Usdz Layer Open

usdz-layer-open

Use this skill when implementing or verifying opening a single layer from a USDZ package.

Spec Sources

• OpenUSD USDZ File Format Specification v1.3 default-layer and package layout requirements
• USD Core Spec Resource Interface package resource model
• USD Core Spec Core File Formats sections Text, Binary, and Package

Pinned AOUSD commit: 6b4f01f2d6d46b01507481524eb516b4ef358c31

Provides

• USDZ layer-format handler over already-opened package bytes
• default-layer selection through usdz-package-format
• explicit package entry selection for outer.usdz[entry]
• dispatch of .usda entries to usda-layer-open
• dispatch of .usdc entries to usdc-layer-open
• target-native LayerOpenResult pass-through

Contract

This skill owns contracts/handles/usdz-layer-open.handle.json.

The generic usd-layer-open entrypoint opens the outer resource through usd-resource-protocol and passes those package bytes here. This handler uses usdz-package-format to index and select the package entry. It then invokes the registered concrete layer-format handler for the selected entry extension: .usda routes to usda-layer-open, and .usdc routes to usdc-layer-open.

For package entries, the standalone file_backed_path from the outer package must not be forwarded to the inner handler. The path names the entire archive, not the selected byte extent. Use the non-owning PackageEntryByteView bytes instead.

Unsupported .usd, nested .usdz, missing default layer, missing explicit entry, and package-layout diagnostics fail before parser-specific layer state is emitted.

Boundary Guards

Defer ZIP/USDZ structure parsing to usdz-package-format.

Defer resource classification, package spelling split, and outer package reads to usd-resource-protocol and usd-layer-open.

Defer USDA text handling to usda-layer-open and USDC binary handling to usdc-layer-open.

Do not implement .usd forwarding, nested package opening, package writes, composition, dependent layer loading, stage population, or asset resolution.

Test Obligations

• open a default .usda layer from a package
• open a default .usdc layer from a package
• ignore later non-layer assets when the default entry is already selected
• open explicit .usda and .usdc package entries
• preserve exact package diagnostics for invalid ZIP, compression, encryption, alignment, duplicate names, unsafe paths, missing default layer, missing explicit entry, unsupported .usd, and nested .usdz
• return the same target-native layer result shape as USDA and USDC handlers