add logging for activity pause, emit application failure on activity pause

Author: THardy98

packages/worker/src/activity.ts

@@ -143,7 +143,11 @@ export class Activity {
         (error instanceof CancelledFailure || isAbortError(error)) &&
         this.context.cancellationSignal.aborted
       ) {
-        this.workerLogger.debug('Activity completed as cancelled', { durationMs });
+        if (this.context.cancellationDetails.details?.paused) {
+          this.workerLogger.debug('Activity paused', { durationMs });
+        } else {
+          this.workerLogger.debug('Activity completed as cancelled', { durationMs });
+        }
       } else if (error instanceof CompleteAsyncError) {
         this.workerLogger.debug('Activity will complete asynchronously', { durationMs });
       } else {
@@ -176,9 +180,21 @@ export class Activity {
         } else if (this.cancelReason) {
           // Either a CancelledFailure that we threw or AbortError from AbortController
           if (err instanceof CancelledFailure) {
-            const failure = await encodeErrorToFailure(this.dataConverter, err);
-            failure.stackTrace = undefined;
-            return { cancelled: { failure } };
+            // If cancel due to activity pause, emit an application failure for the pause.
+            if (this.context.cancellationDetails.details?.paused) {
+              return {
+                failed: {
+                  failure: await encodeErrorToFailure(
+                    this.dataConverter,
+                    new ApplicationFailure('Activity paused', 'ActivityPause')
+                  ),
+                },
+              };
+            } else {
+              const failure = await encodeErrorToFailure(this.dataConverter, err);
+              failure.stackTrace = undefined;
+              return { cancelled: { failure } };
+            }
           } else if (isAbortError(err)) {
             return { cancelled: { failure: { source: FAILURE_SOURCE, canceledFailureInfo: {} } } };
           }