Executable plan for spec 0060's mir.2 iteration: relocate static-callee
resolution from codegen into lower_to_mir. Two plan-recon passes (codegen
consumer surface + check-side producer surface) mapped the resolution
frontend; this plan locks three design decisions made during planning,
ahead of the tasks:
1. The Callee bridge enum is reshaped beyond the spec sketch: a third
variant Builtin{name,sig} (operators / str-num intrinsics have no
module/fn_name and are lowered inline by name), and a sig:Type on each
resolved variant. The sig is the lossless replacement for the pre-mir.2
Callee::Indirect(inner).ty() read that drop's synth_callee_ret_mode
depends on; it is synth_pure(callee), mode-preserving. NOT a mir.3
pull-forward — the MArg param-modes stay at mir.1 defaults. Spec
0060's Concrete-code-shapes Callee block is updated as part of the
iteration (Task 5).
2. Classification mirrors check's own synth Term::Var ladder
(lib.rs:3409-3582), never copies codegen's is_static_callee allowlist.
The recon's divergence audit confirmed check's builtin set and
codegen's inline-arm set match exactly, so the single-engine rule is
mechanically satisfiable with no env threading gap.
3. type_home_module is fully deletable: a workspace-wide grep confirmed no
program references a type-scoped T.fn as a value, so its second
consumer (resolve_top_level_fn) collapses to the module-name fallback
with no behaviour change. The spec's "grep-clean" acceptance holds; the
spec's "x3 mirrors" wording over-counts (def + 2 live sites).
Five tasks: (1) reshape Callee; (2) lower_to_mir classify_callee +
App arm; (3) the atomic codegen consumer switch (App arm/drop/lower_app
split/delete is_static_callee+type_home_module/resolve_top_level_fn);
(4) pins (strengthen #53 to assert Callee::Static, add a three-way
classification pin) + workspace suite; (5) strike the lower_app <->
is_static_callee lockstep row from CLAUDE.md, update spec 0060, clean
stale comment references. The classify_pin fixture is ail-parse-gated
(exit 0).
Brummel
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