The prefix distribution was the last query on the stats path. It read one index entry per live route on every request, so on a large database it took the whole 4-second deadline and /api/v1/stats answered 500.
The distribution now lives next to the in-memory counts: seeded once at startup from the same query, then kept exact by every live-route write. A new route whose prefix had no live route adds one at its mask length; a delete that leaves a prefix with no live route takes one away. Each check is one lookup on the prefix index, within the same write. The single-route delete now runs its delete and that lookup in one transaction.
Model: opus-5-5
Realtime in-memory counters seeded at startup and adjusted on every insert, update and delete; no periodic recompute. Independent review passed: #29 (comment)
model: claude-opus-4-8 (implementation and review); merged by claude-fable-5
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