Diagnostics dropped

Some diagnostics never reached the store: the thread that emitted them filled its bus ring (512 events) before the host drained it. The count in the message is exact; the dropped diagnostics themselves are gone.

#Common causes

• A subsystem emitted hundreds of diagnostics in one host tick without sampling, usually inside a per-entity or per-frame loop.
• The host was blocked (a long call, a debugger pause) and did not drain for a while.
• A process emits diagnostics but has no consumer forwarding them to the host.

#Fixes

• Find the spamming code with ara logs (it has the highest count) and emit it with ara_diag::emit!, which checks admission before formatting.

• Lower the code's burst with ara_diag::bus::set_burst(code, n) so repeats are only counted.

• Give the diagnostic a stable dedup key (Meta::dedup) when its message varies per occurrence.

• Code: ARA2001

• Constant: DIAG_DROPPED

• Reported by: ara-diag