diff --git a/client-sdks/stainless/openapi.yml b/client-sdks/stainless/openapi.yml
index da61a6385f..b328836c96 100644
--- a/client-sdks/stainless/openapi.yml
+++ b/client-sdks/stainless/openapi.yml
@@ -4151,6 +4151,16 @@ components:
             type: array
           - type: 'null'
           nullable: true
+        reasoning_content:
+          anyOf:
+          - type: string
+          - type: 'null'
+          nullable: true
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
+          nullable: true
       title: OpenAIAssistantMessageParam
       type: object
     OpenAIChatCompletionContentPartImageParam:
@@ -4218,6 +4228,11 @@ components:
             title: OpenAIChatCompletionToolCallFunction
           - type: 'null'
           title: OpenAIChatCompletionToolCallFunction
+        extra_content:
+          anyOf:
+          - additionalProperties: true
+            type: object
+          - type: 'null'
       type: object
       title: OpenAIChatCompletionToolCall
       description: Tool call specification for OpenAI-compatible chat completion responses.
@@ -4880,6 +4895,11 @@ components:
           - type: string
           - type: 'null'
           nullable: true
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
+          nullable: true
       title: OpenAIChoiceDelta
       type: object
     OpenAIChunkChoice:
@@ -11747,6 +11767,14 @@ components:
               $ref: '#/components/schemas/OpenAIChatCompletionToolCall'
             type: array
           - type: 'null'
+        reasoning_content:
+          anyOf:
+          - type: string
+          - type: 'null'
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
       type: object
       title: OpenAIAssistantMessageParam
       description: A message containing the model's (assistant) response in an OpenAI-compatible chat completion request.
@@ -11776,6 +11804,14 @@ components:
               $ref: '#/components/schemas/OpenAIChatCompletionToolCall'
             type: array
           - type: 'null'
+        reasoning_content:
+          anyOf:
+          - type: string
+          - type: 'null'
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
       type: object
       title: OpenAIAssistantMessageParam
       description: A message containing the model's (assistant) response in an OpenAI-compatible chat completion request.
diff --git a/docs/static/deprecated-llama-stack-spec.yaml b/docs/static/deprecated-llama-stack-spec.yaml
index d07b216b01..804e44d8c4 100644
--- a/docs/static/deprecated-llama-stack-spec.yaml
+++ b/docs/static/deprecated-llama-stack-spec.yaml
@@ -994,6 +994,16 @@ components:
             type: array
           - type: 'null'
           nullable: true
+        reasoning_content:
+          anyOf:
+          - type: string
+          - type: 'null'
+          nullable: true
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
+          nullable: true
       title: OpenAIAssistantMessageParam
       type: object
     OpenAIChatCompletionContentPartImageParam:
@@ -1061,6 +1071,11 @@ components:
             title: OpenAIChatCompletionToolCallFunction
           - type: 'null'
           title: OpenAIChatCompletionToolCallFunction
+        extra_content:
+          anyOf:
+          - additionalProperties: true
+            type: object
+          - type: 'null'
       type: object
       title: OpenAIChatCompletionToolCall
       description: Tool call specification for OpenAI-compatible chat completion responses.
@@ -1723,6 +1738,11 @@ components:
           - type: string
           - type: 'null'
           nullable: true
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
+          nullable: true
       title: OpenAIChoiceDelta
       type: object
     OpenAIChunkChoice:
@@ -8590,6 +8610,14 @@ components:
               $ref: '#/components/schemas/OpenAIChatCompletionToolCall'
             type: array
           - type: 'null'
+        reasoning_content:
+          anyOf:
+          - type: string
+          - type: 'null'
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
       type: object
       title: OpenAIAssistantMessageParam
       description: A message containing the model's (assistant) response in an OpenAI-compatible chat completion request.
@@ -8619,6 +8647,14 @@ components:
               $ref: '#/components/schemas/OpenAIChatCompletionToolCall'
             type: array
           - type: 'null'
+        reasoning_content:
+          anyOf:
+          - type: string
+          - type: 'null'
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
       type: object
       title: OpenAIAssistantMessageParam
       description: A message containing the model's (assistant) response in an OpenAI-compatible chat completion request.
diff --git a/docs/static/experimental-llama-stack-spec.yaml b/docs/static/experimental-llama-stack-spec.yaml
index 4d5a436939..b6fff643b2 100644
--- a/docs/static/experimental-llama-stack-spec.yaml
+++ b/docs/static/experimental-llama-stack-spec.yaml
@@ -859,6 +859,16 @@ components:
             type: array
           - type: 'null'
           nullable: true
+        reasoning_content:
+          anyOf:
+          - type: string
+          - type: 'null'
+          nullable: true
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
+          nullable: true
       title: OpenAIAssistantMessageParam
       type: object
     OpenAIChatCompletionContentPartImageParam:
@@ -926,6 +936,11 @@ components:
             title: OpenAIChatCompletionToolCallFunction
           - type: 'null'
           title: OpenAIChatCompletionToolCallFunction
+        extra_content:
+          anyOf:
+          - additionalProperties: true
+            type: object
+          - type: 'null'
       type: object
       title: OpenAIChatCompletionToolCall
       description: Tool call specification for OpenAI-compatible chat completion responses.
@@ -1588,6 +1603,11 @@ components:
           - type: string
           - type: 'null'
           nullable: true
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
+          nullable: true
       title: OpenAIChoiceDelta
       type: object
     OpenAIChunkChoice:
@@ -7582,6 +7602,14 @@ components:
