Bedrock AgentCore session endpoints let coding agents serve live web-app previews

AWS has added a feature aimed at coding agents. AgentCore Runtime session endpoints give each session its own authenticated URL that forwards HTTP and WebSocket traffic to ports the operator allows. In AWS's demo, a coding agent runs a Vite development server inside its session, and the user watches the live site update in a browser as the agent edits files.

The mechanism solves a real problem. Agent sandboxes are isolated by design, which makes it hard to see what a web-building agent is producing until it exports code. Session endpoints expose a controlled port through an authenticated proxy, so preview works without opening the sandbox to the internet. WebSocket support enables hot module reload.

This matches features from Replit, Vercel's v0, Lovable and Bolt, which made live preview a default expectation for AI app builders. AWS's angle is enterprise: the same governance, identity and isolation as the rest of AgentCore, usable by teams building their own coding agents. It fits Swami Sivasubramanian's claim that AgentCore agent deployments doubled in Q3.

Watch the security model closely. Authenticated URLs to running agent sessions are an attack surface, especially in a week dominated by sandbox escape disclosures. Pricing for session time and egress will also determine whether it is practical at scale.