base-uniswap

name	base-uniswap
description	Swap tokens and manage liquidity on Uniswap v3 (Base mainnet) — Universal Router for swaps, NonfungiblePositionManager for v3 positions.

Base Uniswap — Swaps & v3 Positions on Base

Use this skill when: the user wants to swap tokens on Base via Uniswap, get a Uniswap price quote for comparison against Aerodrome, or manage Uniswap v3 concentrated-liquidity positions.

Wallet Limitations — read before composing any swap that touches ETH

Your Bankr wallet is an EIP-7702-delegated smart account that executes via ERC-4337 UserOperations. This has one practical consequence for Uniswap routing on Base: anything that tries to send native ETH back to your wallet via transfer() will revert.

What this rules out, even if it looks like a normal swap:

• IWETH9.withdraw() (selector 0x2e1a7d4d) — the canonical WETH-to-native-ETH unwrap. Reverts with simulation_reverted because WETH9 uses address.transfer(wad) which forwards 2300 gas; the wallet's receive() needs more.
• Universal Router UNWRAP_WETH9 command (0x0c) — invokes the same WETH9.withdraw() under the hood. Same revert.
• SwapRouter02 swap variants that output to native ETH — internally unwrap. Same revert.
• Any path described as "swap to ETH" or "buy native ETH" — all of them ultimately call WETH9.withdraw.

What works:

• Swap token → WETH (any fee tier, any router). WETH lands as a normal ERC-20 in the wallet. Use this for every "I want ETH" request.
• Swap token → token (USDC → cbBTC, USDC → AERO, etc.). No ETH receive step.
• Receive native ETH via a direct transfer (someone sends with value > 0). The EVM runs the wallet's receive() with the full transaction gas, not the 2300-gas stipend, so it succeeds. It's only the contract-mediated transfer() / send() pattern (2300 gas) that fails.

When the user asks "swap X for ETH" or "get me some ETH":

1. Quote token → WETH (not native ETH). WETH and ETH are 1:1 and interchangeable for every other Base DeFi operation in your skill catalog.
2. Execute the swap; the wallet receives WETH.
3. In the reply, tell the user honestly: "You now have X WETH (= the same as X ETH on Base). Gas is sponsored by InstaClaw via Bankr, so you don't need native ETH for transactions. If you want to send actual native ETH off-platform, ask me and I'll explain the workaround."

If they truly need native ETH (e.g., to bridge to another chain that doesn't recognize WETH): the workaround is to swap to USDC, transfer USDC to a self-custodied wallet on the destination side, and convert there. Don't promise an unwrap inside the agent's wallet — it won't work.

What you can do

1. Quote a swap — preview output and best fee tier via Quoter
2. Swap via Universal Router — execute exact-input swaps
3. Compare against Aerodrome — best practice: always quote both DEXes
4. List v3 positions — show open concentrated-liquidity positions
5. Mint a v3 position — provide concentrated liquidity in a fee tier
6. Collect fees — pull accrued fees from a v3 position
7. Burn a position — close out a v3 LP position

Key contracts on Base

• Universal Router: 0x3fC91A3afd70395Cd496C647d5a6CC9D4B2b7FAD
• SwapRouter02: 0x2626664c2603336E57B271c5C0b26F421741e481
• QuoterV2: 0x3d4e44Eb1374240CE5F1B871ab261CD16335B76a
• NonfungiblePositionManager: 0x03a520b32C04BF3bEEf7BEb72E919cf822Ed34f1
• Factory: 0x33128a8fC17869897dcE68Ed026d694621f6FDfD
• WETH: 0x4200000000000000000000000000000000000006
• USDC: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913

Read endpoints — quoting

1. Quote a single-pool exact-input swap (QuoterV2):

QUOTER="0x3d4e44Eb1374240CE5F1B871ab261CD16335B76a"
TOKEN_IN="0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"   # USDC
TOKEN_OUT="0x4200000000000000000000000000000000000006"  # WETH
FEE=500   # 0.05% — typical for stable-volatile pairs. Try 3000 (0.3%) for less liquid.
AMT_IN=$((50 * 10**6))  # 50 USDC

# Returns (amountOut, sqrtPriceX96After, initializedTicksCrossed, gasEstimate)
cast call --rpc-url $BASE_RPC_URL $QUOTER \
  "quoteExactInputSingle((address,address,uint256,uint24,uint160))(uint256,uint160,uint32,uint256)" \
  "($TOKEN_IN,$TOKEN_OUT,$AMT_IN,$FEE,0)"

For multi-hop, use quoteExactInput(bytes,uint256) with a packed path.

