Imported from JTCGL/AI3 (src/scene/AGENTS.md). Install upstream with npx skills add JTCGL/AI3 --skill scene. Copyright stays with the author.

Scene Layer Instructions

These instructions extend src/AGENTS.md and the repository root instructions.

• Keep scene data, transform/camera math, procedural geometry, and render-target sizing independent of ImGui, SDL, and graphics APIs.
• Use GLM as the canonical vector and matrix math library; do not add parallel project-owned math types.
• Use the project-wide right-handed Z-up world (+X right, +Y forward, +Z up) and meters for stored lengths. Display units are presentation only.
• Store orientations as glm::quat. Human-facing Euler values are degrees using intrinsic XYZ and must use the centralized scene conversion helpers.
• Core Scene owns object identity, hierarchy, authoritative transforms, primitive semantic parameters, materials, lights, cameras, revision, and persisted naming-counter semantics. EditorState remains a compatibility façade around its one authoritative Core Scene.
• Scene state must not acquire selection, bounds-display state, panels, layout, dialogs, console presentation, or other frontend/workspace state.
• Procedural primitive meshes are derived from Core Scene semantic parameters and must never become authoritative scene data.
• Add only math and scene behavior required by an implemented editor feature; do not grow this layer into an ECS, asset system, or serialization framework.