Amagi survives the earthquake as a battlecruiser

What if Amagi's keel survived the earthquake and Japan kept her as a battlecruiser under the Washington treaty?

Japan gains a fast and heavily armed ship, but the looser treaty needed to retain her would also permit a stronger British response.

The surviving Amagi would be a useful fast capital ship with ten 16-inch guns, a 30-knot design speed, and armor respectable for a battlecruiser. Later reconstruction could reduce the main battery to eight or nine guns to release weight and internal space for other improvements. The larger consequence is diplomatic: a treaty that permits this ship of roughly 47,000 tons at full load cannot retain the historical 35,000-ton capital-ship limit. A standard displacement ceiling nearer 45,000 tons would let Britain reshape the G3 design or produce another powerful fast battleship. Allowing Amagi to survive as a battlecruiser would therefore change the size assumptions of the interwar treaty system.