[cryptoharry]

Provider read failures or read-time expiry can stop pricing even when another usable quote or a valid stored price remains available. This adds reusable components that preserve access to valid quotes and their original timestamps during update outages.

Changes

• DualFeedPriceFeed extends ChainlinkBasePriceFeed, reusing ownership, source configuration, heartbeat management, decimal normalization and strict primary bounds. The base contract only marks latestRoundData and setHeartbeat as virtual; its existing behaviour is unchanged.
• Prefer a fresh valid primary, then a fresh valid fallback, then the newest valid stale quote. Ties prefer the primary. Failed/malformed reads, bounds failures and normalization errors invalidate only the affected source. An absent fallback is supported. If neither source is usable, pricing reverts with NoValidPrice().
• RedstoneStoredPriceFeed reads the provider's existing stored record without a read-time age expiry. Adapter address, feed ID, value decimals, allowed forward timestamp skew and description are constructor settings. Signed updates remain validated by RedStone. The reported timestamp is the earlier of observation and publication.
• Generic documentation and fixtures contain no deployment-specific market wiring. The test provider's expiry is a constructor setting, with coverage across different expiries and source decimals. Switching freshness remains the selector's configurable heartbeat; action-specific freshness remains the consumer's policy.

Validation

• 149 targeted tests passed: 54 feed/integration tests and 95 existing Market, Oracle and BorrowController tests.
• Four cases preserve distinct round IDs, answered-in-round IDs, start times and update times for fresh and stale primary/fallback selection.
• Three differential fuzz tests compare complete quotes against ChainlinkBasePriceFeed across source decimals from 0 to 36, freshness boundaries, and prices below, at and above primary bounds.
• Six feed fuzz tests each ran 256 cases. Existing regressions cover provider/decoding failures, normalization, RedStone configuration, combining feeds, stale borrowing rejection, liquidation settlement and pessimistic-cache recovery.

Formatting and whitespace checks passed. The latest commit changes only a test file; production sources are unchanged. Dedicated CI needs no RPC credentials. The full fork suite requires RPC_MAINNET; a complete deployment/governance fork simulation remains outstanding.

Usage and configuration

Tracking: https://maestro.inverse.finance/boards/2/tasks/419