The sandbox is a mock Open Banking service. It lets you run full proof cycles
without a real bank connection, with deterministic scenarios for demos.

## What it provides [#what-it-provides]

* An OAuth 2.0 consent flow, authorize then token.
* A balance endpoint that returns ECDSA-signed payloads, the cryptographic
  substitute for a real bank's attestation.
* Two or three mock banks with configurable balances.
* An admin endpoint to seed scenarios: solvent, near-breach, and insolvent.

## Seeding a scenario [#seeding-a-scenario]

Point a reserve source at a sandbox bank, seed the scenario you want, then run a
cycle. The near-breach scenario is useful for exercising the anomaly agent,
which flags drift before the circuit ever proves a breach.

```ts
const solva = new Solva({ network: "local", tenant: "demo-institution" });
await solva.connectSource({
  type: "openbanking",
  label: "Sandbox Bank A",
  settings: { bank: "a", scenario: "near-breach" },
});
await solva.runProofCycle();
```