Add tests for notification handler fixes

- Test that null _meta is converted to undefined in OpenAI transport
- Test that default no-op handlers accept tool notifications without error

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: ochafik

src/app-bridge.test.ts

@@ -215,6 +215,21 @@ describe("App <-> AppBridge integration", () => {
       expect(receivedCancellations[0]).toEqual({});
     });
 
+    it("tool notifications work with default no-op handlers", async () => {
+      // Don't set any custom handlers - use defaults
+      await app.connect(appTransport);
+
+      // These should not throw (default handlers silently accept them)
+      // Just verify they complete without error
+      await bridge.sendToolInput({ arguments: {} });
+      await bridge.sendToolInputPartial({ arguments: {} });
+      await bridge.sendToolResult({ content: [{ type: "text", text: "ok" }] });
+      await bridge.sendToolCancelled({});
+
+      // If we got here without throwing, the test passes
+      expect(true).toBe(true);
+    });
+
     it("setHostContext triggers app.onhostcontextchanged", async () => {
       const receivedContexts: unknown[] = [];
       app.onhostcontextchanged = (params) => {

src/openai/transport.test.ts

@@ -429,6 +429,29 @@ describe("OpenAITransport", () => {
       });
     });
 
+    test("converts null _meta to undefined in tool result", async () => {
+      // Simulate null being set (e.g., from JSON parsing where null is valid)
+      (mockOpenAI as unknown as { toolResponseMetadata: null }).toolResponseMetadata = null;
+
+      const transport = new OpenAITransport();
+      const messages: unknown[] = [];
+      transport.onmessage = (msg) => {
+        messages.push(msg);
+      };
+
+      transport.deliverInitialState();
+
+      await new Promise((resolve) => setTimeout(resolve, 0));
+
+      const toolResultNotification = messages.find(
+        (m: unknown) =>
+          (m as { method?: string }).method === "ui/notifications/tool-result",
+      ) as { params?: { _meta?: unknown } } | undefined;
+      expect(toolResultNotification).toBeDefined();
+      // _meta should be undefined, not null (SDK rejects null)
+      expect(toolResultNotification?.params?._meta).toBeUndefined();
+    });
+
     test("does not deliver notifications when data is missing", async () => {
       delete mockOpenAI.toolInput;
       delete mockOpenAI.toolOutput;