               $ref: '#/components/schemas/OpenAIChatCompletionToolCall'
             type: array
           - type: 'null'
+        reasoning_content:
+          anyOf:
+          - type: string
+          - type: 'null'
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
       type: object
       title: OpenAIAssistantMessageParam
       description: A message containing the model's (assistant) response in an OpenAI-compatible chat completion request.
@@ -7611,6 +7639,14 @@ components:
               $ref: '#/components/schemas/OpenAIChatCompletionToolCall'
             type: array
           - type: 'null'
+        reasoning_content:
+          anyOf:
+          - type: string
+          - type: 'null'
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
       type: object
       title: OpenAIAssistantMessageParam
       description: A message containing the model's (assistant) response in an OpenAI-compatible chat completion request.
diff --git a/docs/static/llama-stack-spec.yaml b/docs/static/llama-stack-spec.yaml
index 0d91aeaaa4..7e3a5c8383 100644
--- a/docs/static/llama-stack-spec.yaml
+++ b/docs/static/llama-stack-spec.yaml
@@ -3172,6 +3172,16 @@ components:
             type: array
           - type: 'null'
           nullable: true
+        reasoning_content:
+          anyOf:
+          - type: string
+          - type: 'null'
+          nullable: true
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
+          nullable: true
       title: OpenAIAssistantMessageParam
       type: object
     OpenAIChatCompletionContentPartImageParam:
@@ -3239,6 +3249,11 @@ components:
             title: OpenAIChatCompletionToolCallFunction
           - type: 'null'
           title: OpenAIChatCompletionToolCallFunction
+        extra_content:
+          anyOf:
+          - additionalProperties: true
+            type: object
+          - type: 'null'
       type: object
       title: OpenAIChatCompletionToolCall
       description: Tool call specification for OpenAI-compatible chat completion responses.
@@ -3901,6 +3916,11 @@ components:
           - type: string
           - type: 'null'
           nullable: true
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
+          nullable: true
       title: OpenAIChoiceDelta
       type: object
     OpenAIChunkChoice:
@@ -10417,6 +10437,14 @@ components:
               $ref: '#/components/schemas/OpenAIChatCompletionToolCall'
             type: array
           - type: 'null'
+        reasoning_content:
+          anyOf:
+          - type: string
+          - type: 'null'
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
       type: object
       title: OpenAIAssistantMessageParam
       description: A message containing the model's (assistant) response in an OpenAI-compatible chat completion request.
@@ -10446,6 +10474,14 @@ components:
               $ref: '#/components/schemas/OpenAIChatCompletionToolCall'
             type: array
           - type: 'null'
+        reasoning_content:
+          anyOf:
+          - type: string
+          - type: 'null'
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
       type: object
       title: OpenAIAssistantMessageParam
       description: A message containing the model's (assistant) response in an OpenAI-compatible chat completion request.
diff --git a/docs/static/stainless-llama-stack-spec.yaml b/docs/static/stainless-llama-stack-spec.yaml
index da61a6385f..b328836c96 100644
--- a/docs/static/stainless-llama-stack-spec.yaml
+++ b/docs/static/stainless-llama-stack-spec.yaml
@@ -4151,6 +4151,16 @@ components:
             type: array
           - type: 'null'
           nullable: true
+        reasoning_content:
+          anyOf:
+          - type: string
+          - type: 'null'
+          nullable: true
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
+          nullable: true
       title: OpenAIAssistantMessageParam
       type: object
     OpenAIChatCompletionContentPartImageParam:
@@ -4218,6 +4228,11 @@ components:
             title: OpenAIChatCompletionToolCallFunction
           - type: 'null'
           title: OpenAIChatCompletionToolCallFunction
+        extra_content:
+          anyOf:
+          - additionalProperties: true
+            type: object
+          - type: 'null'
       type: object
       title: OpenAIChatCompletionToolCall
       description: Tool call specification for OpenAI-compatible chat completion responses.
@@ -4880,6 +4895,11 @@ components:
           - type: string
           - type: 'null'
           nullable: true
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
+          nullable: true
       title: OpenAIChoiceDelta
       type: object
     OpenAIChunkChoice:
@@ -11747,6 +11767,14 @@ components:
               $ref: '#/components/schemas/OpenAIChatCompletionToolCall'
             type: array
           - type: 'null'
+        reasoning_content:
+          anyOf:
+          - type: string
+          - type: 'null'
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
       type: object
       title: OpenAIAssistantMessageParam
       description: A message containing the model's (assistant) response in an OpenAI-compatible chat completion request.
@@ -11776,6 +11804,14 @@ components:
               $ref: '#/components/schemas/OpenAIChatCompletionToolCall'
             type: array
           - type: 'null'
+        reasoning_content:
+          anyOf:
+          - type: string
+          - type: 'null'
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
       type: object
       title: OpenAIAssistantMessageParam
       description: A message containing the model's (assistant) response in an OpenAI-compatible chat completion request.
diff --git a/src/llama_stack_api/inference.py b/src/llama_stack_api/inference.py
index 4a169486a5..4613fb226b 100644
--- a/src/llama_stack_api/inference.py
+++ b/src/llama_stack_api/inference.py
@@ -438,6 +438,7 @@ class OpenAIChatCompletionToolCall(BaseModel):
     id: str | None = None
     type: Literal["function"] = "function"
     function: OpenAIChatCompletionToolCallFunction | None = None
+    extra_content: dict[str, Any] | None = None
 
