feat(price): ChainlinkPriceAdapter — multi-feed chaining for asset/USDC precision

[ojasarora77]

Feature: Multi-Feed ChainlinkPriceAdapter for USDC-Normalised Pricing

Background

ChainlinkPriceAdapter currently accepts a single Chainlink feed per asset.

All production feeds are USD-denominated (e.g. ETH/USD, BTC/USD), while the protocol’s protocolUnderlying is USDC.

The adapter implicitly assumes:

USD = USDC (1:1 peg)

This assumption is acceptable on testnet, but introduces a correctness gap in production.

Failure Mode During USDC Depeg

During a USDC depeg:

• estimatedUnderlying returned by getPrice() is USD-denominated
• Actual execution through Uniswap returns USDC

This causes a mismatch:

estimatedUnderlying ≠ actualUnderlying

As a result:

• The slippage budget may be consumed prematurely
• Buy-leg operations may exceed allowed slippage or revert

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Proposed Change

Add an optional quoteFeed parameter to configureFeed.

Example quote feed:

USDC/USD
0x8fFfFfd4AfB6115b954Bd326cbe7B4BA576818f6

The adapter computes a USDC-normalised price when the quote feed is provided.

Price Formula

price = baseFeed.latestAnswer() × 10^quoteFeed.decimals
─────────────────────────────────────────────
quoteFeed.latestAnswer() × 10^baseFeed.decimals

Performance

• scaleFactor computed once during configureFeed()
• Runtime cost remains minimal:

1–2 latestRoundData() calls

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Reference Design

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Feed Configurations

Asset	baseFeed	quoteFeed	Result
WETH	ETH/USD	—	ETH/USD (current behaviour)
WETH	ETH/USD	USDC/USD	ETH/USDC
WBTC	BTC/USD	USDC/USD	BTC/USDC

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Backward Compatibility

Existing integrations remain unchanged.

If:

quoteFeed = address(0)

Then the adapter behaves exactly as today:

price = baseFeed.latestAnswer()

This ensures:

• No breaking changes
• Existing deployments remain compatible
• IChainlinkPriceAdapter interface unchanged

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Acceptance Criteria

Adapter Changes

• configureFeed accepts optional quoteFeed
• scaleFactor computed and stored at configuration time
• Runtime pricing supports 1 or 2 feeds

Behaviour

• If quoteFeed == address(0) → existing behaviour
• If quoteFeed == USDC/USD → return asset/USDC price

Validation

validatePriceAdapter should ensure:

• latestAnswer != 0 for all configured feeds
• Feed decimals are valid

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