LSP argMapping completions and diagnostics answer the bindable-target question from the census with no per-directive reservation

Two LSP surfaces answer the question "which Java parameter names may an argMapping entry target" from the jvm_method_parameter census with no type predicate and no per-directive reservation: ArgMappingCompletions.leftCandidates selects PARAMETER_NAME for the named class and method and offers the union across overload descriptors (its javadoc states the union is deliberate), and Diagnostics.parameterNames unions parameterNames() across answers.overloads(...), so judgeArgMappingJavaParam accepts any name in that union. The build answers the same question from live reflection, and on the @condition path it reserves the Table-assignable slots (ServiceCatalog.checkConditionOverrideTargets): with cond(Film film, FilmFilter kriterier), the LSP offers film as a left-hand target and accepts argMapping: "film: ..." without a diagnostic, while the build rejects it. Two producers of one fact, nothing binding them; the divergence is one name per method today and gets multiplied by the participant count once R675’s overload admission lands (per-participant sets deliberately name their table slots differently, and every admitted table-slot name becomes reserved set-wide).

The census already carries JVM_METHOD_PARAMETER.PARAMETER_TYPE and DECLARED_PARAMETER_TYPE, so the filter is expressible without new capture. The design question is where the fact lives, not which query gets a predicate: the argMapping coordinate (InputField("ExternalCodeReference", "argMapping"), keyed by Behavior.ArgMappingBinding) is shared with @service and @externalField, and a Table-assignable parameter is a reserved slot only on the @condition path (ArgCallEmitter’s `ParamSource.Table arm exists on the @service path precisely to fail loudly on a leaked table slot, not to reserve one). So the bindable-target set wants to be a derivation over the census keyed on (class, method), with reservation a per-directive projection over it, rather than a blanket type filter patched into two queries at a shared coordinate; a third spelling of the rule is the failure mode to avoid. Split out of R675, whose build-side admission deliverable states the reservation invariant this item’s surfaces must agree with.