Use this when you need to encode or decode text and want multi-byte and entity edge cases handled correctly rather than doing it by hand.

Use this when you need to encode or decode text and want multi-byte and entity edge cases handled correctly rather than doing it by hand. Deterministic: same input, same output. The mode selects the operation: url-encode/url-decode (percent-encoding), html-encode/html-decode (entity table plus numeric character references), base64-encode/base64-decode (UTF-8 safe; decode tolerates URL-safe alphabet, whitespace, and missing padding), and unicode-encode/unicode-decode (\uXXXX and \u{...} escapes for non-ASCII). Every mode returns the same shape: {mode, output}. Example: mode base64-encode, text "héllo" -> output "aMOpbGxv".