fix: tolerate missing pi-coding-agent backend export

src/agents/pi-model-discovery.compat.test.ts

@@ -0,0 +1,26 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+describe("pi-model-discovery module compatibility", () => {
+  afterEach(() => {
+    vi.resetModules();
+    vi.doUnmock("@mariozechner/pi-coding-agent");
+  });
+
+  it("loads when InMemoryAuthStorageBackend is not exported", async () => {
+    vi.resetModules();
+    vi.doMock("@mariozechner/pi-coding-agent", () => {
+      class MockAuthStorage {}
+      class MockModelRegistry {}
+
+      return {
+        AuthStorage: MockAuthStorage,
+        ModelRegistry: MockModelRegistry,
+      };
+    });
+
+    await expect(import("./pi-model-discovery.js")).resolves.toMatchObject({
+      discoverAuthStorage: expect.any(Function),
+      discoverModels: expect.any(Function),
+    });
+  });
+});