flowchart TB
  subgraph build["BuildRaytracingAccelerationStructure (replay)"]
    M4a["Metal 4 command buffer<br/>committed before the run"] --> K["Metal 4 kernels:<br/>headers, triangle gather,<br/>instance descs → Metal"]
    K --> M3["Metal 3 queue:<br/>build into an<br/>MTLAccelerationStructure"]
    M3 -- "shared event" --> M4b["next Metal 4<br/>command buffer waits"]
  end
  K -. "writes 16 bytes at the D3D12 VA" .-> H["header<br/>{MTLResourceID, instances}<br/>+ contributions at VA + 16"]
  M3 -. "table keyed by VA" .-> H
  subgraph shader["RayQuery in DXIL"]
    S["RTAS SRV or root SRV<br/>= a 64-bit VA"] --> C["dxil-spirv: ConvertUToAS<br/>SPIRV-Cross patch: read the header"]
    C --> Q["MSL intersection_query<br/>on instance_acceleration_structure"]
  end
  H --> C
  H -. "contribution lookup<br/>(dxil-spirv patch 0002)" .-> Q