diff --git a/app/models/onboarding_scenarios/default_join.rb b/app/models/onboarding_scenarios/default_join.rb
index 5b13a28..27681b0 100644
--- a/app/models/onboarding_scenarios/default_join.rb
+++ b/app/models/onboarding_scenarios/default_join.rb
@@ -17,6 +17,6 @@ module OnboardingScenarios
 
         def slack_channels = Rails.configuration.slack_channels.slice(:waiting_room).values
 
-        def promotion_channels = Rails.configuration.slack_channels.slice(:announcements, :welcome, :ship, :neighbourhood, :library, :lounge).values
+        def promotion_channels = Rails.configuration.slack_channels.slice(:announcements, :happenings, :community, :hardware, :code, :ship, :neighbourhood, :library, :lounge).values
     end
 end
diff --git a/config/slack_channels.yml b/config/slack_channels.yml
index 2305962..1de866b 100644
--- a/config/slack_channels.yml
+++ b/config/slack_channels.yml
@@ -1,5 +1,10 @@
 production:
   announcements: C0266FRGT
+  happenings: C05B6DBN802
+  community: C01D7AHKMPF
+  ysws: C0710J7F4U9
+  hardware: C6C026NHJ
+  code: C0EA9S0A0
   library: C078Q8PBD4G
   ship: C0M8PUPU6
   welcome: C75M7C0SY
diff --git a/lib/tasks/slack.rake b/lib/tasks/slack.rake
new file mode 100644
index 0000000..39c9740
--- /dev/null
+++ b/lib/tasks/slack.rake
@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+namespace :slack do
+  desc "Join all channels defined in config/slack_channels.yml"
+  task join_channels: :environment do
+    config = YAML.load_file(Rails.root.join("config/slack_channels.yml"))
+    client = SlackService.client
+    joined_ids = Set.new
+
+    config.each do |env, channels|
+      puts "\n=== #{env} ==="
+      channels.each do |name, channel_id|
+        next if joined_ids.include?(channel_id)
+
+        joined_ids << channel_id
+        print "Joining ##{name} (#{channel_id})... "
+        client.conversations_join(channel: channel_id)
+        puts "✓"
+      rescue Slack::Web::Api::Errors::MethodNotSupportedForChannelType
+        puts "skipped (DM or unsupported type)"
+      rescue Slack::Web::Api::Errors::ChannelNotFound
+        puts "not found"
+      rescue Slack::Web::Api::Errors::SlackError => e
+        puts "failed: #{e.message}"
+      end
+    end
+
+    puts "\nDone!"
+  end
+end