iter 22-tidy.1: DESIGN.md — reconcile Decision 11 with milestone-22 outcome (no Prelude, '__' separator)

docs/DESIGN.md

@@ -1724,46 +1724,59 @@ axis-5 (kind `*` only) covers the space.
 
 ### Prelude (built-in) classes
 
-22a/22b ship a fixed Prelude consisting of three classes: **`Show`,
-`Eq`, `Ord`**, with instances for the four primitive types `Int`,
-`Float`, `Bool`, `String`. `Ord` declares `Eq` as its superclass.
+Milestone 22 ships **no built-in Prelude classes**. The original
+22a draft committed to a fixed Prelude (Show / Eq / Ord on the
+primitives), but the implementation work to wire `int_to_str` as a
+heap-allocated-string runtime primitive proved substantively
+separable from the typeclass machinery itself, and the LLM-utility
+case for primitive `Show` is weak (LLM-natural form is `int_to_str
+x`, not `show x` through a single-instance class). The user-class
+end-to-end path is the milestone's typeclass acceptance gate
+(22c's `class Foo a` + `data IntBox` + `instance Foo IntBox`
+fixture); see `docs/specs/2026-05-09-22-typeclasses.md`
+"Amendments" §"22b.4b dropped" for the substantive rationale.
 
-`print x` is rewired through `Show.show`: at codegen, the existing
-print primitive routes its argument through the resolved `show@T`.
-This is the one operator-routing change in 22b.
+A future milestone may add a Prelude when concrete LLM-author code
+surfaces a case that benefits from `Show a` / `Eq a` / `Ord a`
+over per-type primitive functions. Until then, primitive output
+goes through `io/print_int` / `io/print_bool` / `io/print_str`
+directly.
 
-`==`, `<`, `<=`, `>`, `>=` REMAIN primitive operators. Class methods
-are accessed by name (`eq x y`, `lt x y`, …), not via these operators.
-Routing operators through classes is deliberately deferred — it would
-require migrating every existing fixture and would risk firing the
-bench gate. A future iteration may add operator routing once the
-typeclass layer has settled and the bench corpus is stable.
+`==`, `<`, `<=`, `>`, `>=` REMAIN primitive operators (unchanged
+from the 22a draft). Class methods are accessed by name (`eq x y`,
+`lt x y`, …), not via these operators. Routing operators through
+classes is deliberately deferred — it would require migrating every
+existing fixture and would re-baseline the bench corpus, which is a
+new-baseline decision rather than an iter detail.
 
-`Num` is NOT in the 22a/22b Prelude. Arithmetic operators (`+`, `-`,
-`*`, `/`) stay primitive and per-type. The LLM-natural pattern of
-distinct `Int` and `Float` arithmetic is preserved; class-based
-numeric overloading would invoke literal-defaulting which axis-7
-already excluded.
+`Num` is NOT in milestone 22. Arithmetic operators (`+`, `-`, `*`,
+`/`) stay primitive and per-type. Class-based numeric overloading
+would invoke literal-defaulting which axis-7 already excluded.
 
 ### What this decision does NOT commit to
 
-- **Operator routing.** `==`, `<`, etc. stay primitive in 22a/22b.
-  Class-routing operators is a future-iteration option, not a
+- **Operator routing.** `==`, `<`, etc. stay primitive in milestone
+  22. Class-routing operators is a future-iteration option, not a
   Decision-11 commitment.
 - **Form-B (prose) projection of class/instance.** The prose
-  renderer for the new schema nodes is 22b implementer scope; the
-  form is not pinned in 22a.
-- **Specific monomorphised-symbol naming format.** The naming is
-  deterministic from `(method, type-hash)`; the exact textual form
-  is fixed in 22b alongside the existing mangling scheme.
+  renderer for the new schema nodes is one-way (no parser by
+  design) and was deferred from milestone 22 entirely; the
+  placeholder render in `crates/ailang-prose/src/lib.rs` is
+  informational only. A future iter ships the full prose
+  projection if/when prose-side authoring needs surface.
+- **Specific monomorphised-symbol naming format.** Milestone 22
+  uses `<method>__<type-surface-name>` for primitive type targets
+  (e.g. `show__Int`) and `<method>__<8-hex-prefix>` for compound
+  types (where `<8-hex-prefix>` is the BLAKE3 hash of the canonical
+  type bytes). The `__` separator was chosen over `#` and `@` for
+  LLVM IR identifier legality.
 - **Mode annotations on class methods.** Class method signatures
   ARE full FnSigs and DO carry mode annotations per Decision 10;
-  the convention for default modes (typically `borrow` for
-  read-only methods like `show`, `eq`) is settled in 22b.
-- **Number of Prelude classes.** Three classes (Show, Eq, Ord) is
-  the 22b commitment. Adding `Num`, `Functor`-substitutes
-  (per-type), or domain-specific classes is gated on the Feature-
-  acceptance criterion at the time of proposal.
+  the convention is `borrow` for read-only methods. User-defined
+  classes pick modes per method.
+- **Number of Prelude classes.** Milestone 22 ships zero (no
+  Prelude). A future Prelude milestone gates class additions on
+  the Feature-acceptance criterion at the time of proposal.
 
 ## Mangling scheme (Iter 5c)