refactor(imessage): split monitor inbound processing

src/imessage/monitor.shutdown.unhandled-rejection.test.ts

@@ -0,0 +1,49 @@
+import { describe, expect, it, vi } from "vitest";
+import { attachIMessageMonitorAbortHandler } from "./monitor/abort-handler.js";
+
+describe("monitorIMessageProvider", () => {
+  it("does not trigger unhandledRejection when aborting during shutdown", async () => {
+    const abortController = new AbortController();
+    let subscriptionId: number | null = 1;
+    const requestMock = vi.fn((method: string, _params?: Record<string, unknown>) => {
+      if (method === "watch.unsubscribe") {
+        return Promise.reject(new Error("imsg rpc closed"));
+      }
+      return Promise.resolve({});
+    });
+    const stopMock = vi.fn(async () => {});
+
+    const unhandled: unknown[] = [];
+    const onUnhandled = (reason: unknown) => {
+      unhandled.push(reason);
+    };
+    process.on("unhandledRejection", onUnhandled);
+
+    try {
+      const detach = attachIMessageMonitorAbortHandler({
+        abortSignal: abortController.signal,
+        client: {
+          request: requestMock,
+          stop: stopMock,
+        },
+        getSubscriptionId: () => subscriptionId,
+      });
+      abortController.abort();
+      // Give the event loop a turn to surface any unhandledRejection, if present.
+      await new Promise<void>((resolve) => {
+        if (typeof setImmediate === "function") {
+          setImmediate(resolve);
+          return;
+        }
+        setTimeout(resolve, 0);
+      });
+      detach();
+    } finally {
+      process.off("unhandledRejection", onUnhandled);
+    }
+
+    expect(unhandled).toHaveLength(0);
+    expect(stopMock).toHaveBeenCalled();
+    expect(requestMock).toHaveBeenCalledWith("watch.unsubscribe", { subscription: 1 });
+  });
+});