Template
A published database port puts the data on the public internet, and Docker's own iptables rules bypass ufw — the server looks firewalled while the port is open. Previously this was only a comment in compose.yaml, which an agent adding a db service later is free to ignore. Anchored at every point where a service could be added or shipped: - rules/security.md: the rule, the reasoning, and the audit commands - rules/backend.md + architecture SKILL: constraint when picking the data layer - agents/backend-dev.md: non-negotiable for any service it adds - agents/qa-engineer.md: a published port is a Critical finding - skills/deploy: blocking pre-flight audit - compose.yaml: db example now uses expose:, with depends_on healthcheck - docs/DEPLOYMENT.md + README: SSH tunnel instead of publishing for debugging