Revert "Revert "[Web] Enable Quota System for AI Features"" (#31771)

* Revert "Revert "[Web] Enable Quota System for AI Features (#31544)" (#31767)"

This reverts commit f6589bdbf0ac7e71313739e3e3f4fb5bedd48c22.

* Update writefull entitlement syncing for commons (#31774)

* feat: update wf entitlement syncing logic

* feat: remove unused env variable, and parse quota tier as string for analytics

GitOrigin-RevId: 37ae7522a249501719a64327e2b6aaff01a3cc0b

services/web/app/src/Features/SplitTests/SplitTestHandler.mjs

@@ -306,6 +306,20 @@ async function getOneTimeAssignment(splitTestName) {
   }
 }
 
+/**
+ * Checks if a feature flag is enabled for a specific user
+ *
+ * Retrieves the feature flag assignment for a user and determines if the assigned variant is 'enabled'
+ *
+ * @param {string} userId - The ID of the user to check the feature flag for
+ * @param {string} splitTestName - The unique name of the feature flag
+ * @returns {Promise<boolean>} True if the user's assigned variant is 'enabled', false otherwise
+ */
+async function featureFlagEnabledForUser(userId, splitTestName) {
+  const { variant } = await getAssignmentForUser(userId, splitTestName)
+  return variant === 'enabled'
+}
+
 /**
  * Returns an array of valid variant names for the given split test, including default
  *
@@ -802,6 +816,7 @@ export default {
   getPercentile,
   getAssignment: callbackify(getAssignment),
   getAssignmentForUser: callbackify(getAssignmentForUser),
+  featureFlagEnabledForUser: callbackify(featureFlagEnabledForUser),
   getOneTimeAssignment: callbackify(getOneTimeAssignment),
   getActiveAssignmentsForUser: callbackify(getActiveAssignmentsForUser),
   hasUserBeenAssignedToVariant: callbackify(hasUserBeenAssignedToVariant),
@@ -810,6 +825,7 @@ export default {
   promises: {
     getAssignment,
     getAssignmentForUser,
+    featureFlagEnabledForUser,
     getOneTimeAssignment,
     getActiveAssignmentsForUser,
     hasUserBeenAssignedToVariant,