classDiagram
    direction LR
    class CollectJob {
        -List~SnapshotSource~ sources
        -CallBudget budget
        -SnapshotRepository snapshots
        -Clock clock
        +collectAll() void
    }
    class SnapshotSource {
        <<interface>>
        +id() String
        +costPerCall() int
        +collect(String routeId, Instant now) Snapshot
    }
    class GbisLocationSource {
        -RestClient client
        -String serviceKey
        +id() String
        +costPerCall() int
        +collect(String routeId, Instant now) Snapshot
    }
    class CallBudget {
        -Map usedBySource
        -LocalDate windowDate
        -int dailyLimit
        +tryConsume(String sourceId, int cost) boolean
    }
    class Snapshot {
        -Long id
        -String sourceId
        -String routeId
        -Instant observedAt
        -Instant collectedAt
        -int normalizationVersion
        -List~BusObservation~ buses
        +from(String sourceId, String routeId, Instant observedAt, List raw) Snapshot
    }
    class BusObservation {
        -Long id
        -String vehicleId
        -int stationSeq
        -Integer remainingSeats
        -Integer crowded
    }
    class SnapshotRepository {
        <<repository>>
        +save(Snapshot s) Snapshot
    }
    CollectJob --> SnapshotSource
    CollectJob --> CallBudget
    CollectJob --> SnapshotRepository
    SnapshotSource <|.. GbisLocationSource
    SnapshotSource ..> Snapshot
    Snapshot o-- BusObservation
    SnapshotRepository ..> Snapshot