2065273 - Add Add-ons Manager preference to hide the Recommendations pane for enterprise policies

Status: NEW

(Thunderbird :: Add-Ons: General, task, P3)

Description

[Toby Pilling [:tobyp]]

Based on the FF policy, Thunderbird's ExtensionSettings enterprise policy already disables recommendation-related preferences when extensions are globally blocked:

• extensions.getAddons.showPane = false
• extensions.htmlaboutaddons.recommendations.enabled = false

However, extensions.htmlaboutaddons.recommendations.enabled is already set to false in all-thunderbird.js to hide the recommended extension and theme cards in the extension and themes list views. (See bug 1566782)

Thunderbird has a separate Recommendations pane/tab which is not controlled by any pref/enterprise policy so UI remains visible even when:

• extensions.getAddons.showPane = false
• the global ExtensionSettings policy specifies:

{
  "ExtensionSettings": {
    "*": {
      "installation_mode": "blocked"
    }
  }
}

Even when this policy is set, users can open the Recommendations pane and see extensions that they cannot install. Attempting to install one is rejected by the enterprise policy.

Firefox's ExtensionSettings policy hides the corresponding extension discovery UI when extension installation is globally blocked so ideally Thunderbird should provide equivalent UI behavior.

Proposed implementation

• Add a Thunderbird preference specifically controlling the visibility of the Recommendations pane/tab, for example: extensions.getAddons.recommendationsPane.enabled with a default value of true
• The Add-ons Manager should use this preference to determine whether the Recommendations pane/tab is displayed.
• The ExtensionSettings policy should set and lock this preference to false when: ExtensionSettings["*"].installation_mode == "blocked"
• The existing extensions.htmlaboutaddons.recommendations.enabled preference should continue to control recommendation cards and recommended themes in the list views, as it does today.
• The new preference should specifically control the separate Recommendations pane/tab.

Because this is a Thunderbird-specific UI preference, it should also be registered in mail/app/profile/all-thunderbird.js, covered by the appropriate enterprise-policy preference tests, and the diff between FF and TB implementations of the ExtensionSettings policy inside Policies.sys.mjs should be included in the relevant allowedDifferences object in mail/components/enterprisepolicies/tests/browser/browser_policies_differences.js so that the test doesn't start failing but we remain aligned.