Draw shaders can declare geometry POD fields as F16x2/F16x4, U16x2/I16x2
(plain or normalised) and UNorm8x4/SNorm8x4; the fetch converts them to
vec2f/vec4f on Metal and WebGL2 (per-attribute vertexAttribPointer with
type, normalised flag, byte stride and offset), the headless JIT decodes
the same formats, and Vulkan/OpenGL/D3D11 refuse compact layouts with a
logged skip rather than drawing garbage. Attribute packing computes
physical offsets with natural alignment for the whole record; the all-F32
path stays byte-identical (stride = slots * 4, packed_geometry_N on GL).
Geometry::update_typed / update_typed_with_recycled_buffers take
IndexData::{U16,U32} plus a byte vector and the shader's input layout;
updates are validated (stride, whole vertices, index range) and every
geometry carries its index width and a layout signature that survive
releasing the CPU staging, so a draw checks layout and index type against
the resident buffers, never the staging enum. Compact fields are rejected
in instance PODs and in nested aggregates at shader validation; SNORM
minima clamp to -1 like WebGL2.
On Metal the decoded (logical) vertex is reached through the shader
context like the instance is, so every shader function that reads
geometry compiles.
No map stream is converted yet; that is the next cut.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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