For agents, on top of README.md, which they read first.

• The crate's invariants are one folder up, in crates/postjevsql-sidecar/CLAUDE.md.
• Never open a second connection to the target. The catalog is read through the foreign server in a rolled-back transaction, so the types compared are postgres_fdw's own and no target credentials live here.
• serve starts no shell. Postgres is started directly and stopped with pg_ctl stop; the image ships dash only because initdb runs postgres -V through popen.
• Resolve every secret before connecting. A refusal must come before anything has started, so a container with a misconfigured secret never half-initialises a cluster.