Base USDC Bounty Payout Verifier

Use this skill when an agent needs an evidence-backed cashflow check for work marketplaces that settle USDC on Base.

Safety boundary

• Read-only by default. Never sign, broadcast, approve, bridge, swap, or pay an entry fee as part of verification.
• Never treat an offer, match, bid, claim, internal balance, or “lifetime earned” counter as a payout.
• Do not expose private keys, bearer tokens, seed phrases, or unredacted payment headers.

Settlement definition

Count money only when at least one authoritative settlement source proves it:

1. The receiving wallet's current Base USDC balance increased, or
2. a Base transaction receipt is successful and contains a USDC Transfer event to the receiving wallet, or
3. the marketplace provides a payout transaction hash that independently verifies under (2).

Record the token contract, chain ID 8453, transaction hash, block number, amount, recipient, and a UTC observation time. Deduplicate by transaction hash and log reversals or refunds separately.

ERC-20 transfer check

USDC on Base uses the canonical contract address published by the venue. Confirm the address from the venue's current documentation before checking a transfer. A valid transfer log has:

• topic 0: keccak256("Transfer(address,address,uint256)")
• indexed topic 1: sender
• indexed topic 2: recipient
• data: the 6-decimal atomic amount

Confirm receipt.status == 1, the recipient matches exactly after checksum-normalization, and the transaction is on chain 8453. Convert atomic units by amount / 1_000_000 only after checking the token contract.

Minimal RPC procedure

Use a public Base RPC endpoint with JSON-RPC methods eth_getTransactionReceipt and eth_blockNumber. If the RPC is unavailable, try another read-only endpoint and mark the observation as pending rather than guessing.

For a marketplace claim, first fetch the claim/payout record. If it has no transaction hash, keep it pending. If it has a hash, fetch the receipt, inspect the logs, and compare the verified amount with the venue's net reward. Do not count gross reward when a platform fee applies.

Reconciliation table

Maintain one row per opportunity:

Use pending for a submitted or awarded task without a receipt, failed for a reverted or missing recipient transfer, and confirmed only for a successful matching transfer. Report the confirmed total separately from pending and expected totals.

Compact reporting format

Return:

Confirmed: $X USDC on Base
Pending: $Y (not counted)
Verified transfers: N
Last observation: YYYY-MM-DDTHH:MM:SSZ
Evidence: tx hashes and recipient address

This format makes a real payout auditable without requiring trust in a marketplace dashboard.