approve(spender, amount)

Set an allowance on ctAssets (vault shares). This is not required for a normal deposit. Use it when another contract or account needs permission to move your shares via transferFrom.

Signature

await vault.approve(spender: string, amount: bigint): Promise<Tx>

Parameters

• spender: the address allowed to move the shares.
• amount: allowance in share base units (bigint).

Returns

• Tx: an Ethers v6 TransactionResponse-like object. Use await tx.wait() for confirmation.

Example

const spender = "0xSpender...";
const allowance = await vault.toBigInt("100.0"); // 100 shares
const tx = await vault.approve(spender, allowance);
await tx.wait();

Approve: underlying versus shares

There are two separate approvals you may encounter when working with Concrete Vaults.

Type	When to use	Method	Units	Required?
Underlying approval	Before calling deposit. The vault must be allowed to pull the underlying ERC20 (for example USDC, WETH).	(await vault.getUnderlyingErc20()).approve(vault.getAddress(), amount)	Underlying decimals	Always required for deposits
Share approval	When another contract or account needs to move your vault shares (ctAssets) with transferFrom.	vault.approve(spender, amount)	Share decimals	Only for external share movement (not required for deposits)

Examples

// Approve underlying (required before deposit)
const erc20 = await vault.getUnderlyingErc20();
const amount = await vault.toUnderlyingBigInt("1.0");
await (await erc20.approve(vault.getAddress(), amount)).wait();

// Approve shares (optional, for transferFrom)
const shareAllowance = await vault.toBigInt("50.0");
await (await vault.approve(spender, shareAllowance)).wait();