# Wave C-2 — game-server enhanced: anti-cheat + interest management + lag compensation

## Why

The `@suaveplan/game-server` package's Wave A–B foundation (core / engine /
state / network / matchmaking / performance) is in place. The next layer —
the `enhanced/` family — adds server-authoritative safeguards and
broadcast-scope optimisations needed for any open-world multiplayer game.

Wave C-2 ships the three foundational `enhanced/` modules that are entirely
self-contained from a dependency standpoint and underpin the rest of the
`enhanced/` tree (anti-cheat consumed by leaderboard/persistence; interest
management by state-sync; lag compensation by replay/state-sync):

- `enhanced/anti-cheat/anti-cheat-validator/` — server-authoritative move /
  action validator with movement, rate-limit, and custom-action rules;
  player-violation history; punishment escalation FSM.
- `enhanced/interest-management/interest-manager/` — area-of-interest
  manager: circular/rectangular/custom zones, per-player view-distance
  culling, priority-weighted entity visibility, visibility-change deltas.
- `enhanced/lag-compensation/lag-compensator/` — server-side state-rewind +
  RTT-aware hit validation: per-entity bounded snapshot ring buffer,
  per-player RTT statistics (avg/min/max/jitter), interpolated state
  lookups, clamped compensation.

## What Changes

Add three feature modules under `packages/gaming/games/game-server/src/enhanced/`,
each as a self-contained `5-files-per-feature` directory:

- `anti-cheat/anti-cheat-validator/{anti-cheat-validator.ts,.test.ts,.types.ts,.md,index.ts}`
- `interest-management/interest-manager/{interest-manager.ts,.test.ts,.types.ts,.md,index.ts}`
- `lag-compensation/lag-compensator/{lag-compensator.ts,.test.ts,.types.ts,.md,index.ts}`

Behaviour shift versus the upstream `main` implementation:

- Inject `Clock` (and where ids are minted, `IdGenerator`) from
  `@suaveplan/types` rather than reading `Date.now`/`Math.random` directly.
- Replace ad-hoc `Logger` dependency + `EventEmitter` inheritance with a
  pluggable listener registry (no `@suaveplan/events` runtime dep) and OTel
  metrics for observability.
- Throw `GameServerError` via the package-wide `GAME_SERVER_CODES` registry
  on invalid input or out-of-bounds operations instead of silently
  returning sentinel values.
- Validate all caller-supplied configuration with Zod at the boundary.

Extend `GAME_SERVER_CODES` with the following new codes (appended, no
re-order):

- `CHEAT_DETECTED`
- `INVALID_VALIDATION_RULE`
- `INVALID_ANTI_CHEAT_CONFIG`
- `INTEREST_REGION_INVALID`
- `INVALID_INTEREST_CONFIG`
- `INTEREST_PLAYER_NOT_REGISTERED`
- `LAG_COMPENSATION_HISTORY_EXCEEDED`
- `INVALID_LAG_COMPENSATION_CONFIG`
- `LAG_COMPENSATION_ENTITY_NOT_TRACKED`

Extend `package.json` `exports` map additively with subpath exports for the
three new feature modules.

## Impact

- Affected specs: `game-server` (new requirements for enhanced anti-cheat,
  interest management, lag compensation).
- Affected code: `packages/gaming/games/game-server/src/enhanced/**` (new),
  `packages/gaming/games/game-server/src/errors/game-server-error.ts`
  (new codes appended), `packages/gaming/games/game-server/package.json`
  (additive subpath exports), `packages/gaming/games/game-server/src/index.ts`
  (re-exports for the three new modules).
- Out of scope: all other `enhanced/*` subtrees (leaderboard, persistence,
  replay, tournament, service-discovery, state-sync, timing) — owned by
  Wave C-3/C-4. The orchestrator `src/index.ts` is updated only to add the
  three Wave C-2 re-exports.