What is the Hanbali maddhab concerning the actions of a سفيه (person of unsound judgment) if his condition was unknown before puberty?

The Hanbalis and the majority of scholars hold the view that if a person reaches maturity after puberty and then reverts to foolishness (safaha), an interdiction (hajr) can only be imposed on him by a judge's ruling. This is because interdiction requires ijtihad (definition) (independent reasoning) and proof, unlike someone who reached puberty foolish; in such a case, the interdiction continues, and his guardian remains the same as his guardian before puberty. As for someone whose situation is unknown—whether he reached puberty foolish or became foolish after puberty—the default principle for Muslims' contracts is validity and soundness. There is no obligation to investigate his condition before puberty. The contracts of someone whose interdiction after puberty is unknown are valid, and the default assumption for someone whose condition is unknown is maturity.