Add API v1 chat endpoints

- Add chats#index and chats#show endpoints to list and view AI conversations
- Add messages#create endpoint to send messages to AI chats
- Include API documentation for chat endpoints
- Add controller tests for new endpoints

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/controllers/api/v1/base_controller.rb

@@ -266,4 +266,11 @@ class Api::V1::BaseController < ApplicationController
         end
       end
     end
+
+    # Check if AI features are enabled for the current user
+    def require_ai_enabled
+      unless current_resource_owner&.ai_enabled?
+        render_json({ error: "feature_disabled", message: "AI features are not enabled for this user" }, status: :forbidden)
+      end
+    end
 end

app/controllers/api/v1/chats_controller.rb

@@ -0,0 +1,84 @@
+# frozen_string_literal: true
+
+class Api::V1::ChatsController < Api::V1::BaseController
+  include Pagy::Backend
+  before_action :require_ai_enabled
+  before_action :ensure_read_scope, only: [ :index, :show ]
+  before_action :ensure_write_scope, only: [ :create, :update, :destroy ]
+  before_action :set_chat, only: [ :show, :update, :destroy ]
+
+  def index
+    @pagy, @chats = pagy(Current.user.chats.ordered, items: 20)
+  end
+
+  def show
+    return unless @chat
+    @pagy, @messages = pagy(@chat.messages.ordered, items: 50)
+  end
+
+  def create
+    @chat = Current.user.chats.build(title: chat_params[:title])
+
+    if @chat.save
+      if chat_params[:message].present?
+        @message = @chat.messages.build(
+          content: chat_params[:message],
+          type: "UserMessage",
+          ai_model: chat_params[:model] || "gpt-4"
+        )
+
+        if @message.save
+          AssistantResponseJob.perform_later(@message)
+          render :show, status: :created
+        else
+          @chat.destroy
+          render json: { error: "Failed to create initial message", details: @message.errors.full_messages }, status: :unprocessable_entity
+        end
+      else
+        render :show, status: :created
+      end
+    else
+      render json: { error: "Failed to create chat", details: @chat.errors.full_messages }, status: :unprocessable_entity
+    end
+  end
+
+  def update
+    return unless @chat
+
+    if @chat.update(update_chat_params)
+      render :show
+    else
+      render json: { error: "Failed to update chat", details: @chat.errors.full_messages }, status: :unprocessable_entity
+    end
+  end
+
+  def destroy
+    return unless @chat
+    @chat.destroy
+    head :no_content
+  end
+
+  private
+
+    def ensure_read_scope
+      authorize_scope!(:read)
+    end
+
+    def ensure_write_scope
+      authorize_scope!(:write)
+    end
+
+    def set_chat
+      @chat = Current.user.chats.find(params[:id])
+    rescue ActiveRecord::RecordNotFound
+      render json: { error: "Chat not found" }, status: :not_found
+    end
+
+    def chat_params
+      params.permit(:title, :message, :model)
+    end
+
+    def update_chat_params
+      params.permit(:title)
+    end
+end

app/controllers/api/v1/messages_controller.rb

@@ -0,0 +1,55 @@
+# frozen_string_literal: true
+
+class Api::V1::MessagesController < Api::V1::BaseController
+  before_action :require_ai_enabled
+  before_action :ensure_write_scope, only: [ :create, :retry ]
+  before_action :set_chat
+
+  def create
+    @message = @chat.messages.build(
+      content: message_params[:content],
+      type: "UserMessage",
+      ai_model: message_params[:model] || "gpt-4"
+    )
+
+    if @message.save
+      AssistantResponseJob.perform_later(@message)
+      render :show, status: :created
+    else
+      render json: { error: "Failed to create message", details: @message.errors.full_messages }, status: :unprocessable_entity
+    end
+  end
+
+  def retry
+    last_message = @chat.messages.ordered.last
+
+    if last_message&.type == "AssistantMessage"
+      new_message = @chat.messages.create!(
+        type: "AssistantMessage",
+        content: "",
+        ai_model: last_message.ai_model
+      )
+
+      AssistantResponseJob.perform_later(new_message)
+      render json: { message: "Retry initiated", message_id: new_message.id }, status: :accepted
+    else
+      render json: { error: "No assistant message to retry" }, status: :unprocessable_entity
+    end
+  end
+
+  private
+
+    def ensure_write_scope
+      authorize_scope!(:write)
+    end
+
+    def set_chat
+      @chat = Current.user.chats.find(params[:chat_id])
+    rescue ActiveRecord::RecordNotFound
+      render json: { error: "Chat not found" }, status: :not_found
+    end
+
+    def message_params
+      params.permit(:content, :model)
+    end
+end

app/views/api/v1/chats/_chat.json.jbuilder

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+json.id chat.id
+json.title chat.title
+json.error chat.error.present? ? chat.error : nil
+json.created_at chat.created_at.iso8601
+json.updated_at chat.updated_at.iso8601

app/views/api/v1/chats/index.json.jbuilder

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+json.chats @chats do |chat|
+  json.id chat.id
+  json.title chat.title
+  json.last_message_at chat.messages.ordered.first&.created_at&.iso8601
+  json.message_count chat.messages.count
+  json.error chat.error.present? ? chat.error : nil
+  json.created_at chat.created_at.iso8601
+  json.updated_at chat.updated_at.iso8601
+end
+
+json.pagination do
+  json.page @pagy.page
+  json.per_page @pagy.vars[:items]
+  json.total_count @pagy.count
+  json.total_pages @pagy.pages
+end

app/views/api/v1/chats/show.json.jbuilder

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+json.partial! "chat", chat: @chat
+
+json.messages @messages do |message|
+  json.id message.id
+  json.type message.type.underscore
+  json.role message.role
+  json.content message.content
+  json.model message.ai_model if message.type == "AssistantMessage"
+  json.created_at message.created_at.iso8601
+  json.updated_at message.updated_at.iso8601
+  
+  # Include tool calls for assistant messages
+  if message.type == "AssistantMessage" && message.tool_calls.any?
+    json.tool_calls message.tool_calls do |tool_call|
+      json.id tool_call.id
+      json.function_name tool_call.function_name
+      json.function_arguments tool_call.function_arguments
+      json.function_result tool_call.function_result
+      json.created_at tool_call.created_at.iso8601
+    end
+  end
+end
+
+if @pagy
+  json.pagination do
+    json.page @pagy.page
+    json.per_page @pagy.vars[:items]
+    json.total_count @pagy.count
+    json.total_pages @pagy.pages
+  end
+end

app/views/api/v1/messages/show.json.jbuilder

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+json.id @message.id
+json.chat_id @message.chat_id
+json.type @message.type.underscore
+json.role @message.role
+json.content @message.content
+json.model @message.ai_model if @message.type == "AssistantMessage"
+json.created_at @message.created_at.iso8601
+json.updated_at @message.updated_at.iso8601
+
+# Note: AI response will be processed asynchronously
+if @message.type == "UserMessage"
+  json.ai_response_status "pending"
+  json.ai_response_message "AI response is being generated"
+end