0004 · JSON WebSocket protocol

• Status: accepted (2026-09-29), to be revisited with benchmarks

#Decision

Text JSON messages with short field names. A binary format only enters if measurement shows a benefit.

Optimisations already applied, all independent of the wire format:

• client input is sent only when the direction changes (plus a resend every 400 ms while a key is held);
• deltas are batched per client, one frame per tick;
• positions are integers in pixels;
• WebSocket compression is disabled (it costs CPU and memory per connection);
• a 2 KB cap per incoming frame and per-connection rate limits.

#Consequences

Debugging is easy (traffic is readable in the browser). The cost is bandwidth and serialisation CPU above a binary format; how much that matters is a question for the presence benchmark (scenario A).