pyth-price-feeds

Pyth Price Feeds (Hedera)

Pull pattern: Pyth is not a fire-and-forget push feed. Fresh reads usually need a Hermes payload submitted on-chain (payable) before getPriceNoOlderThan.

Hermes → updatePriceFeeds{value: fee}(updateData) → getPriceNoOlderThan(priceId, maxAge)

Consumers may wrap Pyth behind a local interface; that is optional. Do not assume a project-specific adapter name.

Quick Reference

Piece	Role
Pyth contract	Network IPyth address
Price ID	bytes32 feed id (not an aggregator address)
Update	Payable updatePriceFeeds with Hermes updateData
Fee	getUpdateFee(updateData) — msg.value must cover it
Read	getPriceNoOlderThan(priceId, maxAge)
Confidence	Reject when conf > uint64(price)
Scale	Signed price + expo → consumer decimals (often 18)

Hedera chain IDs: testnet 296, mainnet 295.

See references/hedera-feeds.md for where to source the Pyth contract and price IDs. See references/examples.md for update / read / expo sketches.

Critical: Update Before Fresh Reads

If the on-chain price is older than your staleness bound, fetch Hermes update data and submit it:

function updatePrice(bytes[] calldata updateData) external payable {
    uint256 fee = PYTH.getUpdateFee(updateData);
    if (msg.value < fee) revert UpdateFeeTooLow(msg.value, fee);
    PYTH.updatePriceFeeds{ value: msg.value }(updateData);
}

Hedera msg.value is tinybars via JSON-RPC — attach enough native value for the Pyth fee. Do not treat a stale getPriceUnsafe as a valid trading price.

Critical: Confidence And Signed Expo

After getPriceNoOlderThan:

Check	Why
publishTime != 0	Incomplete
price > 0	Invalid / non-positive
conf > uint64(price)	Confidence wider than the price
Normalize expo	expo is signed; not the same as ERC-20 decimals

PythStructs.Price memory price = PYTH.getPriceNoOlderThan(priceId, maxStaleness);
if (price.publishTime == 0) revert IncompleteRound();
if (price.price <= 0) revert InvalidPrice();
if (price.conf > uint64(price.price)) revert InvalidConfidence();

Checklist

When implementing or reviewing Pyth on Hedera:

• Pyth contract + price IDs taken from Pyth Hedera / Hermes docs (not Ethereum defaults)
• Hermes payloads submitted with sufficient msg.value before relying on a fresh price
• Reads use getPriceNoOlderThan (or equivalent max-age API), not unbounded unsafe prices for trading
• Confidence wider than price reverts
• Signed expo normalized to the consumer scale
• Chain ID is 295 or 296 (or the project’s documented Hedera network)

References

• references/examples.md — update, read, and expo sketches
• references/hedera-feeds.md — where to source Pyth contract and price IDs
• Pyth Price Feeds
• Pyth EVM contract addresses
• Hermes price feeds