Bug 1932502 - Remove the Suggest JS backend: Part 2: Remove the backend. r=daisuke

This is part 2 of 4, the main part. It removes the backend and the code in `BaseFeature` and feature subclasses that hook into it. As a consequence it also makes the other following changes: * Remove `QuickSuggest.backend` (eventually I'd like to add a Merino backend and then add a new `QuickSuggest.backends` list that has the Rust, Merino, and ML backends) * Add `QuickSuggest.config` * Replace uses of `QuickSuggest.backend.config` and `QuickSuggest.jsBackend.config` with `QuickSuggest.config` * Remove the `quickSuggestRustEnabled` Nimbus variable * Update most remaining tests so that they do not assume the JS backend exists I left the `browser.urlbar.quicksuggest.rustEnabled` pref. I would like to preserve the ability to toggle off Rust suggestions while keeping other parts of Suggest enabled even if we don't need it now. That seems like a wise thing to do and is similar to how both Merino and the ML backends can be toggled separately. Depends on D231465 Differential Revision: https://phabricator.services.mozilla.com/D231466
2024-12-11 20:50:45 +00:00
parent b76d20ad1a
commit 2033165d91
29 changed files with 91 additions and 1060 deletions
@@ -28,8 +28,6 @@ const FEATURES = {
  MDNSuggestions: "resource:///modules/urlbar/private/MDNSuggestions.sys.mjs",
  PocketSuggestions:
    "resource:///modules/urlbar/private/PocketSuggestions.sys.mjs",
-  SuggestBackendJs:
-    "resource:///modules/urlbar/private/SuggestBackendJs.sys.mjs",
  SuggestBackendMl:
    "resource:///modules/urlbar/private/SuggestBackendMl.sys.mjs",
  SuggestBackendRust:
@@ -98,30 +96,22 @@ class _QuickSuggest {
    return ONBOARDING_URI;
  }

-  /**
-   * @returns {SuggestBackendJs|SuggestBackendRust}
-   *   The currently active backend.
-   */
-  get backend() {
-    return lazy.UrlbarPrefs.get("quickSuggestRustEnabled")
-      ? this.rustBackend
-      : this.jsBackend;
-  }
-
  /**
   * @returns {SuggestBackendRust}
-   *   The Rust backend. Not used when the JS backend is enabled.
+   *   The Rust backend, which manages the Rust component.
   */
  get rustBackend() {
    return this.#features.SuggestBackendRust;
  }

  /**
-   * @returns {SuggestBackendJs}
-   *   The JS backend. Not used when the Rust backend is enabled.
+   * @returns {object}
+   *   Global Suggest configuration stored in remote settings and ingested by
+   *   the Rust component. See remote settings or the Rust component for the
+   *   latest schema.
   */
-  get jsBackend() {
-    return this.#features.SuggestBackendJs;
+  get config() {
+    return this.rustBackend?.config || {};
  }

  /**
@@ -128,9 +128,8 @@ class ProviderQuickSuggest extends UrlbarProvider {

    // Fetch suggestions from all enabled sources.
    let promises = [];
-    let { backend } = lazy.QuickSuggest;
-    if (backend?.isEnabled) {
-      promises.push(backend.query(searchString));
+    if (lazy.QuickSuggest.rustBackend?.isEnabled) {
+      promises.push(lazy.QuickSuggest.rustBackend.query(searchString));
    }
    if (
      lazy.UrlbarPrefs.get("quicksuggest.dataCollection.enabled") &&
@@ -633,10 +632,7 @@ class ProviderQuickSuggest extends UrlbarProvider {
   */
  cancelQuery() {
    // Cancel the Rust query.
-    let backend = lazy.QuickSuggest.getFeature("SuggestBackendRust");
-    if (backend?.isEnabled) {
-      backend.cancelQuery();
-    }
+    lazy.QuickSuggest.rustBackend?.cancelQuery();

    // Cancel the Merino timeout timer so it doesn't fire and record a timeout.
    // If it's already canceled or has fired, this is a no-op.
@@ -76,7 +76,6 @@ EXTRA_JS_MODULES["urlbar/private"] += [
    "private/MDNSuggestions.sys.mjs",
    "private/MLSuggest.sys.mjs",
    "private/PocketSuggestions.sys.mjs",
-    "private/SuggestBackendJs.sys.mjs",
    "private/SuggestBackendMl.sys.mjs",
    "private/SuggestBackendRust.sys.mjs",
    "private/Weather.sys.mjs",
@@ -9,7 +9,6 @@ const lazy = {};
 ChromeUtils.defineESModuleGetters(lazy, {
  AddonManager: "resource://gre/modules/AddonManager.sys.mjs",
  QuickSuggest: "resource:///modules/QuickSuggest.sys.mjs",
-  SuggestionsMap: "resource:///modules/urlbar/private/SuggestBackendJs.sys.mjs",
  UrlbarPrefs: "resource:///modules/UrlbarPrefs.sys.mjs",
  UrlbarResult: "resource:///modules/UrlbarResult.sys.mjs",
  UrlbarUtils: "resource:///modules/UrlbarUtils.sys.mjs",
@@ -51,58 +50,6 @@ export class AddonSuggestions extends BaseFeature {
    return ["Amo"];
  }

-  enable(enabled) {
-    if (enabled) {
-      lazy.QuickSuggest.jsBackend.register(this);
-    } else {
-      lazy.QuickSuggest.jsBackend.unregister(this);
-      this.#suggestionsMap?.clear();
-    }
-  }
-
-  queryRemoteSettings(searchString) {
-    const suggestions = this.#suggestionsMap?.get(searchString);
-    if (!suggestions) {
-      return [];
-    }
-
-    return suggestions.map(suggestion => ({
-      icon: suggestion.icon,
-      url: suggestion.url,
-      title: suggestion.title,
-      description: suggestion.description,
-      guid: suggestion.guid,
-      score: suggestion.score,
-    }));
-  }
-
-  async onRemoteSettingsSync(rs) {
-    const records = await rs.get({ filters: { type: "amo-suggestions" } });
-    if (!this.isEnabled) {
-      return;
-    }
-
-    const suggestionsMap = new lazy.SuggestionsMap();
-
-    for (const record of records) {
-      const { buffer } = await rs.attachments.download(record);
-      if (!this.isEnabled) {
-        return;
-      }
-
-      const results = JSON.parse(new TextDecoder("utf-8").decode(buffer));
-      await suggestionsMap.add(results, {
-        mapKeyword:
-          lazy.SuggestionsMap.MAP_KEYWORD_PREFIXES_STARTING_AT_FIRST_WORD,
-      });
-      if (!this.isEnabled) {
-        return;
-      }
-    }
-
-    this.#suggestionsMap = suggestionsMap;
-  }
-
  async makeResult(queryContext, suggestion, searchString) {
    if (!this.isEnabled) {
      // The feature is disabled on the client, but Merino may still return
@@ -270,10 +217,8 @@ export class AddonSuggestions extends BaseFeature {
  get canShowLessFrequently() {
    const cap =
      lazy.UrlbarPrefs.get("addonsShowLessFrequentlyCap") ||
-      lazy.QuickSuggest.backend.config?.showLessFrequentlyCap ||
+      lazy.QuickSuggest.config.showLessFrequentlyCap ||
      0;
    return !cap || this.showLessFrequentlyCount < cap;
  }
-
-  #suggestionsMap = null;
 }
@@ -8,7 +8,6 @@ const lazy = {};

 ChromeUtils.defineESModuleGetters(lazy, {
  QuickSuggest: "resource:///modules/QuickSuggest.sys.mjs",
-  SuggestionsMap: "resource:///modules/urlbar/private/SuggestBackendJs.sys.mjs",
  UrlbarPrefs: "resource:///modules/UrlbarPrefs.sys.mjs",
  UrlbarResult: "resource:///modules/UrlbarResult.sys.mjs",
  UrlbarUtils: "resource:///modules/UrlbarUtils.sys.mjs",
@@ -21,11 +20,6 @@ const NONSPONSORED_IAB_CATEGORIES = new Set(["5 - Education"]);
 * called "expanded Wikipedia") suggestions in remote settings.
 */
 export class AdmWikipedia extends BaseFeature {
-  constructor() {
-    super();
-    this.#suggestionsMap = new lazy.SuggestionsMap();
-  }
-
  get shouldEnable() {
    return (
      lazy.UrlbarPrefs.get("suggest.quicksuggest.nonsponsored") ||
@@ -69,78 +63,6 @@ export class AdmWikipedia extends BaseFeature {
    return false;
  }

