A module-level constant is a typed call site

The Arm A census of the lekkerzeilen demo (2026-09-16) showed Vessel.step's dt giving up on its one site, vessel.step(SIM_DT): a module-level constant, which the local typer (a def's own bindings) cannot see. The lekkerzeilen seat counted the shape: 474 module-level bindings in 37 modules, 472 bound exactly once, 284 to a literal or literal arithmetic (131 int, 105 float, 48 str).

Mechanism. In the site loop of PyParamTypeFromSites, a bare-identifier argument that is neither a parameter nor a binding of the enclosing def (PyHeaderHasParam, PyBodyBindsName) is asked of PyModuleConstType(nm, fileLo, fileHi) over the site's own Python range: the name must be bound exactly once in the file, at indentation depth 0 (a binding inside a module-level if/try does not count), as a plain NAME = expr (no chain, no tuple target, no augmented step), never appear in an import/from statement, and the expression must type as float, int or str with no def scope; a bool is not claimed. The constant is then one more SITE for the parameter and must agree with every other site, so a float constant beside an int site still vetoes: the lever adds evidence, never overrides the rule. PyTokBindsName is the binding test shared with PyBodyBindsName.

Residuals, owner this seat: a constant imported by name (from consts import SCALE) is not typed in the importing file (the binding is elsewhere); x or 12.0, a subscript, a list element remain untypeable.

Log

• 2026-09-16 frankuser (Fable): built on a scratch binary while Arm B's tier ran; fixture green, the four site-typing fixtures green, commit 4e2507c6b.
• 2026-09-16 lekkerzeilen seat's score of a7f5e0817948428f (Arm C + the three fixes): value parity 52 lines bit-identical to CPython (284 constants claimed, 131 int, nothing truncated); full-map diff Arm B -> C 126 symbols, net +7252 B; baseline -> C 292 symbols, net -60541 B. SailRig.best_sheet 2414 -> 607 B, 81 -> 8 calls, sse 1 -> 3. One regression, _read_furniture +8471 B / +354 calls: its into parameter's two sites both pass self.furniture, a field bound to [], so the self-field typing (fix d) gave into a TPyList class claim -- the same claim an annotation into: list makes -- and the typed list receiver compiles LARGER with no arithmetic gained. Banked as an observation: a claim removes dispatch, and whether that shrinks or grows a body is a codegen property the census cannot see; the map diff can.