The SQLite network-map query expanded a router's groups with from network_routers, json_each(peer_groups). That comma is an inner join, so a router row survives only when json_each returns at least one row. A router targeting an individual peer carries no groups — the write path stores NULL for a nil slice and '[]' for an empty one — and json_each yields nothing for either, so the join erased the router before it could be keyed by its peer. Postgres reads the same rows through a correlated subquery and was never affected.
The fix expands the groups with a left join, so the router survives with a NULL group_peers.peer_id and the existing scan loop keys it by router.Peer. Group routers still fan out one row per member.
