Emergency Auto-Withdrawal

When risk is detected, GuardAI returns every user's funds instantly — automatically, on-chain, with no human trigger.

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The Circuit Breaker

VaultSentinel implements a one-way circuit breaker pattern:

ACTIVE ──── score ≥ 70 ────► EMERGENCY
              (automatic)
                │
                ▼
        _returnAllFunds()
        ├── Return ETH to every depositor
        └── Return all ERC20s to every depositor

EMERGENCY ──── resetVault() ────► ACTIVE
                (owner only)

Once triggered, the vault stays in EMERGENCY until the owner explicitly resets it. This prevents re-entrancy and ensures funds aren't re-deposited into a still-dangerous vault.

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What Happens During Emergency

When setRiskScore(score) receives a score ≥ 70:

1. _executeEmergency() is called internally

2. vaultState flips to EMERGENCY — new deposits immediately blocked

3. EmergencyTriggered event emitted on-chain

4. _returnAllFunds() iterates every depositor:

   • Returns ETH via low-level call{value}

   • Returns each whitelisted ERC20 via IERC20.transfer()

5. Individual transfer failures are handled gracefully — one failed transfer does not block others

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Safety Design

Concern	How GuardAI handles it
Re-entrancy	EMERGENCY state set before transfers begin
Failed ETH transfer	Balance reverted for that user only, others unaffected
Failed ERC20 transfer	try/catch — balance reverted for that user only
Idempotency	_executeEmergency() is a no-op if already in EMERGENCY
Deposit during emergency	notEmergency modifier reverts with "Vault is in emergency"

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On-Chain Proof

Every emergency withdrawal emits verifiable events:

event EmergencyTriggered(uint256 riskScore, uint256 timestamp);
event FundsReturnedETH(address indexed user, uint256 amount);
event FundsReturnedERC20(address indexed user, address indexed token, uint256 amount);

All events are queryable on Tenderly explorer — full transparency, no trust required.

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Demo

# 1. Deposit 2 ETH via frontend
# 2. Trigger emergency
SCORE=82 npx hardhat run scripts/simulate-attack.ts --network tenderly
# → Vault enters EMERGENCY, 2 ETH returned to wallet instantly

# 3. Reset vault
npx hardhat run scripts/reset-vault.ts --network tenderly