docs: PLAN-RACE status — folding done, next blocker is nested comptime-type-call composition

current/PLAN-RACE.md

@@ -67,7 +67,22 @@ backed by the pointer TypeInfo's pointee TypeId (`src/ir/types.zig`). Lock with
 
 ## Status
 
-- **Step 0 (prereq) DONE:** issue 0195 (tuple/array/vector field reflection) fixed + committed
+Prereqs DONE (each committed + adversarially reviewed + suite-green):
-  (`8ac6c573`). Tuple reflection works on inline + `$T`-param forms. Issue 0196 (tuple *alias*) filed,
+- **issue 0195** (tuple/array/vector field reflection) fixed (`8ac6c573`). Tuple reflection works on
-  not on the critical path.
+  inline + `$T`-param forms. Issue 0196 (tuple *alias*) filed, not on the critical path.
-- **NEXT: Step 1 — the `pointee` builtin.**
+- **`pointee($P) -> Type`** builtin added (`f1d29876`) — projects `*Task(A)` → `Task(A)`.
+- **`field_count`/`size_of`/`align_of` fold as comptime constants** (`2a6ef398`) — so a generic
+  `($T) -> Type` builder can `inline for 0..field_count(T)` and size `[field_count(T)]EnumVariant`.
+  Verified: the variable-arity loop + array dim now work inside `RaceResult`.
+
+**NEXT BLOCKER (step 2, not yet resolved): nested comptime-type-call composition.** Building each
+variant payload needs `*Task(A) → A`, i.e. `field_type(pointee(field_type(T, i)), 0)`. Today:
+- passing a `field_type(...)` RESULT as the type-arg to a generic (`TaskResult(field_type(T, i))`) →
+  *"cannot infer generic type parameter 'P'"*;
+- the same nested inline (`field_type(pointee(field_type(T, i)), 0)`) → *"cannot infer 'T' for
+  field_type"*;
+- a `::` alias bound to a comptime-type-call result (`P0 :: field_type(NT, 0)`) → *"unresolved type
+  'P0'"* (kin to issue 0196).
+So a comptime-type-call's Type result isn't usable as a generic type-arg / `::` alias / nested
+type-call arg. This composition gap is the next thing to fix (or design around) before the variable-
+arity `RaceResult` payloads can be built. Everything up to the payload projection works.