[Model] Use explicit types in `get_generation_prompt` (#33551)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

vllm/entrypoints/openai/translations/speech_to_text.py

@@ -37,7 +37,8 @@ from vllm.entrypoints.openai.translations.protocol import (
     TranslationStreamResponse,
 )
 from vllm.exceptions import VLLMValidationError
-from vllm.inputs.data import PromptType
+from vllm.inputs.data import ExplicitEncoderDecoderPrompt, PromptType
+from vllm.inputs.parse import is_explicit_encoder_decoder_prompt
 from vllm.logger import init_logger
 from vllm.logprobs import FlatLogprobs, Logprob
 from vllm.model_executor.models import SupportsTranscription, supports_transcription
@@ -296,25 +297,36 @@ class OpenAISpeechToText(OpenAIServing):
                 to_language=to_language,
             )
             if request.response_format == "verbose_json":
-                if not isinstance(prompt, dict):
+                if not is_explicit_encoder_decoder_prompt(prompt):
                     raise VLLMValidationError(
-                        "Expected prompt to be a dict",
+                        "Expected prompt to be an encoder-decoder prompt",
                         parameter="prompt",
                         value=type(prompt).__name__,
                     )
-                prompt_dict = cast(dict, prompt)
-                decoder_prompt = prompt.get("decoder_prompt")
-                if not isinstance(decoder_prompt, str):
+
+                prompt = self._preprocess_verbose_prompt(prompt)
+
+            prompts.append(prompt)
+        return prompts, duration
+
+    def _repl_verbose_text(self, text: str):
+        return text.replace("<|notimestamps|>", "<|0.00|>")
+
+    def _preprocess_verbose_prompt(self, prompt: ExplicitEncoderDecoderPrompt):
+        dec_prompt = prompt["decoder_prompt"]
+
+        if isinstance(dec_prompt, str):
+            prompt["decoder_prompt"] = self._repl_verbose_text(dec_prompt)
+        elif isinstance(dec_prompt, dict) and "prompt" in dec_prompt:
+            dec_prompt["prompt"] = self._repl_verbose_text(dec_prompt["prompt"])
+        else:
             raise VLLMValidationError(
-                        "Expected decoder_prompt to be str",
+                "Expected decoder_prompt to contain text",
                 parameter="decoder_prompt",
-                        value=type(decoder_prompt).__name__,
-                    )
-                prompt_dict["decoder_prompt"] = decoder_prompt.replace(
-                    "<|notimestamps|>", "<|0.00|>"
+                value=type(dec_prompt).__name__,
             )
-            prompts.append(prompt)
-        return prompts, duration
+
+        return prompt
 
     def _get_verbose_segments(
         self,

vllm/model_executor/models/gemma3n_mm.py

 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 from collections.abc import Iterable, Mapping, Sequence
-from typing import Annotated, Any, Literal, cast
+from typing import Annotated, Any, Literal
 
 import numpy as np
 import torch
@@ -19,7 +19,7 @@ from transformers.models.siglip import SiglipImageProcessorFast
 
 from vllm.config import ModelConfig, SpeechToTextConfig, VllmConfig
 from vllm.config.multimodal import BaseDummyOptions
-from vllm.inputs.data import PromptType
+from vllm.inputs.data import PromptType, TextPrompt
 from vllm.logger import init_logger
 from vllm.model_executor.layers.layernorm import RMSNorm
 from vllm.model_executor.layers.linear import RowParallelLinear
@@ -807,9 +807,10 @@ class Gemma3nForConditionalGeneration(
 
         prompt += ": <audio_soft_token><end_of_turn>\n<start_of_turn>model\n"
 
-        audio = (audio, stt_config.sample_rate)
-        prompts_dict = {"multi_modal_data": {"audio": audio}, "prompt": prompt}
-        return cast(PromptType, prompts_dict)
+        return TextPrompt(
+            prompt=prompt,
+            multi_modal_data={"audio": (audio, stt_config.sample_rate)},
+        )
 
