Three review findings from the follower receive path.
Non-finite scroll x reached follower rendering. json.loads accepts the
bare NaN/Infinity literals and float() accepts them as strings, so
"x": NaN arrived as a real float and was stored verbatim. NaN loses
every comparison the scroll code makes, so a follower given one sits on
a position it can never advance past. It now raises through the existing
malformed-control-message guard, which logs and drops the packet and
leaves the last good position in place.
_broadcast_available() only proves the host accepts sendto() for a
broadcast; a network that accepts the send and drops the packet would
let TestRealSocketHandshake run to its five-second deadline and fail on
assertions the code did not break. The deadline now distinguishes the
two: if not one packet crossed in either direction, that is the
environment, and the test skips rather than reporting a protocol
failure.
That skip could hide a real regression in the announcing side, so
TestFollowerAnnounceLoop covers it on mock sockets, where no network is
involved and nothing can skip: hello carries this display's hardware
config and goes to the broadcast address, heartbeats follow, an empty
hardware config falls back to 32x64x1, hello is not resent before its
interval, and a send failure is swallowed rather than killing the loop.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NohXi78cwsAKtN1sCfxjUh
Claude
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