Preview web apps live as your coding agent builds them with Amazon Bedrock AgentCore runtime

What changed

AWS's AgentCore Session endpoints provide an authenticated URL to an application running inside a single agent runtime session. The walkthrough keeps a Vite site running while a coding agent edits its files, so a reviewer can open the preview and see changes as they happen. This is a development and review pattern, not a production hosting setup.

How the preview works

1. The runtime permits specified ports. The application server must actually listen on an allowed port; opening a port does not start it.
2. The agent changes files in the same session where the Vite server runs. Vite sends updates to the preview through a WebSocket connection.
3. Requests to the session endpoint require authentication. AWS describes IAM SigV4 and inbound JWT options; possessing the URL alone does not grant access.
4. The URL lasts only for the session. A user-facing application still needs deployment to a hosting service.

When this helps

A product or engineering reviewer can try an agent-built interface, request a change, and check the result before creating a separate deployment. The useful question for a team is how to keep this feedback loop secure: allow only needed ports, use the intended authentication path, and separate temporary previews from released environments.

For MTREXA's software and AI workflow projects, this is a potential review pattern to evaluate, not a claim that MTREXA has deployed the AWS sample.

Source and attribution

This briefing interprets AWS's AgentCore Session endpoint walkthrough. Consult AWS's sample and documentation for current setup requirements.