Fly.io

Generate the Docker artifact, initialize a Fly application from that directory, and configure the internal port as 3000.

fh build --target docker
cd .fabricharness/build/docker
fly launch --no-deploy
fly secrets set FABRIC_HARNESS_API_TOKEN=... FABRIC_MODEL=...
fly deploy

Use managed or external Postgres for durable state; do not rely on an ephemeral root filesystem. Restrict public routes, configure health/readiness checks, pin regions and machine resources, and test process restart plus rolling deployment behavior.