-  enable(enabled) {
-    if (enabled) {
-      lazy.QuickSuggest.jsBackend.register(this);
-    } else {
-      lazy.QuickSuggest.jsBackend.unregister(this);
-      this.#suggestionsMap.clear();
-    }
-  }
-
-  async queryRemoteSettings(searchString) {
-    let suggestions = this.#suggestionsMap.get(searchString);
-    if (!suggestions) {
-      return [];
-    }
-
-    // Start each icon fetch at the same time and wait for them all to finish.
-    let icons = await Promise.all(
-      suggestions.map(({ icon }) => this.#fetchIcon(icon))
-    );
-
-    return suggestions.map(suggestion => ({
-      full_keyword: this.#getFullKeyword(searchString, suggestion.keywords),
-      title: suggestion.title,
-      url: suggestion.url,
-      click_url: suggestion.click_url,
-      impression_url: suggestion.impression_url,
-      block_id: suggestion.id,
-      advertiser: suggestion.advertiser,
-      iab_category: suggestion.iab_category,
-      is_sponsored: !NONSPONSORED_IAB_CATEGORIES.has(suggestion.iab_category),
-      score: suggestion.score,
-      position: suggestion.position,
-      icon: icons.shift(),
-    }));
-  }
-
-  async onRemoteSettingsSync(rs) {
-    let dataType = lazy.UrlbarPrefs.get("quickSuggestRemoteSettingsDataType");
-    this.logger.debug("Loading remote settings", { dataType });
-
-    let [data] = await Promise.all([
-      rs.get({ filters: { type: dataType } }),
-      rs
-        .get({ filters: { type: "icon" } })
-        .then(icons =>
-          Promise.all(icons.map(i => rs.attachments.downloadToDisk(i)))
-        ),
-    ]);
-    if (!this.isEnabled) {
-      return;
-    }
-
-    let suggestionsMap = new lazy.SuggestionsMap();
-
-    this.logger.debug("Got remote settings data", { recordCount: data.length });
-    for (let record of data) {
-      let { buffer } = await rs.attachments.download(record);
-      if (!this.isEnabled) {
-        return;
-      }
-
-      let results = JSON.parse(new TextDecoder("utf-8").decode(buffer));
-      this.logger.debug("Adding results", { resultCount: results.length });
-      await suggestionsMap.add(results);
-      if (!this.isEnabled) {
-        return;
-      }
-    }
-
-    this.#suggestionsMap = suggestionsMap;
-  }
-
  makeResult(queryContext, suggestion) {
    let originalUrl;
    if (suggestion.source == "rust") {
@@ -241,88 +163,4 @@ export class AdmWikipedia extends BaseFeature {

    return result;
  }
-
-  /**
-   * Gets the "full keyword" (i.e., suggestion) for a query from a list of
-   * keywords. The suggestions data doesn't include full keywords, so we make
-   * our own based on the result's keyword phrases and a particular query. We
-   * use two heuristics:
-   *
-   * (1) Find the first keyword phrase that has more words than the query. Use
-   *     its first `queryWords.length` words as the full keyword. e.g., if the
-   *     query is "moz" and `keywords` is ["moz", "mozi", "mozil", "mozill",
-   *     "mozilla", "mozilla firefox"], pick "mozilla firefox", pop off the
-   *     "firefox" and use "mozilla" as the full keyword.
-   * (2) If there isn't any keyword phrase with more words, then pick the
-   *     longest phrase. e.g., pick "mozilla" in the previous example (assuming
-   *     the "mozilla firefox" phrase isn't there). That might be the query
-   *     itself.
-   *
-   * @param {string} query
-   *   The query string.
-   * @param {Array} keywords
-   *   An array of suggestion keywords.
-   * @returns {string}
-   *   The full keyword.
-   */
-  #getFullKeyword(query, keywords) {
-    let longerPhrase;
-    let trimmedQuery = query.toLocaleLowerCase().trim();
-    let queryWords = trimmedQuery.split(" ");
-
-    for (let phrase of keywords) {
-      if (phrase.startsWith(query)) {
-        let trimmedPhrase = phrase.trim();
-        let phraseWords = trimmedPhrase.split(" ");
-        // As an exception to (1), if the query ends with a space, then look for
-        // phrases with one more word so that the suggestion includes a word
-        // following the space.
-        let extra = query.endsWith(" ") ? 1 : 0;
-        let len = queryWords.length + extra;
-        if (len < phraseWords.length) {
-          // We found a phrase with more words.
-          return phraseWords.slice(0, len).join(" ");
-        }
-        if (
-          query.length < phrase.length &&
-          (!longerPhrase || longerPhrase.length < trimmedPhrase.length)
-        ) {
-          // We found a longer phrase with the same number of words.
-          longerPhrase = trimmedPhrase;
-        }
-      }
-    }
-    return longerPhrase || trimmedQuery;
-  }
-
-  /**
-   * Fetch the icon from RemoteSettings attachments.
-   *
-   * @param {string} path
-   *   The icon's remote settings path.
-   * @returns {string}
-   *   The absolute file path to the downloaded attachment.
-   */
-  async #fetchIcon(path) {
-    if (!path) {
-      return null;
-    }
-
-    let { rs } = lazy.QuickSuggest.jsBackend;
-    if (!rs) {
-      return null;
-    }
-
-    let record = (
-      await rs.get({
-        filters: { id: `icon-${path}` },
-      })
-    ).pop();
-    if (!record) {
-      return null;
-    }
-    return rs.attachments.downloadToDisk(record);
-  }
-
-  #suggestionsMap;
 }
@@ -27,14 +27,6 @@ ChromeUtils.defineESModuleGetters(lazy, {
 *   place, without mixing it with unrelated code and cluttering up
 *   `QuickSuggest`. You can also test it in isolation from `QuickSuggest`.
 *
- * - Remote settings management. You can register your feature with
- *   `QuickSuggestRemoteSettings` and it will be called at appropriate times to
- *   sync from remote settings.
- *
- * - If your feature also serves suggestions from remote settings, you can
- *   implement one method, `queryRemoteSettings()`, to hook into
- *   `UrlbarProviderQuickSuggest`.
- *
 * - Your feature will automatically get its own logger.
 *
 * To register your subclass with `QuickSuggest`, add it to the `FEATURES` const
@@ -116,31 +108,6 @@ export class BaseFeature {
   */
  enable(_enabled) {}

-  /**
-   * If the feature manages suggestions from remote settings that should be
-   * returned by UrlbarProviderQuickSuggest, the subclass should override this
-   * method. It should return remote settings suggestions matching the given
-   * search string.
-   *
-   * @param {string} _searchString
-   *   The search string.
-   * @returns {Array}
-   *   An array of matching suggestions, or null if not implemented.
-   */
-  async queryRemoteSettings(_searchString) {
-    return null;
-  }
-
-  /**
-   * If the feature manages data in remote settings, the subclass should
-   * override this method. It should fetch the data and build whatever data
-   * structures are necessary to support the feature.
-   *
-   * @param {RemoteSettings} _rs
-   *   The `RemoteSettings` client object.
-   */
-  async onRemoteSettingsSync(_rs) {}
-
  /**
   * If the feature manages suggestions that either aren't served by Merino or
   * whose telemetry type is different from `merinoProvider`, the subclass
@@ -108,7 +108,7 @@ export class FakespotSuggestions extends BaseFeature {
  get canShowLessFrequently() {
    let cap =
      lazy.UrlbarPrefs.get("fakespotShowLessFrequentlyCap") ||
-      lazy.QuickSuggest.backend.config?.showLessFrequentlyCap ||
+      lazy.QuickSuggest.config.showLessFrequentlyCap ||
      0;
    return !cap || this.showLessFrequentlyCount < cap;
  }
@@ -52,7 +52,7 @@ export class ImpressionCaps extends BaseFeature {
    this.logger.debug("Starting impression stats update", {
      type,
      currentStats: this.#stats,
-      impression_caps: lazy.QuickSuggest.jsBackend.config.impression_caps,
+      impression_caps: lazy.QuickSuggest.config.impression_caps,
    });

    // Don't bother recording anything if caps are disabled.
@@ -151,7 +151,9 @@ export class ImpressionCaps extends BaseFeature {

    // Validate stats against any changes to the impression caps in the config.
    this._onConfigSet = () => this.#validateStats();
-    lazy.QuickSuggest.jsBackend.emitter.on("config-set", this._onConfigSet);
+    // TODO: If impression caps are ever enabled again, this will need to be
+    // fixed.
+    // lazy.QuickSuggest.jsBackend.emitter.on("config-set", this._onConfigSet);

