Fix ISA.001 to validate composition instead of the filesystem

[NV-JBapst]

Summary

The ISA.001 Isaac composition checker inspects the OS filesystem for a hardcoded set of payload filenames. As a result it fails assets that are correctly composed, including this repository's own sample prop.

Both defects are in nv_core/sr_specs/docs/capabilities/isaac_sim/composition/validation.py.

1. The payload check is filesystem-only, so every .usdz fails.
_check_payload_structure resolves Path(stage_root).parent / "payloads" and calls .exists(). A .usdz is a single package: its payloads/ layers are archive members, so there is never a sibling payloads/ directory on disk and the check fails unconditionally for packaged assets.

2. The expected filenames are the robot layout, applied to prop assets too.
The checker expects ["geometries.usd", "base.usda", "instances.usda", "materials.usda"] and a literal ./payloads/base.usda reference. That is the robot payload layout. ISA.001 is also carried by Prop-Robotics-Isaac (via FET100_BASE_ISAACSIM), and its requirement doc specifies {asset_name}_base / _meshes / _physics — so correctly-authored prop assets fail even unpacked.

Concretely, sample_content/.../obs_workbench_tool_a01/isaacsim_usd/sm_obs_workbench_tool_a01_01.usd uses payloads/obs_workbench_tool_01_{base,meshes,physics}.usd and fails ISA.001 on main today:

  [FAILED] Prop-Robotics-Isaac v1.0.0
           FET100_BASE_ISAACSIM: failing requirements: ['com.nvidia.simready.ISA.001']

What changed

Both checks are now driven by the composed stage rather than the surrounding directory listing:

• Payload layers are detected from stage.GetUsedLayers(), unioned with the reference/payload arcs authored on the default prim. Layer identifiers cover the on-disk form (.../payloads/x_base.usd) and the packaged form (asset.usdz[payloads/x_base.usd]) alike, so packaging no longer changes the verdict. Unioning with the arcs also keeps the check correct when a stage is opened with a load rule other than LoadAll.
• Layers are matched by role, not by exact filename. The payload stem does not have to equal the main asset file name — the sample prop above is sm_obs_workbench_tool_a01_01.usd with obs_workbench_tool_01_* payloads.
• Both layouts ISA.001 governs are accepted: the prop layout (payloads/{asset_name}_base.usd + _meshes.usd + _physics.usd) and the robot layout used by Robot-Body-Isaac (payloads/base.usda + geometries.usd + instances.usda + materials.usda). An asset must match one of them completely; a partial structure fails and is reported against the closest layout.

composition.md is reconciled with the checker: it names the validator entry point, records that either layout satisfies the requirement, notes the stem/filename independence, and documents that .usdz delivery is validated identically.

The Meshes/Visuals invisibility check is unchanged in intent; it now runs only on scopes actually present in the composed stage, and the dead found_looks/found_meshes/found_visuals bookkeeping and unused imports were removed.

Verification

Swept every .usd/.usda under sample_content plus 100 packaged SimReady .usdz assets — 176 stages — with the checker before and after:

	ISA.001 passing
before	1
after	102

Zero regressions: no asset that passed before fails now. ur10.usd, the one asset passing on main, still passes — that case is what motivated accepting both layouts rather than only the prop one.

Tests

New nv_core/sr_specs/tests/test_isaac_composition.py (10 tests, pytest nv_core/sr_specs/tests/test_isaac_composition.py) covering:

• a packaged .usdz asset passes, and agrees with the identical unpacked tree
• the usdz premise itself — payload layers exist only as archive members
• the robot layout passes; a partial robot layout fails naming the missing layer
• a flat asset with no payload structure still fails
• kind='component' and scope-invisibility failures are still reported
• the repository's own sample prop passes

The .usdz fixture is built at test time rather than committed: *.usdz is a Git LFS pattern here, and constructing it in the test keeps the required layout readable in review. Against the current checker 6 of the 10 tests fail; all 10 pass with this change.

Note on a related bug not fixed here

simready-validate's validate_asset() rejects any path whose extension is not .usd/.usda and returns None silently, so .usdz assets produce no verdict from the CLI at all. That lives in the simready-validate package rather than this repository, so it is out of scope for this PR, but it compounds the same problem and is worth tracking separately.

🤖 Generated with Claude Code