skill-11-oracle-data-feeds

name	skill-11-oracle-data-feeds
description	Integrates oracle and data feed services including Chainlink and Pyth price feeds, VRF randomness, and Chainlink Automation keepers. Use when consuming on-chain price data, random numbers, or conditional automation.
metadata	{"phase":4,"chains":"ethereum,polygon,arbitrum,base,optimism,avalanche,bnb"}

Oracle & Data Feeds

When to Use

• Reading price feeds for DeFi calculations
• Requesting verifiable random numbers (VRF)
• Setting up Chainlink Automation (keepers)
• Validating oracle freshness and deviation thresholds
• Comparing multi-oracle prices for manipulation detection

Prerequisites

• MCP: price-feed-server, blockchain-rpc-server
• Skill-08 for oracle manipulation risk assessment

Workflow

1. Chainlink Price Feeds

AggregatorV3Interface feed = AggregatorV3Interface(aggregatorAddress);
(, int256 price, , uint256 updatedAt, ) = feed.latestRoundData();

Validation checks:

• updatedAt within heartbeat (varies: 1h ETH/USD, 24h long-tail)
• price > 0
• Compare with Pyth/CoinGecko — flag if deviation > 2%

Feed addresses: see knowledge-base/protocols/ and Chainlink docs per chain.

2. Pyth Network

• Pull model: update price feeds in same tx via getUpdateData()
• Hermes API for off-chain price reads
• Lower latency than push oracles for L2s

3. Chainlink VRF v2.5

1. Subscribe or direct funding
2. Request randomness: requestRandomWords(keyHash, subId, minConfirmations, callbackGasLimit, numWords)
3. Fulfill in callback: fulfillRandomWords(requestId, randomWords)
4. Never use block variables (blockhash, timestamp) for randomness

4. Chainlink Automation

Type	Use Case
Time-based	Periodic harvest, rebalance
Custom logic	checkUpkeep() returns upkeepNeeded
Log trigger	React to specific events

Register upkeep with LINK funding; monitor balance.

5. Oracle Security

• Use multiple sources for critical decisions (liquidations, minting)
• Implement staleness checks and circuit breakers
• TWAP for AMM-derived prices (minimum 30-minute window)
• Never use spot DEX price as sole oracle for high-value ops

References

• references/chainlink-feeds.md
• references/pyth-integration.md
• price-feed-server MCP tools