    // Periodically record impression counters reset telemetry.
    this.#setCountersResetInterval();
@@ -165,7 +167,9 @@ export class ImpressionCaps extends BaseFeature {
  }

  #uninit() {
-    lazy.QuickSuggest.jsBackend.emitter.off("config-set", this._onConfigSet);
+    // TODO: If impression caps are ever enabled again, this will need to be
+    // fixed.
+    // lazy.QuickSuggest.jsBackend.emitter.off("config-set", this._onConfigSet);
    this._onConfigSet = null;

    lazy.clearInterval(this._impressionCountersResetInterval);
@@ -207,7 +211,7 @@ export class ImpressionCaps extends BaseFeature {
   *   corresponding to each impression cap. See the `#stats` comment for info.
   */
  #validateStats() {
-    let { impression_caps } = lazy.QuickSuggest.jsBackend.config;
+    let { impression_caps } = lazy.QuickSuggest.config;

    this.logger.debug("Validating impression stats", {
      impression_caps,
@@ -325,7 +329,7 @@ export class ImpressionCaps extends BaseFeature {
  #resetElapsedCounters() {
    this.logger.debug("Checking for elapsed impression cap intervals", {
      currentStats: this.#stats,
-      impression_caps: lazy.QuickSuggest.jsBackend.config.impression_caps,
+      impression_caps: lazy.QuickSuggest.config.impression_caps,
    });

    let now = Date.now();
@@ -446,8 +450,7 @@ export class ImpressionCaps extends BaseFeature {
  // cap is the one with the same suggestion type (sponsored or non-sponsored)
  // and interval. See `#validateStats()` for more.
  //
-  // Impression caps are stored in the remote settings config. See
-  // `SuggestBackendJs.config.impression_caps`.
+  // Impression caps are stored in the Suggest remote settings global config.
  #stats = {};

  // Whether impression stats are currently being updated.
@@ -8,7 +8,6 @@ const lazy = {};

 ChromeUtils.defineESModuleGetters(lazy, {
  QuickSuggest: "resource:///modules/QuickSuggest.sys.mjs",
-  SuggestionsMap: "resource:///modules/urlbar/private/SuggestBackendJs.sys.mjs",
  UrlbarPrefs: "resource:///modules/UrlbarPrefs.sys.mjs",
  UrlbarResult: "resource:///modules/UrlbarResult.sys.mjs",
  UrlbarUtils: "resource:///modules/UrlbarUtils.sys.mjs",
@@ -48,49 +47,6 @@ export class MDNSuggestions extends BaseFeature {
    return ["Mdn"];
  }

-  enable(enabled) {
-    if (enabled) {
-      lazy.QuickSuggest.jsBackend.register(this);
-    } else {
-      lazy.QuickSuggest.jsBackend.unregister(this);
-      this.#suggestionsMap?.clear();
-    }
-  }
-
-  queryRemoteSettings(searchString) {
-    const suggestions = this.#suggestionsMap?.get(searchString);
-    return suggestions
-      ? suggestions.map(suggestion => ({ ...suggestion }))
-      : [];
-  }
-
-  async onRemoteSettingsSync(rs) {
-    const records = await rs.get({ filters: { type: "mdn-suggestions" } });
-    if (!this.isEnabled) {
-      return;
-    }
-
-    const suggestionsMap = new lazy.SuggestionsMap();
-
-    for (const record of records) {
-      const { buffer } = await rs.attachments.download(record);
-      if (!this.isEnabled) {
-        return;
-      }
-
-      const results = JSON.parse(new TextDecoder("utf-8").decode(buffer));
-      await suggestionsMap.add(results, {
-        mapKeyword:
-          lazy.SuggestionsMap.MAP_KEYWORD_PREFIXES_STARTING_AT_FIRST_WORD,
-      });
-      if (!this.isEnabled) {
-        return;
-      }
-    }
-
-    this.#suggestionsMap = suggestionsMap;
-  }
-
  async makeResult(queryContext, suggestion) {
    if (!this.isEnabled) {
      // The feature is disabled on the client, but Merino may still return
@@ -193,6 +149,4 @@ export class MDNSuggestions extends BaseFeature {
        break;
    }
  }
-
-  #suggestionsMap = null;
 }
@@ -8,7 +8,6 @@ const lazy = {};

 ChromeUtils.defineESModuleGetters(lazy, {
  QuickSuggest: "resource:///modules/QuickSuggest.sys.mjs",
-  SuggestionsMap: "resource:///modules/urlbar/private/SuggestBackendJs.sys.mjs",
  UrlbarPrefs: "resource:///modules/UrlbarPrefs.sys.mjs",
  UrlbarResult: "resource:///modules/UrlbarResult.sys.mjs",
  UrlbarUtils: "resource:///modules/UrlbarUtils.sys.mjs",
@@ -25,12 +24,6 @@ const RESULT_MENU_COMMAND = {
 * A feature that manages Pocket suggestions in remote settings.
 */
 export class PocketSuggestions extends BaseFeature {
-  constructor() {
-    super();
-    this.#lowConfidenceSuggestionsMap = new lazy.SuggestionsMap();
-    this.#highConfidenceSuggestionsMap = new lazy.SuggestionsMap();
-  }
-
  get shouldEnable() {
    return (
      lazy.UrlbarPrefs.get("pocketFeatureGate") &&
@@ -59,94 +52,11 @@ export class PocketSuggestions extends BaseFeature {
  get canShowLessFrequently() {
    let cap =
      lazy.UrlbarPrefs.get("pocketShowLessFrequentlyCap") ||
-      lazy.QuickSuggest.backend.config?.showLessFrequentlyCap ||
+      lazy.QuickSuggest.config.showLessFrequentlyCap ||
      0;
    return !cap || this.showLessFrequentlyCount < cap;
  }

