🧩 How hidden unicode characters can break your system

A developer encountered a hard-to-find bug where an invisible Unicode character (U+202D Left-to-Right Override) was embedded in a phone number string, causing API validation to fail despite the number appearing correct visually. The character was likely introduced by copying text from a messaging app or multilingual context. The fix involved inspecting the string at the byte level and stripping non-visible Unicode characters before validation.