 
 @json_schema_type
@@ -448,12 +449,16 @@ class OpenAIAssistantMessageParam(BaseModel):
     :param content: The content of the model's response
     :param name: (Optional) The name of the assistant message participant.
     :param tool_calls: List of tool calls. Each tool call is an OpenAIChatCompletionToolCall object.
+    :param reasoning_content: (Optional) The reasoning content from the model (for vLLM ≤ v0.8.4)
+    :param reasoning: (Optional) The reasoning content from the model (for vLLM ≥ v0.9.x)
     """
 
     role: Literal["assistant"] = "assistant"
     content: OpenAIChatCompletionTextOnlyMessageContent | None = None
     name: str | None = None
     tool_calls: list[OpenAIChatCompletionToolCall] | None = None
+    reasoning_content: str | None = None
+    reasoning: str | None = None
 
 
 @json_schema_type
@@ -605,7 +610,8 @@ class OpenAIChoiceDelta(BaseModel):
     :param refusal: (Optional) The refusal of the delta
     :param role: (Optional) The role of the delta
     :param tool_calls: (Optional) The tool calls of the delta
-    :param reasoning_content: (Optional) The reasoning content from the model (non-standard, for o1/o3 models)
+    :param reasoning_content: (Optional) The reasoning content from the model (for vLLM ≤ v0.8.4)
+    :param reasoning: (Optional) The reasoning content from the model (for vLLM ≥ v0.9.x)
     """
 
     content: str | None = None
@@ -613,6 +619,7 @@ class OpenAIChoiceDelta(BaseModel):
     role: str | None = None
     tool_calls: list[OpenAIChatCompletionToolCall] | None = None
     reasoning_content: str | None = None
+    reasoning: str | None = None
 
 
 @json_schema_type