# PM-77 native LDraw compatibility harness

This directory is the native-only process boundary. The reusable
`polymodel-ldraw-testkit` crate has no filesystem, process, archive, parser, or
native dependencies and is wasm-checkable.

## Commands

```sh
cargo run --manifest-path tools/ldraw-compat-harness/Cargo.toml -- validate
cargo run --manifest-path tools/ldraw-compat-harness/Cargo.toml -- inventory
cargo run --manifest-path tools/ldraw-compat-harness/Cargo.toml -- corpus
cargo run --manifest-path tools/ldraw-compat-harness/Cargo.toml -- fuzz
cargo run --manifest-path tools/ldraw-compat-harness/Cargo.toml -- differential
```

`differential` is deliberately fail-closed: it requires Nix, builds the
pinned `.#ldraw-oracle` package, resolves that output with `nix path-info`, and
runs the C++17 oracle over the complete evidenced inventory. It never invokes
the Rust parser for the oracle result. The oracle emits `ldraw-oracle-v3`, and
the harness compares the generated oracle projection against a fresh oracle
run using the declared normalization rules.

Expected records are generated by the standalone oracle generator from exact
fixture bytes and the pinned LDParse output. Their provenance and versioned
projection rules are checked in, while the Rust adapter is exercised separately
as the candidate under test. Geometry, instances, transforms, winding,
TEXMAP, points, explicit edges, and H-owned conditional-line classification
remain covered by their declared field-authority rules when the pinned LDParse
wrapper does not expose those surfaces.