Forecast upcoming occurrences

Counts the occurrences this project and environment expect to fire, in epoch-aligned time buckets, with a latency-class split on every bucket and an optional customer partition-key breakdown. A recurring series contributes every instant it fires inside the window rather than only its next one, and nextFireCount reports how many of a bucket's occurrences are a schedule's next firing. The answer states freshness and explicit coverage. Clients sending X-Greatwait-Accept-Partial-Forecast: true receive bounded lower-bound counts when a book reaches a row, cell or recurrence-work bound, with coverage.complete false and the exact bounds reached. Without this capability header the previous refusal behavior remains safe for clients that only read totals. Unavailable or stale sources still refuse. Coverage identifies the selected recurring schedule range but never includes destinations, payload or endpoint detail.