[BugFix] Typing fixes to RequestOutput.prompt and beam search (#9473)

vllm/beam_search.py

@@ -1,5 +1,7 @@
 from dataclasses import dataclass
-from typing import List, Optional
+from typing import Dict, List, Optional
+
+from vllm.sequence import Logprob
 
 
 @dataclass
@@ -11,6 +13,7 @@ class BeamSearchSequence:
     """
     # The tokens includes the prompt.
     tokens: List[int]
+    logprobs: List[Dict[int, Logprob]]
     cum_logprob: float = 0.0
     text: Optional[str] = None
 
@@ -28,7 +31,7 @@ class BeamSearchInstance:
 
     def __init__(self, prompt_tokens: List[int]):
         self.beams: List[BeamSearchSequence] = [
-            BeamSearchSequence(tokens=prompt_tokens)
+            BeamSearchSequence(tokens=prompt_tokens, logprobs=[])
         ]
         self.completed: List[BeamSearchSequence] = []