Leaderboard & Counting Service  ·  View 01 of 21  ·  Context and scope

System Context

Who generates the numbers, who consumes them, and the one decision the platform refuses to make.

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Accountable for the number Product owner Platform engineer People who generate the numbers Product member Product engineer Trust & safety analyst Systems it reads and writes Product backends Member directory Identity provider Analytics warehouse Leaderboard & Counting Service count, rank, publish Consumers of the result Product clients Reward & fulfilment Notification service earns, views rank declares counters retracts, freezes emit events display names authN export owns the surface owns capacity render rank standings rank changes Leaderboard & Counting Service — System Context Person or role External / third party synchronous batch event / async The platform never decides what earns a point: the product does, and emits the event. Display names are resolved from the member directory at read time and are never stored in a counter. v 1.0 · owner Platform Architecture · date 2026-10

Decisions

  • The platform never decides what earns a point. The product emits an event with a signed delta; the platform counts it. That boundary is what makes one service serve 25 unrelated product surfaces.
  • Display identity is resolved from the member directory at read time and never stored in a counter, so a counter row carries a pseudonymous reference and a number and nothing a leak could use.
  • The reward service is in the context as a consumer of closed standings only. Nothing pays out against a live projection.

Deliberately out of scope

  • The rules of the game: what counts as a lesson completed, a valid ride or a legitimate vote.
  • The screens that render the number, and any product notification logic beyond a rank-change event.
  • Analytical querying of counting history — the warehouse receives an export and is never on the serving path.

Assumptions

  • 80 million monthly active members across 25 product tenants; a tenant is a product team.
  • 250,000 counting events per second steady state, 400,000 leaderboard reads per second.
  • Every figure in this set is a stated assumption unless tied to a named provider SLA.
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Solution Architecture v1.0 · Google Cloud · Platform Architecture · 2026-1001-system-context