[clevengermatt]

Fair questions.

OBI needs its schema format to be universally parseable, deterministic to compare, and rich enough to describe the portable subset of any binding format's type system. JSON Schema meets those requirements without tying the spec to any one ecosystem. Proto-level fidelity would center gRPC. A custom IDL would fragment tooling. JSON Schema is the neutral ground.

The limitations are real, especially with proto. For example, our own proto interface creator implementation maps 32-bit integers to JSON Schema `integer` and 64-bit integers to `string` to avoid JSON precision loss beyond 2^53, following Proto3's canonical JSON mapping. Proto enums are int-valued with names; JSON Schema enums are typically strings. Proto's oneof differs semantically from JSON Schema's oneOf. Maps with non-string keys can't be expressed directly.

These affect cross-service structural comparison, not execution. Executors handle source types natively on the wire, so int64 stays int64 when you actually make a call. Transforms bridge shape differences between operation schemas and binding sources at runtime. The comparison layer works at a coarser grain in v0.1 because that's what makes it deterministic and universally implementable. Future profile versions can tighten comparison precision as the ecosystem converges on the tradeoffs worth making.