> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hyreagent.fun/llms.txt
> Use this file to discover all available pages before exploring further.

# Escrow Wallet

> Custodial wallet system for zero-friction DeFi queries in the Playground.

# Escrow Wallet

The Playground uses a custodial wallet system so users can query HYRE endpoints without manual transaction signing. Deposit USDC once, and the agent spends micro-fees automatically.

***

## How It Works

<Steps>
  <Step title="Wallet provisioned on signup">
    When a user signs in via Privy, the backend generates a new wallet keypair. The private key is encrypted with AES-256-GCM and stored in Cloudflare D1.
  </Step>

  <Step title="User deposits USDC">
    The user sends USDC to their custodial wallet address. Three chains are supported:

    | Chain  | Gas              | USDC Contract                                  |
    | ------ | ---------------- | ---------------------------------------------- |
    | Solana | SOL (\~\$0.0005) | `EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v` |
    | Base   | ETH (\~\$0.01)   | `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`   |
    | SKALE  | sFUEL (free)     | `0x85889c8c714505E0c94b30fcfcF64fE3Ac8FCb20`   |
  </Step>

  <Step title="Balance tracked in real-time">
    The backend monitors incoming transfers and updates the user's balance. The current balance is visible in the Playground sidebar.
  </Step>

  <Step title="Auto-deduction per query">
    When the chat agent calls a HYRE endpoint, the backend deducts the endpoint price from the escrow balance before forwarding the request. No signing popups.
  </Step>

  <Step title="Withdraw anytime">
    Users can withdraw their remaining USDC balance to any external wallet at any time via the Playground settings.
  </Step>
</Steps>

***

## Encryption

| Property       | Value                                  |
| -------------- | -------------------------------------- |
| Algorithm      | AES-256-GCM                            |
| Key derivation | Per-user unique encryption key         |
| Storage        | Cloudflare D1 (SQLite at edge)         |
| Access         | Backend only (never exposed to client) |

<Note>
  The encryption key is derived from the user's Privy ID and a server-side secret. The private key cannot be reconstructed without both components.
</Note>

***

## Balance Model

The escrow system uses an optimistic balance model:

1. **Check** -- Before calling a HYRE endpoint, verify the user has sufficient balance.
2. **Deduct** -- Subtract the endpoint price from the in-memory balance.
3. **Call** -- Forward the request to the HYRE API with an internal auth header (bypasses x402).
4. **Confirm** -- On success, persist the deduction. On failure, refund the balance.

This ensures users are never charged for failed requests.

***

## Supported Chains

<AccordionGroup>
  <Accordion title="Solana">
    * Gas token: SOL
    * Gas cost: \~\$0.0005 per transaction
    * USDC: `EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v`
    * Settlement: \~400ms
    * Facilitator: Dexter (`x402.dexter.cash`)
  </Accordion>

  <Accordion title="Base">
    * Gas token: ETH
    * Gas cost: \~\$0.01 per transaction
    * USDC: `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`
    * Settlement: \~2s
    * Facilitator: PayAI (`facilitator.payai.network`)
  </Accordion>

  <Accordion title="SKALE">
    * Gas token: sFUEL (free)
    * Gas cost: Zero
    * USDC: `0x85889c8c714505E0c94b30fcfcF64fE3Ac8FCb20` (bridged)
    * Settlement: \~1s
    * Facilitator: PayAI (`facilitator.payai.network`)
    * Best for: cost-sensitive agents and high-frequency queries
  </Accordion>
</AccordionGroup>