Property-scoped @context makes roundtrip.generated drop an unrelated property

[simontaurus]

What happens

OOLD-CMP-5266 asks a term that brings in an embedded object by $ref to declare a scoped @context. Declaring it makes roundtrip.generated fail, and the property it reports as lost is not the one that carries the scoped context:

FAIL roundtrip.generated    Composition.schema.json: property lost through RDF despite being mapped: type

oold-python 0.18.0, meta-schema 1.0.0-rc.3. Removing the scoped @context and changing nothing else: 29 ok, 0 failed, and the OOLD-CMP-5266 warning returns. So the rule and the check contradict each other on the same document.

Repro

One file, no siblings needed. amount is defined in $defs, is not reachable from the root object, and the generated instance is {"type": ["Composition"]}.

Composition.schema.json

{
  "$schema": "https://oo-ld.org/latest/meta/oold-meta-schema.json",
  "$id": "Composition.schema.json",
  "x-oold-version": "0.1.0",
  "x-oold-uuid": "21e7c9d7-bf27-5c8f-a02d-03ae1075d090",
  "title": "Composition",
  "type": "object",
  "properties": {
    "type": {"type": "array", "items": {"type": "string"}, "default": ["Composition"]}
  },
  "$defs": {
    "Component": {
      "type": "object",
      "title": "Component",
      "properties": {
        "type": {"type": "array", "items": {"type": "string"}, "default": ["Component"]},
        "amount": {"$ref": "https://w3id.org/oo-ld/schemas/quantities/0.2/MassFraction.schema.json"}
      },
      "required": ["type", "amount"]
    }
  },
  "@context": [
    "https://w3id.org/oo-ld/schemas/quantities/0.2/MassFraction.schema.json",
    {
      "@version": 1.1,
      "comp": {"@id": "https://w3id.org/oo-ld/schemas/materials/0.2/Composition.schema.json#", "@prefix": true},
      "id": "@id",
      "type": {"@id": "@type", "@container": "@set"},
      "Composition": "https://w3id.org/oo-ld/schemas/materials/0.2/Composition.schema.json",
      "Component": "comp:/$defs/Component",
      "amount": {
        "@id": "comp:/$defs/Component/properties/amount",
        "@type": "@id",
        "@context": "https://w3id.org/oo-ld/schemas/quantities/0.2/MassFraction.schema.json"
      }
    }
  ]
}

oold validate <dir>          # FAIL, type lost
# delete the "@context" entry inside the amount term definition
oold validate <dir>          # 29 ok, 1 warning (OOLD-CMP-5266)

Not caused by the surrounding modelling: dropping the remote context from the root array, dropping "@type": "@id", and using a plain comp:amount instead of the JSON-pointer CURIE each still fail the same way.

Where it is not

JSON-LD processing itself is fine. Same document, same loader, compaction through the schema URL:

doc = {"@context": url, "type": ["Composition"]}
back = jsonld.compact(jsonld.from_rdf(jsonld.to_rdf(doc, {"format": "application/n-quads"})), url)
# {"id": "_:b0", "type": ["Composition"]}   with and without the scoped context

jsonld.expand also resolves the scoped remote context correctly through the validator's DocumentLoader: a term inside amount reaches qudt:value exactly as it does when the same context sits at the root. So the loss looks like it comes from the round-trip step of the pipeline (framing / promoted terms), not from context processing.

Why it matters here

Without the scoped context, the terms of an embedded schema resolve globally. Two sibling properties that embed the same base then cannot share a term name, because one global definition would win for both. In the materials reference schemas that forces components (chemical composition) and constituents (material composition) to be spelled differently to keep distinct predicates, where a scoped context would let both be components. It also leaves three OOLD-CMP-5266 warnings standing that we cannot act on.

Ask

• Fix the generated round-trip under a property-scoped @context, or
• state in the specification which form a scoped context may take when the target is an OO-LD schema (schema IRI as here, versus a context document), and make OOLD-CMP-5266 recommend only what the round-trip supports.

[simontaurus]

Tooling bug, no spec change needed. OOLD-CMP-5266 recommends only what the round-trip supports.

embedded_properties counted every @context term carrying a scoped @context, without checking that the schema declares a property of that name. amount sits in $defs/Component, and its term is in the root context because OOLD-CMP-b926 requires every $ref to be reflected there - but the root object has no amount. That one call feeds two things: roundtrip() chose framed over compacted, and schema_to_frame() emitted "amount": {}. A frame property is a match filter, so the frame selected nodes carrying amount, {"type": ["Composition"]} matched none, and framing returned nothing. type was reported because it was the only property present.

That is also why the two branches looked contradictory: without the scoped context there is no phantom embed, the round-trip falls back to compaction and passes, and the OOLD-CMP-5266 warning returns.

Fix: require a scoped term to name a declared property.

• fix(validation): count a scoped @context term only where it is a property oold-python#135
• fix(scripts): count a scoped @context term only where it is a property #151 - same fix in scripts/schema_to_frame.mjs, which has the defect too and is not covered by the compliance fixtures

Your repro: 30 ok, 0 failed, 0 warning(s). The three OOLD-CMP-5266 warnings in the materials schemas can be acted on now, and components / constituents can share a term name.