test: settled in-flight auto-title request between orphan-submit iterations

The title latch from PR #8911 dedupes a second title start while one is in flight; the orphan-submit loop implicitly relied on the first mocked request having settled. Drain its promise chain at a macrotask boundary before the next submit.

packages/coding-agent/test/input-controller-orphan-submit.test.ts

@@ -331,6 +331,13 @@ describe("InputController orphaned submit", () => {
 					images: undefined,
 				});
 				expect(titleSpy).toHaveBeenCalledWith(forwardedText);
+				// Drain the title request's .then/.finally chain so the in-flight
+				// latch clears before the next submit; a request still in flight is
+				// deliberately deduped (see agent-session-title-generation-dispose).
+				// The chain exposes no settlement promise; sleep(0) is a macrotask
+				// boundary that deterministically drains all pending microtasks —
+				// not a wall-clock wait, so fake timers would not help here.
+				await Bun.sleep(0);
 			}
 		} finally {
 			vi.restoreAllMocks();