     @classmethod
     def get_speech_to_text_config(

vllm/model_executor/models/glmasr.py

@@ -2,7 +2,7 @@
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 
 from collections.abc import Iterable, Mapping, Sequence
-from typing import Annotated, Any, Literal, TypeAlias, cast
+from typing import Annotated, Any, Literal, TypeAlias
 
 import numpy as np
 import torch
@@ -14,7 +14,7 @@ from transformers.models.whisper import WhisperFeatureExtractor
 from vllm.config import ModelConfig, SpeechToTextConfig, VllmConfig
 from vllm.config.multimodal import BaseDummyOptions
 from vllm.distributed.parallel_state import get_tensor_model_parallel_world_size
-from vllm.inputs.data import PromptType
+from vllm.inputs.data import PromptType, TokensPrompt
 from vllm.model_executor.layers.activation import get_act_fn
 from vllm.model_executor.layers.attention import MMEncoderAttention
 from vllm.model_executor.layers.linear import (
@@ -1159,8 +1159,8 @@ class GlmAsrForConditionalGeneration(
         )
 
         prompt_token_ids = tokenizer.encode(prompt)
-        prompt_dict = {
-            "prompt_token_ids": prompt_token_ids,
-            "multi_modal_data": {"audio": audio},
-        }
-        return cast(PromptType, prompt_dict)
+
+        return TokensPrompt(
+            prompt_token_ids=prompt_token_ids,
+            multi_modal_data={"audio": audio},
+        )

vllm/model_executor/models/granite_speech.py

@@ -26,7 +26,7 @@
 
 import math
 from collections.abc import Iterable, Mapping
-from typing import Annotated, Literal, cast
+from typing import Annotated, Literal
 
 import numpy as np
 import torch
@@ -36,7 +36,7 @@ from transformers import BatchFeature, PretrainedConfig
 
 from vllm.config import CacheConfig, ModelConfig, SpeechToTextConfig, VllmConfig
 from vllm.config.multimodal import BaseDummyOptions
-from vllm.inputs.data import PromptType
+from vllm.inputs.data import PromptType, TokensPrompt
 from vllm.model_executor.layers.linear import ColumnParallelLinear, RowParallelLinear
 from vllm.model_executor.layers.quantization import QuantizationConfig
 from vllm.model_executor.models.module_mapping import MultiModelKeys
@@ -879,11 +879,11 @@ class GraniteSpeechForConditionalGeneration(
         )
 
         prompt_token_ids = tokenizer.encode(prompt)
-        prompt = {
-            "prompt_token_ids": prompt_token_ids,
-            "multi_modal_data": {"audio": audio},
-        }
-        return cast(PromptType, prompt)
+
+        return TokensPrompt(
+            prompt_token_ids=prompt_token_ids,
+            multi_modal_data={"audio": audio},
+        )
 
     # Adapted from https://github.com/huggingface/transformers/blob/v4.56.0/src/transformers/models/granite_speech/feature_extraction_granite_speech.py#L122 # noqa: E501
     @classmethod

vllm/model_executor/models/qwen3_asr.py

@@ -23,7 +23,7 @@
 """Inference-only Qwen3-ASR model."""
 
 from collections.abc import Iterable, Mapping, Sequence
-from typing import Any, Literal, cast
+from typing import Any, Literal
 
 import numpy as np
 import torch
@@ -33,7 +33,7 @@ from transformers.models.whisper import WhisperFeatureExtractor
 
 from vllm.config import ModelConfig, SpeechToTextConfig, VllmConfig
 from vllm.config.multimodal import BaseDummyOptions
-from vllm.inputs.data import PromptType
+from vllm.inputs.data import PromptType, TokensPrompt
 from vllm.logger import init_logger
 from vllm.model_executor.models.interfaces import (
     MultiModalEmbeddings,
@@ -561,11 +561,11 @@ class Qwen3ASRForConditionalGeneration(
             )
 
         prompt_token_ids = tokenizer.encode(prompt)
-        prompt_dict = {
-            "prompt_token_ids": prompt_token_ids,
-            "multi_modal_data": {"audio": audio},
-        }
-        return cast(PromptType, prompt_dict)
+
+        return TokensPrompt(
+            prompt_token_ids=prompt_token_ids,
+            multi_modal_data={"audio": audio},
+        )
 
