A format reads the flag for a coordinate/version at serve time and translates it to its own native signal (npm's {@code deprecated} string, Cargo's {@code yanked} boolean, ...), and the operator endpoint writes and clears it through the same store-key convention this module owns. A thin, dependency-minimal helper over the store SPI; pure JDK, so the language format plugins can {@code requires} it without pulling in a peer format or the server.