-  enable(enabled) {
-    if (enabled) {
-      lazy.QuickSuggest.jsBackend.register(this);
-    } else {
-      lazy.QuickSuggest.jsBackend.unregister(this);
-      this.#lowConfidenceSuggestionsMap.clear();
-      this.#highConfidenceSuggestionsMap.clear();
-    }
-  }
-
-  async queryRemoteSettings(searchString) {
-    // If the search string matches high confidence suggestions, they should be
-    // treated as top picks. Otherwise try to match low confidence suggestions.
-    let is_top_pick = false;
-    let suggestions = this.#highConfidenceSuggestionsMap.get(searchString);
-    if (suggestions.length) {
-      is_top_pick = true;
-    } else {
-      suggestions = this.#lowConfidenceSuggestionsMap.get(searchString);
-    }
-
-    let lowerSearchString = searchString.toLocaleLowerCase();
-    return suggestions.map(suggestion => {
-      // Add `full_keyword` to each matched suggestion. It should be the longest
-      // keyword that starts with the user's search string.
-      let full_keyword = lowerSearchString;
-      let keywords = is_top_pick
-        ? suggestion.highConfidenceKeywords
-        : suggestion.lowConfidenceKeywords;
-      for (let keyword of keywords) {
-        if (
-          keyword.startsWith(lowerSearchString) &&
-          full_keyword.length < keyword.length
-        ) {
-          full_keyword = keyword;
-        }
-      }
-      return { ...suggestion, is_top_pick, full_keyword };
-    });
-  }
-
-  async onRemoteSettingsSync(rs) {
-    let records = await rs.get({ filters: { type: "pocket-suggestions" } });
-    if (!this.isEnabled) {
-      return;
-    }
-
-    let lowMap = new lazy.SuggestionsMap();
-    let highMap = new lazy.SuggestionsMap();
-
-    this.logger.debug("Got records", { recordCount: records.length });
-    for (let record of records) {
-      let { buffer } = await rs.attachments.download(record);
-      if (!this.isEnabled) {
-        return;
-      }
-
-      let suggestions = JSON.parse(new TextDecoder("utf-8").decode(buffer));
-      this.logger.debug("Adding suggestions", {
-        suggestionsCount: suggestions.length,
-      });
-
-      await lowMap.add(suggestions, {
-        keywordsProperty: "lowConfidenceKeywords",
-        mapKeyword:
-          lazy.SuggestionsMap.MAP_KEYWORD_PREFIXES_STARTING_AT_FIRST_WORD,
-      });
-      if (!this.isEnabled) {
-        return;
-      }
-
-      await highMap.add(suggestions, {
-        keywordsProperty: "highConfidenceKeywords",
-      });
-      if (!this.isEnabled) {
-        return;
-      }
-    }
-
-    this.#lowConfidenceSuggestionsMap = lowMap;
-    this.#highConfidenceSuggestionsMap = highMap;
-  }
-
  makeResult(queryContext, suggestion, searchString) {
    if (!this.isEnabled) {
      // The feature is disabled on the client, but Merino may still return
@@ -320,7 +230,4 @@ export class PocketSuggestions extends BaseFeature {
      );
    }
  }
-
-  #lowConfidenceSuggestionsMap;
-  #highConfidenceSuggestionsMap;
 }
@@ -1,442 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-import { BaseFeature } from "resource:///modules/urlbar/private/BaseFeature.sys.mjs";
-
-const lazy = {};
-
-ChromeUtils.defineESModuleGetters(lazy, {
-  EventEmitter: "resource://gre/modules/EventEmitter.sys.mjs",
-  RemoteSettings: "resource://services-settings/remote-settings.sys.mjs",
-  UrlbarPrefs: "resource:///modules/UrlbarPrefs.sys.mjs",
-  UrlbarUtils: "resource:///modules/UrlbarUtils.sys.mjs",
-});
-
-const RS_COLLECTION = "quicksuggest";
-
-// Entries are added to `SuggestionsMap` map in chunks, and each chunk will add
-// at most this many entries.
-const SUGGESTIONS_MAP_CHUNK_SIZE = 1000;
-
-const TELEMETRY_LATENCY = "FX_URLBAR_QUICK_SUGGEST_REMOTE_SETTINGS_LATENCY_MS";
-
-// See `SuggestionsMap.MAP_KEYWORD_PREFIXES_STARTING_AT_FIRST_WORD`. When a full
-// keyword starts with one of the prefixes in this list, the user must type the
-// entire prefix to start triggering matches based on that full keyword, instead
-// of only the first word.
-const KEYWORD_PREFIXES_TO_TREAT_AS_SINGLE_WORDS = ["how to"];
-
-/**
- * The Suggest JS backend. Not used when the Rust backend is enabled.
- */
-export class SuggestBackendJs extends BaseFeature {
-  constructor(...args) {
-    super(...args);
-    this.#emitter = new lazy.EventEmitter();
-  }
-
-  get shouldEnable() {
-    return !lazy.UrlbarPrefs.get("quickSuggestRustEnabled");
-  }
-
-  /**
-   * @returns {RemoteSettings}
-   *   The underlying `RemoteSettings` client object.
-   */
-  get rs() {
-    return this.#rs;
-  }
-
-  /**
-   * @returns {EventEmitter}
-   *   The client will emit events on this object.
-   */
-  get emitter() {
-    return this.#emitter;
-  }
-
-  /**
-   * @returns {object}
-   *   Global quick suggest configuration stored in remote settings. When the
-   *   config changes the `emitter` property will emit a "config-set" event. The
-   *   config is an object that looks like this:
-   *
-   *   {
-   *     impression_caps: {
-   *       nonsponsored: {
-   *         lifetime,
-   *         custom: [
-   *           { interval_s, max_count },
-   *         ],
-   *       },
-   *       sponsored: {
-   *         lifetime,
-   *         custom: [
-   *           { interval_s, max_count },
-   *         ],
-   *       },
-   *     },
-   *     show_less_frequently_cap,
-   *   }
-   */
-  get config() {
-    return this.#config;
-  }
-
-  /**
-   * @returns {Array}
-   *   Array of `BasicFeature` instances.
-   */
-  get features() {
-    return [...this.#features];
-  }
-
-  enable(enabled) {
-    if (!enabled) {
-      this.#enableSettings(false);
-    } else if (this.#features.size) {
-      this.#enableSettings(true);
-      this.#syncAll();
-    }
-  }
-
-  /**
-   * Registers a quick suggest feature that uses remote settings.
-   *
-   * @param {BaseFeature} feature
-   *   An instance of a `BaseFeature` subclass. See `BaseFeature` for methods
-   *   that the subclass must implement.
-   */
-  register(feature) {
-    this.logger.debug("Registering feature: " + feature.name);
-    this.#features.add(feature);
-    if (this.isEnabled) {
-      if (this.#features.size == 1) {
-        this.#enableSettings(true);
-      }
-      this.#syncFeature(feature);
-    }
-  }
-
-  /**
-   * Unregisters a quick suggest feature that uses remote settings.
-   *
-   * @param {BaseFeature} feature
-   *   An instance of a `BaseFeature` subclass.
-   */
-  unregister(feature) {
-    this.logger.debug("Unregistering feature: " + feature.name);
-    this.#features.delete(feature);
-    if (!this.#features.size) {
-      this.#enableSettings(false);
-    }
-  }
-
-  /**
-   * Queries remote settings suggestions from all registered features.
-   *
-   * @param {string} searchString
-   *   The search string.
-   * @returns {Array}
-   *   The remote settings suggestions. If there are no matches, an empty array
-   *   is returned.
-   */
-  async query(searchString) {
-    let suggestions;
-    let stopwatchInstance = {};
-    TelemetryStopwatch.start(TELEMETRY_LATENCY, stopwatchInstance);
-    try {
-      suggestions = await this.#queryHelper(searchString);
-      TelemetryStopwatch.finish(TELEMETRY_LATENCY, stopwatchInstance);
-    } catch (error) {
-      TelemetryStopwatch.cancel(TELEMETRY_LATENCY, stopwatchInstance);
-      this.logger.error("Query error: " + error);
-    }
-
-    return suggestions || [];
-  }
-
-  async #queryHelper(searchString) {
-    this.logger.info("Handling query: " + JSON.stringify(searchString));
-
-    let results = await Promise.all(
-      [...this.#features].map(async feature => {
-        let suggestions = await feature.queryRemoteSettings(searchString);
-        return [feature, suggestions ?? []];
-      })
-    );
-
-    let allSuggestions = [];
-    for (let [feature, suggestions] of results) {
-      for (let suggestion of suggestions) {
-        // Features typically return suggestion objects straight from their
-        // suggestion maps. We don't want consumers to modify those objects
-        // since they are the source of truth (tests especially tend to do
-        // this), so return copies to consumers.
-        allSuggestions.push({
-          ...suggestion,
-          source: "remote-settings",
-          provider: feature.name,
-        });
-      }
-    }
-
-    return allSuggestions;
-  }
-
-  async #enableSettings(enabled) {
-    if (enabled && !this.#rs) {
-      this.logger.debug("Creating RemoteSettings client");
-      this.#onSettingsSync = event => this.#syncAll({ event });
-      this.#rs = lazy.RemoteSettings(RS_COLLECTION);
-      this.#rs.on("sync", this.#onSettingsSync);
-      await this.#syncConfig();
-    } else if (!enabled && this.#rs) {
-      this.logger.debug("Destroying RemoteSettings client");
-      this.#rs.off("sync", this.#onSettingsSync);
-      this.#rs = null;
-      this.#onSettingsSync = null;
-    }
-  }
-