     @classmethod
     def post_process_output(cls, text: str) -> str:

vllm/model_executor/models/voxtral.py

@@ -25,7 +25,7 @@ from transformers.tokenization_utils_base import TextInput
 
 from vllm.config import ModelConfig, SpeechToTextConfig, VllmConfig
 from vllm.config.multimodal import BaseDummyOptions
-from vllm.inputs.data import PromptType
+from vllm.inputs.data import PromptType, TokensPrompt
 from vllm.logger import init_logger
 from vllm.model_executor.layers.quantization import QuantizationConfig
 from vllm.model_executor.model_loader.weight_utils import default_weight_loader
@@ -488,10 +488,13 @@ class VoxtralForConditionalGeneration(
         )
 
         tokenized = tokenizer.instruct.encode_transcription(req)
-        audio = (tokenized.audios[0].audio_array, stt_config.sample_rate)
-        prompts_dict = {"multi_modal_data": {"audio": audio}}
-        prompts_dict["prompt_token_ids"] = tokenized.tokens
-        return cast(PromptType, prompts_dict)
+
+        return TokensPrompt(
+            prompt_token_ids=tokenized.tokens,
+            multi_modal_data={
+                "audio": (tokenized.audios[0].audio_array, stt_config.sample_rate)
+            },
+        )
 
     @classmethod
     def get_num_audio_tokens(

vllm/model_executor/models/voxtral_realtime.py

@@ -4,7 +4,7 @@
 import asyncio
 import math
 from collections.abc import AsyncGenerator, Mapping
-from typing import Literal, cast
+from typing import Literal
 
 import numpy as np
 import torch
@@ -453,7 +453,10 @@ class VoxtralRealtimeGeneration(VoxtralForConditionalGeneration, SupportsRealtim
         )
 
         tokenized = tokenizer.instruct.encode_transcription(req)
-        audio = (tokenized.audios[0].audio_array, stt_config.sample_rate)
-        prompts_dict = {"multi_modal_data": {"audio": audio}}
-        prompts_dict["prompt_token_ids"] = tokenized.tokens
-        return cast(PromptType, prompts_dict)
+
+        return TokensPrompt(
+            prompt_token_ids=tokenized.tokens,
+            multi_modal_data={
+                "audio": (tokenized.audios[0].audio_array, stt_config.sample_rate)
+            },
+        )

vllm/model_executor/models/whisper.py

@@ -5,7 +5,7 @@ import enum
 import math
 from collections.abc import Iterable, Mapping, Sequence
 from contextlib import nullcontext
-from typing import Annotated, Literal, cast
+from typing import Annotated, Literal
 
 import numpy as np
 import torch
@@ -21,7 +21,7 @@ from vllm.compilation.decorators import support_torch_compile
 from vllm.config import CacheConfig, ModelConfig, SpeechToTextConfig, VllmConfig
 from vllm.config.multimodal import BaseDummyOptions
 from vllm.distributed import get_tensor_model_parallel_world_size
-from vllm.inputs.data import PromptType
+from vllm.inputs.data import ExplicitEncoderDecoderPrompt, PromptType, TextPrompt
 from vllm.logger import init_logger
 from vllm.model_executor.layers.activation import get_act_fn
 from vllm.model_executor.layers.attention import (
@@ -815,21 +815,18 @@ class WhisperForConditionalGeneration(
             raise ValueError(
                 "Language must be specified when creating the Whisper prompt"
             )
-        prompt = {
-            "encoder_prompt": {
-                # Whisper does not support encoder prompt.
-                "prompt": "",
-                "multi_modal_data": {
-                    "audio": (audio, stt_config.sample_rate),
-                },
-            },
-            "decoder_prompt": (
-                (f"<|prev|>{request_prompt}" if request_prompt else "")
-                + f"<|startoftranscript|><|{language}|>"
-                + f"<|{task_type}|><|notimestamps|>"
+
+        decoder_text = (
+            f"<|prev|>{request_prompt}" if request_prompt else ""
+        ) + f"<|startoftranscript|><|{language}|><|{task_type}|><|notimestamps|>"
+
+        return ExplicitEncoderDecoderPrompt(
+            encoder_prompt=TextPrompt(
+                prompt="",  # Whisper does not support encoder prompt.
+                multi_modal_data={"audio": (audio, stt_config.sample_rate)},
             ),
-        }
-        return cast(PromptType, prompt)
+            decoder_prompt=TextPrompt(prompt=decoder_text),
+        )
 
     @classmethod
     def get_placeholder_str(cls, modality: str, i: int) -> str | None: