E2E Test Selection:
The change adds TransactionControllerIsAtomicBatchSupportedAction to the TransactionPayControllerInitMessenger, enabling the TransactionPayController to call TransactionController:isAtomicBatchSupported during its initialization flows.

Nature of change: Additive messenger configuration change (adding a new allowed action). Per the architecture skill, adding actions is "usually safe, extends functionality" - Medium risk.

Impact areas:

1. SmokePredictions: The TransactionPayController is directly used for Polymarket/Predictions flows (polymarket-callbacks.ts uses the initMessenger). The new isAtomicBatchSupported action may be used in deposit wallet batch flows, which are core to Predictions functionality.

2. SmokeConfirmations: isAtomicBatchSupported is an EIP-7702 atomic batch transaction feature. SmokeConfirmations explicitly covers "advanced EIP-7702 account abstraction features like batch transactions and gas fee token payments." The TransactionPayController is involved in transaction payment flows that go through confirmations.

3. SmokeWalletPlatform: Required per SmokePredictions tag description - "When selecting SmokePredictions, also select SmokeWalletPlatform (Trending section)."

Why not broader coverage: This is a targeted additive change to a specific controller's messenger configuration. It doesn't affect Phase 2 controllers (Network, Keyring), doesn't change initialization order, and doesn't remove any existing actions. The blast radius is limited to TransactionPayController's functionality domain.

Performance Test Selection:
This change is a messenger configuration update (adding a new allowed action to TransactionPayControllerInitMessenger). It does not affect UI rendering, data loading, list components, or critical user flow performance. No performance tests are warranted.