# Stage 01 — Architecture sync

This decision record captures the non-obvious choice from
[`../PLAN.md` Stage 01](../PLAN.md#stage-01-update-architecturemd):
the drop of `ships_built` from every architectural mention of
`player_turn_stats`.

## Context

Before Stage 01, `ARCHITECTURE.md` and `lobby/README.md` described
`player_turn_stats` as carrying `{user_id, planets, population,
ships_built}`, and the Race Name Directory capability rule was wired in
prose as if `ships_built` could affect the outcome. In practice, the
formal capability rule was already
`max_planets > initial_planets AND max_population > initial_population`
— `ships_built` was named in the stats payload but never referenced by
the rule.

## Decision

`player_turn_stats` carries `{user_id, planets, population}` only.
`ships_built` is removed from:

- `ARCHITECTURE.md §8 Game Master` — `runtime_snapshot_update` payload
  description.
- `ARCHITECTURE.md §7 Game Lobby` — per-member aggregate description
  (`current and running-max of planets and population`).
- `gamemaster/README.md` — already aligned at the stage-02 README
  freeze.

The capability rule wording is unchanged because it was already
`planets`/`population`-only; only the surrounding prose mentioning the
unused field was inaccurate.

This is a documentation-only change. No runtime behaviour, wire format,
schema, or test fixture is affected.

## Why

`ships_built` was unused. Naming it in the contract obliged every
producer (GM) and consumer (Lobby aggregator) to populate and forward a
field with no consumer. Dropping it now — before any GM code lands —
keeps the contract minimal and avoids future drift between "what the
spec lists" and "what the code uses". `lobby/README.md` and the lobby
aggregate code are aligned in Stage 03 of the same plan.

## Alternatives considered

- **Keep `ships_built` in the contract for future use.** Rejected: no
  concrete plan exists for a `ships_built`-driven capability or stat
  surface; speculative fields rot.
- **Add `ships_built` only as an opaque stat without changing the
  capability rule.** Rejected: the runtime cost of carrying it is
  negligible, but the documentation burden of explaining why an unused
  field is in the payload is not.

## References

- [`../PLAN.md` Stage 01](../PLAN.md)
- [`../../ARCHITECTURE.md` §7 Game Lobby](../../ARCHITECTURE.md)
- [`../../ARCHITECTURE.md` §8 Game Master](../../ARCHITECTURE.md)
- [`../README.md`](../README.md) — `player_turn_stats[]` description.