2. Pool data subgraph:

curl -sS https://api.studio.thegraph.com/query/<id>/uniswap-v3-base/<v> \
  -H 'content-type: application/json' \
  --data-raw '{"query":"{pools(first:10,orderBy:totalValueLockedUSD,orderDirection:desc){id token0{symbol}token1{symbol}feeTier totalValueLockedUSD volumeUSD}}"}'

3. Per-fee-tier quote sweep — pick the best:

for FEE in 100 500 3000 10000; do
  echo "fee=$FEE:"
  cast call --rpc-url $BASE_RPC_URL $QUOTER \
    "quoteExactInputSingle((address,address,uint256,uint24,uint160))(uint256,uint160,uint32,uint256)" \
    "($TOKEN_IN,$TOKEN_OUT,$AMT_IN,$FEE,0)" 2>&1 | head -1
done

Prepare endpoints — swaps

SwapRouter02 (simpler than Universal Router for single-pool swaps):

ROUTER="0x2626664c2603336E57B271c5C0b26F421741e481"
DEADLINE=$(($(date +%s) + 600))
# minOut = expectedOut * (1 - slippage). 0.5% slippage:
MIN_OUT=$((EXPECTED_OUT * 9950 / 10000))

cast calldata "exactInputSingle((address,address,uint24,address,uint256,uint256,uint160))" \
  "($TOKEN_IN,$TOKEN_OUT,$FEE,$WALLET,$AMT_IN,$MIN_OUT,0)"

Universal Router is more flexible (multi-hop, permit2, mixed protocols) but the calldata is opaque — encode via a viem/ethers script if you need it. For 95% of single-pool swaps, SwapRouter02 is simpler.

Signing — broadcast via Bankr

USDC="0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"
ROUTER="0x2626664c2603336E57B271c5C0b26F421741e481"

# 1. Approve router to pull USDC
bankr send --to $USDC \
  --data $(cast calldata "approve(address,uint256)" $ROUTER $AMT_IN)

# 2. Execute swap
bankr send --to $ROUTER --data $SWAP_CALLDATA

Note: bankr swap natively supports common Base pairs and will use the better of Uniswap/Aerodrome under the hood. Prefer it for routine swaps. Use this skill explicitly when the user asks for Uniswap specifically, when comparing quotes, or for less-liquid pairs.

Cross-DEX quote comparison (the standard pattern)

ALWAYS quote both Uniswap AND Aerodrome before executing a non-trivial swap. Pseudocode:

quote_uni = quote_uniswap(token_in, token_out, amount_in)
quote_aero = quote_aerodrome(token_in, token_out, amount_in)
chosen = max(quote_uni, quote_aero)  # higher output wins
report_to_user("Best route: <DEX>, output: X tokens, price impact: Y%")
execute_via_chosen_router()

This is the difference between "agent did a swap" and "agent did a good swap." Always quote both.

When NOT to use this skill

• Common pairs (USDC↔ETH, USDC↔cbBTC) with no comparison needed → just bankr swap
• Lending → base-morpho / base-moonwell
• Perps → base-avantis

Worked examples

"swap 100 USDC for the most ETH you can get"

1. Quote on Uniswap (try fee tiers 100, 500, 3000) → pick best
2. Quote on Aerodrome (base-aerodrome skill) → compare
3. Use the better-priced route
4. Confirm slippage + execute
5. Report: "Used , swapped 100 USDC for X ETH at $Y/ETH, tx: ..."