GP 20: Migrate BOB pool to USDC on Optimism

The proposal was confirmed and executed.

• Optimism Safe Transactions #16 and #17

• Optimism txs:

  • 16: https://optimism.blockscout.com/tx/0xf8734380296530c69571251fce0f61451a165e166f4205e967801e7fa86de4f0

  • 17: https://optimism.blockscout.com/tx/0xc87ce1f36ecff741d76f921f09fed979f9ab0520acc6d30afe2a5964920ec77b

Proposal objective

Following the successful transition from BOB to USDC on Polygon, this proposal replaces the underlying token from BOB to USDC for the zkBob pool on Optimism.

The migration replaces the zkBob pool implementation to the new contract 0x8f4127D3131789a9e2f7380AF903F643d0ae721C and the Direct Deposit Queue implementation to 0x9bf586ceB3F3C1bebBE8b0262c2AE7D0952ce3B1. To allow further swaps of USDC to ETH as part of withdrawals, the Token Seller contract is replaced by 0x48CE9dAb591d737F2fa8955c6283CbcA84A86544.

During proposal execution all BOB owned by the zkBob pool contract is swapped to USDC using UniswapV3. The amount of BOB tokens paid as fees on Uniswap will be reimbursed with the corresponding amount of USDC from the Governance Safe account. The logic of the tokens swap is defined in the migrationToUSDC() pool method.

Proposal breakdown

To avoid undesirable interactions with the zkBob pool prior to the migration the proposal consists of two steps:

Step 1: Disable direct deposits

Transaction #16 in the Safe on Optimism contains two setLimits calls to disallow users to transfer tokens directly to the pool by setting limits for tier 0 and 1 to zero for direct deposits. New interim limits are:

Tier	Single deposit	Daily user deposit	Daily deposit	Daily withdrawal	Pool size	Single DD	Daily user DD
Default, id 0	10,000 BOB	10,000 BOB	300,000 BOB	300,000 BOB	10,000,000 BOB	0 BOB	0 BOB
Partners, id 1	100,000 BOB	100,000 BOB	300,000 BOB	300,000 BOB	10,000,000 BOB	0 BOB	0 BOB

This step is executed 20 minutes prior to step 2.

Step 2: Migrate the pool from BOB to USDC

Transaction #17 in the Safe executes the following calls:

• Increase allowance of the pool contract 0x1CA8C2B9B20E18e86d5b9a72370fC6c91814c97C to transfer USDC from Governance Safe by approve made to the USDC token contract 0x0b2C639c533813f4Aa9D7837CAf62653d097Ff85.
• Upgrade the pool implementation with the upgradeToAndCall method. The method migrationToUSDC() (selector c4a688b8) is invoked after the upgrade.

• Remove allowance of the pool contract to transfer USDC from the Governance Safe by approve made to the USDC token contract 0x0b2C639c533813f4Aa9D7837CAf62653d097Ff85.
• Upgrade the implementation of the direct deposit queue 0x15B8C75c024acba8c114C21F42eb515A762c0014 by upgradeTo .
• Configure new Token Seller contract on the pool by setTokenSeller.

• The remaining two calls invoke setLimits for tier 0 and 1 users. The reinstated limits are:

Tier	Single deposit	Daily user deposit	Daily deposit	Daily withdrawal	Pool size	Single DD	Daily user DD
Default, id 0	10,000 USDC	10,000 USDC	300,000 USDC	300,000 USDC	10,000,000 USDC	1,000 USDC	10,000 USDC
Partners, id 1	100,000 USDC	100,000 USDC	300,000 USDC	300,000 USDC	10,000,000 USDC	1,000 USDC	10,000 USDC

Additional verification

The migration procedure has been verified by using the following Foundry-script.

To check the safe contract execution run the following script: https://gist.github.com/akolotov/9e70b43a75426c8276c061d9176b0968

1. forge test --match-path ./script/scripts/VerifySafeTx_Gov44.t.sol --ffi -vvvv

2. Make sure jq CLI is installed