Brummel
1631f6065c
Closes the gap between Iter 13a (parameterised ADTs in the checker) and end-to-end execution. ADT ctor code stays inlined at every use site — no mono-queue for types, no new symbols — but LLVM field types are now derived per use site via substitution. `CtorRef` gains `type_vars: Vec<String>` so use sites can identify which fields reference rigid vars. `cref.fields` (precomputed LLVM strings) is documented as monomorphic-only and read past for parameterised ADTs. `lower_ctor`: derives a `BTreeMap<String, Type>` substitution from `synth_arg_type` of each arg via `unify_for_subst`, then maps every `ail_field` through `apply_subst_to_type` + `llvm_type` for the per-store types. Monomorphic ADTs hit the original fast path. `lower_match`: builds `arm_subst` from `s_ail.args` ↔ `cref.type_vars`, substitutes through each `cref.ail_fields[idx]`, and uses the substituted type both for the LLVM `load` AND as the AILang slot of the local — so a downstream `unbox(b)` sees `b: Int`, not `b: a`. `synth_arg_type` for `Term::Ctor`: returns concrete type-args derived from the ctor's term-args. Vars left unpinned (e.g. `None` for `Maybe a`) fall back to `Type::unit()`. `llvm_type(Type::Var)` now hard-errors. Earlier this silently fell through to `ptr` (the ADT-via-ptr fallback), producing garbage IR. Failing loudly here surfaces missed substitutions in the test suite. Two e2e tests (`box.ail.json`, `maybe_int.ail.json`) cover ctor lower with substituted field types and match-arm field substitution. 64 tests green; clippy clean (two pre-existing warnings untouched). Hash invariant holds. Out of scope per agent assignment: poly-fn-as-value, higher-rank polymorphism, DESIGN/JOURNAL updates (deferred to 13c).