Producer-binding probe grounds a dot-path leaf parameter against the outer input type

RecordBindingResolver’s producer-binding probe resolves each reflected parameter to an SDL argument name and then grounds an input-axis observation against that argument’s type: `sdlArgName from the argMapping override, inputSdl = unwrappedTypeName(arg.getType()), then addInputObservation(inputSdl, new ProducerBinding.RootService(paramElement, ...)). The override value it reads is head-only (the file-private parser drops everything after the first .), so for a dot-path entry the argument it grounds against is the outer input object while paramElement is the Java type of the parameter that receives the leaf value. argMapping: "req: input.request" therefore records the outer Input SDL type as backed by req’s Java class, which is a different type than the one that parameter actually carries. `shouldBind filters primitives, String, Number, Boolean, Character, enums, arrays and java.*, so the mis-grounding only fires when the leaf parameter is a consumer-authored class, which is precisely the dot-path-into-input-object shape that the argMapping seam unification widens. Fixing it means deciding what the right grounding is for a path-bound parameter (most likely the leaf field’s input type rather than the head argument’s, which needs the resolved path rather than the head string), so it is a design question about producer grounding rather than a rename. Surfaced by two independent Spec reviews of the argMapping seam unification, which deliberately left the probe’s behaviour unchanged apart from deleting its private parser.