MetaMask does not support Optimism’s Operator Fee mechanism

**What is this about?**

MetaMask currently does not recognize or handle the Operator Fee recently introduced by Optimism. As a result, transactions on OP Stack chains that include this new fee component are not being displayed or processed correctly. Including Katana + BOB.

Docs for reference: [Optimism Operator Fee](https://docs.optimism.io/stack/transactions/fees#operator-fee)

This creates friction for users and dapps who rely on MetaMask for accurate fee display and signing.

**Scenario**

GIVEN a user is interacting with an OP Stack chain that has enabled Operator Fees
WHEN the user attempts to send a transaction
AND MetaMask calculates/display fees
THEN the Operator Fee is missing

**Design**

N/A

**Threat Modeling Framework**

**What are we working on?**
Supporting Operator Fee in MetaMask for OP Stack chains.

**What can go wrong?**
Fees displayed incorrectly, leading to user confusion.

**What are we going to do about it?**
Align MetaMask’s transaction parsing and fee estimation logic with Optimism’s new spec.

**Did we do a good job?**
Transactions should show correct fee representation.

**Stakeholder review needed before the work gets merged**

- [ ] Engineering (needed in most cases)
- [ ] Design
- [ ] Product
- [ ] QA (automation tests are required to pass before merging PRs but not all changes are covered by automation tests - please review if QA is needed beyond automation tests)
- [ ] Security
- [ ] Legal
- [ ] Marketing
- [ ] Management (please specify)
- [ ] Other (please specify)

**References**

https://docs.optimism.io/stack/transactions/fees#operator-fee

Start with the Optimism Operator Fee specification linked in the issue, then trace MetaMask’s transaction parsing and fee-estimation entry points for OP Stack chains. Confirm how Operator Fees apply to transactions on chains such as Katana and BOB. Done means transactions display and process the complete fee representation, with relevant automation tests passing.

Written by the indexing model from the issue text.