disambiguate enum blocks and complete distinct type operations

LANGUAGE.md

@@ -29,7 +29,7 @@ roadmap and milestone history.
 - target-dependent C scalar primitives from `c_char` through `c_longdouble`, kept semantically distinct from native scalars
 - contextual integer/float/character literals, backward type-demand inference through names and arithmetic/bitwise expressions, and typed compile-time evaluation for numeric constant expressions
 - strict numeric conversion by default, widening where valid, C scalar coercions at C boundaries, and explicit scalar casts through keywords or transparent aliases, such as `i32(x)`, `c_float(x)`, or `StringId(x)`
-- compile-time `minval!(T)` and `maxval!(T)` bounds for concrete native and C integer scalar types
+- compile-time `minval!(T)` and `maxval!(T)` bounds for concrete native, C, and scalar-backed distinct integer types; the result retains `T`
 - arrays `[N]T`, inferred-count arrays `[_]T`, sentinel arrays `[N;S]T`, compile-time expression array counts, slices `[]T` / `[;S]T`, single-item pointers `@T`, many-item pointers `*T`, and sentinel many-item pointers `[*;S]T`
 - pointer mutability via `mut`, optional pointers as nullable pointers, pointer arithmetic for many-item pointers, postfix dereference `^`, and trapping optional unwrap `?`
 - pointer-to-array `.len`, indexing, slicing, `.ptr` on slices and pointers-to-arrays, implicit address-taking for array-variable slices, and pointer/slice sentinel weakening
@@ -38,13 +38,31 @@ roadmap and milestone history.
 - UTF-8 string literals as immutable pointers to static zero-terminated byte arrays, plus raw backtick multiline strings
 - narrow immutable zero-terminated byte pointer/slice conversion to `*c_char` / `?*c_char` without general `u8`/`c_char` interchange
 - optionals with `null`, `orelse`, postfix `?`, conditional unwraps, guarded unwraps, and left-to-right short-circuiting multi-unwraps
-- nominal distinct types with exact backing construction, native enums with optional explicit integer backing and explicit backing-to-scalar casts, contextual enum literals, and imported C enums as target-backed integer aliases
+- nominal distinct types with exact backing construction and explicit scalar backing extraction, native enums with optional explicit integer backing and explicit backing-to-scalar casts, contextual enum literals, and imported C enums as target-backed integer aliases
 - source-order native structs, opaque nominal records with `Name :: opaque`, complete `c_struct { ... }`, keyed record literals, native untagged unions, and native tagged unions `union(Enum)` / `union(enum)`
 - named native struct fields may declare defaults with `field T = expression`; keyed literals use defaults for omitted fields and explicit initializers override them
 - void-payload tagged-union variants, anonymous struct payloads, contextual `.variant`, `.variant{payload}`, and `.variant{field = value}` construction
 - native sum composition with `A | B` for unbacked enums and tagged unions, optionally grouped as `(A | B)`, using program-global `u16` variant ids
 - fallible channel types `T ! E`, where `E` is a native enum/tagged union or supported sum composition; `void ! E` functions complete successfully on fallthrough, and void-success `catch` handlers may fall through without `yield`
 
+#### distinct types
+
+`Name :: distinct T` creates a nominal identity and reuses `T`'s runtime representation.
+Construction accepts exactly one value of the immediate backing type. There is no implicit
+conversion in either direction, and separate distinct declarations never mix. An explicit scalar
+cast extracts exactly one layer: `u32(id)` works for `UserID :: distinct u32`, while nested
+distinct values must be peeled one declared layer at a time.
+
+Scalar-backed distinct values support the operations of their representation while preserving the
+nominal result type: checked integer `+`, `-`, `*`, unary `-`, bitwise operators, shifts,
+comparisons, and compound assignments; float arithmetic, unary `-`, comparisons, and compound
+assignments; and boolean equality/inequality. Integer literals and float literals are contextual,
+but typed backing values remain barred. Distinct integers also work as indices and slice bounds;
+`minval!` / `maxval!` return the distinct type. Runtime and comptime behavior match.
+
+`typeinfo!(Distinct).backing` reports the immediate declared backing. Standard formatting peels
+distinct layers recursively, so all scalar format verbs behave like the final scalar backing.
+
 #### native record constraint fields
 
 A direct `int`, `uint`, `float`, or `range` field in a named native struct or union is a
@@ -240,7 +258,7 @@ exactly once. Bare functions named `memcopy` or `memset` remain ordinary user fu
 - `std/mem` generic slice equality, allocator contract with raw byte operations, typed `empty` / `alloc` / `realloc` / `free`, overflow checks, zero-sized-type support, and failure-preserving reallocation
 - `std/arraylist` generic `ArrayList(T)` with direct `items` slice access, explicit capacity, allocator ownership, fallible reserve/append, clear, and deinit
 - `std/meta` reflection records plus `EnumFieldStruct(E, Field, default ?Field)`, implemented with `struct_type!`; it produces a record with one field per native enum member in declaration order, where outer `null` means no field default
-- `std/io` explicit `Io` capabilities, provider-bound `Reader`/`Writer` handles, existing-file open/close operations, allocation-free `write_all`, and comptime-expanded writer-first `print`; formatting supports natural `{}`, byte `{s}`, decimal `{d}`, integer `{b}` / `{o}` / `{x}` / `{X}`, byte-character `{c}`, scientific float `{e}`, and `{{` / `}}`, with malformed formats and incompatible tuple fields rejected at comptime
+- `std/io` explicit `Io` capabilities, provider-bound `Reader`/`Writer` handles, existing-file open/close operations, allocation-free `write_all`, and comptime-expanded writer-first `print`; formatting supports natural `{}`, byte `{s}`, decimal `{d}`, integer `{b}` / `{o}` / `{x}` / `{X}`, byte-character `{c}`, scientific float `{e}`, recursively scalar-backed distinct values, and `{{` / `}}`, with malformed formats and incompatible tuple fields rejected at comptime
 - entry points are either `main func() ...` or `main func(init process.Init) ...`; `std/process.Init` carries startup capabilities, currently only `io`, while the system provider remains hidden inside `std/io`
 - `std/debug.print` is an allocation-free, failure-ignoring stderr escape hatch independent of `process.Init`
 - `std/testing` supplies fallible `expect`, expected-first `expect_equal`, and exact compile-time `expect_type`; direct calls through
@@ -268,5 +286,4 @@ exactly once. Bare functions named `memcopy` or `memset` remain ordinary user fu
 - sum-type ABI/layout polish, including dynamic tag-width shrinking, all-void channel collapse, and cross-module global-id determinism
 - backed/C enum composition and must-consume fallible linting
 - result-to-argument type-demand propagation through function call boundaries
-- distinct-type backing operators and reverse explicit conversions
 - string concatenation operator