Review: USD Best Practices Alignment

Overall, this is a solid contribution that fills an important gap in the spec. The hierarchical concatenation model, TF scoping rule, and multi-robot deployment guidance are well thought out and consistent with USD composition semantics. The suggestions below are refinements, not blockers.

Suggestions

1. Normalize namespace segments explicitly. The concatenation rules should specify that each ros:context:namespace segment must be a bare name (no leading or trailing /). The simulator is responsible for inserting separators and normalizing the final path. This prevents ambiguity and aligns with the Asset Structure Principles guidance that identifiers should embed cleanly in paths and queries.

2. Anchor namespace to defaultPrim. In the "Intra-robot asset composition" paragraph, consider noting that the sub-asset's ros:context:namespace should be authored on its defaultPrim, consistent with the USD reference-payload entrypoint pattern.

3. Instancing caveat for duplicate sub-assets. If a sub-asset is marked instanceable = True, local opinions on its root prim (like overriding ros:context:namespace) are not permitted by USD's instancing rules — only the entrypoint prim remains editable. Sub-assets intended for per-instance namespace override must not set instanceable = True, or the namespace attribute must be lofted above the payload boundary. Worth a brief note here.

4. USD pseudocode example for the override. The "Duplicate sub-assets" paragraph is dense. A short snippet would ground the LIVRPS explanation, e.g.:

   def Xform "robot" (
       prepend apiSchemas = ["RosContextAPI"]
   ) {
       string ros:context:namespace = "robot_1"
   
       def Xform "camera_left" (
           references = @./camera_module.usd@
           prepend apiSchemas = ["RosContextAPI"]
       ) {
           string ros:context:namespace = "camera_left"  # overrides "camera" from source
       }
   
       def Xform "camera_right" (
           references = @./camera_module.usd@
           prepend apiSchemas = ["RosContextAPI"]
       ) {
           string ros:context:namespace = "camera_right"
       }
   }
   

5. Cross-reference payload boundary rule. A brief note linking back to Section 2.2's rule ("Interface prims must reside outside payloads") would reinforce that RosContextAPI prims participate in the lightweight interface graph and must remain traversable without loading geometry payloads.

Review performed against the NVIDIA Asset Structure Principles and the existing composition rules in Sections 1.2.1–1.2.6 of this REP.