-  async #syncConfig() {
-    this.logger.debug("Syncing config");
-    let rs = this.#rs;
-
-    let configArray = await rs.get({ filters: { type: "configuration" } });
-    if (rs != this.#rs) {
-      return;
-    }
-
-    this.logger.debug("Got config array: " + JSON.stringify(configArray));
-    this.#setConfig(configArray?.[0]?.configuration || {});
-  }
-
-  async #syncFeature(feature) {
-    this.logger.debug("Syncing feature: " + feature.name);
-    await feature.onRemoteSettingsSync(this.#rs);
-  }
-
-  async #syncAll({ event = null } = {}) {
-    this.logger.debug("Syncing all");
-    let rs = this.#rs;
-
-    // Remove local files of deleted records
-    if (event?.data?.deleted) {
-      await Promise.all(
-        event.data.deleted
-          .filter(d => d.attachment)
-          .map(entry =>
-            Promise.all([
-              this.#rs.attachments.deleteDownloaded(entry), // type: data
-              this.#rs.attachments.deleteFromDisk(entry), // type: icon
-            ])
-          )
-      );
-      if (rs != this.#rs) {
-        return;
-      }
-    }
-
-    let promises = [this.#syncConfig()];
-    for (let feature of this.#features) {
-      promises.push(this.#syncFeature(feature));
-    }
-    await Promise.all(promises);
-  }
-
-  /**
-   * Sets the quick suggest config and emits a "config-set" event.
-   *
-   * @param {object} config
-   *   The config object.
-   */
-  #setConfig(config) {
-    config = lazy.UrlbarUtils.copySnakeKeysToCamel(config ?? {});
-    this.logger.debug("Setting config: " + JSON.stringify(config));
-    this.#config = config;
-    this.#emitter.emit("config-set");
-  }
-
-  async _test_syncAll() {
-    if (this.#rs) {
-      // `RemoteSettingsClient` won't start another import if it's already
-      // importing. Wait for it to finish before starting the new one.
-      await this.#rs._importingPromise;
-      await this.#syncAll();
-    }
-  }
-
-  // The `RemoteSettings` client.
-  #rs = null;
-
-  // Registered `BaseFeature` instances.
-  #features = new Set();
-
-  // Configuration data synced from remote settings. See the `config` getter.
-  #config = {};
-
-  #emitter = null;
-  #onSettingsSync = null;
-}
-
-/**
- * A wrapper around `Map` that handles quick suggest suggestions from remote
- * settings. It maps keywords to suggestions. It has two benefits over `Map`:
- *
- * - The main benefit is that map entries are added in batches on idle to avoid
- *   blocking the main thread for too long, since there can be many suggestions
- *   and keywords.
- * - A secondary benefit is that the interface is tailored to quick suggest
- *   suggestions, which have a `keywords` property.
- */
-export class SuggestionsMap {
-  /**
-   * Returns the list of suggestions for a keyword.
-   *
-   * @param {string} keyword
-   *   The keyword.
-   * @returns {Array}
-   *   The array of suggestions for the keyword. If the keyword isn't in the
-   *   map, the array will be empty.
-   */
-  get(keyword) {
-    let object = this.#suggestionsByKeyword.get(keyword.toLocaleLowerCase());
-    if (!object) {
-      return [];
-    }
-    return Array.isArray(object) ? object : [object];
-  }
-
-  /**
-   * Adds a list of suggestion objects to the results map. Each suggestion must
-   * have a property whose value is an array of keyword strings. The
-   * suggestion's keywords will be taken from this array either exactly as they
-   * are specified or by generating new keywords from them; see `mapKeyword`.
-   *
-   * @param {Array} suggestions
-   *   Array of suggestion objects.
-   * @param {object} options
-   *   Options object.
-   * @param {string} options.keywordsProperty
-   *   The name of the keywords property in each suggestion.
-   * @param {Function} options.mapKeyword
-   *   If null, the keywords for each suggestion will be taken from the keywords
-   *   array exactly as they are specified. Otherwise, this function will be
-   *   called for each string in the array, and it should return an array of
-   *   strings. The suggestion's final list of keywords will be the union of all
-   *   strings returned by this function. See also the `MAP_KEYWORD_*` consts.
-   */
-  async add(
-    suggestions,
-    { keywordsProperty = "keywords", mapKeyword = null } = {}
-  ) {
-    // There can be many suggestions, and each suggestion can have many
-    // keywords. To avoid blocking the main thread for too long, update the map
-    // in chunks, and to avoid blocking the UI and other higher priority work,
-    // do each chunk only when the main thread is idle. During each chunk, we'll
-    // add at most `chunkSize` entries to the map.
-    let suggestionIndex = 0;
-    let keywordIndex = 0;
-
-    // Keep adding chunks until all suggestions have been fully added.
-    while (suggestionIndex < suggestions.length) {
-      await new Promise(resolve => {
-        Services.tm.idleDispatchToMainThread(() => {
-          // Keep updating the map until the current chunk is done.
-          let indexInChunk = 0;
-          while (
-            indexInChunk < SuggestionsMap.chunkSize &&
-            suggestionIndex < suggestions.length
-          ) {
-            let suggestion = suggestions[suggestionIndex];
-            let keywords = suggestion[keywordsProperty];
-            if (keywordIndex == keywords.length) {
-              // We've added entries for all keywords of the current suggestion.
-              // Move on to the next suggestion.
-              suggestionIndex++;
-              keywordIndex = 0;
-              continue;
-            }
-
-            // As a convenience, allow `mapKeyword` to return a string even
-            // though the JSDoc says an array must be returned.
-            let originalKeyword = keywords[keywordIndex];
-            let mappedKeywords =
-              mapKeyword?.(originalKeyword) ?? originalKeyword;
-            if (typeof mappedKeywords == "string") {
-              mappedKeywords = [mappedKeywords];
-            }
-
-            for (let keyword of mappedKeywords) {
-              // If the keyword's only suggestion is `suggestion`, store it
-              // directly as the value. Otherwise store an array of unique
-              // suggestions. See the `#suggestionsByKeyword` comment.
-              let object = this.#suggestionsByKeyword.get(keyword);
-              if (!object) {
-                this.#suggestionsByKeyword.set(keyword, suggestion);
-              } else {
-                let isArray = Array.isArray(object);
-                if (!isArray && object != suggestion) {
-                  this.#suggestionsByKeyword.set(keyword, [object, suggestion]);
-                } else if (isArray && !object.includes(suggestion)) {
-                  object.push(suggestion);
-                }
-              }
-            }
-
-            keywordIndex++;
-            indexInChunk++;
-          }
-
-          // The current chunk is done.
-          resolve();
-        });
-      });
-    }
-  }
-
-  clear() {
-    this.#suggestionsByKeyword.clear();
-  }
-
-  /**
-   * @returns {Function}
-   *   A `mapKeyword` function that maps a keyword to an array containing the
-   *   keyword's first word plus every subsequent prefix of the keyword. The
-   *   strings in `KEYWORD_PREFIXES_TO_TREAT_AS_SINGLE_WORDS` will modify this
-   *   behavior: When a full keyword starts with one of the prefixes in that
-   *   list, the generated prefixes will start at that prefix instead of the
-   *   first word.
-   */
-  static get MAP_KEYWORD_PREFIXES_STARTING_AT_FIRST_WORD() {
-    return fullKeyword => {
-      let prefix = KEYWORD_PREFIXES_TO_TREAT_AS_SINGLE_WORDS.find(p =>
-        fullKeyword.startsWith(p + " ")
-      );
-      let spaceIndex = prefix ? prefix.length : fullKeyword.indexOf(" ");
-
-      let keywords = [fullKeyword];
-      if (spaceIndex >= 0) {
-        for (let i = spaceIndex; i < fullKeyword.length; i++) {
-          keywords.push(fullKeyword.substring(0, i));
-        }
-      }
-      return keywords;
-    };
-  }
-
-  // Maps each keyword in the dataset to one or more suggestions for the
-  // keyword. If only one suggestion uses a keyword, the keyword's value in the
-  // map will be the suggestion object. If more than one suggestion uses the
-  // keyword, the value will be an array of the suggestions. The reason for not
-  // always using an array is that we expect the vast majority of keywords to be
-  // used by only one suggestion, and since there are potentially very many
-  // keywords and suggestions and we keep them in memory all the time, we want
-  // to save as much memory as possible.
-  #suggestionsByKeyword = new Map();
-
-  // This is only defined as a property so that tests can override it.
-  static chunkSize = SUGGESTIONS_MAP_CHUNK_SIZE;
-}
@@ -108,6 +108,14 @@ export class SuggestBackendRust extends BaseFeature {
    }
  }

