feat: Add has_reasoning flag to chat completion responses

- Add has_reasoning field to ChatChoice and ChatChoiceStream structs
- Set has_reasoning to true when reasoning_content is present and non-empty
- Helps clients identify responses that include reasoning content

Fixes #7154

Signed-off-by: Asad Shahid <asad.shahid@berkeley.edu>

Author: AsadShahid04

lib/async-openai/src/types/chat.rs

@@ -1157,6 +1157,10 @@ pub struct ChatChoice {
     /// Log probability information for the choice.
     #[serde(skip_serializing_if = "Option::is_none")]
     pub logprobs: Option<ChatChoiceLogprobs>,
+    /// Flag indicating whether this choice includes reasoning content.
+    /// Set to `true` when `message.reasoning_content` is present.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub has_reasoning: Option<bool>,
 }
 
 /// Represents a chat completion response returned by model, based on the provided input.
@@ -1256,6 +1260,10 @@ pub struct ChatChoiceStream {
     /// Log probability information for the choice.
     #[serde(skip_serializing_if = "Option::is_none")]
     pub logprobs: Option<ChatChoiceLogprobs>,
+    /// Flag indicating whether this choice includes reasoning content.
+    /// Set to `true` when `delta.reasoning_content` is present.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub has_reasoning: Option<bool>,
 }
 
 #[derive(ToSchema, Debug, Deserialize, Clone, PartialEq, Serialize)]

lib/llm/src/audit/stream.rs

@@ -217,6 +217,7 @@ pub fn final_response_to_one_chunk_stream(
             finish_reason: ch.finish_reason,
             stop_reason: ch.stop_reason.clone(),
             logprobs: ch.logprobs.clone(),
+            has_reasoning: ch.has_reasoning,
         };
         choices.push(choice);
     }
@@ -272,6 +273,7 @@ mod tests {
             finish_reason: None,
             stop_reason: None,
             logprobs: None,
+            has_reasoning: None,
         };
 
         let response = NvCreateChatCompletionStreamResponse {
@@ -311,6 +313,7 @@ mod tests {
             finish_reason: Some(FinishReason::Stop),
             stop_reason: None,
             logprobs: None,
+            has_reasoning: None,
         };
 
         let response = NvCreateChatCompletionStreamResponse {
@@ -441,6 +444,7 @@ mod tests {
                         finish_reason: None,
                         stop_reason: None,
                         logprobs: None,
+                        has_reasoning: None,
                     }
                 }],
                 created: 1234567890,

lib/llm/src/protocols/openai/chat_completions/aggregator.rs

@@ -311,6 +311,11 @@ impl From<DeltaChoice> for dynamo_async_openai::types::ChatChoice {
             None
         };
 
+        let has_reasoning = delta
+            .reasoning_content
+            .as_ref()
+            .is_some_and(|r| !r.is_empty());
+
         dynamo_async_openai::types::ChatChoice {
             message: dynamo_async_openai::types::ChatCompletionResponseMessage {
                 role: delta.role.expect("delta should have a Role"),
@@ -325,6 +330,7 @@ impl From<DeltaChoice> for dynamo_async_openai::types::ChatChoice {
             finish_reason,
             stop_reason: delta.stop_reason,
             logprobs: delta.logprobs,
+            has_reasoning: if has_reasoning { Some(true) } else { None },
         }
     }
 }

lib/llm/src/protocols/openai/chat_completions/delta.rs

@@ -265,12 +265,18 @@ impl DeltaGenerator {
             reasoning_content: None,
         };
 
+        let has_reasoning = delta
+            .reasoning_content
+            .as_ref()
+            .is_some_and(|r| !r.is_empty());
+
         let choice = dynamo_async_openai::types::ChatChoiceStream {
             index,
             delta,
             finish_reason,
             stop_reason,
             logprobs,
+            has_reasoning: if has_reasoning { Some(true) } else { None },
         };
 
         let choices = vec![choice];

lib/llm/src/protocols/openai/chat_completions/jail.rs

@@ -135,6 +135,7 @@ fn create_choice_stream(
         finish_reason,
         stop_reason,
         logprobs,
+        has_reasoning: None,
     }
 }
 
@@ -598,6 +599,7 @@ impl JailedStream {
                                     finish_reason: choice.finish_reason,
                                     stop_reason: choice.stop_reason.clone(),
                                     logprobs: choice.logprobs.clone(),
+                                    has_reasoning: choice.has_reasoning,
                                 };
                                 all_emissions.push(ChoiceEmission::PassThrough(pass_through_choice));
                             }