iPad users hit a spurious "network error" on the first tap of
"Send sign-in link", with a second tap succeeding. Cause is iOS
Safari dispatching the POST onto a pooled keep-alive socket the
server/proxy already closed; unlike a GET it isn't transparently
re-sent, so it surfaces as a transport TypeError. The single 500ms
auto-retry was too quick and reused the same dead socket.
Both sign-in entry points (auth.html postWithRetry, index.html
fetchWithRetry) now retry 3x with growing backoff (0 -> +400ms ->
+1.6s) to outlast Safari evicting the socket. Frontend-only.
Ships as 0.2.156.
Keysat