feat: add override functionality to remote feature flags

[asalsys]

Remote Feature Flag Controller - Override Support & A/B Test Visibility

Explanation

Current State & Problem

The RemoteFeatureFlagController currently only supports remote feature flags with no ability to locally override them. This creates several pain points for developers and QA teams:

• No local testing capability: Developers cannot test different flag configurations without changing remote settings
• A/B test visibility gap: Once A/B test arrays are processed into single values, the raw options are lost, making it impossible to see what alternatives were available
• Limited debugging: No way to understand current flag assignments vs. available options
• QA testing constraints: Testing teams cannot systematically test different flag scenarios locally

Solution Overview

This PR adds local override functionality with A/B test visibility through direct state access:

Core Features:

• Local Overrides: New localOverrides state field allows manual flag overrides that take precedence over remote flags
• A/B Test Visibility: New rawRemoteFeatureFlags field stores raw A/B test arrays (preserves original flag data before processing)
• Override Management: Complete CRUD operations for managing overrides (setFlagOverride, clearFlagOverride, clearAllOverrides)
• State-Based Access: Flag values and A/B test data accessible through controller state properties

How It Works:

1. Processing Enhancement: The #updateCache method now stores raw flag data in rawRemoteFeatureFlags before processing A/B tests into single values
2. Priority System: Consumers can check state.localOverrides[flagName] ?? state.remoteFeatureFlags[flagName] for override-aware access
3. Raw Storage: Raw flag data is stored for all flags, allowing visibility into original A/B test arrays
4. Persistence: All override data persists across sessions and remote flag updates via the #updateCache method

Implementation Details

• State Management: Three state fields work together:

  • remoteFeatureFlags: Processed flags (A/B tests resolved to single values)
  • localOverrides: Manual overrides that take precedence
  • rawRemoteFeatureFlags: Original flag data before processing (preserves A/B test arrays)

• Override Persistence: Remote flag updates preserve existing local overrides through state preservation in #updateCache

• Messenger Integration: All override methods are exposed as controller actions for external access

• Metadata Configuration: All new state fields are properly configured for logging, persistence, and UI exposure

Access Patterns

Getting Flag Values (with override support):

// Manual override-aware access
const flagValue = controller.state.localOverrides.flagName ?? 
                  controller.state.remoteFeatureFlags.flagName;

Accessing A/B Test Groups:

// View available A/B test options
const abTestGroups = controller.state.rawRemoteFeatureFlags.flagName;

Managing Overrides:

// Set override
controller.setFlagOverride('flagName', 'testValue');

// Clear specific override
controller.clearFlagOverride('flagName');

// Clear all overrides
controller.clearAllOverrides();

Dependencies & Imports

• Added Json type import from @metamask/utils for type safety
• No new external dependencies required

References

This enhancement addresses the need for local flag testing and A/B test visibility that has been requested by development and QA teams for improved testing workflows.

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

Note: No breaking changes were introduced - this is purely additive functionality that maintains full backward compatibility.

---

Note

Adds local override support and raw A/B test flag visibility to RemoteFeatureFlagController, updates exports/metadata, and adjusts consumers/tests accordingly.

• Remote Feature Flag Controller:
  • State: Add localOverrides and rawRemoteFeatureFlags; update metadata (persistence, logging, UI exposure).
  • Overrides API: Add setFlagOverride, clearFlagOverride, clearAllOverrides; local overrides take precedence; preserved across remote updates via #updateCache.
  • Processing/Cache: Store processed flags in remoteFeatureFlags and raw flags in rawRemoteFeatureFlags; export controllerName.
  • Types/Actions/Exports: Export new action types (RemoteFeatureFlagControllerSetFlagOverrideAction, ...ClearFlagOverrideAction, ...ClearAllOverridesAction) and updated state type via index.ts.
• Consumers & Tests:
  • Update tests in transaction-controller and transaction-pay-controller to include new state fields and use updated flag state.
  • Add tests for override behavior and metadata exposure.
• Docs:
  • Update CHANGELOG.md with new features and behavior changes.

^{Written by Cursor Bugbot for commit c1af969. This will update automatically on new commits. Configure here.}

[cursor]

Bug: Raw A/B flags not stored when threshold equals zero

The new raw flag storage code on lines 297-299 is inside a conditional that checks Array.isArray(processedValue) && thresholdValue. Since thresholdValue is a number that can be exactly 0 (when a user's metaMetricsId produces the minimum UUID value), and 0 is falsy in JavaScript, the entire block is skipped. This means rawProcessedRemoteFeatureFlags won't capture A/B test arrays for users with threshold value 0, breaking the new A/B test visibility feature for this edge case. The raw flag storage logic likely needs to be independent of the thresholdValue check.

 

[asalsys]

this is existing functionality

[Cal-L]

Left a comment

[Cal-L]

Can spread ...this.state for unaffected states

[Cal-L]

spread ..this.state for unaffected states

[Cal-L]

Spread state for unaffected states

[cursor]

Bug: rawRemoteFeatureFlags stores all flags instead of only A/B test flags

The #updateCache method stores the entire remoteFeatureFlags object as rawRemoteFeatureFlags, but the PR description, CHANGELOG, and tests clearly indicate that only A/B test flags (threshold arrays) should be stored for efficiency. The test 'only stores raw values for A/B test flags, not simple flags' expects rawRemoteFeatureFlags to contain only threshold-based flags like testFlagForThreshold, excluding simple boolean/string flags. The implementation stores everything, contradicting the documented "selective raw storage" behavior and causing the test to fail.