v0.6.1

Patch Changes

• 7d048b9: Fix MCP_INVALID_RESPONSE errors on every dispatch against businesses that
  publish JSON Schema draft 2020-12 inputSchemas, and make client-side
  pre-flight validation best-effort instead of fail-closed.

  The pre-flight input validator previously used AJV's draft-07-only build and
  threw on the 2020-12 meta-schema URI (https://json-schema.org/draft/2020-12/schema)
  before inspecting any payload. Every catalog search, cart create,
  checkout *, and order * call against MCP servers that advertise the
  2020-12 dialect returned:

  MCP_INVALID_RESPONSE: business returned an invalid input schema for "<tool>"
  Details: no schema with key or ref "https://json-schema.org/draft/2020-12/schema"
  

  Three changes:

  1. 2020-12 dialect support. The validator now uses AJV's 2020-12 build
     (Ajv2020), which registers the 2020-12 meta-schema. Schemas declaring
     2020-12 — or no $schema at all — compile and validate normally.

  2. Soft signals replace hard throws for client-side uncertainty. When
     the published schema cannot be compiled (unknown dialect, malformed JSON
     Schema) or when an argument carries a plain key not listed in the
     published schema, the dispatcher no longer fails the call. The server is
     the authoritative validator and returns SCHEMA_VALIDATION_FAILED for
     genuinely bad payloads. Three modes:

     • default — silent; the request proceeds and the server decides.
     • --verbose / UCP_VERBOSE=1 — emit a vlog() trace so operators
       can see what was flagged and why.
     • UCP_STRICT_SCHEMA=1 — restore the throw (MCP_INVALID_RESPONSE
       for compile failures, SCHEMA_VALIDATION_FAILED for unknown plain
       keys). Useful in CI or for paranoid local development.

     Payload validation against a successfully compiled schema still throws
     SCHEMA_VALIDATION_FAILED in every mode — local typo-catching saves a
     server round-trip.

  3. Removed patchKnownUpstreamSchemaDefects (the \A regex stopgap).
     The upstream defect it worked around is fixed in production, and the
     new soft-fail path handles any future regex-incompatibility regression
     without a hard failure.

  Upgrade impact:

  • Agents and scripts that previously branched on MCP_INVALID_RESPONSE from
    the pre-flight path will no longer see it in the default mode. Set
    UCP_STRICT_SCHEMA=1 to restore the old strict behavior.
  • The previous client-side rejection of "unknown plain fields" no longer
    fires by default. Reverse-DNS extension keys remain the recommended
    convention; the CLI just doesn't enforce it client-side anymore.
  • No new error codes.