Preset xai builds the OpenAI-compatible adapter against the fixed base URL
https://api.x.ai/v1 with a required API key and no extra headers. It
defaults to json_schema structured output and lets the household select
json_object as a fallback; a request is never retried in another mode.
Migration 0005_ai_provider_xai rebuilds ai_settings and ai_runs the 0004
way so their provider CHECK also accepts xai, keeping every 0004 value.
Maestro task d8be638f-297f-4b7a-a545-74d193055904.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>