Phase: 2 — Networking Foundations + L4 Goal: Slower pace, deeper understanding. Solidify TCP internals, add SNI routing, audit for races, benchmark the full L4 stack. End with the Phase 2 capstone: Secure TCP Gateway.
Background in this wiki: TCP/IP guide Ch 23 (CLOSE_WAIT, reproduced), Ch 22 (framing a byte stream), Ch 56 (certificate rotation), and Ch 32 (reading a ClientHello: the basis of SNI routing); HTTPS guide Ch 14 (HTTP/2 multiplexing and negotiation).