Oracle clamping price difference with market

[mrq1911]

EVM: Add Clamped / Aggregate Oracle (Primary feed clamped by Hydration Market EMA oracle)

Context

We want a small Solidity “aggregate oracle” contract that outputs the primary oracle price, but clamps it within a configurable max deviation from our Market EMA oracle (available via the Chainlink adapter precompile).

Problem

Current setup can allow:

• Primary oracle reports price far from Hydration market (EMA).

We need a bounded output price so that external feeds can’t exceed a safe band around our market.

Proposed solution

Create a Solidity contract that:

• reads from two Chainlink-style feeds (AggregatorV3Interface)
  • Oracle1 (primary): DIA/Chainlink adapter feed
  • Oracle2 (secondary): Hydration Market EMA oracle feed (chainlink_adapter precompile address for the pair)
• clamps primary by a max deviation around secondary:

If maxDiff = 10% and:

• primary = 1.50
• secondary = 1.00
  Bounds: [0.90, 1.10] → output = 1.10

Math (bps):

• lower = S * (10_000 - d) / 10_000
• upper = S * (10_000 + d) / 10_000
• out = clamp(P, lower, upper)

Deployment model:

• one clamped oracle per reserve (different constructor args per reserve)
• both feeds can be constants passed in constructor (no admin setters required)

Scope

• New Solidity contract: ClampedOracle (Chainlink AggregatorV3Interface compatible)
• Foundry tests (unit + fuzz)
• Docs: short README / comments explaining clamp and how to compute EMA feed address

References

• Chainlink adapter precompile example:
  

  hydration-node/runtime/hydradx/src/evm/precompiles/chainlink_adapter.rs

  Line 44 in f389797

  pub struct ChainlinkOraclePrecompile<Runtime>(PhantomData<Runtime>);

• Aave hydration market uses EMA oracle here:
  https://github.com/galacticcouncil/aave-v3-deploy/blob/745c8641161ff7f20726f8a3ee0c799342e457d7/markets/hydration/index.ts#L157

Notes from discussion

• Both parent oracles can be constant; deploy per reserve with constructor args.
• Clamp % can also be set via constructor.