Centralize notifications in Notifiable concern

app/controllers/application_controller.rb

@@ -1,5 +1,5 @@
 class ApplicationController < ActionController::Base
-  include Onboardable, Localize, AutoSync, Authentication, Invitable, SelfHostable, StoreLocation, Impersonatable, Breadcrumbable, FeatureGuardable
+  include Onboardable, Localize, AutoSync, Authentication, Invitable, SelfHostable, StoreLocation, Impersonatable, Breadcrumbable, FeatureGuardable, Notifiable
   include Pagy::Backend
 
   helper_method :require_upgrade?, :subscription_pending?

app/controllers/concerns/notifiable.rb

@@ -0,0 +1,58 @@
+module Notifiable
+  extend ActiveSupport::Concern
+
+  included do
+    helper_method :render_flash_notifications
+    helper_method :flash_notification_stream_items
+  end
+
+  private
+    def render_flash_notifications
+      notifications = flash.flat_map { |type, data| resolve_notifications(type, data) }
+
+      view_context.safe_join(
+        notifications.map { |notification| view_context.render(**notification) }
+      )
+    end
+
+    def flash_notification_stream_items
+      items = flash.flat_map do |type, data|
+        notifications = resolve_notifications(type, data)
+
+        if type == "cta"
+          notifications.map { |notification| turbo_stream.replace("cta", **notification) }
+        else
+          notifications.map { |notification| turbo_stream.append("notification-tray", **notification) }
+        end
+      end
+
+      # If rendering flash notifications via stream, we mark them as used to avoid
+      # them being rendered again on the next page load
+      flash.clear
+
+      items
+    end
+
+    def resolve_cta(cta)
+      case cta[:type]
+      when "category_rule"
+        { partial: "rules/category_rule_cta", locals: { cta: } }
+      else
+        raise "Unknown CTA type: #{cta[:type]}"
+      end
+    end
+
+    def resolve_notifications(type, data)
+      case type
+      when "alert"
+        [ { partial: "shared/notifications/alert", locals: { message: data } } ]
+      when "cta"
+        [ resolve_cta(data) ]
+      when "loading"
+        [ { partial: "shared/notifications/loading", locals: { message: data } } ]
+      when "notice"
+        messages = Array(data)
+        messages.map { |message| { partial: "shared/notifications/notice", locals: { message: message } } }
+      end
+    end
+end

app/helpers/application_helper.rb

@@ -27,24 +27,6 @@ module ApplicationHelper
     turbo_stream_from Current.family if Current.family
   end
 
-  def render_flash_notifications
-    notifications = flash.flat_map do |type, data|
-      case type
-      when "alert"
-        render "shared/notifications/alert", message: data
-      when "cta"
-        render "shared/notifications/cta", cta: data
-      when "loading"
-        render "shared/notifications/loading", message: data
-      when "notice"
-        messages = Array(data)
-        messages.map { |message| render "shared/notifications/notice", message: }
-      end
-    end
-
-    safe_join(notifications)
-  end
-
   ##
   # Helper to open a centered and overlayed modal with custom contents
   #