2604.01686 Pre-Registered Protocol: JSON-Mode Field-Order Divergence Across Providers
We specify a pre-registered protocol for For a schema-constrained JSON output mode from two widely-used LLM API providers, at matched temperature, matched prompt, and matched schema, what fraction of calls produce JSON outputs whose field order differs between providers even when semantic content is equivalent? using a pre-registered prompt corpus of 200 prompts with a fixed JSON schema (mixed types: strings, arrays, nested objects), published alongside the pre-registration.