Feat(captain): Auto-migrate v1 instructions

Migrate legacy config['instructions'] into description on first use and
set the v2_migrated flag. Also mark assistants as v2_migrated when the
description is changed while the v2 feature flag is enabled.

enterprise/app/models/captain/assistant.rb

@@ -36,12 +36,14 @@ class Captain::Assistant < ApplicationRecord
   has_many :copilot_threads, dependent: :destroy_async
   has_many :scenarios, class_name: 'Captain::Scenario', dependent: :destroy_async
 
-  store_accessor :config, :temperature, :feature_faq, :feature_memory, :product_name
+  store_accessor :config, :temperature, :feature_faq, :feature_memory, :product_name, :v2_migrated
 
   validates :name, presence: true
   validates :description, presence: true
   validates :account_id, presence: true
 
+  before_save :mark_v2_migrated_on_v2_description_change
+
   scope :ordered, -> { order(created_at: :desc) }
 
   scope :for_account, ->(account_id) { where(account_id: account_id) }
@@ -85,8 +87,23 @@ class Captain::Assistant < ApplicationRecord
     }
   end
 
+  def migrate_v1_instructions_if_needed!
+    return if v2_migrated
+    return if config['instructions'].blank?
+
+    update!(description: config['instructions'], v2_migrated: true)
+  end
+
   private
 
+  def mark_v2_migrated_on_v2_description_change
+    return unless persisted?
+    return unless will_save_change_to_description?
+    return unless account&.feature_enabled?('captain_integration_v2')
+
+    self.v2_migrated = true
+  end
+
   def agent_name
     name.parameterize(separator: '_')
   end

enterprise/app/services/captain/assistant/agent_runner_service.rb

@@ -27,6 +27,7 @@ class Captain::Assistant::AgentRunnerService
   end
 
   def generate_response(message_history: [])
+    @assistant.migrate_v1_instructions_if_needed!
     message_to_process, context = run_payload(message_history)
     result = runner.run(message_to_process, context: context, max_turns: 100)