The events generated by the agent.
         """
-        # Avoid start_as_current_span in async generators; cancellation may close
-        # the generator from another context and trigger detach token errors.
+        # Manually propagate span context using attach/detach instead of
+        # start_as_current_span. This ensures child spans (agent_run, call_llm,
+        # execute_tool, etc.) can correctly resolve their parent.
+        # We use start_span + attach/detach rather than start_as_current_span
+        # because __aexit__ of the context manager is not guaranteed to run when
+        # an async generator is cancelled, but try/finally always executes
+        # even under CancelledError (PEP 492).
+        from opentelemetry import context as context_api
+        from opentelemetry.trace import set_span_in_context
+
         span = tracer.start_span("invocation")
+        _ctx_token = context_api.attach(set_span_in_context(span, context_api.get_current()))
         try:
             # Create default agent context if not provided
             if agent_context is None:
@@ -621,6 +630,7 @@ async def run_async(
                     session_id=session_id,
                 )
         finally:
+            context_api.detach(_ctx_token)
             span.end()
 
     async def _append_new_message_to_session(
diff --git a/trpc_agent_sdk/telemetry/_trace.py b/trpc_agent_sdk/telemetry/_trace.py
index aac6657b..f6936afe 100644
--- a/trpc_agent_sdk/telemetry/_trace.py
+++ b/trpc_agent_sdk/telemetry/_trace.py
@@ -26,6 +26,7 @@
 from __future__ import annotations
 
 import json
+from collections.abc import Sequence
 from typing import Any
 from typing import Optional
 
@@ -231,7 +232,23 @@ def trace_agent(
         span.set_attribute(f"{_trpc_agent_span_name}.agent.user_id", invocation_context.session.user_id)
 
     input_str = ""
-    if invocation_context.user_content and invocation_context.user_content.parts:
+    # When override_messages is set (e.g., member agent delegated by TeamAgent),
+    # use override_messages as the actual input instead of user_content,
+    # because user_content still holds the original input to the leader agent.
+    # Use getattr + Sequence check to avoid false positives when the context
+    # is a MagicMock (e.g., in unit tests) where accessing an unset attribute
+    # returns a truthy MagicMock object (isinstance(m, Sequence) is False).
+    override_messages = getattr(invocation_context, "override_messages", None)
+    if (isinstance(override_messages, Sequence) and not isinstance(override_messages, (str, bytes))
+            and override_messages):
+        text_parts = []
+        for content in override_messages:
+            if content and content.parts:
+                for part in content.parts:
+                    if part.text and not part.thought:
+                        text_parts.append(part.text)
+        input_str = "\n".join(text_parts)
+    elif invocation_context.user_content and invocation_context.user_content.parts:
         input_str = "\n".join([part.text or "" for part in invocation_context.user_content.parts])
     span.set_attribute(f"{_trpc_agent_span_name}.agent.input", input_str)