Adding upstream version 125.0.1.upstream/125.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

10 files changed, 635 insertions, 194 deletions

diff --git a/toolkit/components/nimbus/FeatureManifest.yaml b/toolkit/components/nimbus/FeatureManifest.yaml
index 746ac4738d..190e29d6db 100644
--- a/toolkit/components/nimbus/FeatureManifest.yaml
+++ b/toolkit/components/nimbus/FeatureManifest.yaml
@@ -2,6 +2,8 @@
 # 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/.
 
+# yaml-language-server: $schema=schemas/ExperimentFeatureManifest.schema.json
+
 # Features must be added here to be accessible through the NimbusFeature API.
 
 "no-feature-firefox-desktop":
@@ -51,7 +53,6 @@ nimbus-qa-1:
 nimbus-qa-2:
   description: A feature for testing pref-setting on the user branch.
   owner: barret@mozilla.com
-  isEarlyStartup: true
   hasExposure: false
   variables:
     value:
@@ -315,7 +316,7 @@ urlbar:
         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.jsm.
+      # IMPORTANT: This should not have a fallbackPref. See UrlbarPrefs.sys.mjs.
       type: string
       description: The Firefox Suggest scenario in which the user is enrolled
       enum:
@@ -421,6 +422,11 @@ urlbar:
         If neither Nimbus nor remote settings defines a cap, no cap will be
         used, and the user will be able to increment the minimum length without
         any limit.
+    weatherSimpleUI:
+      type: boolean
+      description: >-
+        If true, show the weather suggestion by simple UI edition as follows.
+        * Remove the forcast text from the summary text.
     yelpMinKeywordLength:
       type: int
       fallbackPref: browser.urlbar.yelp.minKeywordLength
@@ -567,6 +573,13 @@ aboutwelcome:
       fallbackPref: browser.aboutwelcome.newtabUrlBarFocus
       description: >-
         Should the urlbar be focused when the new tab page loads after new user onboarding
+    toolbarButtonEnabled:
+      type: boolean
+      setPref:
+        branch: user
+        pref: browser.aboutwelcome.toolbarButtonEnabled
+      description: >-
+        Should the return to about:welcome toolbar button be shown
 
 moreFromMozilla:
   description: "New page on about:preferences to suggest more Mozilla products"
@@ -604,7 +617,6 @@ windowsJumpList:
   description: "Controls for the Windows Jump List integration."
   owner: mconley@mozilla.com
   hasExposure: false
-  isEarlyStartup: true
   variables:
     legacyBackend:
       type: boolean
@@ -862,10 +874,15 @@ pocketNewtab:
       fallbackPref: >-
         browser.newtabpage.activity-stream.discoverystream.ctaButtonSponsors
     ctaButtonVariant:
-      description: Specifies which veriant to use for any sponsors in ctaButtonSponsors
+      description: Specifies which variant to use for any sponsors in ctaButtonSponsors
       type: string
       fallbackPref: >-
         browser.newtabpage.activity-stream.discoverystream.ctaButtonVariant
+    spocMessageVariant:
+      description: Adds some message dialogs explainging sponsored content to the user
+      type: string
+      fallbackPref: >-
+        browser.newtabpage.activity-stream.discoverystream.spocMessageVariant
     regionStoriesConfig:
       description: A comma-separated list of region to get stories for.
       type: string
@@ -1064,7 +1081,6 @@ fullPageTranslation:
   description: This feature opens a popup panel to offer to translate a page.
   owner: gtatum@mozilla.com
   hasExposure: false
-  isEarlyStartup: true
   variables:
     boolean:
       description: Set to true to enable the translations feature
@@ -1077,7 +1093,6 @@ fullPageTranslationAutomaticPopup:
   description: Controls whether the popup automatically shows for translations.
   owner: gtatum@mozilla.com
   hasExposure: false
-  isEarlyStartup: true
   variables:
     boolean:
       description: Set to true to automatically popup, and false to only show the button.
@@ -1246,6 +1261,26 @@ fxms-message-11:
     path: "browser/components/asrouter/content-src/schemas/MessagingExperiment.schema.json"
   variables: {}
 
+whatsNewPage:
+  description: "A Firefox Messaging System message for the What's new page channel"
+  owner: omc@mozilla.com
+  hasExposure: true
+  exposureDescription: >-
+    "Exposure is sent if the message is about to be shown after trigger and targeting conditions on the message matched."
+  variables:
+    overrideUrl:
+      description: URL of the What's new page
+      type: string
+      setPref:
+        branch: user
+        pref: startup.homepage_override_url_nimbus
+    maxVersion:
+      description: Maximum Firefox update version
+      type: string
+      setPref:
+        branch: user
+        pref: startup.homepage_override_nimbus_maxVersion
+
 pbNewtab:
   description: "A Firefox Messaging System message for the pbNewtab message channel"
   owner: omc@mozilla.com
@@ -1325,6 +1360,7 @@ glean:
 
 gleanInternalSdk:
   description: "The Glean internal SDK feature intended only for internal Glean Team use"
+  owner: glean-team@mozilla.com
   hasExposure: false
   # Some variables are used through the C++ API and thus require pref-storage.
   # We rely on those values at Glean.init time, which happens at startup.
@@ -1664,7 +1700,6 @@ fxaButtonVisibility:
   description: Prefs to control the visibility of the Firefox Accounts toolbar button when not signed in.
   owner: mconley@mozilla.com
   hasExposure: false
-  isEarlyStartup: true
   variables:
     boolean:
       description: True if the Firefox Accounts toolbar button should be visible when not signed in.
@@ -1802,7 +1837,6 @@ migrationWizard:
   description: Prefs to control the Migration Wizard UI.
   owner: mconley@mozilla.com
   hasExposure: false
-  isEarlyStartup: true
   variables:
     showImportAll:
       description: True if the "Variant 2" of the Migration Wizard browser / profile selection UI should be used. This is only meaningful in the new Migration Wizard.
@@ -1891,36 +1925,205 @@ mixedContentUpgrading:
         branch: default
         pref: security.mixed_content.upgrade_display_content.video
 
