<!--
Please submit this PR as a draft initially.
Do not mark it as "Ready for review" until the template has been
completely filled out, and PR status checks have passed at least once.
-->

## **Description**

- Adds MegaETH as selectable network for Bridge/Swap.
- Adds Bridge/Swap feature for MegaETH (behind feature flags).
- Bumps `bridge-controller` released in
MetaMask/core#7837.

<!--
Write a short description of the changes included in this pull request,
also include relevant motivation and context. Have in mind the following
questions:
1. What is the reason for the change?
2. What is the improvement/solution?
-->

[![Open in GitHub
Codespaces](https://github.com/codespaces/badge.svg)](https://codespaces.new/MetaMask/metamask-extension/pull/39927?quickstart=1)

## **Changelog**

<!--
If this PR is not End-User-Facing and should not show up in the
CHANGELOG, you can choose to either:
1. Write `CHANGELOG entry: null`
2. Label with `no-changelog`

If this PR is End-User-Facing, please write a short User-Facing
description in the past tense like:
`CHANGELOG entry: Added a new tab for users to see their NFTs`
`CHANGELOG entry: Fixed a bug that was causing some NFTs to flicker`

(This helps the Release Engineer do their job more quickly and
accurately)
-->

CHANGELOG entry: Adds Bridge and Swap feature to MegaETH

## **Related issues**

Fixes:

## **Manual testing steps**

1. Open MetaMask extension
2. Click on `Swap` button
3. Click to select a token as a source
4. Click on `All networks`
5. Select `MegaETH` network
6. Select one of the proposed tokens
7. Enter an amount to swap
8. The proposed quote for the swap should appear

## **Screenshots/Recordings**

<!-- If applicable, add screenshots and/or recordings to visualize the
before and after of your change. -->

### **Before**

<!-- [screenshots/recordings] -->

### **After**
<img width="1685" height="1367" alt="Screenshot from 2026-02-09
23-06-09"
src="https://github.com/user-attachments/assets/abd823c2-6996-4e8b-b8b3-0cfbb0d836ff"
/>
<img width="1680" height="1363" alt="Screenshot from 2026-02-10
11-19-30"
src="https://github.com/user-attachments/assets/b6d75c3b-e93d-4b05-8a12-7ad1d53dc62c"
/>
<img width="1680" height="1363" alt="Screenshot from 2026-02-10
11-18-51"
src="https://github.com/user-attachments/assets/aabfacaf-3d36-4209-8cfb-5efab0a6ef2f"
/>

<!-- [screenshots/recordings] -->

## **Pre-merge author checklist**

- [ ] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask
Extension Coding
Standards](https://github.com/MetaMask/metamask-extension/blob/main/.github/guidelines/CODING_GUIDELINES.md).
- [ ] I've completed the PR template to the best of my ability
- [ ] I’ve included tests if applicable
- [ ] I’ve documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [ ] I’ve applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-extension/blob/main/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

## **Pre-merge reviewer checklist**

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [ ] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Medium Risk**
> Expands Bridge/Swap functionality to a new chain and introduces new
contract/token address constants, which could impact routing/quoting if
misconfigured; changes are largely additive and covered by a selector
test update.
> 
> **Overview**
> Adds **MegaETH** as a supported network for Bridge and Swaps by wiring
`CHAIN_IDS.MEGAETH_MAINNET` into the allowed chain lists and
display-name maps, and defining MegaETH-specific default
token/contract/wrapped-token addresses plus a USDT0 common pair.
> 
> Updates slippage/stablecoin detection to recognize MegaETH’s USDT0
asset, adjusts bridge selector tests to include the extra destination
chain, and bumps `@metamask/bridge-controller` to `^65.3.0` (with
lockfile updates).
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
dfb4099. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

---------

Signed-off-by: gabrieledm <gabriele.delmonte@proton.me>

<!--
Please submit this PR as a draft initially.
Do not mark it as "Ready for review" until the template has been
completely filled out, and PR status checks have passed at least once.
-->

## **Description**

- Adds MegaETH as selectable network for Bridge/Swap.
- Adds Bridge/Swap feature for MegaETH (behind feature flags).
- Bumps `bridge-controller` released in
MetaMask/core#7837.

<!--
Write a short description of the changes included in this pull request,
also include relevant motivation and context. Have in mind the following
questions:
1. What is the reason for the change?
2. What is the improvement/solution?
-->

[![Open in GitHub
Codespaces](https://github.com/codespaces/badge.svg)](https://codespaces.new/MetaMask/metamask-extension/pull/39927?quickstart=1)

## **Changelog**

<!--
If this PR is not End-User-Facing and should not show up in the
CHANGELOG, you can choose to either:
1. Write `CHANGELOG entry: null`
2. Label with `no-changelog`

If this PR is End-User-Facing, please write a short User-Facing
description in the past tense like:
`CHANGELOG entry: Added a new tab for users to see their NFTs`
`CHANGELOG entry: Fixed a bug that was causing some NFTs to flicker`

(This helps the Release Engineer do their job more quickly and
accurately)
-->

CHANGELOG entry: Adds Bridge and Swap feature to MegaETH

## **Related issues**

Fixes:

## **Manual testing steps**

1. Open MetaMask extension
2. Click on `Swap` button
3. Click to select a token as a source
4. Click on `All networks`
5. Select `MegaETH` network
6. Select one of the proposed tokens
7. Enter an amount to swap
8. The proposed quote for the swap should appear

## **Screenshots/Recordings**

<!-- If applicable, add screenshots and/or recordings to visualize the
before and after of your change. -->

### **Before**

<!-- [screenshots/recordings] -->

### **After**
<img width="1685" height="1367" alt="Screenshot from 2026-02-09
23-06-09"
src="https://github.com/user-attachments/assets/abd823c2-6996-4e8b-b8b3-0cfbb0d836ff"
/>
<img width="1680" height="1363" alt="Screenshot from 2026-02-10
11-19-30"
src="https://github.com/user-attachments/assets/b6d75c3b-e93d-4b05-8a12-7ad1d53dc62c"
/>
<img width="1680" height="1363" alt="Screenshot from 2026-02-10
11-18-51"
src="https://github.com/user-attachments/assets/aabfacaf-3d36-4209-8cfb-5efab0a6ef2f"
/>

<!-- [screenshots/recordings] -->

## **Pre-merge author checklist**

- [ ] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask
Extension Coding
Standards](https://github.com/MetaMask/metamask-extension/blob/main/.github/guidelines/CODING_GUIDELINES.md).
- [ ] I've completed the PR template to the best of my ability
- [ ] I’ve included tests if applicable
- [ ] I’ve documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [ ] I’ve applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-extension/blob/main/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

## **Pre-merge reviewer checklist**

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [ ] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Medium Risk**
> Expands Bridge/Swap functionality to a new chain and introduces new
contract/token address constants, which could impact routing/quoting if
misconfigured; changes are largely additive and covered by a selector
test update.
> 
> **Overview**
> Adds **MegaETH** as a supported network for Bridge and Swaps by wiring
`CHAIN_IDS.MEGAETH_MAINNET` into the allowed chain lists and
display-name maps, and defining MegaETH-specific default
token/contract/wrapped-token addresses plus a USDT0 common pair.
> 
> Updates slippage/stablecoin detection to recognize MegaETH’s USDT0
asset, adjusts bridge selector tests to include the extra destination
chain, and bumps `@metamask/bridge-controller` to `^65.3.0` (with
lockfile updates).
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
dfb4099. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

---------

Signed-off-by: gabrieledm <gabriele.delmonte@proton.me>