fix: prevent infinite loop when canceling during auto-retry

- Add abort check after backoffAndAnnounce in first-chunk retry logic
- Add abort check after backoffAndAnnounce in mid-stream retry logic
- Properly handle task abortion to break retry loops

Fixes #8901

Author: roomote

src/core/task/Task.ts

@@ -2240,6 +2240,17 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 									error,
 									streamingFailedMessage,
 								)
+
+								// Check if task was aborted during the backoff
+								if (this.abort) {
+									console.log(
+										`[Task#${this.taskId}.${this.instanceId}] Task aborted during mid-stream retry backoff`,
+									)
+									// Abort the entire task
+									this.abortReason = "user_cancelled"
+									await this.abortTask()
+									break
+								}
 							}
 
 							// Push the same content back onto the stack to retry, incrementing the retry attempt counter
@@ -2790,6 +2801,13 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 				// Apply shared exponential backoff and countdown UX
 				await this.backoffAndAnnounce(retryAttempt, error, errorMsg)
 
+				// Check if task was aborted during the backoff
+				if (this.abort) {
+					throw new Error(
+						`[Task#attemptApiRequest] task ${this.taskId}.${this.instanceId} aborted during retry`,
+					)
+				}
+
 				// Delegate generator output from the recursive call with
 				// incremented retry count.
 				yield* this.attemptApiRequest(retryAttempt + 1)