The bug: TextareaAutosize calls onHeightChange from a React layout effect on every render. The original code did onHeightChange={(height) => setTextareaHeight(height)}, which triggered a re-render on every call. Worse, textareaHeight controlled the layout (flex-row vs flex-col), which changed the available width, which changed the textarea's height, which fired onHeightChange again — creating an infinite render loop.

The fix: Removed onHeightChange and the textareaHeight state entirely. Instead, isMultiline is derived from two sources:

• input.includes("\n") — detects explicit newlines (no state needed)
• isWrapped state — detects visual wrapping, but only updated inside handleChange (user input events), never from a layout effect

This breaks the loop because handleChange only fires on actual user input, not on re-renders. Hysteresis prevents flickering at the boundary: expand when scrollHeight exceeds one line, but only collapse when text is under SAFE_SINGLE_LINE_CHARS characters.

Resolves #1012