[Bugfix][MiniCPM-o] Prevent native duplex Stage-1 prompt overflow

Signed-off-by: Sy03 <1370724210@qq.com>

tests/engine/test_orchestrator_error_handling.py

@@ -880,6 +880,39 @@ async def test_diffusion_client_error_output_propagates_status_code(orchestrator
         orchestrator_fixture.thread.join(timeout=5)
 
 
+@pytest.mark.asyncio
+async def test_duplex_input_processor_failure_is_request_scoped(orchestrator_factory, monkeypatch) -> None:
+    class FailingStage(FakeStageClient):
+        def process_engine_inputs(self, source_outputs, prompt=None, streaming_context=None):
+            del source_outputs, prompt, streaming_context
+            raise ValueError("No latent or hidden_states found in thinker output")
+
+    fixture = orchestrator_factory(
+        [FakeStageClient(stage_type="llm"), FailingStage(stage_type="llm", final_output=True)]
+    )
+    state = OrchestratorRequestState(
+        request_id="bad",
+        prompt=SimpleNamespace(request_id="bad", prompt_token_ids=[1]),
+        sampling_params_list=[_sampling_params(), _sampling_params()],
+        final_stage_id=1,
+        duplex_identity=SimpleNamespace(),
+    )
+
+    async def no_cleanup(*_args: object, **_kwargs: object) -> None:
+        return None
+
+    monkeypatch.setattr(fixture.orchestrator, "_cleanup_request_ids", no_cleanup)
+    try:
+        await fixture.orchestrator._forward_to_next_stage_unguarded(
+            "bad", 0, _build_request_output("raw", finished=True), state
+        )
+        error = await _wait_for_error_message(fixture, request_id="bad")
+        assert error.fatal is False
+    finally:
+        fixture.request_sync_q.put_nowait(ShutdownRequestMessage())
+        fixture.thread.join(timeout=5)
+
+
 @pytest.mark.asyncio
 @pytest.mark.parametrize(
     ("status_code", "error_type"),