fix(grpc): use context.abort() with proper status codes instead of in-band errors (#19972)

Signed-off-by: Chang Su <chang.s.su@oracle.com>

python/sglang/srt/grpc/utils.py

@@ -0,0 +1,21 @@
+"""gRPC utility functions."""
+
+from http import HTTPStatus
+
+import grpc
+
+_HTTP_TO_GRPC_CODE = {
+    HTTPStatus.BAD_REQUEST: grpc.StatusCode.INVALID_ARGUMENT,
+    HTTPStatus.SERVICE_UNAVAILABLE: grpc.StatusCode.UNAVAILABLE,
+    HTTPStatus.INTERNAL_SERVER_ERROR: grpc.StatusCode.INTERNAL,
+}
+
+
+def abort_code_from_output(output: dict) -> grpc.StatusCode:
+    """Map a scheduler error output to the appropriate gRPC status code."""
+    finish_reason = output.get("meta_info", {}).get("finish_reason")
+    if isinstance(finish_reason, dict):
+        status_code = finish_reason.get("status_code")
+        if status_code is not None:
+            return _HTTP_TO_GRPC_CODE.get(status_code, grpc.StatusCode.INTERNAL)
+    return grpc.StatusCode.INTERNAL