-jsParallelParsing:
-  description: Pref to toggle JS parallel parsing.
-  owner: dpalmeiro@mozilla.com, nbp@mozilla.com
-  isEarlyStartup: true
+gc:
+  description: Prefs that control gc heuristics.
+  owner: dpalmeiro@mozilla.com
   hasExposure: false
   variables:
-    enabled:
-      description: True to enable parallel parsing.
+    max_nursery_size:
+      description: Set the maximum size of the GC nursery, in kb.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.nursery.max_kb"
+    min_nursery_size:
+      description: Set the minimum size of the GC nursery, in kb.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.nursery.min_kb"
+    gc_allocation_threshold_mb:
+      description: Lower limit for collecting a zone, in MB.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_allocation_threshold_mb"
+    gc_balanced_heap_limits:
+      description: Whether balanced heap limits are enabled.
       type: boolean
       setPref:
         branch: user
-        pref: "javascript.options.parallel_parsing"
+        pref: "javascript.options.mem.gc_balanced_heap_limits"
+    gc_compacting:
+      description: Whether compacting GC is enabled.
+      type: boolean
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_compacting"
+    gc_heap_growth_factor:
+      description: Heap growth parameter for balanced heap limit calculation.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_heap_growth_factor"
+    gc_helper_thread_ratio:
+      description: Number of threads to use for parallel GC work.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_helper_thread_ratio"
+    gc_high_frequency_large_heap_growth:
+      description: Heap growth factor for large heaps in the high-frequency GC state.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_high_frequency_large_heap_growth"
+    gc_high_frequency_small_heap_growth:
+      description: Heap growth factor for small heaps in the high-frequency GC state.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_high_frequency_small_heap_growth"
+    gc_high_frequency_time_limit_ms:
+      description: GCs less than this far apart in milliseconds will be
+                   considered high-frequency GCs.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_high_frequency_time_limit_ms"
+    gc_incremental:
+      description: Whether incremental GC is enabled. If not, GC will always run to completion.
+      type: boolean
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_incremental"
+    incremental_weakmap:
+      description: Enable incremental weakmap marking.
+      type: boolean
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.incremental_weakmap"
+    gc_incremental_slice_ms:
+      description: Max milliseconds to spend in an incremental GC slice.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_incremental_slice_ms"
+    gc_large_heap_incremental_limit:
+      description: Limit of how far over the incremental trigger threshold we allow the
+                   heap to grow before finishing a collection non-incrementally, for large heaps.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_large_heap_incremental_limit"
+    gc_large_heap_size_min_mb:
+      description: Lower limit for classifying a heap as large, in MB.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_large_heap_size_min_mb"
+    gc_low_frequency_heap_growth:
+      description: Heap growth factor for low frequency GCs.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_low_frequency_heap_growth"
+    gc_malloc_threshold_base_mb:
+      description: Set the malloc threshold base value in MB.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_malloc_threshold_base_mb"
+    gc_max_empty_chunk_count:
+      description: Do not keep more than this many unused chunks in the free chunk pool.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_max_empty_chunk_count"
+    gc_max_helper_threads:
+      description: The maximum number of background threads to use for parallel GC work.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_max_helper_threads"
+    gc_min_empty_chunk_count:
+      description: We try to keep at least this many unused chunks in the free chunk
+                   pool at all times, even after a shrinking GC.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_min_empty_chunk_count"
+    gc_parallel_marking:
+      description: Enable parallel marking.
+      type: boolean
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_parallel_marking"
+    gc_parallel_marking_threshold_mb:
+      description: The heap size above which to use parallel marking.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_parallel_marking_threshold_mb"
+    gc_per_zone:
+      description: Whether per-zone GC is enabled. If not, all zones are collected every time.
+      type: boolean
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_per_zone"
+    gc_small_heap_incremental_limit:
+      description: Limit of how far over the incremental trigger threshold we allow the heap
+                   to grow before finishing a collection non-incrementally, for small heaps.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_small_heap_incremental_limit"
+    gc_small_heap_size_max_mb:
+      description: Upper limit for classifying a heap as small, in MB.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_small_heap_size_max_mb"
+    gc_urgent_threshold_mb:
+      description: Set the urgent threshold, in MB.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.gc_urgent_threshold_mb"
+    nursery_eager_collection_threshold_kb:
+      description: Set the eager collection threshold, in kb, for the nursery.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.nursery_eager_collection_threshold_kb"
+    nursery_eager_collection_threshold_percent:
+      description: Set the eager collection percent threshold for the nursery.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.nursery_eager_collection_threshold_percent"
+    nursery_eager_collection_timeout_ms:
+      description: Set the eager collection timeout, in ms, for the nursery.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.nursery_eager_collection_timeout_ms"
 
