Delegate the session key

Session keys are how you avoid wallet popups on every trade. Generate an ephemeral keypair, give it on-chain authority to sign for your sub-account for some bounded time window, and then let it sign all the EIP-712 trade messages off-chain. The InstantLayer verifies these delegations on every executeBatch / executeTemplate call: when your session key's signature recovers, the InstantLayer checks that the calldata's selector is in the active delegated set for (sub, sessionKey).

Signed by. Owner EOA. The call goes to the InstantLayer.

Function. grantDelegation(DelegationInfo info), where DelegationInfo is:

struct DelegationInfo {
    Account  account;            // (subAccount, isPartyB=false)
    address  delegatedSigner;    // the session key's address
    bytes4[] selectors;          // what they're allowed to sign for
    uint256  expiryTimestamp;    // unix seconds
}

The selectors are where this gets subtle. You need five of them:

Selector	Meaning
0xa6d66852	addMarginToNextVA: pre-funding a VA before opening a position
0xa7f3b34b	sendQuoteWithAffiliateAndData: opening a position
0x501e891f	requestToClosePosition: closing a position
0xeaa31b19	ID the COH (TP/SL service) keys delegations under
0x00000001	ID services use to verify session-key auth

The first three are real Symmio function selectors, and the InstantLayer checks them on every executeBatch. The last two are four-byte tags the off-chain services use as lookup keys when they answer "is this session key authorized to talk to me?"

Note. The grantDelegation tx is sent from your owner EOA, but once it lands, the session key (not the EOA) is what signs all subsequent EIP-712 messages on the trade path.