Show HN: db-branch – database branches in seconds for AI agents and CI, via ZFS

db-branch is a self-hosted, Apache-2.0 tool that creates copy-on-write branches of MySQL and PostgreSQL databases in seconds using ZFS clones, with nothing copied at creation. It offers a CLI, REST API, web console and MCP server, plus branch reset, TTL expiry, checkpoints and per-branch version upgrades, and is currently in Beta. It targets AI agent sandboxes, a database per pull request in CI, and version-upgrade checks.