Migrating to 0.4.0

Existing 0.3.0 decoding and schema APIs continue to work. The required Compact or Pretty argument to to_string and schema_string is unchanged.

Component boundaries

Boundary(a, response) binds a definition to a private handler receiving decoded a and original Json. Construct it with boundary, inspect the stored contract with boundary_definition, and submit JSON with forward. Decoding occurs once before a successful handler invocation.

JsonBoundary(a, response) serves handlers that need only verified JSON. Construct it with json_boundary, inspect it with json_boundary_definition, and submit admitted JSON with forward_json. It validates once without conversion and invokes the handler with VerifiedJson(a) only on success. The receiving definition is authoritative; another contract’s certificate cannot bypass this check.

verify(definition, json) creates a certificate independently. Use verified_json and verified_definition to retrieve its original JSON and actual checked contract. Certificates retain no decoded value. The parameter a describes a definition’s output type, not its identity or constraints. Boundary handlers returning Result produce nested results; callback exceptions remain operational failures.

See Verified JSON boundaries for complete examples.

Added schema vocabulary

• examples and standalone default attach admitted JSON metadata, which need not satisfy the associated definition. Neither changes decoding. defaulted remains the distinct record-field operation applying a validated absent-field default, which overrides child default metadata.
• format attaches metadata without validation, including custom names. Keep optional format assertions disabled in external validators for matching acceptance semantics.
• dependent_required adds one-way input property dependencies. Null is present; decoded defaults do not count as input presence. Repeated rules merge their keys.
• integer_multiple_of adds exact divisibility to safe-integer definitions by positive safe-integer divisors. Fractional divisors and number() definitions are not supported by this helper.
• assert_format(_, Uuid) enforces UUID hexadecimal/dash syntax through emitted length and pattern constraints. It preserves case and does not restrict version or variant bits. Other asserted formats are not supplied.

These operations preserve the associated definition’s decoded output type. Details and composition restrictions are in Advanced definitions.