Request lifecycle

1. TCP + startup (handler.rs:165-225): SSLRequest (80877103/4) → N, CancelRequest → close, else require protocol 196608 with user/database defaults.
2. Auth (session.rs, scram.rs): Cleartext (R3), Md5 (R5 salt=pid bytes), Scram (R10→R11→R12, salt=sha256(password)[..16], PBKDF2 4096/32), disabled → R0. Pure-Rust crypto.
3. Simple Q: empty → EmptyQuery; COPY … STDIN/STDOUT → copy frames; DEALLOCATE/DISCARD/UNLISTEN/LISTEN/NOTIFY/CREATE|DROP DATABASE/USE/SHOW DATABASES via registry or stub; else Executor::execute* → T/D/C/E/N/Z (T rowdesc table/col 0, D datarow -1=NULL, text values only).
4. Extended P/B/D/E/S: Parse→1 (store query+types+generation), Bind→2 (decode text/binary per OID), Describe→t/T/n, Execute (append LIMIT max_rows; batchable plain multi-VALUES INSERTs staged, flushed as BEGIN;…;COMMIT at Sync), Sync→flush+Z, errors → E + InFailedTransaction until Sync.
5. Execution: statement_type() dispatch, block_in_place engine calls, pg_catalog/information_schema served from live in-memory catalog + session params (server_version 17.0, search_path "$user",public, …).

Transport: set_nodelay, BufReader/Writer, MAX_FRONTEND_MESSAGE_SIZE 64 MiB, max_connections=100000 graceful reject, connection_id/query_id tracing.