+  get enablingPreferences() {
+    return ["quicksuggest.rustEnabled"];
+  }
+
+  get shouldEnable() {
+    return lazy.UrlbarPrefs.get("quicksuggest.rustEnabled");
+  }
+
  /**
   * @returns {object}
   *   The global Suggest config from the Rust component as returned from
@@ -125,10 +133,6 @@ export class SuggestBackendRust extends BaseFeature {
    return this.#ingestQueue.emptyPromise;
  }

-  get shouldEnable() {
-    return lazy.UrlbarPrefs.get("quickSuggestRustEnabled");
-  }
-
  enable(enabled) {
    if (enabled) {
      this.#init();
@@ -173,7 +173,7 @@ export class Weather extends BaseFeature {
  get canShowLessFrequently() {
    const cap =
      lazy.UrlbarPrefs.get("weatherShowLessFrequentlyCap") ||
-      lazy.QuickSuggest.backend.config?.showLessFrequentlyCap ||
+      lazy.QuickSuggest.config.showLessFrequentlyCap ||
      0;
    return !cap || this.showLessFrequentlyCount < cap;
  }
@@ -64,7 +64,7 @@ export class YelpSuggestions extends BaseFeature {
  get canShowLessFrequently() {
    const cap =
      lazy.UrlbarPrefs.get("yelpShowLessFrequentlyCap") ||
-      lazy.QuickSuggest.backend.config?.showLessFrequentlyCap ||
+      lazy.QuickSuggest.config.showLessFrequentlyCap ||
      0;
    return !cap || this.showLessFrequentlyCount < cap;
  }
@@ -215,9 +215,7 @@ add_task(async function suggest() {
      assertAbandonmentTelemetry([
        {
          groups: "heuristic,suggest",
-          results: UrlbarPrefs.get("quickSuggestRustEnabled")
-            ? "search_engine,rust_adm_nonsponsored"
-            : "search_engine,rs_adm_nonsponsored",
+          results: "search_engine,rust_adm_nonsponsored",
          n_results: 2,
        },
      ]),
@@ -231,9 +231,7 @@ add_task(async function suggest() {
      assertEngagementTelemetry([
        {
          groups: "heuristic,suggest",
-          results: UrlbarPrefs.get("quickSuggestRustEnabled")
-            ? "search_engine,rust_adm_nonsponsored"
-            : "search_engine,rs_adm_nonsponsored",
+          results: "search_engine,rust_adm_nonsponsored",
          n_results: 2,
        },
      ]),
@@ -68,6 +68,5 @@ async function getRowByType(type) {
 }

 function suggestResultType(typeWithoutSource) {
-  let source = UrlbarPrefs.get("quickSuggestRustEnabled") ? "rust" : "rs";
-  return `${source}_${typeWithoutSource}`;
+  return `rust_${typeWithoutSource}`;
 }
@@ -1,7 +1,6 @@
 /* Any copyright is dedicated to the Public Domain.
   http://creativecommons.org/publicdomain/zero/1.0/ */

-/* eslint-disable mozilla/valid-lazy */
 /* eslint-disable jsdoc/require-param */

 const lazy = {};
@@ -9,28 +8,15 @@ const lazy = {};
 ChromeUtils.defineESModuleGetters(lazy, {
  ExperimentAPI: "resource://nimbus/ExperimentAPI.sys.mjs",
  ExperimentFakes: "resource://testing-common/NimbusTestUtils.sys.mjs",
-  NimbusFeatures: "resource://nimbus/ExperimentAPI.sys.mjs",
  QuickSuggest: "resource:///modules/QuickSuggest.sys.mjs",
  Region: "resource://gre/modules/Region.sys.mjs",
-  RemoteSettings: "resource://services-settings/remote-settings.sys.mjs",
-  RemoteSettingsConfig: "resource://gre/modules/RustRemoteSettings.sys.mjs",
  RemoteSettingsServer:
    "resource://testing-common/RemoteSettingsServer.sys.mjs",
  SearchUtils: "resource://gre/modules/SearchUtils.sys.mjs",
-  SuggestBackendRust:
-    "resource:///modules/urlbar/private/SuggestBackendRust.sys.mjs",
-  Suggestion: "resource://gre/modules/RustSuggest.sys.mjs",
-  SuggestionProvider: "resource://gre/modules/RustSuggest.sys.mjs",
-  SuggestStore: "resource://gre/modules/RustSuggest.sys.mjs",
-  TelemetryTestUtils: "resource://testing-common/TelemetryTestUtils.sys.mjs",
  TestUtils: "resource://testing-common/TestUtils.sys.mjs",
  UrlbarPrefs: "resource:///modules/UrlbarPrefs.sys.mjs",
-  UrlbarProviderQuickSuggest:
-    "resource:///modules/UrlbarProviderQuickSuggest.sys.mjs",
-  UrlbarProvidersManager: "resource:///modules/UrlbarProvidersManager.sys.mjs",
  UrlbarUtils: "resource:///modules/UrlbarUtils.sys.mjs",
  setTimeout: "resource://gre/modules/Timer.sys.mjs",
-  sinon: "resource://testing-common/Sinon.sys.mjs",
 });

 let gTestScope;
@@ -42,6 +28,7 @@ let gTestScope;
 // xpcshell tests.
 Object.defineProperty(lazy, "UrlbarTestUtils", {
  get: () => {
+    // eslint-disable-next-line mozilla/valid-lazy
    if (!lazy._UrlbarTestUtils) {
      const { UrlbarTestUtils: module } = ChromeUtils.importESModule(
        "resource://testing-common/UrlbarTestUtils.sys.mjs"
@@ -49,10 +36,13 @@ Object.defineProperty(lazy, "UrlbarTestUtils", {
      module.init(gTestScope);
      gTestScope.registerCleanupFunction(() => {
        // Make sure the utils are re-initialized during the next test.
+        // eslint-disable-next-line mozilla/valid-lazy
        lazy._UrlbarTestUtils = null;
      });
+      // eslint-disable-next-line mozilla/valid-lazy
      lazy._UrlbarTestUtils = module;
    }
+    // eslint-disable-next-line mozilla/valid-lazy
    return lazy._UrlbarTestUtils;
  },
 });
@@ -64,6 +54,7 @@ Object.defineProperty(lazy, "UrlbarTestUtils", {
 // xpcshell tests.
 Object.defineProperty(lazy, "MerinoTestUtils", {
  get: () => {
+    // eslint-disable-next-line mozilla/valid-lazy
    if (!lazy._MerinoTestUtils) {
      const { MerinoTestUtils: module } = ChromeUtils.importESModule(
        "resource://testing-common/MerinoTestUtils.sys.mjs"
@@ -71,10 +62,13 @@ Object.defineProperty(lazy, "MerinoTestUtils", {
      module.init(gTestScope);
      gTestScope.registerCleanupFunction(() => {
        // Make sure the utils are re-initialized during the next test.
+        // eslint-disable-next-line mozilla/valid-lazy
        lazy._MerinoTestUtils = null;
      });
+      // eslint-disable-next-line mozilla/valid-lazy
      lazy._MerinoTestUtils = module;
    }
+    // eslint-disable-next-line mozilla/valid-lazy
    return lazy._MerinoTestUtils;
  },
 });
@@ -222,20 +216,8 @@ class _QuickSuggestTestUtils {
    await this.#remoteSettingsServer.start();
    this.#log("ensureQuickSuggestInit", "Remote settings server started");

-    // Get the cached `RemoteSettings` client used by the JS backend and tell it
-    // to ignore signatures and to always force sync. Otherwise it won't sync if
-    // the previous sync was recent enough, which is incompatible with testing.
-    let rs = lazy.RemoteSettings("quicksuggest");
-    let { get, verifySignature } = rs;
-    rs.verifySignature = false;
-    rs.get = opts => get.call(rs, { forceSync: true, ...opts });
-    this.#restoreRemoteSettings = () => {
-      rs.verifySignature = verifySignature;
-      rs.get = get;
-    };
-
-    // Finally, init Suggest and set prefs. Do this after setting up remote
-    // settings because the current backend will immediately try to sync.
+    // Init Suggest and set prefs. Do this after setting up remote settings
+    // because the Rust backend will immediately try to sync.
    this.#log(
      "ensureQuickSuggestInit",
      "Calling QuickSuggest.init() and setting prefs"
@@ -251,7 +233,7 @@ class _QuickSuggestTestUtils {
      serverUrl: this.#remoteSettingsServer.url.toString(),
    });

-    // Wait for the current backend to finish syncing.
+    // Wait for the Rust backend to finish syncing.
    await this.forceSync();

    // Set up Merino. This can happen any time relative to Suggest init.
@@ -279,8 +261,8 @@ class _QuickSuggestTestUtils {
  async #uninitQuickSuggest(prefs, clearDataCollectionEnabled) {
    this.#log("#uninitQuickSuggest", "Started");

-    // Reset prefs, which can cause the current backend to start syncing. Wait
-    // for it to finish.
+    // Reset prefs, which can cause the Rust backend to start syncing. Wait for
+    // it to finish.
    for (let [name] of prefs) {
      lazy.UrlbarPrefs.clear(name);
    }
@@ -288,7 +270,6 @@ class _QuickSuggestTestUtils {

    this.#log("#uninitQuickSuggest", "Stopping remote settings server");
    await this.#remoteSettingsServer.stop();
-    this.#restoreRemoteSettings();

    if (clearDataCollectionEnabled) {
      lazy.UrlbarPrefs.clear("quicksuggest.dataCollection.enabled");
@@ -356,11 +337,6 @@ class _QuickSuggestTestUtils {
      await lazy.QuickSuggest.rustBackend._test_ingest();
      this.#log("forceSync", "Done syncing Rust backend");
    }
-    if (lazy.QuickSuggest.jsBackend.isEnabled) {
-      this.#log("forceSync", "Syncing JS backend");
-      await lazy.QuickSuggest.jsBackend._test_syncAll();
-      this.#log("forceSync", "Done syncing JS backend");
-    }
    this.#log("forceSync", "Done");
  }

