Server-side save states via js-dos fsChanges hooks

frontend/src/pages/__tests__/Play.test.js

@@ -7,6 +7,9 @@ vi.mock("../../lib/api.js", () => ({
   getGame: vi.fn(),
   bundleUrl: vi.fn(),
   setupBundleUrl: vi.fn(),
+  pullSaves: vi.fn(),
+  pushSaves: vi.fn(),
+  deleteSaves: vi.fn(),
 }));
 
 // Mock router
@@ -74,4 +77,49 @@ describe("Play", () => {
       expect(screen.getByText("Starting emulator...")).toBeTruthy();
     });
   });
+
+  it("starts js-dos with server-backed save hooks", async () => {
+    api.getGame.mockResolvedValue(makeGame());
+    api.bundleUrl.mockReturnValue("/games/game-1.jsdos");
+
+    const dosMock = vi.fn().mockReturnValue({
+      save: vi.fn().mockResolvedValue(true),
+      stop: vi.fn().mockResolvedValue(undefined),
+    });
+    window.Dos = dosMock;
+
+    try {
+      render(Play, { props: { id: "game-1" } });
+      await vi.waitFor(() => {
+        expect(dosMock).toHaveBeenCalled();
+      });
+
+      const opts = dosMock.mock.calls[0][1];
+      expect(opts.url).toBe("/games/game-1.jsdos");
+      expect(opts.autoSave).toBe(true);
+
+      // Both normal and setup bundles map to the same per-game save key
+      await expect(opts.fsChanges.urlToKey("/games/game-1.jsdos")).resolves.toBe("game-1");
+
+      // pull() forwards to the API and returns null when there is no save
+      api.pullSaves.mockResolvedValue(null);
+      await expect(opts.fsChanges.pull("game-1")).resolves.toBeNull();
+      expect(api.pullSaves).toHaveBeenCalledWith("game-1");
+
+      // push()/delete() forward to the API
+      api.pushSaves.mockResolvedValue({ status: "saved" });
+      await opts.fsChanges.push("game-1", new Uint8Array([1]));
+      expect(api.pushSaves).toHaveBeenCalledWith("game-1", expect.any(Uint8Array));
+
+      api.deleteSaves.mockResolvedValue({ status: "deleted" });
+      await opts.fsChanges.delete("game-1");
+      expect(api.deleteSaves).toHaveBeenCalledWith("game-1");
+
+      // pull() survives API errors so the game still boots
+      api.pullSaves.mockRejectedValue(new Error("offline"));
+      await expect(opts.fsChanges.pull("game-1")).resolves.toBeNull();
+    } finally {
+      delete window.Dos;
+    }
+  });
 });