docs(metatype): generic type-fn body locals done; only List growth remains

current/CHECKPOINT-METATYPE.md

@@ -114,17 +114,15 @@ shifts every `.ir` snapshot. On-demand import keeps the prelude clean.
 ## Next step
 The reflect/construct triad is COMPLETE — `` `enum `` (`0619`), `` `struct ``
 (`0622`), `` `tuple `` (`0623`) all reflect AND construct + round-trip. Remaining
-METATYPE work is the deferred enhancements (see below), all clean diagnostics
-rather than crashes:
+METATYPE work is ONE deferred enhancement, a clean diagnostic rather than a crash:
 - **Comptime `List` growth** — `List(EnumVariant).append` at comptime bails
   ("struct_get: base has no fields"); the allocator/List protocol path isn't fully
-  interp-evaluable. Probe `.sx-tmp/probe_makeenum.sx`.
-- **Generic type-fn body locals** — a generic `($T) -> Type` comptime-evals only
-  its return EXPRESSION (`generic.zig:1760`); a local before the return is
-  unresolved. Workaround: non-generic builder (`examples/0620`). Probe
-  `.sx-tmp/probe_me5.sx`.
-Neither blocks anything; the metatype surface (declare/define/type_info/field_type
-+ make_enum) is feature-complete for the locked design.
+  interp-evaluable (heap alloc + protocol dispatch + List internals at comptime —
+  a deeper, multi-step interp effort). Probe `.sx-tmp/probe_makeenum.sx`. Doesn't
+  block anything: array-literal locals already work for building variant lists
+  (`examples/0620`/`0624`).
+The metatype surface (declare/define/type_info/field_type + make_enum) is
+feature-complete for the locked design; generic type-fn body locals now work too.
 - ~~**Validation + loud diagnostics**~~ — COMPLETE. duplicate variant names
   (`examples/1180`); `declare()` never `define()`d (`examples/1181`, was a
   `verifySizes` panic); by-value self-reference for both source (`1178`) and
@@ -149,11 +147,10 @@ capabilities would let the variant list be built more freely; both error cleanly
 - **Comptime `List` growth.** Building variants via `List(EnumVariant).append` at
   comptime bails ("struct_get: base has no fields") — the allocator/List protocol
   path isn't fully interp-evaluable. Probe `.sx-tmp/probe_makeenum.sx`.
-- **Generic type-fn body locals.** A *generic* `($T) -> Type` comptime-evals only
-  its return EXPRESSION (`generic.zig:1760`, `findReturnTypeExpr`), so a local
-  before the return is unresolved. Workaround: build the list inline in the return,
-  or use a non-generic `() -> Type` builder (whose whole body is evaluated — this
-  is what `examples/0620` uses). Probe `.sx-tmp/probe_me5.sx`.
+- ~~Generic type-fn body locals~~ — DONE. A generic `($T) -> Type` now
+  comptime-evaluates its FULL body (prelude statements + return), so a local
+  before the return resolves. `createComptimeFunctionWithPrelude` +
+  `evalComptimeTypeBody`; no-prelude bodies stay on the old path. `examples/0624`.
 
 ## Known issues
 - issue 0140 — comptime type-construction bail panicked instead of diagnosing —
@@ -167,6 +164,12 @@ capabilities would let the variant list be built more freely; both error cleanly
   `examples/1178` locks it).
 
 ## Log
+- **Generic type-fn body locals.** A generic `($T) -> Type` comptime-evaluated
+  only its return EXPRESSION, so a local before the return was unresolved. Now a
+  body with a prelude (statements before the return) has its FULL body evaluated:
+  `createComptimeFunctionWithPrelude` lowers the pre-return statements into the
+  comptime function's scope, then the return expr. No-prelude bodies (RecvResult
+  etc.) stay on the old path → zero regression. `examples/0624`. Suite green (685).
 - **Tuple widening done — reflect/construct triad complete.** `TypeInfo` gained
   `` `tuple(TupleInfo) `` (positional `[]Type`); `reflectTypeInfo` reflects a
   `.tuple` (bare type_tags, tag 2), `defineType` dispatches tag 2 → `defineTuple`