@@ -378,7 +354,7 @@ class _QuickSuggestTestUtils {
   * @see {@link setConfig}
   */
  async withConfig({ config, callback }) {
-    let original = lazy.QuickSuggest.jsBackend.config;
+    let original = lazy.QuickSuggest.config;
    await this.setConfig(config);
    await callback();
    await this.setConfig(original);
@@ -413,15 +389,14 @@ class _QuickSuggestTestUtils {

  /**
   * Returns an expected AMP (sponsored) result that can be passed to
-   * `check_results()` in xpcshell tests regardless of whether the Rust backend
-   * is enabled.
+   * `check_results()` in xpcshell tests.
   *
   * @returns {object}
   *   An object that can be passed to `check_results()`.
   */
  ampResult({
-    source,
-    provider,
+    source = "rust",
+    provider = "Amp",
    keyword = "amp",
    fullKeyword = keyword,
    title = "Amp Suggestion",
@@ -452,6 +427,8 @@ class _QuickSuggestTestUtils {
        url,
        originalUrl,
        requestId,
+        source,
+        provider,
        displayUrl: url.replace(/^https:\/\//, ""),
        isSponsored: true,
        qsSuggestion: fullKeyword ?? keyword,
@@ -473,17 +450,9 @@ class _QuickSuggestTestUtils {
      result.payload.descriptionL10n = descriptionL10n;
    }

-    if (lazy.UrlbarPrefs.get("quickSuggestRustEnabled")) {
-      result.payload.source = source || "rust";
-      result.payload.provider = provider || "Amp";
-      if (result.payload.source == "rust") {
-        result.payload.iconBlob = iconBlob;
-      } else {
-        result.payload.icon = icon;
-      }
+    if (result.payload.source == "rust") {
+      result.payload.iconBlob = iconBlob;
    } else {
-      result.payload.source = source || "remote-settings";
-      result.payload.provider = provider || "AdmWikipedia";
      result.payload.icon = icon;
    }

@@ -519,31 +488,24 @@ class _QuickSuggestTestUtils {

  /**
   * Returns an expected Wikipedia (non-sponsored) result that can be passed to
-   * `check_results()` in xpcshell tests regardless of whether the Rust backend
-   * is enabled.
+   * `check_results()` in xpcshell tests.
   *
   * @returns {object}
   *   An object that can be passed to `check_results()`.
   */
  wikipediaResult({
-    source,
-    provider,
+    source = "rust",
+    provider = "Wikipedia",
    keyword = "wikipedia",
    fullKeyword = keyword,
    title = "Wikipedia Suggestion",
    url = "https://example.com/wikipedia",
    originalUrl = url,
-    icon = null,
    iconBlob = null,
-    impressionUrl = "https://example.com/wikipedia-impression",
-    clickUrl = "https://example.com/wikipedia-click",
-    blockId = 2,
-    advertiser = "Wikipedia",
-    iabCategory = "5 - Education",
    suggestedIndex = -1,
    isSuggestedIndexRelativeToGroup = true,
  } = {}) {
-    let result = {
+    return {
      suggestedIndex,
      isSuggestedIndexRelativeToGroup,
      type: lazy.UrlbarUtils.RESULT_TYPE.URL,
@@ -553,6 +515,9 @@ class _QuickSuggestTestUtils {
        title,
        url,
        originalUrl,
+        iconBlob,
+        source,
+        provider,
        displayUrl: url.replace(/^https:\/\//, ""),
        isSponsored: false,
        qsSuggestion: fullKeyword ?? keyword,
@@ -566,23 +531,6 @@ class _QuickSuggestTestUtils {
        telemetryType: "adm_nonsponsored",
      },
    };
-
-    if (lazy.UrlbarPrefs.get("quickSuggestRustEnabled")) {
-      result.payload.source = source || "rust";
-      result.payload.provider = provider || "Wikipedia";
-      result.payload.iconBlob = iconBlob;
-    } else {
-      result.payload.source = source || "remote-settings";
-      result.payload.provider = provider || "AdmWikipedia";
-      result.payload.icon = icon;
-      result.payload.sponsoredImpressionUrl = impressionUrl;
-      result.payload.sponsoredClickUrl = clickUrl;
-      result.payload.sponsoredBlockId = blockId;
-      result.payload.sponsoredAdvertiser = advertiser;
-      result.payload.sponsoredIabCategory = iabCategory;
-    }
-
-    return result;
  }

  /**
@@ -847,15 +795,14 @@ class _QuickSuggestTestUtils {

  /**
   * Returns an expected AMO (addons) result that can be passed to
-   * `check_results()` in xpcshell tests regardless of whether the Rust backend
-   * is enabled.
+   * `check_results()` in xpcshell tests.
   *
   * @returns {object}
   *   An object that can be passed to `check_results()`.
   */
  amoResult({
-    source,
-    provider,
+    source = "rust",
+    provider = "Amo",
    title = "Amo Suggestion",
    description = "Amo description",
    url = "https://example.com/amo",
@@ -870,7 +817,7 @@ class _QuickSuggestTestUtils {
      url = url.href;
    }

-    let result = {
+    return {
      isBestMatch: true,
      suggestedIndex: 1,
      type: lazy.UrlbarUtils.RESULT_TYPE.URL,
@@ -891,21 +838,11 @@ class _QuickSuggestTestUtils {
        telemetryType: "amo",
      },
    };
-
-    if (lazy.UrlbarPrefs.get("quickSuggestRustEnabled")) {
-      result.payload.source = source || "rust";
-      result.payload.provider = provider || "Amo";
-    } else {
-      result.payload.source = source || "remote-settings";
-      result.payload.provider = provider || "AddonSuggestions";
-    }
-
-    return result;
  }

  /**
   * Returns an expected MDN result that can be passed to `check_results()` in
-   * xpcshell tests regardless of whether the Rust backend is enabled.
+   * xpcshell tests.
   *
   * @returns {object}
   *   An object that can be passed to `check_results()`.
@@ -920,7 +857,7 @@ class _QuickSuggestTestUtils {
    );
    finalUrl.searchParams.set("utm_content", "treatment");

-    let result = {
+    return {
      isBestMatch: true,
      suggestedIndex: 1,
      type: lazy.UrlbarUtils.RESULT_TYPE.URL,
@@ -936,33 +873,24 @@ class _QuickSuggestTestUtils {
        icon: "chrome://global/skin/icons/mdn.svg",
        shouldShowUrl: true,
        bottomTextL10n: { id: "firefox-suggest-mdn-bottom-text" },
+        source: "rust",
+        provider: "Mdn",
      },
    };
-
-    if (lazy.UrlbarPrefs.get("quickSuggestRustEnabled")) {
-      result.payload.source = "rust";
-      result.payload.provider = "Mdn";
-    } else {
-      result.payload.source = "remote-settings";
-      result.payload.provider = "MDNSuggestions";
-    }
-
-    return result;
  }

  /**
   * Returns an expected weather result that can be passed to `check_results()`
-   * in xpcshell tests regardless of whether the Rust backend is enabled.
+   * in xpcshell tests.
   *
   * @returns {object}
   *   An object that can be passed to `check_results()`.
   */
  weatherResult({
-    source,
-    provider,
+    source = "rust",
+    provider = "Weather",
    city = null,
    region = null,
-    telemetryType = undefined,
    temperatureUnit = undefined,
  } = {}) {
    if (!temperatureUnit) {
@@ -970,19 +898,19 @@ class _QuickSuggestTestUtils {
        Services.locale.regionalPrefsLocales[0] == "en-US" ? "f" : "c";
    }

-    let result = {
+    return {
      type: lazy.UrlbarUtils.RESULT_TYPE.DYNAMIC,
      source: lazy.UrlbarUtils.RESULT_SOURCE.SEARCH,
      heuristic: false,
      suggestedIndex: 1,
      payload: {
        temperatureUnit,
+        source,
+        provider,
        url: lazy.MerinoTestUtils.WEATHER_SUGGESTION.url,
        input: lazy.MerinoTestUtils.WEATHER_SUGGESTION.url,
        iconId: "6",
        requestId: lazy.MerinoTestUtils.server.response.body.request_id,
-        source: "merino",
-        provider: "accuweather",
        dynamicType: "weather",
        city: city || lazy.MerinoTestUtils.WEATHER_SUGGESTION.city_name,
        region: region || lazy.MerinoTestUtils.WEATHER_SUGGESTION.region_code,
@@ -998,20 +926,9 @@ class _QuickSuggestTestUtils {
        low: lazy.MerinoTestUtils.WEATHER_SUGGESTION.forecast.low[
          temperatureUnit
        ],
+        telemetryType: "weather",
      },
    };
-
-    if (lazy.UrlbarPrefs.get("quickSuggestRustEnabled")) {
-      result.payload.source = source || "rust";
-      result.payload.provider = provider || "Weather";
-      if (telemetryType !== null) {
-        result.payload.telemetryType = telemetryType || "weather";
-      }
-    } else {
-      throw new Error("Weather result not supported when Rust disabled");
-    }
-
-    return result;
  }

