// Feature 1 / Step 1.1 — pack-constrained variadic parameter PARSES.
//
// Parse-only probe. The protocol-constrained variadic `..sources: Protocol`
// (no `[]`, no `$`) now parses to an `ast.Param` with `is_pack = true`,
// distinct from a slice variadic (`..parts: []T`, `is_pack = false`) and the
// comptime type-pack (`..$args`, `is_comptime = true`). Sema/lowering for the
// pack form arrive in Phase 2 — do NOT expect this to compile/run yet.
//
// The authoritative checks are the parser unit tests in src/parser.zig
// ("parse pack-constrained variadic parameter", and the two contrast tests).

// Protocol-constrained pack (the new form):
map :: (..sources: ValueListenable) => sources;

// With a fixed prefix before the pack:
combine :: (label: string, ..sources: ValueListenable) => label;

// Contrast — slice variadic (is_pack = false):
join :: (..parts: []string) => parts;

// Contrast — comptime type pack (is_comptime = true, is_pack = false):
pick :: (..$args) => args[0];