-gcParallelMarking:
-  description: Pref to toggle parallel marking in the GC.
-  owner: dpalmeiro@mozilla.com, jonco@mozilla.com
-  isEarlyStartup: true
+jsParallelParsing:
+  description: Pref to toggle JS parallel parsing.
+  owner: dpalmeiro@mozilla.com, nbp@mozilla.com
   hasExposure: false
   variables:
     enabled:
-      description: True to enable parallel marking.
+      description: True to enable parallel parsing.
       type: boolean
       setPref:
         branch: user
-        pref: "javascript.options.mem.gc_parallel_marking"
+        pref: "javascript.options.parallel_parsing"
 
 jitThresholds:
   description: Prefs that control jit tier thresholds.
   owner: dpalmeiro@mozilla.com, jdemooij@mozilla.com
-  isEarlyStartup: true
   hasExposure: false
   variables:
     blinterp_threshold:
@@ -1963,7 +2166,6 @@ jitThresholds:
 jitHintsCache:
   description: Pref to toggle the JIT hints cache.
   owner: dpalmeiro@mozilla.com
-  isEarlyStartup: true
   hasExposure: false
   variables:
     enabled:
@@ -1997,17 +2199,6 @@ httpSpeculativeParallelLimit:
         branch: default
         pref: "network.http.speculative-parallel-limit"
 
-deviceMigration:
-  description: Prefs to control aspects of the new device migration experiment
-  owner: hjones@mozilla.com
-  hasExposure: false
-  isEarlyStartup: true
-  variables:
-    helpMenuHidden:
-      description: True if new help menu item should be hidden
-      type: boolean
-      fallbackPref: browser.device-migration.help-menu.hidden
-
 shopping2023:
   description: Prefs to control the 2023 shopping experiment.
   owner: jhirsch@mozilla.com
@@ -2069,7 +2260,6 @@ shoppingOHTTP:
 opaqueResponseBlocking:
   description: Prefs to enable Opaque Response Blocking
   owner: farre@mozilla.com
-  isEarlyStartup: true
   hasExposure: true
   exposureDescription: Exposure is sent when a response is blocked
   variables:
@@ -2124,7 +2314,6 @@ powerSaver:
   description: Prefs to control power saving behaviors
   owner: florian@mozilla.com
   hasExposure: false
-  isEarlyStartup: true
   variables:
     reduceFrameRates:
       type: int
@@ -2165,7 +2354,6 @@ backgroundUpdate:
     feature is enabled and the service registry key (Mozilla Maintenance
     Service) is *not* available for this installation. That is the first time
     the feature can impact Firefox behaviour and the user experience.
-  isEarlyStartup: true
   variables:
     enableUpdatesForUnelevatedInstallations:
       description: >-
@@ -2174,7 +2362,7 @@ backgroundUpdate:
         directory can be written.
       type: boolean
       setPref:
-        branch: default
+        branch: user
         pref: app.update.background.allowUpdatesForUnelevatedInstallations
 
 defaultAgent:
@@ -2195,7 +2383,6 @@ bookmarks:
   description: Prefs to control aspects of the bookmarks system.
   owner: omc@mozilla.com
   hasExposure: false
-  isEarlyStartup: true
   variables:
     enableBookmarksToolbar:
       type: string
@@ -2274,7 +2461,6 @@ backgroundThreads:
   description: Prefs to control MacOS thread priorities for power savings.
   owner: kwright@mozilla.com
   hasExposure: false
-  isEarlyStartup: true
   variables:
     use_low_power:
       description: >-
@@ -2293,9 +2479,9 @@ backgroundThreads:
         pref: threads.lower_mainthread_priority_in_background.enabled
 
 reportBrokenSite:
-  description: the Report Broken Site feature
+  description: The Report Broken Site feature
+  owner: twisniewski@mozilla.com
   hasExposure: false
-  isEarlyStartup: true
   variables:
     enabled:
       type: boolean
@@ -2348,7 +2534,6 @@ phc:
   description: Prefs to control the Probabalistic Heap Checker (PHC)
   owner: pbone@mozilla.com
   hasExposure: false
-  isEarlyStartup: true
   variables:
     phcEnabled:
       description: Whether to enable PHC
@@ -2413,3 +2598,53 @@ nimbusIsReady:
     eventCount:
       description: The number of events that should be sent.
       type: int
+
+nimbusTelemetry:
+  description: A feature that enables or disables Nimbus telemetry.
+  owner: chumphreys@mozilla.com
+  hasExposure: false
+  applications:
+    - firefox-desktop
+  variables:
+    gleanMetricConfiguration:
+      description: A Glean metric configuration JSON blob.
+      type: json
+
+httpsFirst:
+  description: >-
+    Prefs for HTTPS-First, which upgrades all top-level page loads to HTTPS and
+    provides a automatic fallback to HTTP if the site isn't available via HTTPS.
+  owner: mjurgens@mozilla.com, seceng-telemetry@mozilla.com
+  hasExposure: false
+  variables:
+    enabled:
+      description: Enable HTTPS-First
+      type: boolean
+      setPref:
+        branch: default
+        pref: dom.security.https_first
+    enabledPbm:
+      description: Enable HTTPS-First in private browsing only
+      type: boolean
+      setPref:
+        branch: default
+        pref: dom.security.https_first_pbm
+    enabledSchemeless:
+      description: >-
+        Enables schemeless HTTPS-First, which will only apply HTTPS-First to address
+        bar inputs without a scheme. This essentially makes HTTPS the default
+        scheme in the address bar, while providing a fallback to HTTP.
+      type: boolean
+      setPref:
+        branch: default
+        pref: dom.security.https_first_schemeless
+    backgroundTimerMs:
+      description: >-
+        After a request gets upgraded to HTTPS, specifies the time after which a
+        second HTTP request is fired to check if the site is available via
+        HTTPS, but timing out via HTTPS. This also applies to HTTPS-Only, not
+        just HTTPS-First.
+      type: int
+      setPref:
+        branch: default
+        pref: dom.security.https_only_fire_http_request_background_timer_ms
diff --git a/toolkit/components/nimbus/generate/generate_feature_manifest.py b/toolkit/components/nimbus/generate/generate_feature_manifest.py
index c17f320184..14057493c5 100644
--- a/toolkit/components/nimbus/generate/generate_feature_manifest.py
+++ b/toolkit/components/nimbus/generate/generate_feature_manifest.py
@@ -14,7 +14,7 @@ HEADER_LINE = (
     " DO NOT EDIT.\n"
 )
 
