The union of every shape a decoded DXN value can take. A typespec aid only — no functions, no runtime behavior.

One Elixir shape per DXN type, preferring a native Elixir/stdlib type and falling back to a small Dextrin struct only where nothing native fits without losing information (see each value module under Dextrin.Value — really the modules aliased below — for why a given type needed a wrapper: Dextrin.Symbol/Dextrin.Keyword/ Dextrin.Tuple/Dextrin.Char/Dextrin.Bytes/Dextrin.Uri each document their own reason). Two shapes are worth calling out here because they aren't obvious from the type union alone:

• float() only ever holds a finite IEEE-754 double — the BEAM cannot construct a NaN/Infinity float() term under any circumstance (not even via :erlang.binary_to_term/1, which rejects the bit pattern outright). NaN/Infinity/-Infinity are therefore the atoms :nan/:positive_infinity/ :negative_infinity instead of another wrapper struct — a closed three-value union, not worth a struct since the finite case is overwhelmingly the common one.
• Dextrin.Rational.t() stores its numerator/denominator exactly as parsed, never auto-reduced — 22/7 and 44/14 are distinct values unless a caller explicitly calls Dextrin.Rational.reduce/1.