diff --git a/client-sdks/stainless/openapi.yml b/client-sdks/stainless/openapi.yml
index da61a6385..f935afae4 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:
@@ -4880,6 +4890,11 @@ components:
           - type: string
           - type: 'null'
           nullable: true
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
+          nullable: true
       title: OpenAIChoiceDelta
       type: object
     OpenAIChunkChoice:
@@ -11747,6 +11762,14 @@ 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 +11799,14 @@ 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 d07b216b0..c6271bc63 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:
@@ -1723,6 +1733,11 @@ components:
           - type: string
           - type: 'null'
           nullable: true
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
+          nullable: true
       title: OpenAIChoiceDelta
       type: object
     OpenAIChunkChoice:
@@ -8590,6 +8605,14 @@ 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 +8642,14 @@ 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 4d5a43693..d78cfd0e3 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:
@@ -1588,6 +1598,11 @@ components:
           - type: string
           - type: 'null'
           nullable: true
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
+          nullable: true
       title: OpenAIChoiceDelta
       type: object
     OpenAIChunkChoice:
@@ -7582,6 +7597,14 @@ 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 +7634,14 @@ 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 0d91aeaaa..00d038870 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:
@@ -3901,6 +3911,11 @@ components:
           - type: string
           - type: 'null'
           nullable: true
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
+          nullable: true
       title: OpenAIChoiceDelta
       type: object
     OpenAIChunkChoice:
@@ -10417,6 +10432,14 @@ 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 +10469,14 @@ 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 da61a6385..f935afae4 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:
@@ -4880,6 +4890,11 @@ components:
           - type: string
           - type: 'null'
           nullable: true
+        reasoning:
+          anyOf:
+          - type: string
+          - type: 'null'
+          nullable: true
       title: OpenAIChoiceDelta
       type: object
     OpenAIChunkChoice:
@@ -11747,6 +11762,14 @@ 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 +11799,14 @@ 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 4a169486a..fa2a8fd56 100644
--- a/src/llama_stack_api/inference.py
+++ b/src/llama_stack_api/inference.py
@@ -448,12 +448,16 @@ 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 +609,8 @@ 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 +618,7 @@ 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