The authoritative set of `valueSource` keys that siera can resolve when substituting tokens into an ARS method `codeTemplate`. A method-library template may only reference these keys (plus the operation-ID pattern, see below); any other key is left unsubstituted at generation time and the emitted script will not run.
Details
This is the single declared contract for the valueSource vocabulary. It must stay in sync with the `value_sources` list assembled per analysis in [readARS()] (see `R/readARS.R`); the method-library contract test asserts the bundled templates reference only these keys.
In addition to the keys returned here, templates may reference the operation-ID family `operation_1`, `operation_2`, ... `operation_N`. These are derived automatically from the method's own `operations` list (in `order`) and never declared as parameters, so they are matched by pattern rather than being listed here.