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…loses #418) Several Venus vTokens on BSC are deployed behind upgradeable proxies that return 96 bytes (3 32-byte words) where the ABI declares a single uint256 — the leading word carries the value, the trailing 64 bytes are zero padding (likely a Diamond fallback / proxy quirk). alloy's sol!-generated decoder is strict and rejects the surplus bytes with SolTypes(ReserveMismatch), which surfaced as `borrowBalanceStored failed err=AbiError(SolTypes(ReserMismatch))` on every (vToken × seed-borrower) pair. Result: tracked=N returned=0, the bot scanned every block but never emitted an opportunity, even when the seed borrowers were genuinely liquidatable on mainnet. Add `read_uint256_view` helper that issues the eth_call ourselves, takes the first 32 bytes, and decodes as U256 — matching cast's lenient policy. Use the helper for `borrowBalanceStored`, `balanceOf`, and `exchangeRateStored` in fetch_position. The oracle `getUnderlyingPrice` path stays on the typed call because no padding issue has been observed there. Local validation: replay against block 91323624 with the four documented seed borrowers now reports `tracked=4 returned=4 liquidatable=4` (was `returned=0` on main).
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Summary
Several Venus vTokens on BSC are deployed behind upgradeable proxies that return 96 bytes (3 32-byte words) where the ABI declares a single `uint256` — leading word carries the value, trailing 64 bytes are zero padding (Diamond fallback / proxy quirk). `alloy`'s `sol!`-generated decoder rejects the surplus with `SolTypes(ReserveMismatch)`, surfaced as `borrowBalanceStored failed err=AbiError(SolTypes(ReserMismatch))` on every (vToken × seed-borrower) pair. Result on main: `tracked=N returned=0`, no opportunity ever emitted.
Fix
Add `read_uint256_view` helper that issues the `eth_call` ourselves, takes the first 32 bytes, decodes as `U256` — matching `cast call ... '(uint256)'`'s lenient policy. Use it for `borrowBalanceStored`, `balanceOf`, `exchangeRateStored` in `fetch_position`. Oracle `getUnderlyingPrice` stays on the typed call (no padding observed there).
Test plan