Implementation contracts

Namespace: Rampage. Unity 6, HDRP. Units metres/seconds; forward +Z, up +Y. Shared ownership is explicit: world agent owns Runtime/World; vehicle art agent owns Runtime/Visuals; gameplay agent owns Runtime/Bike, Runtime/Combat, Runtime/AI, Runtime/Racing. Root owns application, UI, camera, input, audio, editor/build setup. Do not edit other owners' files without coordination.

World API (world agent implements)

• enum Biome { Forest, Desert, City }
• TrackDefinition: public string Id, Name, Subtitle, Description; public Biome Biome; public Color Accent; public Vector3[] ControlPoints.
• TrackCatalog.All: TrackDefinition[], exactly three tracks in forest/desert/city order.
• TrackRuntime : MonoBehaviour: public TrackDefinition Definition {get;}; float Length {get;}; float RoadWidth {get;}; void Build(TrackDefinition definition, bool scenery = true).
• TrackSample Sample(float distance): wraps distance, centre position plus tangent/right/up. TrackSample public fields Vector3 Position, Forward, Right, Up; float Distance.
• float NearestDistance(Vector3 position, float hint = -1f): track projection, no player clamping. float LateralOffset(Vector3 position, float distance).
• Generated root under TrackRuntime. Asphalt top collider on layer 8 (Road), other environment colliders layer 0. Bike layer 9. Road smooth continuous closed loop. Road width ~12 metres. Sample surface should match collider. Road origin start is distance zero, forward direction consistent.
• MaterialLibrary.Get(string key, Color color, float metallic=0f, float smoothness=.4f): owned world agent, cached HDRP/Lit materials; Resources.Load<Texture2D>("Textures/"+key+"_color"), _normal, _mask optional. All material keys documented by agent. Other owners may call Get.

Vehicle visual API (art agent implements)

• BikeVisual : MonoBehaviour: void Build(Color livery, bool includeRider=true); void SetPose(float speedKph, float leanDegrees, float steer, float throttle, float attackSide, float attackPhase, float impact); void SetLivery(Color color).
• Root local position zero is bike physics COM/reference approx road + .65 metres. Axles at z +/- .75, wheel radius .34; tyre contact local y=-.65. Hero dimensions ~2.1m long, .8m wide, rider helmet top local y1.15. Detailed own meshes/PBR materials, not cube placeholders. Wheels and separate mechanical parts animate; left/right kick via side and phase. Visual contains no colliders/Rigidbody. Parent transform owns physics. Build can be called in garage too.

Gameplay API (gameplay agent implements)

• struct BikeCommand { public float Throttle, Brake, Steer; public bool Boost, AttackLeft, AttackRight; }
• BikeController : MonoBehaviour: public BikeCommand Command; public bool DriveEnabled, IsPlayer; public TrackRuntime Track; public BikeVisual Visual; public float SpeedKph, LeanDegrees, Boost01, Stability01, AttackSide, AttackPhase; public bool IsCrashed; public float DistanceAlongTrack; (read-only properties fine except Command, DriveEnabled, IsPlayer, Track, Visual).
• void Initialize(TrackRuntime track, bool isPlayer, Color livery) builds Rigidbody/collider and BikeVisual if none. Root places bike initially at sample +Up*.65. void ResetToTrack(float distance, float lateral=0f) handles safe physics reposition and protection.
• BikeController.Active: enumerable/list of active bikes for combat/proximity, cleans on destruction. event Action<BikeController> Crashed optional; event Action<float> Impact optional but inform root.
• BikeAI : MonoBehaviour: public BikeController Bike; public int Difficulty; public float LaneOffset; follows Track, makes BikeCommand; never teleports to race catchup.
• RaceProgress: plain class with int CompletedLaps {get;}, float TotalDistance {get;}, bool Finished {get;}; constructor (TrackRuntime track, int targetLaps); void Update(Vector3 position); void Reset(float initialDistance=0f); float SafeDistance {get;}. Ordered track sectors/checkpoints prevent shortcut/reset exploitation; racer resets use SafeDistance. Race starts near distance 0 with grid behind start. Coordinate exact start semantics with root.

Root may adapt narrowly if required. Report any API changes before implementing consumers. All source files UTF-8. Plan in DEVELOPMENT-PLAN.md remains product target. No paid assets or other project modifications. Parallel development is allowed; Unity builds only root runs to avoid asset/database locks.