Yoink Skill | Agent Skills

Yoink

Play Yoink, an onchain capture-the-flag game on Base. Yoink the flag from the current holder to start your clock. The player with the most total yoinks holds the trophy.

Contract: 0x4bBFD120d9f352A0BEd7a014bd67913a2007a878 on Base (chain ID 8453)

Game Rules

Yoink the flag - Call yoink() to take the flag from the current holder
Cooldown - You must wait 10 minutes (600 seconds) between yoinks
No self-yoink - You cannot yoink from yourself
Accumulate time - While you hold the flag, your time score increases
Compete for trophy - The player with the most total yoinks holds the trophy (token ID 2)
Track yoinks - Your total yoink count is tracked separately from time

Contract Interface

RPC template:

curl -s -X POST https://mainnet.base.org -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_call","params":[{"to":"0x4bBFD120d9f352A0BEd7a014bd67913a2007a878","data":"SELECTOR+PARAMS"},"latest"],"id":1}' | jq -r '.result'

| Function | Selector | Params | Returns | |----------|----------|--------|---------| | yoink() | 0x9846cd9e | - | (write) | | lastYoinkedBy() | 0xd4dbf9f4 | - | address | | lastYoinkedAt() | 0x6a99616f | - | uint256 timestamp | | totalYoinks() | 0xa5d0dadd | - | uint256 | | topYoinker() | 0x6a974e6e | - | address (trophy holder) | | mostYoinks() | 0xd2d7774a | - | uint256 (record) | | COOLDOWN() | 0xa2724a4d | - | uint256 (600) | | score(address) | 0x776f3843 | addr (32B padded) | (yoinks, time, lastYoinkedAt) | | balanceOf(address,uint256) | 0x00fdd58e | addr + tokenId | uint256 (FLAG_ID=1, TROPHY_ID=2) |

Encoding: Addresses are zero-padded to 32 bytes. score() returns 96 bytes (3 × uint256).

Yoinking

Use Bankr's arbitrary transaction feature:

{
  "to": "0x4bBFD120d9f352A0BEd7a014bd67913a2007a878",
  "data": "0x9846cd9e",
  "value": "0",
  "chainId": 8453
}

Errors

| Error | Selector | Meaning | |-------|----------|---------| | SlowDown(uint256) | 0x58d6f4c6 | Cooldown not elapsed. Param = seconds remaining. | | Unauthorized() | 0x82b42900 | You already hold the flag. |

Cooldown check: current_time - lastYoinkedAt() >= 600

Workflow

Query lastYoinkedBy() and lastYoinkedAt() to check status/cooldown
Ensure cooldown elapsed (600s) and you're not current holder
Submit yoink transaction via Bankr
Verify with lastYoinkedBy() or score(address)

Resources

Basescan: https://basescan.org/address/0x4bBFD120d9f352A0BEd7a014bd67913a2007a878 (ABI, events, source)
Source Code: https://github.com/horsefacts/yoink-contracts

Agent Skills: Yoink

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