Solon is the third of five layers — sitting between agents and infrastructure. Adapters connect both ways. We never hold a key.
The agent-finance world settles into a five-layer architecture. Solon occupies the control plane — the layer that decides what gets passed down to be signed.
The two architectural commitments that determine where Solon sits, what it can do, and — more importantly — what it will never do.
Layers 1 and 2 are not built. They are adopted. Solon is designed to connect to existing wallets, protocols, custodians, and chains through adapters — a complementary control plane rather than a competing wallet or custody product.
Solon never holds a complete signing key. Policy enforcement is structural: when an evaluation fails, the signing request is never produced. There is no policy-bypass path that Solon can be tricked into taking — because the bypass path doesn't exist in the codepath.
The protocols agents speak with the outside world — HTTP payment, agent-to-agent commerce, multi-party flows. Each is designed to be addressed by Solon through a thin adapter. Adapter coverage will be rolled out progressively as the product matures.
One concrete example. An agent buys 10 USDC of data. Here's everything that happens between the request and the settlement.