Check a question before running it (Sharpen)

Assesses whether a research question is specific enough to run and returns at most ONE next question, with chips, a You decide default and the assumption taken if skipped. The user’s text is never rewritten: unclear words come back as underline spans. Required questions come first; optional breadth questions (sources to read first, a comparison) follow once ready. An already-specific question is ready with score 1 and no required question. Not charged. Rate-limited per account (30 a minute, 600 a day); 429 with Retry-After. 404 feature_not_enabled where Sharpen is off.