FEATURE: per-topic unsubscribe option in emails

[ShashankFC]

Test 2

Summary by CodeRabbit

Release Notes

• New Features
  • Users can now unsubscribe from topic notifications through a dedicated management page, allowing them to stop receiving notification alerts for specific topics.
  • Notification emails now include direct unsubscribe links, providing quick access to manage notification preferences.

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Replicated from ai-code-review-evaluation/discourse-coderabbit#2

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Note

Medium Risk
Touches email template/translation interpolation and adds a new topic-level state toggle endpoint, so mistakes could affect unsubscribe links or notification levels for users.

Overview
Adds a per-topic unsubscribe flow: notification emails now include an unsubscribe_url, and the server unsubscribe_link copy is expanded to offer a per-topic “stop notifications” link alongside the existing global preferences link.

Implements new backend routes/controller action (TopicsController#unsubscribe) plus Topic#unsubscribe_url to toggle a user’s TopicUser.notification_level between regular and muted, and wires a new Ember route/template/controller/view for /t/:slug/:id/unsubscribe with minimal styling.

Includes small related cleanups/refactors (e.g., conditional dropdown title rendering, minor JS/Ruby formatting, and ensuring topic-from-params jumps to the resolved post).

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[ShashankFC]

bugbot run

[cursor]

Cursor Bugbot has reviewed your changes and found 2 potential issues.

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[cursor]

Unsubscribe crashes without topic-user row

Medium Severity

topics_controller.rb assumes TopicUser.find_by always returns a record. If a logged-in user can view a topic but has no topic_users row yet, tu.notification_level raises and the unsubscribe page fails with a server error instead of updating preferences.

 

[cursor]

State-changing unsubscribe uses GET route

Medium Severity

The new GET unsubscribe endpoints mutate TopicUser.notification_level in topics#unsubscribe. Because this state change is performed via GET, third-party pages can trigger unsolicited preference changes for authenticated users through cross-site requests.

Additional Locations (1)

• app/controllers/topics_controller.rb#L97-L115