Breaks the aggregate isConnected check out by ingestion pathway (BACK-2278) — provider billing sync, direct SDK/API metering, coding-assistant telemetry, and distributed traces — each with whether it has ever received data and when it last did, so callers can route and message by source type instead of relying on a single aggregate flag. Note on traces: this requires a multi-hop/agentic chain (a parent-child link, or multiple events sharing a traceId) — it is not simply "has any call been traced," since every ingested event carries a traceId by default (defaulting to its own transaction id when none is set). providerBilling.lastReceived is day-level precision only (normalized to midnight UTC), since provider-billing syncs are not timestamped to the moment.