feat: add feature flag to blacklist custom networks (used to hide Monad before launch)

[khanti42]

Description

This PR introduces support for remotely blacklisting networks from the “Add Popular Network” list in the Custom Networks settings view.

The feature is being added specifically to temporarily hide Monad ahead of its November 19 launch, preventing users from adding or interacting with the network before it is officially live.

The new additionalNetworksBlacklist feature flag can be controlled remotely or via the MM_ADDITIONAL_NETWORK_BLACKLIST environment variable, enabling flexible rollout management for upcoming network launches.

Changelog

CHANGELOG entry: added feature flag support to temporarily hide Monad (and other networks) from the “Add Popular Network” list.

Related issues

Fixes:

Manual testing steps

Feature: Hide blacklisted networks from Custom Networks list

  Scenario: user opens the Add Popular Network view when a network is blacklisted
    Given the app has a remote feature flag "additionalNetworksBlacklist" containing the Monad chain ID
      And the user opens the List of Network pop-up
    When the Custom Network list is displayed
    Then the blacklisted network "Monad" should not be visible in the list
      And other non-blacklisted networks (e.g., Base, Polygon) should still be visible

  Scenario: user opens the Add Popular Network view when no network is blacklisted
    Given the app has an empty "additionalNetworksBlacklist" feature flag
      And the user open the List of Network pop-up
    When the Custom Network list is displayed
    Then all popular networks including "Monad" should be visible

Screenshots/Recordings

Before

After

Pre-merge author checklist

• I’ve followed MetaMask Contributor Docs and MetaMask Mobile Coding Standards.
• 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 format if applicable
• I’ve applied the right labels on the PR (see labeling guidelines). 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.

---

Note

Adds a feature flag (and ENV override) to hide specified chain IDs from the “Add Popular Network” list, with filtering utility and tests.

• Settings UI:
  • CustomNetwork.tsx: Filters PopularList via getFilteredPopularNetworks using selectAdditionalNetworksBlacklistFeatureFlag to hide blacklisted chain IDs.
• Selectors:
  • selectors/featureFlagController/networkBlacklist: New selectAdditionalNetworksBlacklistFeatureFlag with MM_ADDITIONAL_NETWORK_BLACKLIST ENV override parsing.
• Utils:
  • util/networks/customNetworks.tsx: Add getFilteredPopularNetworks(blacklistedChainIds, baseNetworkList?) to exclude blacklisted networks.
• Tests:
  • Component test updates to verify hidden/visible networks based on blacklist.
  • Selector tests for remote flag and ENV parsing edge cases.
  • Utils tests for filtering behavior.
• E2E Mocks:
  • e2e/api-mocking/helpers/remoteFeatureFlagsHelper.ts: Include additionalNetworksBlacklist default in mocked flags.

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[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[vivek-consensys]

Tested with feature flag set as true and false via LD

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
1 Security Hotspot
83.8% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud