Local Core HTTP bridge

kestrel web exposes Local Core's Execution Protocol through an authenticated loopback HTTP endpoint. It is a bridge for trusted local server applications, not a second runtime.

Build identity and compatibility

The bridge and Local Core must report the exact 0.8 line and intended build identity. Stop when the bridge targets a stale or incompatible Core.

Start the bridge

kestrel web

The command ensures Local Core is ready and prints:

• KESTREL_RUNNER_SERVICE_URL
• KESTREL_RUNNER_SERVICE_TOKEN

Connect a local application

kestrel web
export KESTREL_RUNNER_SERVICE_URL='http://127.0.0.1:43102'
export KESTREL_RUNNER_SERVICE_TOKEN='...'
pnpm dev

The SDK uses its remote HTTP transport for this loopback URL, but execution and state remain in Local Core.

Check health and authentication

curl -sS "$KESTREL_RUNNER_SERVICE_URL/health"

If you provided a custom host, port, or token, confirm the printed exports match the values used by the local application server.

Health should also show readiness, build identity, and profile/provider capability status. A successful socket/HTTP check alone does not prove the selected model or tools are ready.

Content-aware restart

Local Core compares the running build identity with the required content and may replace an unhealthy or stale process. Restart is recovery for process ownership, not a workaround for invalid configuration, migrations, or provider authority.

Shutdown and reconnect behavior

Closing the bridge removes the HTTP transport but does not erase Local Core sessions or runs. Reconnect with the newly printed token and inspect durable state before retrying work.

When to use this guide

Use this page when you need:

• the local bridge command
• the printed environment variables
• a local health check

Use Connect to a runner service to compare this local bridge with a remote runner-service deployment.

Continue

• Environment and auth
• Integrating with Next.js
• Production operating model