fix(coding-agent): preserve compaction queue behavior (#6730)

packages/coding-agent/src/modes/interactive/interactive-mode.ts

@@ -4044,10 +4044,12 @@ export class InteractiveMode {
 				await this.session.prompt(message.text);
 			}
 
-			// Send first prompt (starts streaming)
-			const promptPromise = this.session.prompt(firstPrompt.text).catch((error) => {
-				restoreQueue(error);
-			});
+			// Start a prompt when idle, or queue it into a run still finishing compaction.
+			const promptPromise = this.session
+				.prompt(firstPrompt.text, { streamingBehavior: firstPrompt.mode })
+				.catch((error) => {
+					restoreQueue(error);
+				});
 
 			// Queue remaining messages
 			for (const message of rest) {

packages/coding-agent/test/interactive-mode-compaction.test.ts

@@ -56,4 +56,30 @@ describe("InteractiveMode compaction events", () => {
 		);
 		expect(fakeThis.flushCompactionQueue).toHaveBeenCalledWith({ willRetry: false });
 	});
+
+	test("preserves steering behavior when flushing into an active agent run", async () => {
+		const fakeThis = {
+			compactionQueuedMessages: [{ text: "change direction", mode: "steer" as const }],
+			session: {
+				clearQueue: vi.fn(),
+				prompt: vi.fn().mockResolvedValue(undefined),
+				steer: vi.fn().mockResolvedValue(undefined),
+				followUp: vi.fn().mockResolvedValue(undefined),
+			},
+			isExtensionCommand: vi.fn().mockReturnValue(false),
+			updatePendingMessagesDisplay: vi.fn(),
+			showError: vi.fn(),
+		};
+
+		const flushCompactionQueue = Reflect.get(InteractiveMode.prototype, "flushCompactionQueue") as (
+			this: typeof fakeThis,
+			options?: { willRetry?: boolean },
+		) => Promise<void>;
+
+		await flushCompactionQueue.call(fakeThis, { willRetry: false });
+
+		expect(fakeThis.session.prompt).toHaveBeenCalledWith("change direction", { streamingBehavior: "steer" });
+		expect(fakeThis.compactionQueuedMessages).toEqual([]);
+		expect(fakeThis.showError).not.toHaveBeenCalled();
+	});
 });