Stablecoin Peg Monitor — live on-chain DEX peg deviations

What you get in one run: the current pool price of each stablecoin pair read directly from the chain (Uniswap-v3-style slot0), its deviation from peg in basis points, on-range liquidity, tick, and a dislocated flag. No API keys, no accounts, ~3 seconds.

Ships with the pools that matter most for prediction-market flow: Polymarket's pUSD is minted 1:1 from USDC.e only, so every event surge has to cross the Polygon USDC.e/USDC and USDC.e/USDT pools first. The run also reports pUSD total supply — the collateral gauge for those inflows/outflows.

Use it to:

• Catch peg dislocations — schedule every 5 minutes with onlyDislocated: true and wire the dataset to an alert.
• Screen permissionless DEX arb windows — a 20+ bp gap between two USD stables in a 0.01% pool is a tradeable spread.
• Track prediction-market collateral — pUSD supply deltas between runs = net Polymarket inflow/outflow.
• Monitor your own pools — add any Uniswap v3 / Slipstream-compatible pool on Polygon, Base, Ethereum, or Arbitrum.

Sample row

{"chain":"polygon","label":"USDC.e/USDC 0.01%","pool":"0xd36e…a418","token0":"USDC.e","token1":"USDC",
 "price_token1_per_token0":0.99992,"expected_price":1.0,"deviation_bp":-0.8,"tick":-1,
 "liquidity_raw":"18732041125893","dislocated":false,"direction":"token0_premium","ts":1788360000}

The OUTPUT record holds the summary: max_abs_deviation_bp, dislocations[], polymarket_pusd_supply_usd.

Input

Field	Default	Meaning
alertBp	20	|deviation| ≥ this → dislocated: true
includeDefaultPools	true	the three Polygon USDC.e pools
includePusdSupply	true	pUSD totalSupply in OUTPUT
extraPools	[]	{chain, address, label, token0, token1, dec0, dec1, expectedPrice}
onlyDislocated	false	return only flagged pools (pay only for signals)
rpcUrl	—	your own endpoint, tried first

Conventions

• price_token1_per_token0 = (sqrtPriceX96 / 2^96)^2 × 10^(dec0 − dec1); deviation_bp = (price / expectedPrice − 1) × 10⁴.
• Negative deviation = token0 trades at a premium (you get less token1 per token0).
• expectedPrice defaults to 1.0 (USD/USD pairs); set it for non-1:1 pegs (e.g. EUR stables).

Notes

• Read-only eth_call against public RPCs with fallbacks; nothing is stored, no wallet involved.
• Pool addresses in the default list were resolved from the Uniswap v3 factory, not guessed.
• Pricing: pay per pool row returned.