Usd Composed Stage Open

usd-composed-stage-open

Use this skill when implementing runtime stage-open orchestration for composed USD stages.

Normative references:

• aousd/specifications-public@v1.0.1:specification/composition/README.md
• aousd/specifications-public@v1.0.1:specification/glossary

Owned contracts:

• contracts/handles/composed-stage-open.handle.json
• contracts/spec-coverage/composed-stage-open.coverage.json

Responsibilities

• Open the root layer stack through usd-layer-stack-open.
• Discover direct external reference asset identifiers from opened layer specs.
• Support the optional adapter payloadInclusion scenario control: open and supply direct external payload assets for include; omit payload opening and the payload opinion source for omit.
• Recursively discover reference assets through opened referenced layer stacks so bounded recursive reference sources receive their supplied layers.
• When optional payload inclusion is requested, discover and open reference assets authored inside loaded payload layer stacks so the payload source can expand bounded nested references introduced by a loaded payload.
• Resolve those dependency assets through the graph's bounded local resource policy and open them through graph layer-open/layer-stack-open boundaries.
• Build reference, payload, relocates, inherits, specializes, variant, and composition-arbitrator sources from opened graph-owned objects.
• Populate the stage through usd-stage-population.
• Keep every opened layer and source alive for the lifetime of the stage.

Non-Responsibilities

• Do not perform LIVERPS arbitration locally; call usd-composition-arbitrator.
• Do not build traversal indexes locally; call usd-stage-population.
• Do not parse USDA text directly or retain parser-local syntax trees.
• Do not claim full recursive composition until recursive payloads, variant-contained arcs, payload load masks/mutation, and asset resolver contracts exist.

Current Bounds

The generated implementation should load direct local reference dependency assets. As optional support for the AOUSD population-mask payload flag, for payloadInclusion=include it should also load direct local payload dependency assets that can be discovered from opened layer specs. It should then continue opening reference dependencies discovered in referenced and loaded payload layer stacks until a bounded fixed point is reached. For payloadInclusion=omit, it should not open payload assets and should omit the payload opinion source so payload_loading=absent.

It may still report composition as partial because recursive payload arcs, variant body arcs, schema fallbacks, full value resolution, and full instancing/prototypes are not yet covered.