Activation Window Feature

Overview

The Activation Window feature allows the browser to experiment with the first hours of a new profile’s lifetime by temporarily setting different defaults during a configurable time period (typically 48 hours). This enables:

• Hiding or showing specific content sections (top sites, top stories) during the activation window

• Displaying messaging when entering or exiting the activation window

• Reverting to normal defaults after the activation window expires

• Preserving user preference changes made during the activation window

The feature is controlled via Nimbus experiments using the newtabTrainhop feature with type: "activationWindowBehavior".

How It Works

High-level Architecture

1. Profile Creation Time Tracking (AboutNewTab.sys.mjs)

   • The browser computes the profile creation instant on startup using ProfileAge.sys.mjs

   • The createdInstant is cached on the ActivityStream instance for the session

2. Activation Window Evaluation (PrefsFeed.sys.mjs)

   • checkForActivationWindow() runs on:

     • PrefsFeed initialization (startup)

     • Each NEW_TAB_STATE_REQUEST action (when opening a new tab)

   • It compares the current time against the profile age to determine if we’re within the activation window

   • Enters or exits activation window state as needed

3. Default Pref Manipulation

   • When entering the activation window: Sets default branch prefs for top sites/stories to experiment values

   • When exiting the activation window: Restores default branch prefs to original values

   • User pref values always override defaults, even after enabling and then re-disabling.

4. User Preference Tracking

   • Tracks user preference changes during the activation window

   • On exit, ensures that any user changes are persisted

5. State Broadcasting

   • Pref changes are broadcast to all content processes

   • StartupCacheInit queues changes for the cached about:home page if it exists

6. Messaging Integration

   • PrefsFeed sets message ID prefs on enter/exit: activationWindow.enterMessageID and activationWindow.exitMessageID

   • ASRouter messages can target these prefs using JEXL expressions

   • The ActivationWindowMessage component renders messages with bespoke UI (card layout with image, heading, message, and buttons)

Configuration

Nimbus Configuration Schema

The activation window is configured via Nimbus using the newtabTrainhop feature:

{
  featureId: "newtabTrainhop",
  value: {
    type: "activationWindowBehavior",
    payload: {
      enabled: true,
      maxProfileAgeInHours: 48,
      disableTopSites: true,
      disableTopStories: true,
      variant: "a",
      enterActivationWindowMessageID: "ACTIVATION_WINDOW_WELCOME_V1",
      exitActivationWindowMessageID: "ACTIVATION_WINDOW_EXIT_V1"
    }
  }
}

Configuration Fields

• enabled (boolean, default: false): Whether the activation window feature is active

• maxProfileAgeInHours (number, default: 48): Duration of the activation window in hours

• disableTopSites (boolean, default: false): Hide top sites section during activation window

• disableTopStories (boolean, default: false): Hide top stories section during activation window

• variant (string, default: “”): Experiment variant identifier

• enterActivationWindowMessageID (string, default: “”): Message ID to show when entering the window

• exitActivationWindowMessageID (string, default: “”): Message ID to show when exiting the window

Message Structure

Messages for the activation window use the ActivationWindowMessage component and follow this schema:

{
  id: "MESSAGE_ID",
  template: "newtab_message",
  content: {
    messageType: "ActivationWindowMessage",

    // Heading: plain string or Fluent ID
    heading: "Welcome to Your New Tab!",
    // OR
    heading: { string_id: "activation-window-welcome-heading-fluent-id" },

    // Message: plain string or Fluent ID
    message: "We've personalized your experience...",
    // OR
    message: { string_id: "activation-window-welcome-message-fluent-id" },

    // Image (optional, defaults to kit-in-circle.svg if not provided)
    imageSrc: "chrome://newtab/content/data/content/assets/kit.png",

    primaryButton: {
      // Plain text label (for tests)
      label: "Learn More",
      // OR Fluent ID label (for production)
      label: { string_id: "activation-window-primary-button-fluent-id" },

      action: {
        type: "SHOW_PERSONALIZE"
      }
    },

    secondaryButton: {
      label: "Dismiss",
      // OR
      label: { string_id: "activation-window-secondary-button-fluent-id" },

      action: { dismiss: true }
    }
  },
  trigger: { id: "newtabMessageCheck" },
  targeting: `'browser.newtabpage.activity-stream.activationWindow.enterMessageID' | preferenceValue == 'MESSAGE_ID'`,
  groups: []
}

Message Content Fields

• messageType (string, required): Must be "ActivationWindowMessage"

• heading (string or object, optional): Heading text

  • Plain string: "Welcome to Firefox"

  • Fluent ID: { string_id: "activation-window-heading-fluent-id" }

• message (string or object, optional): Message text

  • Plain string: "We've personalized your experience"

  • Fluent ID: { string_id: "activation-window-message-fluent-id" }

• imageSrc (string, optional): Chrome URL to image displayed in the message. If not provided, defaults to "chrome://newtab/content/data/content/assets/kit-in-circle.svg"

• primaryButton (object, optional): Configuration for primary button.

• secondaryButton (object, optional): Configuration for secondary button

Button Configuration

Each button object has:

• label (string or object, required):

  • Plain string for test messages: "Click Me"

  • Fluent object for production: { string_id: "button-label-id-fluent-id" }

• action (object, required): ASRouter action specification

  • { dismiss: true } - Dismiss and block the message

  • { type: "SHOW_PERSONALIZE" } - Open personalization panel

  • More actions may be added in the future.

Testing Locally

Using PanelTestProvider

Test messages are available in browser/components/asrouter/modules/PanelTestProvider.sys.mjs:

• TEST_ACTIVATION_WINDOW_ENTER_MESSAGE

• TEST_ACTIVATION_WINDOW_EXIT_MESSAGE

To test these messages:

1. Open about:newtab#asrouter in Firefox

2. Find either the enter or exit message in the message list

3. Modify any of the parameters in the message as you’d like

4. Click “Show” or “Modify” to display the message

5. Open a new tab