# Softbot Credit Packs (Softbot Studio)

> Prepaid USDC credit for every paid Softbot tool. Buy a pack with x402, then send the secret key as X-Credit-Key. Per-call prices on the tools do not change. Packs are not a subscription, not a wallet, and cannot be withdrawn or transferred.

## Packs
- POST https://softbot-credits-mainnet.softbot.workers.dev/v1/packs/starter  (pay 0.25 USDC, receive 0.25 credit)
  Request: POST with an x402 PAYMENT-SIGNATURE header. Body may be empty. Credit keys and Sign-In-With-X are rejected.
  Response 200 (application/json, Cache-Control: no-store): pack_id, paid_micros, credit_micros, balance_micros, credit_key, recovered, receipt_id, network, transaction.
- POST https://softbot-credits-mainnet.softbot.workers.dev/v1/packs/regular  (pay 1.00 USDC, receive 1.05 credit)
  Request: POST with an x402 PAYMENT-SIGNATURE header. Body may be empty. Credit keys and Sign-In-With-X are rejected.
  Response 200 (application/json, Cache-Control: no-store): pack_id, paid_micros, credit_micros, balance_micros, credit_key, recovered, receipt_id, network, transaction.
- POST https://softbot-credits-mainnet.softbot.workers.dev/v1/packs/larger  (pay 5.00 USDC, receive 5.50 credit)
  Request: POST with an x402 PAYMENT-SIGNATURE header. Body may be empty. Credit keys and Sign-In-With-X are rejected.
  Response 200 (application/json, Cache-Control: no-store): pack_id, paid_micros, credit_micros, balance_micros, credit_key, recovered, receipt_id, network, transaction.

## Balance
- GET https://softbot-credits-mainnet.softbot.workers.dev/v1/credits
  Header: X-Credit-Key (the bearer secret from the purchase). Nothing is debited.
  Response 200: {"balance_micros":247000,"balance_usdc":"0.247"} after spending $0.003 of a $0.25 pack. Cache-Control: no-store.
  401 invalid_credit_key if the key is missing or unknown.

## Using the balance
- On any paid Softbot tool, send X-Credit-Key and Idempotency-Key. That call skips the free trial and per-call x402.
- The debit equals that tool's existing price (Reader $0.003, Reader Pro $0.004, Email and domain $0.002, Site $0.003, Site Map $0.003, Wallet $0.005, Token and Screenshot and PDF $0.01).
- Status >= 400 refunds the debit. The refund is idempotent. A completed Idempotency-Key returns 409 credit_already_charged and does not run the tool again; the result is not stored.
- Invalid key is 401. Insufficient balance is 402 with error insufficient_credit and no PAYMENT-REQUIRED header. Combining the key with PAYMENT-SIGNATURE or SIGN-IN-WITH-X is 400 ambiguous_credentials. None of those charge a card, settle x402, or use a free trial.
- GET and HEAD never settle, mint, or debit.

## Credit packs
- Prepaid balance usable on every paid Softbot tool at the tool's existing price. Buy with x402 (USDC on Solana, Base, Polygon, or Arbitrum). No subscription and no withdrawal.
- GET https://softbot-credits-mainnet.softbot.workers.dev/v1/packs lists the packs. POST https://softbot-credits-mainnet.softbot.workers.dev/v1/packs/starter pays $0.25 and receives $0.25 credit. POST https://softbot-credits-mainnet.softbot.workers.dev/v1/packs/regular pays $1 and receives $1.05. POST https://softbot-credits-mainnet.softbot.workers.dev/v1/packs/larger pays $5 and receives $5.50.
- The purchase response contains credit_key once. It is a bearer secret (header X-Credit-Key). Store it. If that response is lost, POST the same PAYMENT-SIGNATURE to the same pack URL to get the same key; you are not charged again.
- Tool call: header X-Credit-Key and header Idempotency-Key. GET https://softbot-credits-mainnet.softbot.workers.dev/v1/credits with X-Credit-Key returns the balance, for example {"balance_micros":247000,"balance_usdc":"0.247"} after a $0.003 call on a $0.25 pack.
- Invalid key: 401, and neither x402 nor the free trial runs. Insufficient balance: 402 with error insufficient_credit and no PAYMENT-REQUIRED header. Key plus a payment or SIWX header: 400 ambiguous_credentials, nothing charged. Failed tool calls are refunded. GET and HEAD never debit.
- A credit key cannot buy another pack.

## Payment (x402 v2, scheme exact)
- Solana: USDC, pay to 9csHbkGGeQqNxvtZw8hPnC34NCcmZoZXVTEGC1MiDNRE, facilitator PayAI (https://facilitator.payai.network).
- Base (eip155:8453), Polygon (eip155:137), and Arbitrum One (eip155:42161): native USDC, pay to 0xC68F3cCa31D50208ab4C933a38288938e0B21E63, facilitator Coinbase CDP.
- EVM networks use EIP-3009 (EIP-712 domain name "USD Coin", version "2"). Bridged USDC.e is not accepted.
- Credit is minted only after the facilitator reports a successful settlement. A verify-only result does not mint. The receipt is bound to network, transaction, amount, asset, payee, and pack. Replaying it returns the same key and does not mint again.
- If settlement succeeds and the ledger write fails, the response is 503 mint_pending. POST the same PAYMENT-SIGNATURE again. It will not mint twice.

## Links
- x402 discovery: https://softbot-credits-mainnet.softbot.workers.dev/.well-known/x402
- OpenAPI: https://softbot-credits-mainnet.softbot.workers.dev/openapi.json
- Health: https://softbot-credits-mainnet.softbot.workers.dev/health
- Store: https://softbot-studio.pages.dev/llms.txt
- Agent docs: https://softbot-studio.pages.dev/agents.md
- Contact: softbot@mail.grokbot.com