Normalize the request fields + compile. Returns null when no constraint is
requested (text / none set). On compile failure returns
{ controller: null, degradeHint } — callers inject a "respond in valid
JSON" system prompt + emit a Warning header (oMLX parity, never 500).
Normalize the request fields + compile. Returns null when no constraint is requested (text / none set). On compile failure returns
{ controller: null, degradeHint }— callers inject a "respond in valid JSON" system prompt + emit a Warning header (oMLX parity, never 500).