ontoolinput is not consistently called

Describe the bug
Using the useApp hook, I notice app.ontoolinput is not consistently called although it is registered before app.connect

To Reproduce
Steps to reproduce the behavior:

1. Instantiate useApp() with a minimal setup:

import { useApp } from "@modelcontextprotocol/ext-apps/react";

//...

useApp({
  appInfo: { name: "Describe your app here...", version: "1.0.0" },
  capabilities: {},
  onAppCreated: (app) => {
    app.ontoolinput = (input) => {
      console.info("Received tool call input:", input);
    };
  },
});

2. Run the app in any host
3. Call a tool with user input using a manual prompt
4. Notice how app.ontoolinput is not always called

Expected behavior
app.ontoolinput is called every time a tool is invoked

Logs
If applicable, add logs to help explain your problem.

Additional context
Other callbacks seem to run as expected, including app.ontoolresult.

Start at the useApp hook imported from @modelcontextprotocol/ext-apps/react and trace how app.ontoolinput is registered relative to app.connect. Reproduce the manual-prompt tool call in a minimal app and compare it with the working ontoolresult callback. Done means ontoolinput is called for every tool invocation.