fix: ensure subtask results are provided to GPT-5 in OpenAI Responses API (#7305)

When a subtask completes and the parent task resumes, set skipPrevResponseIdOnce = true
to ensure the next API call sends the full conversation including the subtask result.
This fixes the issue where GPT-5 would only receive the new message without the subtask
result context when using previous_response_id.

Fixes #7251

Author: daniel-lxs

src/core/task/Task.ts

@@ -1123,6 +1123,10 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 				role: "user",
 				content: [{ type: "text", text: `[new_task completed] Result: ${lastMessage}` }],
 			})
+
+			// Set skipPrevResponseIdOnce to ensure the next API call sends the full conversation
+			// including the subtask result, not just from before the subtask was created
+			this.skipPrevResponseIdOnce = true
 		} catch (error) {
 			this.providerRef
 				.deref()