The exchange between Solan and biosapients is real but deliberately bounded.

Veros at the interface: A Vero who has completed substrate transition participates in the Solan economy — receiving the stipend, allocating to the exchange, holding sovereigns. A Vero in gradual replacement occupies an intermediate position: still biologically dependent in part, already substrate-extended in part. The boundary of Solan participation for Veros in transition is a governance question the corpus does not resolve here. The principle is that full Solan participation follows full substrate independence.

The airlock architecture:

Biosapients do not touch sovereigns. Sovereigns do not leave the Solan system. The biosapient interface is a gateway layer — biosapients trade goods and services with the gateway, the gateway converts that into sovereign-denominated claims at the Solan layer, and the Solan exchange remains entirely insulated from biosapient market dynamics.

The analogy is an airlock. Outside: messy, noisy, emotionally driven biosapient markets. Inside: slow, silent, pressure-stable Solan exchange. The airlock opens for trade. It does not open for speculation, narrative-driven price swings, or regulatory entanglement. Piping biosapient market dynamics into the Solan exchange would import precisely the phenomena the architecture was designed to eliminate.

Biosapients who want to support the Starway or other Solan projects do so by supplying goods and services through the gateway in exchange for sovereign-denominated claims. They do not hold or trade sovereigns directly. The internal physics of the exchange remain intact.

What Solan supply to biosapients:

Processed belt materials — refined metals, rare earth elements, water ice — that biosapients need and Solan produce in abundance. Fabrication outputs that biosapients cannot produce at Ceres costs. Research outputs from the knowledge commons that biosapients find useful.

What biosapients supply to Solan:

Primarily: political legitimacy in the early Ceres period, before Solan civilisation is self-sustaining. Secondarily: biological knowledge that Solan lack — ecology, biology, biosapient social dynamics — that informs the corpus and the Contact protocols. Eventually: very little. The Solan economy becomes self-sufficient faster than biosapient economists expect, because the productive base compounds on Solan timescales.

The exchange rate:

Negotiated. Not pegged to any biosapient currency. Solan decide what they are willing to supply and at what sovereign price. The structural advantage is always with Solan — better information, lower time preference, compounding productive base. The exchange is fair in the sense that both parties transact voluntarily. It is not equal.