-FEATURE_MANIFEST_SCHEMA = Path("schemas", "ExperimentFeatureManifest.schema.json")
+FEATURE_SCHEMA = Path("schemas", "ExperimentFeature.schema.json")
 
 NIMBUS_FALLBACK_PREFS = (
     "constexpr std::pair<nsLiteralCString, nsLiteralCString>"
@@ -26,36 +26,17 @@ NIMBUS_FALLBACK_PREFS = (
 ALLOWED_ISEARLYSTARTUP_FEATURE_IDS = {
     "abouthomecache",
     "aboutwelcome",
-    "backgroundThreads",
-    "backgroundUpdate",
-    "bookmarks",
     "dapTelemetry",
-    "deviceMigration",
-    "frecency",
-    "fullPageTranslation",
-    "fullPageTranslationAutomaticPopup",
-    "fxaButtonVisibility",
-    "gcParallelMarking",
     "gleanInternalSdk",
-    "jitHintsCache",
-    "jitThresholds",
-    "jsParallelParsing",
     "majorRelease2022",
-    "migrationWizard",
     "newtab",
-    "nimbus-qa-2",
-    "opaqueResponseBlocking",
-    "phc",
     "pocketNewtab",
-    "powerSaver",
-    "reportBrokenSite",
     "saveToPocket",
     "searchConfiguration",
     "shellService",
     "testFeature",
     "updatePrompt",
     "upgradeDialog",
-    "windowsJumpList",
 }
 
 
@@ -91,7 +72,7 @@ def validate_feature_manifest(schema_path, manifest_path, manifest):
                         f"Feature {feature_id} is not early startup but is in the allow list."
                     )
                     print("Please remove it from generate_feature_manifest.py")
-                raise Exception("isEarlyStatup is deprecated")
+                raise Exception("isEarlyStartup is deprecated")
 
             for variable, variable_def in feature.get("variables", {}).items():
                 set_pref = variable_def.get("setPref")
@@ -158,7 +139,7 @@ def generate_feature_manifest(fd, input_file):
             manifest = yaml.safe_load(f)
 
         validate_feature_manifest(
-            Path(input_file).parent / FEATURE_MANIFEST_SCHEMA, input_file, manifest
+            Path(input_file).parent / FEATURE_SCHEMA, input_file, manifest
         )
 
         fd.write(f"export const FeatureManifest = {json.dumps(manifest)};")
diff --git a/toolkit/components/nimbus/lib/ExperimentManager.sys.mjs b/toolkit/components/nimbus/lib/ExperimentManager.sys.mjs
index 8e1acc4803..d0f313a2ae 100644
--- a/toolkit/components/nimbus/lib/ExperimentManager.sys.mjs
+++ b/toolkit/components/nimbus/lib/ExperimentManager.sys.mjs
@@ -32,6 +32,25 @@ const STUDIES_OPT_OUT_PREF = "app.shield.optoutstudies.enabled";
 
 const STUDIES_ENABLED_CHANGED = "nimbus:studies-enabled-changed";
 
+const ENROLLMENT_STATUS = {
+  ENROLLED: "Enrolled",
+  NOT_ENROLLED: "NotEnrolled",
+  DISQUALIFIED: "Disqualified",
+  WAS_ENROLLED: "WasEnrolled",
+  ERROR: "Error",
+};
+
+const ENROLLMENT_STATUS_REASONS = {
+  QUALIFIED: "Qualified",
+  OPT_IN: "OptIn",
+  OPT_OUT: "OptOut",
+  NOT_SELECTED: "NotSelected",
+  NOT_TARGETED: "NotTargeted",
+  ENROLLMENTS_PAUSED: "EnrollmentsPaused",
+  FEATURE_CONFLICT: "FeatureConflict",
+  ERROR: "Error",
+};
+
 function featuresCompat(branch) {
   if (!branch || (!branch.feature && !branch.features)) {
     return [];
@@ -182,6 +201,14 @@ export class _ExperimentManager {
     }
 
     this.observe();
+
+    lazy.NimbusFeatures.nimbusTelemetry.onUpdate(() => {
+      const cfg =
+        lazy.NimbusFeatures.nimbusTelemetry.getVariable(
+          "gleanMetricConfiguration"
+        ) ?? {};
+      Services.fog.setMetricsFeatureConfig(JSON.stringify(cfg));
+    });
   }
 
