Two real-world failures hit the Pico W gateway that the headless e2e
(node fetch, tiny request, fast timing) didn't surface:
- A browser sends KILOBYTES of headers (cookies, User-Agent, sec-*).
Forwarded verbatim, the request overran the chip's small recv()
(e.g. recv(1024)); lwIP then RST the connection on close-with-unread-
data, crashing blocking-socket sketches with ECONNRESET. Now we forward
a MINIMAL request (method, path, Host, Connection: close, and
Content-Type/Length for bodies) — nothing a tiny server can choke on.
- After a gateway request completed we dropped the connection immediately,
so a late chip segment (retransmitted FIN / trailing ACK) no longer
matched and fell through to the chip-initiated NAT, which RST it. Add a
short TIME_WAIT: keep the connection briefly and re-ACK late segments so
the chip closes cleanly, never RSTing it.
bb4d06cc7a