dragonked2 / defi-accounting

DEFI ACCOUNTING

Core test: paired-state walk

For every pair that must stay in sync (totalAssets/totalSupply,
debt/collateral, reserves/LP, balances/accounting):

1. List all writers of A and all writers of B.
2. For each path writing A: does it write B? In which order?

3. Flag early returns, fast paths, callbacks, and donation-receivable
   functions (anything accepting raw transfer without deposit).

Bug shapes

• Share inflation (empty/near-empty vault): deposit 1 wei, donate to
  inflate totalAssets, victim deposit rounds to 0 shares. Check
  _decimalsOffset() / virtual shares; absence on an ERC4626 is a red flag.

• Donation via direct transfer: totalAssets() reading
  token.balanceOf(vault) diverges from internally tracked balances.

• Rounding direction: mint rounds down, withdraw rounds up — verify
  each preview*/convertTo* pair; test first/last wei amounts.

• Decimal mismatch: underlying (6) vs shares (18) vs oracle (8);
  trace every scale factor at mint, conversion, and liquidation.

• Stale/desynced views: interest accrual, rewards, or strategy profit
  updated on some paths only; read-only re-entry returning stale data.

• Missing debit/credit: deposit path credits but withdraw path skips
  the debit on one leg (compare sibling functions line by line).

• Fee/reserve errors: fees taken from the wrong base, reserves
  double-counted as both backing and profit.

Grep anchors

grep -rn "totalAssets\|totalSupply\|totalDebt\|convertTo\|previewDeposit\|previewMint\|_decimalsOffset" contracts/
grep -rn "balanceOf(address(this))" contracts/

Rule

Never report an accounting anomaly without showing the
attacker-controlled economic effect: which invariant breaks, the
before→after state transition, and the asset movement. A rounding error
worth 1 wei with no amplification path is informational at best.