   /**
@@ -223,16 +250,22 @@ export class _ExperimentManager {
     missingL10nIds
   ) {
     for (const enrollment of enrollments) {
-      const { slug, source } = enrollment;
+      const { slug, source, branch } = enrollment;
       if (sourceToCheck !== source) {
         continue;
       }
+      const statusTelemetry = {
+        slug,
+        branch: branch.slug,
+      };
       if (!this.sessions.get(source)?.has(slug)) {
         lazy.log.debug(`Stopping study for recipe ${slug}`);
         try {
           let reason;
           if (recipeMismatches.includes(slug)) {
             reason = "targeting-mismatch";
+            statusTelemetry.status = ENROLLMENT_STATUS.DISQUALIFIED;
+            statusTelemetry.reason = ENROLLMENT_STATUS_REASONS.NOT_TARGETED;
           } else if (invalidRecipes.includes(slug)) {
             reason = "invalid-recipe";
           } else if (invalidBranches.has(slug) || invalidFeatures.has(slug)) {
@@ -243,12 +276,23 @@ export class _ExperimentManager {
             reason = "l10n-missing-entry";
           } else {
             reason = "recipe-not-seen";
+            statusTelemetry.status = ENROLLMENT_STATUS.WAS_ENROLLED;
+            statusTelemetry.branch = branch.slug;
+          }
+          if (!statusTelemetry.status) {
+            statusTelemetry.status = ENROLLMENT_STATUS.DISQUALIFIED;
+            statusTelemetry.reason = ENROLLMENT_STATUS_REASONS.ERROR;
+            statusTelemetry.error_string = reason;
           }
           this.unenroll(slug, reason);
         } catch (err) {
           console.error(err);
         }
+      } else {
+        statusTelemetry.status = ENROLLMENT_STATUS.ENROLLED;
+        statusTelemetry.reason = ENROLLMENT_STATUS_REASONS.QUALIFIED;
       }
+      this.sendEnrollmentStatusTelemetry(statusTelemetry);
     }
   }
 
@@ -685,7 +729,7 @@ export class _ExperimentManager {
   /**
    * Unenroll from all active studies if user opts out.
    */
-  observe(aSubject, aTopic, aPrefName) {
+  observe() {
     if (!this.studiesEnabled) {
       for (const { slug } of this.store.getAllActiveExperiments()) {
         this.unenroll(slug, "studies-opt-out");
@@ -756,6 +800,34 @@ export class _ExperimentManager {
   }
 
   /**
+   *
+   * @param {object} enrollmentStatus
+   * @param {string} enrollmentStatus.slug
+   * @param {string} enrollmentStatus.status
+   * @param {string?} enrollmentStatus.reason
+   * @param {string?} enrollmentStatus.branch
+   * @param {string?} enrollmentStatus.error_string
+   * @param {string?} enrollmentStatus.conflict_slug
+   */
+  sendEnrollmentStatusTelemetry({
+    slug,
+    status,
+    reason,
+    branch,
+    error_string,
+    conflict_slug,
+  }) {
+    Glean.nimbusEvents.enrollmentStatus.record({
+      slug,
+      status,
+      reason,
+      branch,
+      error_string,
+      conflict_slug,
+    });
+  }
+
+  /**
    * Sets Telemetry when activating an experiment.
    *
    * @param {Enrollment} experiment
diff --git a/toolkit/components/nimbus/lib/ExperimentStore.sys.mjs b/toolkit/components/nimbus/lib/ExperimentStore.sys.mjs
index 7fd7fd987e..a7a3069fe5 100644
--- a/toolkit/components/nimbus/lib/ExperimentStore.sys.mjs
+++ b/toolkit/components/nimbus/lib/ExperimentStore.sys.mjs
@@ -237,7 +237,7 @@ export class ExperimentStore extends SharedDataMap {
   async init() {
     await super.init();
 
-    this.getAllActiveExperiments().forEach(({ slug, branch, featureIds }) => {
+    this.getAllActiveExperiments().forEach(({ branch, featureIds }) => {
       (featureIds || getAllBranchFeatureIds(branch)).forEach(featureId =>
         this._emitFeatureUpdate(featureId, "feature-experiment-loaded")
       );
diff --git a/toolkit/components/nimbus/lib/RemoteSettingsExperimentLoader.sys.mjs b/toolkit/components/nimbus/lib/RemoteSettingsExperimentLoader.sys.mjs
index 8e026e5cba..e372cf57a5 100644
--- a/toolkit/components/nimbus/lib/RemoteSettingsExperimentLoader.sys.mjs
+++ b/toolkit/components/nimbus/lib/RemoteSettingsExperimentLoader.sys.mjs
@@ -350,7 +350,7 @@ export class _RemoteSettingsExperimentLoader {
     }
   }
 
