The idle-heartbeat test failed deterministically on linux (not the
timing flake it was first read as): TCP_KEEPIDLE/TCP_KEEPINTVL have
whole-second granularity there, so the test config's 50ms heartbeat
truncated to zero and setsockopt returned EINVAL on both ends of the
handshake — a real runtime bug for any sub-second heartbeat config,
fixed by clamping only the kernel keepalive cadence to >= 1s.
The 6 MiB gzip tripwire was set when the bundle measured ~4.5 MiB;
feature growth since (collab, prompt center, templates) added ~4.5 MiB
of embedded product assets, ~2 MiB of it pre-compressed JPEG that gzip
passes through. Reset the tripwire to 8 MiB and document that it is a
regression guard, not a budget, with the asset-split TODO that brings
the bundle back down.
1030f5b131