diff --git a/python/packages/core/agent_framework/_types.py b/python/packages/core/agent_framework/_types.py
index 6ffebae8700..d45e821a38a 100644
--- a/python/packages/core/agent_framework/_types.py
+++ b/python/packages/core/agent_framework/_types.py
@@ -2224,6 +2224,11 @@ def _process_update(response: ChatResponse | AgentResponse, update: ChatResponse
             and response.messages[-1].message_id
             and response.messages[-1].message_id != update.message_id
         )
+        or (
+            update.author_name
+            and response.messages[-1].author_name
+            and response.messages[-1].author_name != update.author_name
+        )
         or (update.role and response.messages[-1].role != update.role)
     ):
         is_new_message = True
diff --git a/python/packages/core/tests/core/test_types.py b/python/packages/core/tests/core/test_types.py
index 2c41acd93b4..f9945b42f08 100644
--- a/python/packages/core/tests/core/test_types.py
+++ b/python/packages/core/tests/core/test_types.py
@@ -2000,6 +2000,63 @@ def test_agent_run_response_from_updates(agent_response_update: AgentResponseUpd
     assert response.text == "Test contentTest content"
 
 
+@pytest.mark.parametrize(
+    ("response_type", "update_type"),
+    [(ChatResponse, ChatResponseUpdate), (AgentResponse, AgentResponseUpdate)],
+    ids=["chat", "agent"],
+)
+def test_from_updates_starts_new_message_when_author_changes(response_type: Any, update_type: Any) -> None:
+    """Test that updates from different authors without message ids are not merged into one message."""
+    response = response_type.from_updates([
+        update_type(contents=[Content.from_text("Draft ")], role="assistant", author_name="writer"),
+        update_type(contents=[Content.from_text("text.")], role="assistant"),
+        update_type(contents=[Content.from_text("Looks good.")], role="assistant", author_name="reviewer"),
+    ])
+
+    assert [(message.author_name, message.text) for message in response.messages] == [
+        ("writer", "Draft text."),
+        ("reviewer", "Looks good."),
+    ]
+
+
+def test_from_updates_keeps_one_message_when_author_is_first_set() -> None:
+    """Test that a message without an author takes the author of a later update instead of splitting."""
+    response = AgentResponse.from_updates([
+        AgentResponseUpdate(contents=[Content.from_text("Hello ")], role="assistant"),
+        AgentResponseUpdate(contents=[Content.from_text("world")], role="assistant", author_name="writer"),
+    ])
+
+    assert [(message.author_name, message.text) for message in response.messages] == [("writer", "Hello world")]
+
+
+def test_from_updates_starts_new_message_for_interleaved_authors() -> None:
+    """Test that interleaved updates from two authors keep each run of updates with its author."""
+    response = AgentResponse.from_updates([
+        AgentResponseUpdate(contents=[Content.from_text("A1")], role="assistant", author_name="alpha"),
+        AgentResponseUpdate(contents=[Content.from_text("B1")], role="assistant", author_name="beta"),
+        AgentResponseUpdate(contents=[Content.from_text("A2")], role="assistant", author_name="alpha"),
+    ])
+
+    assert [(message.author_name, message.text) for message in response.messages] == [
+        ("alpha", "A1"),
+        ("beta", "B1"),
+        ("alpha", "A2"),
+    ]
+
+
+def test_from_updates_starts_new_message_for_authors_sharing_a_message_id() -> None:
+    """Test that a different author starts a new message even when the message id is the same."""
+    response = AgentResponse.from_updates([
+        AgentResponseUpdate(contents=[Content.from_text("Hi")], role="assistant", author_name="alpha", message_id="m1"),
+        AgentResponseUpdate(contents=[Content.from_text("Yo")], role="assistant", author_name="beta", message_id="m1"),
+    ])
+
+    assert [(message.author_name, message.message_id, message.text) for message in response.messages] == [
+        ("alpha", "m1", "Hi"),
+        ("beta", "m1", "Yo"),
+    ]
+
+
 def test_agent_run_response_from_updates_uses_last_non_none_agent_id() -> None:
     response = AgentResponse.from_updates([
         AgentResponseUpdate(agent_id="first-agent"),
diff --git a/python/packages/orchestrations/tests/test_sequential.py b/python/packages/orchestrations/tests/test_sequential.py
index 162b2e8971b..4e4006456ed 100644
--- a/python/packages/orchestrations/tests/test_sequential.py
+++ b/python/packages/orchestrations/tests/test_sequential.py
@@ -193,6 +193,25 @@ async def test_sequential_as_agent_returns_only_last_agent_response() -> None:
     assert "hello as_agent" not in combined
 
 
+async def test_sequential_as_agent_streaming_keeps_one_message_per_agent() -> None:
+    """Streaming `workflow.as_agent()` with `output_from="all"` keeps each agent's reply as its own message,
+    the same messages a non-streaming run returns."""
+
+    def build_agent() -> Any:
+        participants = [_EchoAgent(id="agent1", name="A1"), _EchoAgent(id="agent2", name="A2")]
+        return SequentialBuilder(participants=participants, output_from="all").build().as_agent()
+
+    response = await build_agent().run("hello")
+    stream = build_agent().run("hello", stream=True)
+    async for _ in stream:
+        pass
+    streamed = await stream.get_final_response()
+
+    assert [m.text for m in response.messages] == ["A1 reply", "A2 reply"]
+    assert [m.text for m in streamed.messages] == ["A1 reply", "A2 reply"]
+    assert [m.author_name for m in streamed.messages] == ["A1", "A2"]
+
+
 async def test_sequential_with_custom_executor_summary() -> None:
     """A custom-executor terminator yields its own AgentResponse — that becomes the workflow output.