-  observe(aSubect, aTopic, aData) {
+  observe(aSubect, aTopic) {
     if (aTopic === STUDIES_ENABLED_CHANGED) {
       this.onEnabledPrefChange();
     }
diff --git a/toolkit/components/nimbus/metrics.yaml b/toolkit/components/nimbus/metrics.yaml
index 4faecce490..5b5ff4bd3a 100644
--- a/toolkit/components/nimbus/metrics.yaml
+++ b/toolkit/components/nimbus/metrics.yaml
@@ -223,10 +223,46 @@ nimbus_events:
       An event sent when Nimbus is ready — sent upon completion of each update of the recipes.
     bugs:
       - https://bugzilla.mozilla.org/show_bug.cgi?id=1875510
-    data_reviews: []
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1875510
     data_sensitivity:
       - technical
     notification_emails:
       - chumphreys@mozilla.com
       - project-nimbus@mozilla.com
     expires: 180
+
+  enrollment_status:
+    type: event
+    description: >
+      Recorded for each enrollment status each time the SDK completes application of pending experiments.
+    extra_keys:
+      slug:
+        type: string
+        description: The slug/unique identifier of the experiment
+      status:
+        type: string
+        description: The status of this enrollment
+      reason:
+        type: string
+        description: The reason the client is in the noted status
+      branch:
+        type: string
+        description: The branch slug/identifier that was randomly chosen (if the client is enrolled)
+      error_string:
+        type: string
+        description: If the enrollment resulted in an error, the associated error string
+      conflict_slug:
+        type: string
+        description: If the enrollment hit a feature conflict, the slug of the conflicting experiment/rollout
+    bugs:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1817481
+    data_reviews:
+      - https://bugzilla.mozilla.org/show_bug.cgi?id=1817481
+    data_sensitivity:
+      - technical
+    notification_emails:
+      - chumphreys@mozilla.com
+      - project-nimbus@mozilla.com
+    expires: never
+    disabled: true
diff --git a/toolkit/components/nimbus/schemas/ExperimentFeature.schema.json b/toolkit/components/nimbus/schemas/ExperimentFeature.schema.json
new file mode 100644
index 0000000000..977c18e09e
--- /dev/null
+++ b/toolkit/components/nimbus/schemas/ExperimentFeature.schema.json
@@ -0,0 +1,125 @@
+{
+  "$schema": "https://json-schema.org/draft/2019-09/schema",
+  "additionalProperties": false,
+  "type": "object",
+  "properties": {
+    "description": {
+      "type": "string"
+    },
+    "owner": {
+      "type": "string",
+      "description": "The owner of the feature."
+    },
+    "applications": {
+      "description": "The applications that can enroll in experiments for this feature. Defaults to firefox-desktop if not present.",
+      "type": "array",
+      "items": {
+        "type": "string",
+        "enum": ["firefox-desktop", "firefox-desktop-background-task"]
+      },
+      "minItems": 1
+    },
+    "hasExposure": {
+      "type": "boolean",
+      "description": "If the feature sends an exposure event."
+    },
+    "exposureDescription": {
+      "type": "string",
+      "description": "A description of the implementation details of the exposure event, if one is sent."
+    },
+    "isEarlyStartup": {
+      "type": "boolean",
+      "description": "If the feature values should be cached in prefs for fast early startup."
+    },
+    "schema": {
+      "type": "object",
+      "description": "For features with large number of variables we instead point to a JSONSchema file instead of specifying them in the variables field",
+      "properties": {
+        "uri": {
+          "type": "string",
+          "description": "A resource:// URI that can be loaded at runtime from within Firefox.",
+          "format": "uri"
+        },
+        "path": {
+          "type": "string",
+          "description": "The path to the schema file relative to the repository root"
+        }
+      },
+      "required": ["uri", "path"]
+    },
+    "variables": {
+      "additionalProperties": false,
+      "type": "object",
+      "patternProperties": {
+        "[a-zA-Z0-9_]+": {
+          "type": "object",
+          "properties": {
+            "type": {
+              "type": "string",
+              "enum": ["json", "boolean", "int", "string"]
+            },
+            "fallbackPref": {
+              "type": "string",
+              "description": "A pref that provides the default value for a feature when none is present"
+            },
+            "setPref": {
+              "description": "A pref that should be set to the value of this variable when enrolling in experiments.",
+              "type": "object",
+              "properties": {
+                "branch": {
+                  "type": "string",
+                  "enum": ["default", "user"],
+                  "description": "The branch the pref will be set on."
+                },
+                "pref": {
+                  "type": "string",
+                  "description": "The name of the pref."
+                }
+              },
+              "required": ["branch", "pref"],
+              "additionalProperties": false
+            },
+            "enum": {
+              "description": "Validate feature value using a list of possible options (for string only values)."
+            },
+            "description": {
+              "type": "string",
+              "description": "Explain how this value is being used"
+            }
+          },
+          "required": ["type", "description"],
+          "additionalProperties": false,
+          "dependentSchemas": {
+            "fallbackPref": {
+              "description": "setPref is mutually exclusive with fallbackPref",
+              "properties": {
+                "setPref": {
+                  "const": null
+                }
+              }
