CONSTANT_CASE Converter

In short CONSTANT_CASE, also called SCREAMING_SNAKE_CASE, joins words with underscores and capitalises everything, so "api base url" becomes API_BASE_URL. It marks a value that does not change: constants in most languages, and environment variables almost universally. The environment variable case is the one with real force behind it. The POSIX specification reserves uppercase names for the shell and utilities, and the convention is strong enough that tooling assumes it — Docker, systemd, CI systems and every deployment platform expect DATABASE_URL rather than databaseUrl, and some will not read a lowercase name at all. Within code the convention is looser but consistent: Python, Java, C, Go and JavaScript all use it for module-level constants. Two practical notes. A leading digit is invalid in an identifier in most languages, so "2fa secret" needs rewriting rather than converting. And the convention says nothing about whether the value is actually immutable — it is a signal to the reader, and in Python and JavaScript object properties it is only a signal.