Worth clarifying, our implementation is explicitly not a singleton. That’s the core of the architectural debate we opened in the ERC-8004 factory thread (https://ethereum-magicians.org/t/erc-8004-in-production-per-collection-factory-vs-chain-singleton-which-should-be-the-reference-architecture/).
Discoverability in the factory model doesn’t require a singleton, it requires a factory:
factory.lookup(collectionAddress) → (registryAddress, isDelisted)
One canonical factory address, arbitrary number of collection registries. Consumers always know where to look. Indexers watch the factory for RegistryDeployed events to discover all registries. Discoverability is preserved without concentrating admin control.
The singleton pattern’s discoverability benefit comes at a cost we weren’t willing to accept: one admin key controls agent identity for the entire chain, one vulnerability affects every collection, collections can’t have independent economics or ownership. If Adapter8004 is a singleton, it inherits all of those tradeoffs too.
The interesting question isn’t singleton vs. factory for discoverability, it’s whether the spec should define a standard factory interface so that both patterns are interoperable. That’s what we’re asking in the factory thread. Would value your take there.