diff --git a/packages/edge-worker/src/EdgeWorker.ts b/packages/edge-worker/src/EdgeWorker.ts
index 095364d68..adb40e661 100644
--- a/packages/edge-worker/src/EdgeWorker.ts
+++ b/packages/edge-worker/src/EdgeWorker.ts
@@ -1512,7 +1512,8 @@ Your base branch \`${branchName}\` has received ${commitCount} new commit(s). Co
 			if (
 				isRunning &&
 				existingRunner?.supportsStreamingInput &&
-				existingRunner.addStreamMessage
+				existingRunner.addStreamMessage &&
+				existingRunner.isStreaming?.()
 			) {
 				existingRunner.addStreamMessage(notification);
 				this.logger.debug(
@@ -3521,7 +3522,8 @@ ${taskSection}`;
 			if (
 				isRunning &&
 				existingRunner?.supportsStreamingInput &&
-				existingRunner.addStreamMessage
+				existingRunner.addStreamMessage &&
+				existingRunner.isStreaming?.()
 			) {
 				existingRunner.addStreamMessage(fullPrompt);
 				delivered = true;
@@ -6616,7 +6618,8 @@ ${input.userComment}
 		if (
 			existingRunner?.isRunning() &&
 			existingRunner.supportsStreamingInput &&
-			existingRunner.addStreamMessage
+			existingRunner.addStreamMessage &&
+			existingRunner.isStreaming?.()
 		) {
 			log.debug(
 				`Adding prompt to existing stream for ${sessionId} (${logContext})`,
@@ -6703,7 +6706,8 @@ ${input.userComment}
 		if (
 			existingRunner?.isRunning() &&
 			existingRunner.supportsStreamingInput &&
-			existingRunner.addStreamMessage
+			existingRunner.addStreamMessage &&
+			existingRunner.isStreaming?.()
 		) {
 			let fullPrompt = promptBody;
 			if (attachmentManifest) {
diff --git a/packages/edge-worker/test/EdgeWorker.issue-update-multiple-sessions.test.ts b/packages/edge-worker/test/EdgeWorker.issue-update-multiple-sessions.test.ts
index cb6d4bcd6..14f3751fb 100644
--- a/packages/edge-worker/test/EdgeWorker.issue-update-multiple-sessions.test.ts
+++ b/packages/edge-worker/test/EdgeWorker.issue-update-multiple-sessions.test.ts
@@ -83,6 +83,7 @@ describe("EdgeWorker - Issue Update Session Delivery (CYPACK-954)", () => {
 			agentRunner: hasRunner
 				? {
 						isRunning: vi.fn().mockReturnValue(isRunning),
+						isStreaming: vi.fn().mockReturnValue(isRunning),
 						supportsStreamingInput: supportsStreaming,
 						addStreamMessage: vi.fn(),
 						stop: vi.fn(),