DEV: Update rate limits for image captioning (#816)

This PR updates the rate limits for AI helper so that image caption follows a specific rate limit of 20 requests per minute. This should help when uploading multiple files that need to be captioned. This PR also updates the UI so that it shows toast message with the extracted error message instead of having a blocking `popupAjaxError` error dialog.
---------

Co-authored-by: Rafael dos Santos Silva <xfalcox@gmail.com>
Co-authored-by: Penar Musaraj <pmusaraj@gmail.com>

app/controllers/discourse_ai/ai_helper/assistant_controller.rb

@@ -6,10 +6,21 @@ module DiscourseAi
       requires_plugin ::DiscourseAi::PLUGIN_NAME
       requires_login
       before_action :ensure_can_request_suggestions
-      before_action :rate_limiter_performed!, except: %i[prompts]
+      before_action :rate_limiter_performed!
 
       include SecureUploadEndpointHelpers
 
+      RATE_LIMITS = {
+        "default" => {
+          amount: 6,
+          interval: 3.minutes,
+        },
+        "caption_image" => {
+          amount: 20,
+          interval: 1.minute,
+        },
+      }.freeze
+
       def suggest
         input = get_text_param!
         force_default_locale = params[:force_default_locale] || false
@@ -161,7 +172,13 @@ module DiscourseAi
       end
 
       def rate_limiter_performed!
-        RateLimiter.new(current_user, "ai_assistant", 6, 3.minutes).performed!
+        action_rate_limit = RATE_LIMITS[action_name] || RATE_LIMITS["default"]
+        RateLimiter.new(
+          current_user,
+          "ai_assistant",
+          action_rate_limit[:amount],
+          action_rate_limit[:interval],
+        ).performed!
       end
 
       def ensure_can_request_suggestions

assets/javascripts/initializers/ai-image-caption.js

@@ -1,5 +1,5 @@
 import { ajax } from "discourse/lib/ajax";
-import { popupAjaxError } from "discourse/lib/ajax-error";
+import { extractError, popupAjaxError } from "discourse/lib/ajax-error";
 import { apiInitializer } from "discourse/lib/api";
 import { getUploadMarkdown, isImage } from "discourse/lib/uploads";
 import I18n from "discourse-i18n";
@@ -111,7 +111,13 @@ export default apiInitializer("1.25.0", (api) => {
       });
       return response.caption;
     } catch (error) {
-      popupAjaxError(error);
+      toasts.error({
+        class: "ai-image-caption-error-toast",
+        duration: 3000,
+        data: {
+          message: extractError(error),
+        },
+      });
     }
   }
 
@@ -129,6 +135,7 @@ export default apiInitializer("1.25.0", (api) => {
     return;
   }
 
+  const toasts = api.container.lookup("service:toasts");
   // Automatically caption uploaded images
   api.addComposerUploadMarkdownResolver(async (upload) => {
     const autoCaptionEnabled = currentUser.get(

spec/requests/ai_helper/assistant_controller_spec.rb

@@ -100,6 +100,23 @@ RSpec.describe DiscourseAi::AiHelper::AssistantController do
           expect(response.parsed_body["diff"]).to eq(expected_diff)
         end
       end
+
+      context "when performing numerous requests" do
+        it "rate limits" do
+          RateLimiter.enable
+          rate_limit = described_class::RATE_LIMITS["default"]
+          amount = rate_limit[:amount]
+
+          amount.times do
+            post "/discourse-ai/ai-helper/suggest", params: { mode: mode, text: text_to_proofread }
+            expect(response.status).to eq(200)
+          end
+          DiscourseAi::Completions::Llm.with_prepared_responses([proofread_text]) do
+            post "/discourse-ai/ai-helper/suggest", params: { mode: mode, text: text_to_proofread }
+            expect(response.status).to eq(429)
+          end
+        end
+      end
     end
   end
 
@@ -258,6 +275,25 @@ RSpec.describe DiscourseAi::AiHelper::AssistantController do
           end
         end
       end
+
+      context "when performing numerous requests" do
+        it "rate limits" do
+          RateLimiter.enable
+
+          rate_limit = described_class::RATE_LIMITS["caption_image"]
+          amount = rate_limit[:amount]
+
+          amount.times do
+            request_caption({ image_url: image_url, image_url_type: "long_url" }) do |r|
+              expect(r.status).to eq(200)
+            end
+          end
+
+          request_caption({ image_url: image_url, image_url_type: "long_url" }) do |r|
+            expect(r.status).to eq(429)
+          end
+        end
+      end
     end
   end
 end