# USDF

> USDF is a compute dollar on Robinhood Chain (chain id 4663): a stock OpenZeppelin ERC20Wrapper over USDG at 0x4A35a5eC2A50A4d2957B2F2366E017f526cAB318. 1 USDF = 1 USDG = $1 of compute, redeemable 1:1 for USDG through the token contract (withdrawTo). The token contract has no fee, cap or pause of its own; redemption depends on USDG itself being transferable. The gateway at https://api.usdf.fi is an OpenAI-compatible inference API that meters requests in USDF.

## How to pay

- Prepaid: wrap USDG into USDF (depositFor on the token), link a wallet to an account, deposit USDF to the gateway's hot wallet, then call POST https://api.usdf.fi/v1/chat/completions (or /v1/completions) with Authorization: Bearer sk_... Every request places a hold for its maximum cost and is charged the provider's reported usage at the published price.
- Per request, no account: x402 at POST https://api.usdf.fi/x402/v1/chat/completions. An unpaid request answers 402 with a payment-required header; pay in USDF (Permit2 witness transfer, one approval ever) or USDG (EIP-3009 transferWithAuthorization) and retry.
- The same for every endpoint, each quoted at the most the request can cost in its own unit: POST https://api.usdf.fi/x402/v1/completions, https://api.usdf.fi/x402/v1/embeddings, https://api.usdf.fi/x402/v1/images/generations, https://api.usdf.fi/x402/v1/images/edits (multipart), https://api.usdf.fi/x402/v1/audio/transcriptions (multipart), https://api.usdf.fi/x402/v1/audio/speech (the body is the audio; read the receipt by its x-request-id), https://api.usdf.fi/x402/v1/rerank and https://api.usdf.fi/x402/v1/videos/generations (a job: poll GET https://api.usdf.fi/x402/v1/videos/{id}, then GET its /content, each with the read_token from the 202 as the bearer). Receipt of any request, no key: GET https://api.usdf.fi/x402/v1/receipts/{request_id}
- Agents: MCP server at POST https://api.usdf.fi/mcp (tools list_models, quote, list_tools, quote_tool, chat, balance, receipt; with no key, chat is paid with x402, receipt answers the public receipt and balance a wallet's USDF and USDG given its address).
- Agent skill, step by step from buying USDF to paying with x402: https://api.usdf.fi/skill.md

## Catalog and prices

- Signed catalog (every listed model: price and its unit, tier for text models, modality, context, region, attested hardware; latency measured over 7 days once a model has 20 requests, and throughput for text models): https://api.usdf.fi/v1/catalog
- Catalog signer address: https://api.usdf.fi/v1/catalog/signer; detached signature as JSON: https://api.usdf.fi/v1/catalog/signature
- Pricing (USD per 1M tokens, same figures in USDF): https://api.usdf.fi/v1/pricing; every sheet ever served, by hash: https://api.usdf.fi/v1/pricing/sheets; upstream list prices observed: https://api.usdf.fi/v1/pricing/observations
- Models (OpenAI format): https://api.usdf.fi/v1/models

## Receipts and logs

- Receipt for one request: GET https://api.usdf.fi/v1/receipts/{request_id} with the key that made it
- Usage log (RFC 6962 Merkle log over every request, key and x402): https://api.usdf.fi/v1/log/checkpoints, https://api.usdf.fi/v1/log/proof/{request_id}, https://api.usdf.fi/v1/log/consistency, https://api.usdf.fi/v1/log/frontier, https://api.usdf.fi/v1/log/leaves
- Settlements (burns carrying the batch digest and a log checkpoint in calldata): https://api.usdf.fi/v1/settlements
- Money path (every claimed USDF/USDG movement): https://api.usdf.fi/v1/flows; costs recomputed from public inputs: https://api.usdf.fi/v1/audit/costs

## Proof of reserve

- Live: https://api.usdf.fi/v1/reserve (USDG held by the token contract against USDF supply, custody against ledger liabilities, and the address of the read-only ReserveView contract)
- Daily signed attestation: https://api.usdf.fi/v1/reserve/attestations/latest and https://api.usdf.fi/v1/reserve/attestations/YYYY-MM-DD
- Health: https://api.usdf.fi/health

## Token

- Logo: https://api.usdf.fi/usdf.png (512 px; https://api.usdf.fi/usdf-{32,64,128,256,512,1024}.png for each size), transparent outside the coin
- Token list (token-lists schema, each chain's USDF with its logo): https://api.usdf.fi/tokenlist.json