diff --git a/tests/config/test_config_factory.py b/tests/config/test_config_factory.py
index 9ba96dd89..078fab250 100644
--- a/tests/config/test_config_factory.py
+++ b/tests/config/test_config_factory.py
@@ -1159,7 +1159,7 @@ class TestDeployConfigLoading:
         stages = merge_pipeline_deploy(pipeline, deploy)
 
         assert deploy.session_mode == "duplex"
-        assert deploy.active_stream_window == 1
+        assert deploy.active_stream_window == max_sessions
         assert deploy.duplex_session.max_sessions == max_sessions
         assert [stage.session_mode for stage in stages] == ["duplex", "duplex", "duplex"]
         assert [stage.to_omegaconf().session_mode for stage in stages] == ["duplex", "duplex", "duplex"]
diff --git a/vllm_omni/deploy/minicpmo_4_5.yaml b/vllm_omni/deploy/minicpmo_4_5.yaml
index 9e5a2dec9..6903fcae0 100644
--- a/vllm_omni/deploy/minicpmo_4_5.yaml
+++ b/vllm_omni/deploy/minicpmo_4_5.yaml
@@ -4,7 +4,9 @@ async_chunk: true
 # Native full-duplex shares this profile with /v1/chat/completions. Every other
 # duplex_session knob keeps its runtime default.
 session_mode: duplex
-active_stream_window: 1
+# Keep the active window aligned with the session and stage capacities below.
+# A smaller window serializes first-packet generation for concurrent chat turns.
+active_stream_window: 4
 duplex_session:
   # Matches Stage 0/1 max_num_seqs below.
   max_sessions: 4
diff --git a/vllm_omni/deploy/minicpmo_4_5_2gpu.yaml b/vllm_omni/deploy/minicpmo_4_5_2gpu.yaml
index 9cc6fd302..9c3818813 100644
--- a/vllm_omni/deploy/minicpmo_4_5_2gpu.yaml
+++ b/vllm_omni/deploy/minicpmo_4_5_2gpu.yaml
@@ -7,7 +7,9 @@ async_chunk: true
 # Native full-duplex shares this profile with /v1/chat/completions. Every other
 # duplex_session knob keeps its runtime default.
 session_mode: duplex
-active_stream_window: 1
+# Keep the active window aligned with the session and stage capacities below.
+# A smaller window serializes first-packet generation for concurrent chat turns.
+active_stream_window: 4
 duplex_session:
   # Matches Stage 0/1 max_num_seqs below.
   max_sessions: 4
diff --git a/vllm_omni/deploy/minicpmo_4_5_3gpu.yaml b/vllm_omni/deploy/minicpmo_4_5_3gpu.yaml
index c179824a2..5eddbb6f4 100644
--- a/vllm_omni/deploy/minicpmo_4_5_3gpu.yaml
+++ b/vllm_omni/deploy/minicpmo_4_5_3gpu.yaml
@@ -7,7 +7,9 @@ async_chunk: true
 # Native full-duplex shares this profile with /v1/chat/completions. Every other
 # duplex_session knob keeps its runtime default.
 session_mode: duplex
-active_stream_window: 1
+# Keep the active window aligned with the session and stage capacities below.
+# A smaller window serializes first-packet generation for concurrent chat turns.
+active_stream_window: 4
 duplex_session:
   # Matches Stage 0/1 max_num_seqs below.
   max_sessions: 4