Terminal UI Box components now validate key props for uniqueness and strip them before rendering
In the terminal interface's internal layout system, Box elements can carry a key prop, similar to how React list items use keys. Claude Code now checks that each key is a short string (between 1 and a fixed maximum length) with no control characters, and warns if the same key is used twice under the same parent. If it is duplicated, only the first instance is treated as a valid hover target. After the key has been used to wire up hover behavior, it's now removed from the internal tree before final rendering.
This is internal plumbing that guards against subtle rendering bugs from malformed or duplicate keys in the terminal UI, and keeps the key prop from leaking into what actually gets drawn on screen.