  /**
@@ -1437,7 +1354,6 @@ class _QuickSuggestTestUtils {
  }

  #remoteSettingsServer;
-  #restoreRemoteSettings;
 }

 export var QuickSuggestTestUtils = new _QuickSuggestTestUtils();
@@ -93,10 +93,7 @@ async function doOneBasicBlockTest({ result, block }) {
  // The suggested index is -1 even for sponsored since search suggestions are
  // disabled.
  let suggested_index = -1;
-  let expectedBlockId =
-    UrlbarPrefs.get("quicksuggest.rustEnabled") && !isSponsored
-      ? null
-      : result.id;
+  let expectedBlockId = !isSponsored ? null : result.id;

  let pingsSubmitted = 0;
  GleanPings.quickSuggest.testBeforeNextSubmit(() => {
@@ -48,10 +48,7 @@ add_task(async function basic() {
      UrlbarProviderQuickSuggest.name,
      "The result should be from the expected provider"
    );
-    Assert.equal(
-      result.payload.provider,
-      UrlbarPrefs.get("quickSuggestRustEnabled") ? "Mdn" : "MDNSuggestions"
-    );
+    Assert.equal(result.payload.provider, "Mdn");

    const onLoad = BrowserTestUtils.browserLoaded(
      gBrowser.selectedBrowser,
@@ -27,7 +27,6 @@ add_setup(async function () {
  await QuickSuggestTestUtils.ensureQuickSuggestInit({
    remoteSettingsRecords: REMOTE_SETTINGS_RECORDS,
    prefs: [
-      ["quicksuggest.rustEnabled", true],
      ["suggest.quicksuggest.sponsored", true],
      ["suggest.yelp", true],
      ["yelp.featureGate", true],
@@ -39,10 +39,7 @@ add_task(async function nonsponsored() {
  let match_type = "firefox-suggest";
  let advertiser = REMOTE_SETTINGS_RESULT.advertiser.toLowerCase();
  let reporting_url = undefined;
-  let source = UrlbarPrefs.get("quicksuggest.rustEnabled")
-    ? "rust"
-    : "remote-settings";
-  let block_id = source == "rust" ? undefined : REMOTE_SETTINGS_RESULT.id;
+  let source = "rust";

  // Make sure `improve_suggest_experience_checked` is recorded correctly
  // depending on the value of the related pref.
@@ -66,7 +63,6 @@ add_task(async function nonsponsored() {
            source,
            match_type,
            position,
-            block_id,
            advertiser,
            reporting_url,
            suggested_index: -1,
@@ -85,7 +81,6 @@ add_task(async function nonsponsored() {
              source,
              match_type,
              position,
-              block_id,
              advertiser,
              reporting_url,
              suggested_index: -1,
@@ -100,7 +95,6 @@ add_task(async function nonsponsored() {
              source,
              match_type,
              position,
-              block_id,
              advertiser,
              reporting_url,
              suggested_index: -1,
@@ -121,7 +115,6 @@ add_task(async function nonsponsored() {
                source,
                match_type,
                position,
-                block_id,
                advertiser,
                reporting_url,
                suggested_index: -1,
@@ -136,7 +129,6 @@ add_task(async function nonsponsored() {
                source,
                match_type,
                position,
-                block_id,
                advertiser,
                suggested_index: -1,
                suggested_index_relative_to_group: true,
@@ -156,7 +148,6 @@ add_task(async function nonsponsored() {
                source,
                match_type,
                position,
-                block_id,
                advertiser,
                reporting_url,
                suggested_index: -1,
@@ -40,9 +40,7 @@ add_setup(async function () {
 // sponsored
 add_task(async function sponsored() {
  let match_type = "firefox-suggest";
-  let source = UrlbarPrefs.get("quicksuggest.rustEnabled")
-    ? "rust"
-    : "remote-settings";
+  let source = "rust";

  // Make sure `improve_suggest_experience_checked` is recorded correctly
  // depending on the value of the related pref.
@@ -171,9 +169,7 @@ add_task(async function sponsored() {
 // higher-placement sponsored, a.k.a sponsored priority, sponsored best match
 add_task(async function sponsoredBestMatch() {
  let match_type = "best-match";
-  let source = UrlbarPrefs.get("quicksuggest.rustEnabled")
-    ? "rust"
-    : "remote-settings";
+  let source = "rust";

  await SpecialPowers.pushPrefEnv({
    set: [["browser.urlbar.quicksuggest.sponsoredPriority", true]],
@@ -502,8 +502,6 @@ async function doOneShowLessFrequentlyTest({
 *     The order doesn't matter.
 */
 async function doRustProvidersTests({ searchString, tests }) {
-  UrlbarPrefs.set("quicksuggest.rustEnabled", true);
-
  for (let { prefs, expectedUrls } of tests) {
    info(
      "Starting Rust providers test: " + JSON.stringify({ prefs, expectedUrls })
@@ -531,8 +529,4 @@ async function doRustProvidersTests({ searchString, tests }) {
    }
    await QuickSuggestTestUtils.forceSync();
  }
-
-  info("Clearing rustEnabled pref and forcing sync");
-  UrlbarPrefs.clear("quicksuggest.rustEnabled");
-  await QuickSuggestTestUtils.forceSync();
 }
@@ -672,7 +672,7 @@ add_task(async function maxResults() {
  await QuickSuggestTestUtils.forceSync();

  let searchString = "maxresults";
-  let suggestions = await QuickSuggest.backend.query(searchString);
+  let suggestions = await QuickSuggest.rustBackend.query(searchString);
  Assert.equal(
    suggestions.length,
    gMaxResultsSuggestionsCount,
@@ -784,7 +784,7 @@ async function doManySuggestResultsTest({

  // Make sure many Suggest suggestions match the search string.
  let searchString = "maxresults";
-  let suggestions = await QuickSuggest.backend.query(searchString);
+  let suggestions = await QuickSuggest.rustBackend.query(searchString);
  Assert.equal(
    suggestions.length,
    gMaxResultsSuggestionsCount,
@@ -75,10 +75,9 @@ add_task(async function basic() {
        providers: [UrlbarProviderQuickSuggest.name],
        isPrivate: false,
      }),
-      matches:
-        UrlbarPrefs.get("quickSuggestRustEnabled") && !fullKeyword.includes(" ")
-          ? [QuickSuggestTestUtils.mdnResult(suggestion)]
-          : [],
+      matches: !fullKeyword.includes(" ")
+        ? [QuickSuggestTestUtils.mdnResult(suggestion)]
+        : [],
    });
  }
 });
@@ -479,17 +479,10 @@ function makeExpectedResult({
  searchString,
  fullKeyword = searchString,
  suggestion = REMOTE_SETTINGS_DATA[0].attachment[0],
-  source = "remote-settings",
+  source = "rust",
  isTopPick = false,
  suggestedIndex,
 } = {}) {
-  if (
-    source == "remote-settings" &&
-    UrlbarPrefs.get("quicksuggest.rustEnabled")
-  ) {
-    source = "rust";
-  }
-
  let provider;
  let keywordSubstringNotTyped = fullKeyword.substring(searchString.length);
  let description = suggestion.description;
@@ -277,6 +277,5 @@ add_task(async function manyExposureResults_hidden_manyMatched() {
 });

 function suggestResultType(typeWithoutSource) {
-  let source = UrlbarPrefs.get("quickSuggestRustEnabled") ? "rust" : "rs";
-  return `${source}_${typeWithoutSource}`;
+  return `rust_${typeWithoutSource}`;
 }
@@ -467,12 +467,6 @@ urlbar:
    quickSuggestRemoteSettingsDataType:
      type: string
      description: The `type` of the suggestions data in remote settings. If not specified, "data" is used.
-    quickSuggestRustEnabled:
-      type: boolean
-      fallbackPref: browser.urlbar.quicksuggest.rustEnabled
-      description: >-
-        Whether Firefox Suggest will use the new Rust backend instead of the
-        original JS backend.
    quickSuggestScenario:
      # IMPORTANT: This should not have a fallbackPref. See UrlbarPrefs.sys.mjs.
      type: string