feat: harden oracle quorum, freshness, and canonical price persistence (#1376)

[s6pa1rta3n-lab]

Overview

Hardens oracle quorum, freshness validation, price sign verification, and canonical price persistence prior to market settlement in predictify-hybrid.

Key Changes

• Feed Freshness & Sign Validation:
  • In contracts/predictify-hybrid/src/oracles.rs, updated validate_oracle_data to reject future publish times (publish_time > now), enforce staleness bounds against max_staleness_secs, and reject non-positive prices (price <= 0) with Error::InvalidInput.
  • In contracts/predictify-hybrid/src/resolution.rs, updated fetch_oracle_result and fetch_quote_fail_closed to validate positive prices and prevent future-dated publish timestamps.
• Deterministic Quorum Boundaries:
  • In contracts/predictify-hybrid/src/resolution.rs, updated set_median_config to enforce configuration boundaries (min_sources >= 1, max_deviation_bps <= 10_000) returning Error::InvalidOracleConfig.
  • In resolve_with_median, collect_included_sorted, weighted_median, average_included_price, and price_variance, excluded non-positive quotes (price <= 0) from quorum calculation and required included_count >= med_cfg.min_sources and positive aggregate median.
• Atomic Canonical Price Persistence & Settlement Gate:
  • Added CanonicalPriceRecord struct in contracts/predictify-hybrid/src/types.rs (price: i128, timestamp: u64, outcome: String).
  • Added store_canonical_price, get_canonical_price_record, get_canonical_price, and validate_canonical_price_before_settlement in OracleResolutionManager.
  • Enforced validate_canonical_price_before_settlement prior to automated market settlement in execute_automated_resolution.
  • Emitted emit_canonical_price_updated via EventEmitter with compatible topic registration in event_topic_compat.rs.
• Comprehensive Regression & Outage Test Suite:
  • Added contracts/predictify-hybrid/src/oracle_hardening_tests.rs with 13 focused test cases validating stale feeds, future timestamps, non-positive price feeds, exact and insufficient quorum, outlier filtering breaking quorum, canonical price atomic persistence, fail-closed outage paths on missing/non-positive canonical price, and outage recovery.

Acceptance Criteria

• Stale or invalid feeds cannot settle (validate_oracle_data checks staleness and rejects price <= 0 and future timestamps; verified in test_stale_feed_cannot_settle, test_future_timestamp_rejected, test_non_positive_price_feed_rejected).
• Quorum boundaries are deterministic (set_median_config enforces min_sources >= 1 and max_deviation_bps <= 10_000; resolve_with_median enforces strict minimum included source counts; non-positive quotes excluded; verified in test_quorum_boundaries_insufficient_sources, test_quorum_boundaries_exact_quorum, test_outlier_filtering_breaks_quorum, test_non_positive_quotes_excluded_from_quorum, test_set_median_config_boundaries).
• Canonical price updates are atomic (store_canonical_price persists CanonicalPriceRecord atomically alongside oracle verification and emits audit events; verified in test_canonical_price_atomic_persistence).
• Outage and recovery tests cover all failure paths (pre-settlement gate validate_canonical_price_before_settlement ensures markets fail closed if canonical price is missing or invalid, and resume settlement once fresh data is published; verified in test_outage_missing_canonical_price_fails_closed, test_outage_non_positive_canonical_price_fails_closed, test_outage_recovery_path).

Security Considerations

• Settlement requires positive, fresh feeds with verified signatures.
• Outages or compromised feeds failing quorum fail closed rather than settling on corrupted or stale prices.
• Canonical price state transitions are persistent and verified prior to balance and state mutations.

Closes #1376

Payout Routing

• EVM (Base/Arbitrum/Polygon/ETH): 0xF46C9F6d70C50BF81ef3588AB523a90a594a2F89
• Stellar: GCL6OXAMLD75BMTINA6EMRUDWK5THQUSHMYNLSNBCJAPZJHNYJTUNIBC