chore(runway): cherry-pick fix: start Ramps V2 init when remote feature flags hydrate cp-7.71.0

[runway-github]

• fix: start Ramps V2 init when remote feature flags hydrate cp-7.71.0 (fix: start Ramps V2 init when remote feature flags hydrate cp-7.71.0 #27778)

Description

On a fresh install, RemoteFeatureFlagController loads flags
asynchronously while Engine builds controllers. rampsControllerInit
previously read the unified buy V2 flag only once; if flags were not in
state yet, RampsController.init() never ran, so buy token lists stayed
empty until a full app restart.

This change subscribes to RemoteFeatureFlagController:stateChange
(already delegated on RampsControllerInitMessenger) and re-runs the
same V2 startup path when remote flag state updates. Order-status
subscriptions are registered at most once. RampsController.init()
remains idempotent for repeated calls.

Changelog

CHANGELOG entry: null

Related issues

Fixes: https://consensyssoftware.atlassian.net/browse/TRAM-3350

Manual testing steps

Feature: Unified buy V2 after fresh install

  Scenario: Buy token list loads without restarting the app
    Given a dev build with unified buy V2 enabled via remote flags
    And the app is installed fresh (or remote flag cache cleared)

    When the user completes onboarding and opens Buy / token selection
    Then tokens and providers load without requiring an app restart

Screenshots/Recordings

Fix Ramps controller not initializing on fresh install - Watch Video

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

Medium Risk
Adds a new subscription-driven initialization path triggered by
RemoteFeatureFlagController:stateChange, which can change startup
behavior and potentially cause repeated init/polling if underlying
idempotency assumptions are wrong.

Overview
Ensures Unified Buy V2 startup runs even when remote feature flags
hydrate after Engine/controller initialization by subscribing to
RemoteFeatureFlagController:stateChange and re-checking the V2 flag.

Refactors V2 startup into a helper that conditionally calls
RampsController.init()/startOrderPolling() and registers
order-status subscriptions only once. Updates tests to cover the “flag
off at startup then enabled on stateChange” scenario and to include
subscribe in the thrown-state mock.

^{Written by Cursor
Bugbot for commit
78ff800. This will update automatically
on new commits. Configure
here.}

[c6d96b6](https://github.com/MetaMask/metamask-mobile/commit/c6d96b6ff1e0efa6ad7172666f29e817a3e3ce9e)

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✅ E2E Fixture Validation — Schema is up to date
17 value mismatches detected (expected — fixture represents an existing user).
View details

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
87.5% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[chloeYue]

LGTM