+            },
+            "setPref": {
+              "description": "fallbackPref is mutually exclusive with setPref",
+              "properties": {
+                "fallbackPref": {
+                  "const": null
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  },
+  "required": ["description", "hasExposure", "owner", "variables"],
+  "if": {
+    "properties": {
+      "hasExposure": {
+        "const": true
+      }
+    }
+  },
+  "then": {
+    "required": ["exposureDescription"]
+  }
+}
diff --git a/toolkit/components/nimbus/schemas/ExperimentFeatureManifest.schema.json b/toolkit/components/nimbus/schemas/ExperimentFeatureManifest.schema.json
index c25b7dbf69..ee28f7d93e 100644
--- a/toolkit/components/nimbus/schemas/ExperimentFeatureManifest.schema.json
+++ b/toolkit/components/nimbus/schemas/ExperimentFeatureManifest.schema.json
@@ -1,125 +1,8 @@
 {
   "$schema": "https://json-schema.org/draft/2019-09/schema",
-  "additionalProperties": false,
   "type": "object",
-  "properties": {
-    "description": {
-      "type": "string"
-    },
-    "owner": {
-      "type": "string",
-      "description": "The owner of the feature."
-    },
-    "applications": {
-      "description": "The applications that can enroll in experiments for this feature. Defaults to firefox-desktop if not present.",
-      "type": "array",
-      "items": {
-        "type": "string",
-        "enum": ["firefox-desktop", "firefox-desktop-background-task"]
-      },
-      "minItems": 1
-    },
-    "hasExposure": {
-      "type": "boolean",
-      "description": "If the feature sends an exposure event."
-    },
-    "exposureDescription": {
-      "type": "string",
-      "description": "A description of the implementation details of the exposure event, if one is sent."
-    },
-    "isEarlyStartup": {
-      "type": "boolean",
-      "description": "If the feature values should be cached in prefs for fast early startup."
-    },
-    "schema": {
-      "type": "object",
-      "description": "For features with large number of variables we instead point to a JSONSchema file instead of specifying them in the variables field",
-      "properties": {
-        "uri": {
-          "type": "string",
-          "description": "A resource:// URI that can be loaded at runtime from within Firefox.",
-          "format": "uri"
-        },
-        "path": {
-          "type": "string",
-          "description": "The path to the schema file relative to the repository root"
-        }
-      },
-      "required": ["uri", "path"]
-    },
-    "variables": {
-      "additionalProperties": false,
-      "type": "object",
-      "patternProperties": {
-        "[a-zA-Z0-9_]+": {
-          "type": "object",
-          "properties": {
-            "type": {
-              "type": "string",
-              "enum": ["json", "boolean", "int", "string"]
-            },
-            "fallbackPref": {
-              "type": "string",
-              "description": "A pref that provides the default value for a feature when none is present"
-            },
-            "setPref": {
-              "description": "A pref that should be set to the value of this variable when enrolling in experiments.",
-              "type": "object",
-              "properties": {
-                "branch": {
-                  "type": "string",
-                  "enum": ["default", "user"],
-                  "description": "The branch the pref will be set on."
-                },
-                "pref": {
-                  "type": "string",
-                  "description": "The name of the pref."
-                }
-              },
-              "required": ["branch", "pref"],
-              "additionalProperties": false
-            },
-            "enum": {
-              "description": "Validate feature value using a list of possible options (for string only values)."
-            },
-            "description": {
-              "type": "string",
-              "description": "Explain how this value is being used"
-            }
-          },
-          "required": ["type", "description"],
-          "additionalProperties": false,
-          "dependentSchemas": {
-            "fallbackPref": {
-              "description": "setPref is mutually exclusive with fallbackPref",
-              "properties": {
-                "setPref": {
-                  "const": null
-                }
-              }
-            },
-            "setPref": {
-              "description": "fallbackPref is mutually exclusive with setPref",
-              "properties": {
-                "fallbackPref": {
-                  "const": null
-                }
-              }
-            }
-          }
-        }
-      }
-    }
-  },
-  "required": ["description", "hasExposure", "variables"],
-  "if": {
-    "properties": {
-      "hasExposure": {
-        "const": true
-      }
-    }
-  },
-  "then": {
-    "required": ["exposureDescription"]
+  "additionalProperties": false,
+  "patternProperties": {
+    "^[A-Za-z0-9_-]*$": { "$ref": "ExperimentFeature.schema.json" }
   }
 }
diff --git a/toolkit/components/nimbus/test/unit/test_ExperimentManager_unenroll.js b/toolkit/components/nimbus/test/unit/test_ExperimentManager_unenroll.js
index 3c53148c7a..a32de32cd6 100644
--- a/toolkit/components/nimbus/test/unit/test_ExperimentManager_unenroll.js
+++ b/toolkit/components/nimbus/test/unit/test_ExperimentManager_unenroll.js
@@ -6,6 +6,9 @@ const { TelemetryEvents } = ChromeUtils.importESModule(
 const { TelemetryEnvironment } = ChromeUtils.importESModule(
   "resource://gre/modules/TelemetryEnvironment.sys.mjs"
 );
+const { ExperimentAPI } = ChromeUtils.importESModule(
+  "resource://nimbus/ExperimentAPI.sys.mjs"
+);
 const STUDIES_OPT_OUT_PREF = "app.shield.optoutstudies.enabled";
 const UPLOAD_ENABLED_PREF = "datareporting.healthreport.uploadEnabled";
 
