feat(scanner): Chainlink PriceCache with staleness check#35
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Per-chain, per-asset Chainlink feed reader that backs the scanner and (soon) the profit calculator with USD prices that are either fresh or explicitly rejected — no silent reliance on stale rounds. - `IAggregatorV3` sol! binding covering `decimals()` and `latestRoundData()` - `CachedPrice` struct (price, decimals, updatedAt, fetchedAt) - `PriceCache` — provider + `(symbol → feed address)` + DashMap cache, `refresh / refresh_all / get / is_fresh` surface - 10-minute default `max_age`; negative `answer` rejected as degraded - New `[chainlink.<chain>]` config section with the five BSC feeds used by Venus (BNB, BTCB, ETH, USDT, USDC) - CLI `listen` performs one startup refresh and logs each feed's price + decimals; cache is ready for downstream consumers - Unit tests on freshness predicate + feed iterator - Live integration tests (`tests/chainlink_refresh.rs`) hit BSC mainnet: one happy-path refresh, one forced-stale rejection
This was referenced Apr 22, 2026
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… fail-loud clock, BTCB fix
- Reject answeredInRound < roundId in refresh(): a partially-aggregated
round carries the previous answer behind a fresh updatedAt, silently
serving stale prices to the liquidation path.
- Reject updatedAt == 0 explicitly — distinguishes an uninitialized
aggregator from a merely-stale one in the log message.
- unix_now() returns Result; refresh() and is_fresh() propagate the clock
error instead of coercing to 0. Previously a clock skew made every
cached entry look fresh-forever ('some_updated_at + max_age >= 0' is
always true), bypassing the staleness gate entirely.
- with_per_symbol_max_age constructor accepts a HashMap<String, Duration>
so stablecoin feeds with day-long heartbeats and sub-second deviation
feeds can coexist without needing a single global compromise.
- CachedPrice::scaled_to(target_decimals) normalizes the raw feed answer
into the consumer's decimal space using integer arithmetic (no f64).
Venus oracle (36 - underlying) and Aave 1e18 consumers now get a
correctly-sized USD value instead of being off by 10^10.
- Fix BTCB/USD feed address in config/default.toml:
0x264990fbd0A4796A3E3d8E37C4d5F87a3aCa5Ebf (malformed, 41 hex chars) ->
0x264990fbd0A4796A3E3d8E37022BdAf1A5a4C1f0 (canonical docs.chain.link).
Tag each feed with the human-readable pair so future audits are one
grep away.
Closes #108 #109 #110 #111 #112
…cecache # Conflicts: # config/default.toml # crates/charon-cli/src/main.rs # crates/charon-scanner/Cargo.toml # crates/charon-scanner/src/lib.rs
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…loses #109) (#337) The address shipped in #109's "fix" — 0x264990fbd0…1f0 — has no bytecode on BSC mainnet. `cast code` returns 0x against both dRPC and bsc-dataseed.binance.org, so every `decimals()` / `latestRoundData()` call against it abi-decodes garbage and BTCB-collateral positions have been silently unpriceable since #35 landed. Discovered the live address by walking the on-chain Venus oracle path: ResilientOracle (0x6592b5DE…) → ChainlinkOracle facet (0x1B210344…) → tokenConfigs(BTCB) → 0x8ECF7dE377F788A813F5215668E282556b35f300 Verified live against bsc.drpc.org: cast code → 19,145 bytes of bytecode decimals() → 18 (Venus uses 18-decimal Chainlink wrappers, not the standard 8-decimal feeds) description() → "BTC / USD" latestRoundData → answer ≈ 78,090e18 (= $78,090), fresh round Confirmed Chainlink-ops-owned: feed `owner()` is 0xcb6754D5…, the same multisig that owns the BNB/USD canonical feed. PriceCache (`crates/charon-scanner/src/oracle.rs:33,59`) reads `decimals()` per feed at startup and `CachedPrice::scaled_to` rescales to a target — the 8→18 decimal difference is invisible to consumers, no Rust changes required. Same swap applied to `config/fork.toml` since the fork profile pins mainnet block forks and would have hit the same garbage decode. Comment block above [chainlink.bnb] in default.toml records the Venus-oracle discovery path so future reviewers don't have to walk it again. Adjacent finding (separate issue recommended): the other four [chainlink.bnb] entries (BNB, ETH, USDT, USDC) were sourced the same way from docs.chain.link. Given one of five was bytecodeless, the remaining four warrant the same cast-code/decimals/description sanity check.
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Closes #11
Per-chain, per-asset Chainlink feed reader that backs the scanner and (soon) the profit calculator with USD prices that are either fresh or explicitly rejected — no silent reliance on stale rounds.
IAggregatorV3sol!binding coveringdecimals()andlatestRoundData()CachedPricestruct (price, decimals, updatedAt, fetchedAt)PriceCache— provider +(symbol → feed address)+ DashMap cache;refresh / refresh_all / get / is_freshmax_age; negativeanswerrejected as degraded[chainlink.<chain>]config section with five BSC feeds (BNB, BTCB, ETH, USDT, USDC)listenperforms one startup refresh and logs each feed's price + decimalsDepends on #10 (
feat/09-health-scanner).