refactor(openai): remove unused streaming response timestamp

Co-Authored-By: gpt-5.3-codex-high <noreply@anthropic.com>

Author: cursoragent

packages/core/src/tracing/openai/streaming.ts

@@ -36,8 +36,6 @@ interface StreamingState {
 responseId: string;
 /** The model name. */
 responseModel: string;
-/** The timestamp of the response. */
-responseTimestamp: number;
 /** Number of prompt/input tokens used. */
 promptTokens: number|undefined;
 /** Number of completion/output tokens used. */
@@ -99,7 +97,6 @@ function processChatCompletionToolCalls(toolCalls: ChatCompletionToolCall[], sta
 functionprocessChatCompletionChunk(chunk: ChatCompletionChunk,state: StreamingState,recordOutputs: boolean): void{
 state.responseId=chunk.id??state.responseId;
 state.responseModel=chunk.model??state.responseModel;
-state.responseTimestamp=chunk.created??state.responseTimestamp;
 
 if(chunk.usage){
 // For stream responses, the input tokens remain constant across all events in the stream.
@@ -183,7 +180,6 @@ function processResponsesApiEvent(
 const{ response }=eventas{response: OpenAIResponseObject};
 state.responseId=response.id??state.responseId;
 state.responseModel=response.model??state.responseModel;
-state.responseTimestamp=response.created_at??state.responseTimestamp;
 
 if(response.usage){
 // For stream responses, the input tokens remain constant across all events in the stream.
@@ -227,7 +223,6 @@ export async function* instrumentStream<T>(
 finishReasons: [],
 responseId: '',
 responseModel: '',
-responseTimestamp: 0,
 promptTokens: undefined,
 completionTokens: undefined,
 totalTokens: undefined,