fix(0118): cast accepts compound type args; compound type literals are first-class Type values

issues/0118-cast-compound-type-arg-unresolved.md

@@ -1,5 +1,20 @@
 # 0118 — `cast(<compound type>) expr` dies with "unresolved 'unknown_expr'"
 
+> **RESOLVED** (2026-06-11, same session, Agra-authorized in-session fix).
+> Two-part root cause: (1) `lowerCall` lowers args BEFORE the cast handler,
+> and compound type literals had NO expression-position lowering — they hit
+> `lowerExpr`'s catch-all `unknown_expr` error. Fixed by giving the six
+> compound type-expr shapes (`*T`, `[*]T`, `[]T`, `?T`, `[N]T`, fn types) a
+> first-class `const_type` lowering arm in `src/ir/lower/expr.zig`,
+> mirroring named types (`t : Type = *s64;` now works like `t : Type =
+> f64;`). (2) The cast handler's private static-type gate only accepted
+> bare names — replaced with the canonical `isStaticTypeArg`
+> (`src/ir/lower/call.zig`), so static compound casts route through
+> `coerceExplicit` while the runtime-`Type`-variable form (`cast(type) val`
+> in category arms) still falls through to runtime dispatch. Regression
+> test: examples/0182-types-cast-compound-types.sx (all compound cast
+> forms + the first-class Type value). Suite 579/579.
+
 ## Symptom
 
 `cast(T) expr` with a COMPOUND static type argument (`*s64`, `[]u8`, `?s32`,