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# Simulation and clear signing

WalletChan tries to answer two questions before you confirm: “What is this call
trying to do?” and “What is likely to change if it succeeds?”

## Estimated changes

Simulation can show:

* Native token and ERC-20 sends/receives.
* ERC-721 and ERC-1155 NFT changes.
* ERC-20, ERC-2612, and Permit2 approval increases.
* Batch-dependent changes in call order.
* Post-state metadata and prices where safely available.

Simulation is an estimate against current chain state. State can change before
inclusion, and some contracts deliberately make simulation difficult.

## Clear signing

When a trusted ERC-7730 descriptor or WalletChan built-in pattern matches the
deployed contract, the review can show a human-readable action with formatted
token amounts, addresses, names, timestamps, durations, and nested calls.

If no descriptor resolves, WalletChan falls back to decoded calldata, then raw
calldata. Clear Signing is on by default and can be disabled under **Settings →
Security → Clear Signing**; disabling also purges the descriptor cache.

## Approval safety

Unlimited or unverified approvals receive stronger warning treatment.
Standalone ERC-20 `approve` requests show an editable allowance, including zero
for revocation. Residual outgoing-token allowances may produce an **Approval
remains** warning and cleanup option.

## Failed or unavailable simulation

* **Likely to fail** means the simulation observed a revert. WalletChan blocks
  normal confirmation until you explicitly acknowledge the risk.
* **Unavailable** means it could not get a trustworthy simulation result. Read
  the decoded/raw request, origin, recipient, value, and approvals manually.
* **Malformed calldata** is a validation warning, not a cosmetic decode failure.

WalletChan may offer a Tenderly link for a supported non-deployment
transaction.

## Privacy

Remote descriptor and simulation services receive the minimum public
transaction/network context needed for their role. They never receive your
private key, seed phrase, or master password.

## Related guides

* [Read the full transaction review](/transactions/review)
* [Clean up residual token approvals](/transactions/approval-cleanup)
* [Review signatures and typed data](/transactions/signatures)
* [Understand gas estimates and fees](/transactions/gas-and-fees)