diff --git a/app/models/ai_persona.rb b/app/models/ai_persona.rb
index a1ed5f88..c2e97313 100644
--- a/app/models/ai_persona.rb
+++ b/app/models/ai_persona.rb
@@ -72,6 +72,24 @@ class AiPersona < ActiveRecord::Base
     end
   end
 
+  def self.message_responder_for(group_id: nil)
+    return nil if !group_id
+
+    all_responders =
+      persona_cache[:message_responders] ||= AiPersona
+        .where(role: "message_responder")
+        .where(enabled: true)
+        .pluck(:id, :role_group_ids)
+
+    id, _ = all_responders.find { |id, role_group_ids| role_group_ids.include?(group_id) }
+
+    if id
+      { id: id }
+    else
+      nil
+    end
+  end
+
   def self.mentionables(user: nil)
     all_mentionables =
       persona_cache[:mentionable_usernames] ||= AiPersona
@@ -114,6 +132,7 @@ class AiPersona < ActiveRecord::Base
     vision_max_pixels = self.vision_max_pixels
     rag_conversation_chunks = self.rag_conversation_chunks
     question_consolidator_llm = self.question_consolidator_llm
+    role_whispers = self.role_whispers
 
     persona_class = DiscourseAi::AiBot::Personas::Persona.system_personas_by_id[self.id]
     if persona_class
@@ -161,6 +180,10 @@ class AiPersona < ActiveRecord::Base
         rag_conversation_chunks
       end
 
+      persona_class.define_singleton_method :role_whispers do
+        role_whispers
+      end
+
       return persona_class
     end
 
@@ -252,6 +275,10 @@ class AiPersona < ActiveRecord::Base
         question_consolidator_llm
       end
 
+      define_singleton_method :role_whispers do
+        role_whispers
+      end
+
       define_singleton_method :to_s do
         "#<DiscourseAi::AiBot::Personas::Persona::Custom @name=#{self.name} @allowed_group_ids=#{self.allowed_group_ids.join(",")}>"
       end
@@ -343,8 +370,8 @@ class AiPersona < ActiveRecord::Base
   private
 
   def system_persona_unchangeable
-    if top_p_changed? || temperature_changed? || system_prompt_changed? || commands_changed? ||
-         name_changed? || description_changed?
+    if role_changed? || top_p_changed? || temperature_changed? || system_prompt_changed? ||
+         commands_changed? || name_changed? || description_changed?
       errors.add(:base, I18n.t("discourse_ai.ai_bot.personas.cannot_edit_system_persona"))
     end
   end
@@ -387,6 +414,12 @@ end
 #  rag_chunk_overlap_tokens    :integer          default(10), not null
 #  rag_conversation_chunks     :integer          default(10), not null
 #  question_consolidator_llm   :text
+#  role                        :enum             default("bot"), not null
+#  role_category_ids           :integer          default([]), not null, is an Array
+#  role_tags                   :string           default([]), not null, is an Array
+#  role_group_ids              :integer          default([]), not null, is an Array
+#  role_whispers               :boolean          default(FALSE), not null
+#  role_max_responses_per_hour :integer          default(50), not null
 #
 # Indexes
 #
diff --git a/db/migrate/20240422054321_add_role_to_ai_persona.rb b/db/migrate/20240422054321_add_role_to_ai_persona.rb
new file mode 100644
index 00000000..431370ca
--- /dev/null
+++ b/db/migrate/20240422054321_add_role_to_ai_persona.rb
@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+class AddRoleToAiPersona < ActiveRecord::Migration[7.0]
+  def change
+    create_enum :ai_persona_role, %w[bot topic_responder message_responder summarizer]
+    add_column :ai_personas, :role, :enum, default: "bot", null: false, enum_type: :ai_persona_role
+
+    add_column :ai_personas, :role_category_ids, :integer, array: true, default: [], null: false
+    add_column :ai_personas, :role_tags, :string, array: true, default: [], null: false
+    add_column :ai_personas, :role_group_ids, :integer, array: true, default: [], null: false
+    add_column :ai_personas, :role_whispers, :boolean, default: false, null: false
+    add_column :ai_personas, :role_max_responses_per_hour, :integer, default: 50, null: false
+  end
+end
diff --git a/spec/models/ai_persona_spec.rb b/spec/models/ai_persona_spec.rb
index 00f86f37..07374a2d 100644
--- a/spec/models/ai_persona_spec.rb
+++ b/spec/models/ai_persona_spec.rb
@@ -128,4 +128,40 @@ RSpec.describe AiPersona do
     RailsMultisite::ConnectionManagement.stubs(:current_db) { "abc" }
     expect(AiPersona.persona_cache[:value]).to eq(nil)
   end
+
+  it "does not allow role change for system personas" do
+    persona = AiPersona.find_by(name: "Forum Helper")
+    expect(persona.update(role: "message_responder")).to eq(false)
+  end
+
+  describe "#message_responder_for" do
+    fab!(:group)
+    fab!(:responder) do
+      AiPersona.create!(
+        name: "responder",
+        description: "responser",
+        system_prompt: "responder prompt",
+        role: "message_responder",
+        role_group_ids: [group.id],
+      )
+    end
+
+    it "properly sets role_whispers on the persona" do
+      responder.update!(role_whispers: true)
+
+      expect(responder.class_instance.role_whispers).to eq(true)
+    end
+
+    it "returns can respond to group pms with a custom persona" do
+      expect(AiPersona.message_responder_for(group_id: group.id)[:id]).to eq(responder.id)
+
+      responder.update!(enabled: false)
+
+      expect(AiPersona.message_responder_for(group_id: group.id)).to eq(nil)
+
+      responder.update!(enabled: true, role: "bot")
+
+      expect(AiPersona.message_responder_for(group_id: group.id)).to eq(nil)
+    end
+  end
 end