[Bugfix] Default missing legacy stage input sources (#5498)

Signed-off-by: wuli666 <421774554@qq.com>

tests/engine/test_stage_metadata.py

@@ -158,3 +158,16 @@ def test_extract_stage_metadata_preserves_legacy_one_argument_api():
     assert metadata.stage_id == 0
     assert metadata.model_stage == "thinker"
     assert metadata.custom_process_input_func is operator.add
+
+
+def test_extract_stage_metadata_defaults_missing_engine_input_source():
+    pipeline, deploy = _metadata_inputs()
+    legacy_config = merge_pipeline_deploy(
+        pipeline,
+        deploy,
+    )[0].to_omegaconf()
+    del legacy_config["engine_input_source"]
+
+    metadata = extract_stage_metadata(legacy_config)
+
+    assert metadata.engine_input_source == []

vllm_omni/engine/stage_init_utils.py

@@ -372,7 +372,7 @@ def extract_legacy_stage_metadata(stage_config: Any) -> StageMetadata:
             engine_args["attention_backend"] = "TRITON_ATTN"
 
     runtime_cfg = stage_config.runtime
-    engine_input_source: list[int] = stage_config.engine_input_source
+    engine_input_source: list[int] = _get_attr_or_item(stage_config, "engine_input_source", [])
     final_output: bool = stage_config.final_output
     final_output_type: str | None = stage_config.final_output_type