Call this when an agent tracks GDACS disasters (see /v1/disaster-events) and needs what changed since a date: alert-level moves, is_current flips with how long the previous state held, and events entering or leaving Orange/Red scope, each dated to the daily snapshot that first showed it. GDACS publishes episode lists free but never when anything changed; these dates are ours, from 2026-08-25. Orange/Red only. Not for life-safety. Filters: since (required), until, kind, event_type.

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