@@ -487,3 +490,112 @@ add_task(async function test_rollout_telemetry_events() {
   );
   globalSandbox.restore();
 });
+
+add_task(async function test_check_unseen_enrollments_telemetry_events() {
+  globalSandbox.restore();
+  const store = ExperimentFakes.store();
+  const manager = ExperimentFakes.manager(store);
+  const sandbox = sinon.createSandbox();
+  sandbox.stub(manager, "unenroll").returns();
+  sandbox.stub(ExperimentAPI, "_store").get(() => manager.store);
+  sandbox.stub(ExperimentAPI, "_manager").get(() => manager);
+
+  await manager.onStartup();
+  await manager.store.ready();
+
+  const experiment = ExperimentFakes.recipe("foo", {
+    branches: [
+      {
+        slug: "wsup",
+        ratio: 1,
+        features: [
+          {
+            featureId: "nimbusTelemetry",
+            value: {
+              gleanMetricConfiguration: {
+                "nimbus_events.enrollment_status": true,
+              },
+            },
+          },
+        ],
+      },
+    ],
+    bucketConfig: {
+      ...ExperimentFakes.recipe.bucketConfig,
+      count: 1000,
+    },
+  });
+
+  await manager.enroll(experiment, "aaa");
+
+  const source = "test";
+  const slugs = [],
+    experiments = [];
+  for (let i = 0; i < 7; i++) {
+    slugs.push(`slug-${i}`);
+    experiments.push({
+      slug: slugs[i],
+      source,
+      branch: {
+        slug: "control",
+      },
+    });
+  }
+
+  manager.sessions.set(source, new Set([slugs[0]]));
+
+  manager._checkUnseenEnrollments(
+    experiments,
+    source,
+    [slugs[1]],
+    [slugs[2]],
+    new Map([]),
+    new Map([[slugs[3], experiments[3]]]),
+    [slugs[4]],
+    new Map([[slugs[5], experiments[5]]])
+  );
+
+  const events = Glean.nimbusEvents.enrollmentStatus.testGetValue();
+
+  Assert.equal(events?.length, 7);
+
+  Assert.equal(events[0].extra.status, "Enrolled");
+  Assert.equal(events[0].extra.reason, "Qualified");
+  Assert.equal(events[0].extra.branch, "control");
+  Assert.equal(events[0].extra.slug, slugs[0]);
+
+  Assert.equal(events[1].extra.status, "Disqualified");
+  Assert.equal(events[1].extra.reason, "NotTargeted");
+  Assert.equal(events[1].extra.branch, "control");
+  Assert.equal(events[1].extra.slug, slugs[1]);
+
+  Assert.equal(events[2].extra.status, "Disqualified");
+  Assert.equal(events[2].extra.reason, "Error");
+  Assert.equal(events[2].extra.error_string, "invalid-recipe");
+  Assert.equal(events[2].extra.branch, "control");
+  Assert.equal(events[2].extra.slug, slugs[2]);
+
+  Assert.equal(events[3].extra.status, "Disqualified");
+  Assert.equal(events[3].extra.reason, "Error");
+  Assert.equal(events[3].extra.error_string, "invalid-branch");
+  Assert.equal(events[3].extra.branch, "control");
+  Assert.equal(events[3].extra.slug, slugs[3]);
+
+  Assert.equal(events[4].extra.status, "Disqualified");
+  Assert.equal(events[4].extra.reason, "Error");
+  Assert.equal(events[4].extra.error_string, "l10n-missing-locale");
+  Assert.equal(events[4].extra.branch, "control");
+  Assert.equal(events[4].extra.slug, slugs[4]);
+
+  Assert.equal(events[5].extra.status, "Disqualified");
+  Assert.equal(events[5].extra.reason, "Error");
+  Assert.equal(events[5].extra.error_string, "l10n-missing-entry");
+  Assert.equal(events[5].extra.branch, "control");
+  Assert.equal(events[5].extra.slug, slugs[5]);
+
+  Assert.equal(events[6].extra.status, "WasEnrolled");
+  Assert.equal(events[6].extra.branch, "control");
+  Assert.equal(events[6].extra.slug, slugs[6]);
+
+  sandbox.restore();
+});
diff --git a/toolkit/components/nimbus/test/unit/test_SharedDataMap.js b/toolkit/components/nimbus/test/unit/test_SharedDataMap.js
index 6186b41a40..84132ab73d 100644
--- a/toolkit/components/nimbus/test/unit/test_SharedDataMap.js
+++ b/toolkit/components/nimbus/test/unit/test_SharedDataMap.js
@@ -115,7 +115,6 @@ with_sharedDataMap(async function test_childInit({ instance, sandbox }) {
 
 with_sharedDataMap(async function test_parentChildSync_synchronously({
   instance: parentInstance,
-  sandbox,
 }) {
   await parentInstance.init();
   parentInstance.set("foo", { bar: 1 });
@@ -142,7 +141,6 @@ with_sharedDataMap(async function test_parentChildSync_synchronously({
 
 with_sharedDataMap(async function test_parentChildSync_async({
   instance: parentInstance,
-  sandbox,
 }) {
   const childInstance = new SharedDataMap("xpcshell", {
     path: PATH,
@@ -169,7 +167,6 @@ with_sharedDataMap(async function test_parentChildSync_async({
 
 with_sharedDataMap(async function test_earlyChildSync({
   instance: parentInstance,
-  sandbox,
 }) {
   const childInstance = new SharedDataMap("xpcshell", {
     path: PATH,
@@ -193,7 +190,7 @@ with_sharedDataMap(async function test_earlyChildSync({
   );
 });
 
-with_sharedDataMap(async function test_updateStoreData({ instance, sandbox }) {
+with_sharedDataMap(async function test_updateStoreData({ instance }) {
   await instance.init();
 
   Assert.ok(!instance.get("foo"), "No value initially");