vampire-like/openspec/changes/archive/2026-04-02-converge-simulationworld-runtime-paths/specs/simulationworld-runtime-convergence/spec.md

ADDED Requirements

Requirement: SimulationWorld SHALL be the sole battle simulation executor

The battle runtime MUST execute movement, projectile stepping, collision broad-phase, and related simulation state updates through SimulationWorld, and it MUST NOT route these responsibilities through an alternative non-SimulationWorld runtime path.

Scenario: Battle tick advances through SimulationWorld

• WHEN the battle update loop advances a gameplay frame
• THEN SimulationWorld executes the simulation pipeline for that frame as the authoritative runtime update path

Scenario: Legacy routing switch does not select an alternate executor

• WHEN runtime configuration related to simulation movement is evaluated
• THEN it does not select or re-enable a separate legacy movement execution path

Requirement: Runtime entities SHALL submit input and consume simulation output only

Enemy entities, the player entity, projectile entities, and MovementComponent MUST submit movement or behavior input into SimulationWorld state and MUST consume position, facing, hit, or lifecycle results from simulation output, rather than computing world-space advancement independently.

Scenario: MovementComponent no longer advances transforms directly

• WHEN movement input, speed, or separation parameters change on an entity
• THEN the component synchronizes those values to SimulationWorld state without directly moving the entity transform

Scenario: Entity presentation follows simulation output

• WHEN simulation state is committed for enemies or projectiles
• THEN entity presentation updates consume the committed output to refresh transforms, facing, visibility, or removal state

Requirement: Spatial queries SHALL use SimulationWorld-owned data and services

Target selection, projectile hits, area hits, and sector hits MUST use SimulationWorld spatial indexing and query services, and MUST NOT fall back to legacy entity-side traversal or solver-specific query paths.

Scenario: Target selection uses simulation spatial data

• WHEN weapon or AI logic requests nearby or nearest targets
• THEN the query resolves against SimulationWorld maintained spatial data for the current frame

Scenario: Projectile and area hit evaluation stay on simulation path

• WHEN projectile, area, or sector hit logic runs during combat
• THEN hit candidates are produced from SimulationWorld collision and query capabilities instead of a fallback entity-side path

Requirement: Runtime surfaces SHALL reflect the single-path architecture

Runtime debug surfaces, automated tests, and architecture documents MUST reflect that the project supports one authoritative SimulationWorld execution path rather than dual-path behavior.

Scenario: Debug panel omits legacy solver controls

• WHEN runtime simulation debugging is displayed
• THEN it shows current SimulationWorld metrics without exposing legacy solver switching or dual-path controls

Scenario: Regression tests validate observable single-path behavior

• WHEN simulation regression coverage is maintained
• THEN tests validate observable outcomes such as movement, projectile lifetime, hit results, and hide/remove lifecycle instead of asserting private compatibility fields for legacy paths