Systems

How engine subsystems behave and compose. Prefer guides/ for day-to-day authoring.

Runtime

• Architecture
• Lifecycle
• Frontends and drivers
• Platforms
• Session services
• Scenes and gameplay
• Actor communication — hi.actors / Actors.*, messages, name-keyed fields
• Refs
• Replication wire version — current hook and codec limits

Presentation and simulation

• Coordinate space — axes, handedness, euler, cameras, clip depth
• Rendering · Renderer architecture · Frame governor
• GPU particles
• Visual Zones · Volumetric media
• Input · Audio · Physics
• Motion Kit · Temporal Kit

Assets

• Assets and Shinra
• Prefabs
• Asset residency
• Asset formats

Editor host

• UI and editor — chrome, command palette, profiler, game hi.editor SDK, Agent MCP (editor-only)
• Editor asset hot reload — daemon events, render-thread pause, and in-place rebind vs full scene re-instantiation
• Editor project selector