FEATURE: configure a default LLM model for all features

app/models/llm_model.rb

@@ -99,7 +99,7 @@ def to_llm
   end
 
   def identifier
-    "custom:#{id}"
+    "#{id}"
   end
 
   def toggle_companion_user

assets/javascripts/discourse/components/ai-default-llm-selector.gjs

@@ -0,0 +1,46 @@
+import Component from "@glimmer/component";
+import { tracked } from "@glimmer/tracking";
+import { ajax } from "discourse/lib/ajax";
+import { i18n } from "discourse-i18n";
+import SiteSettingComponent from "admin/components/site-setting";
+import SiteSetting from "admin/models/site-setting";
+
+export default class AiDefaultLlmSelector extends Component {
+  @tracked defaultLlmSetting = null;
+
+  constructor() {
+    super(...arguments);
+    this.#loadDefaultLlmSetting();
+  }
+
+  async #loadDefaultLlmSetting() {
+    const { site_settings } = await ajax("/admin/config/site_settings.json", {
+      data: {
+        plugin: "discourse-ai",
+        category: "discourse_ai",
+      },
+    });
+
+    const defaultLlmSetting = site_settings.find(
+      (setting) => setting.setting === "ai_default_llm_model"
+    );
+
+    this.defaultLlmSetting = SiteSetting.create(defaultLlmSetting);
+  }
+
+  <template>
+    <div class="ai-configure-default-llm">
+      <div class="ai-configure-default-llm__header">
+        <h3>{{i18n "discourse_ai.default_llm.title"}}</h3>
+        <p>{{i18n "discourse_ai.default_llm.description"}}</p>
+      </div>
+
+      {{#if this.defaultLlmSetting}}
+        <SiteSettingComponent
+          @setting={{this.defaultLlmSetting}}
+          class="ai-configure-default-llm__setting"
+        />
+      {{/if}}
+    </div>
+  </template>
+}

assets/javascripts/discourse/components/ai-features.gjs

@@ -9,6 +9,7 @@ import DPageSubheader from "discourse/components/d-page-subheader";
 import DSelect from "discourse/components/d-select";
 import FilterInput from "discourse/components/filter-input";
 import { i18n } from "discourse-i18n";
+import AiDefaultLlmSelector from "./ai-default-llm-selector";
 import AiFeaturesList from "./ai-features-list";
 
 const ALL = "all";
@@ -202,6 +203,8 @@ export default class AiFeatures extends Component {
         />
       </div>
 
+      <AiDefaultLlmSelector />
+
       {{#if this.filteredFeatures.length}}
         <AiFeaturesList @modules={{this.filteredFeatures}} />
       {{else}}

assets/javascripts/discourse/components/ai-llms-list-editor.gjs

@@ -9,6 +9,7 @@ import I18n, { i18n } from "discourse-i18n";
 import AdminSectionLandingItem from "admin/components/admin-section-landing-item";
 import AdminSectionLandingWrapper from "admin/components/admin-section-landing-wrapper";
 import DTooltip from "float-kit/components/d-tooltip";
+import AiDefaultLlmSelector from "./ai-default-llm-selector";
 import AiLlmEditor from "./ai-llm-editor";
 
 function isPreseeded(llm) {
@@ -137,6 +138,9 @@ export default class AiLlmsListEditor extends Component {
           }}
           @learnMoreUrl="https://meta.discourse.org/t/discourse-ai-large-language-model-llm-settings-page/319903"
         />
+
+        <AiDefaultLlmSelector />
+
         {{#if this.hasLlmElements}}
           <section class="ai-llms-list-editor__configured">
             <DPageSubheader

assets/javascripts/discourse/components/ai-spam.gjs

@@ -90,7 +90,7 @@ export default class AiSpam extends Component {
     this.isEnabled = model.is_enabled;
 
     if (model.llm_id) {
-      this.selectedLLM = "custom:" + model.llm_id;
+      this.selectedLLM = model.llm_id;
     } else {
       if (this.availableLLMs.length) {
         this.selectedLLM = this.availableLLMs[0].id;
@@ -127,7 +127,7 @@ export default class AiSpam extends Component {
   }
 
   get llmId() {
-    return this.selectedLLM.toString().split(":")[1];
+    return this.selectedLLM;
   }
 
   @action

assets/stylesheets/common/ai-features.scss

@@ -158,3 +158,51 @@
 .ai-expanded-list__toggle-button {
   padding: 0;
 }
+
+.ai-configure-default-llm {
+  display: flex;
+  align-items: center;
+  gap: var(--space-2);
+  background: var(--primary-very-low);
+  padding: 1rem;
+  margin-block: 1rem;
+  border-radius: var(--d-border-radius);
+
+  &__header {
+    flex: 3;
+  }
+
+  &__setting {
+    flex: 2;
+    display: flex;
+    gap: var(--space-2);
+    align-items: center;
+    justify-content: center;
+
+    .setting-controls__undo {
+      display: none;
+    }
+  }
+
+  h3 {
+    color: var(--primary);
+    font-size: var(--font-0);
+    margin-bottom: 0;
+  }
+
+  p {
+    margin-top: 0;
+    font-size: var(--font-down-1);
+    color: var(--primary-high-or-secondary-low);
+  }
+
+  .select-kit,
+  .btn {
+    font-size: var(--font-down-1);
+  }
+
+  .setting-label,
+  .desc {
+    display: none;
+  }
+}

config/locales/client.en.yml

@@ -184,6 +184,10 @@ en:
     discourse_ai:
       title: "AI"
 
+      default_llm:
+        title: "Default LLM model"
+        description: "The default LLM model to use for all AI features. This will be used if no LLM is specified in the feature configuration or persona. If no default LLM is specified, the last created LLM will be used."
+
       features:
         short_title: "Features"
         description: "These are the AI features available to visitors on your site. These can be configured to use specific personas and LLMs, and can be access controlled by groups."
@@ -566,7 +570,7 @@ en:
           max_usages_required: "Must be set if max tokens is not set"
         usage:
           ai_bot: "AI bot"
-          ai_helper: "Helper"
+          ai_helper: "Helper (%{persona})"
           ai_helper_image_caption: "Image caption"
           ai_persona: "Persona (%{persona})"
           ai_summarization: "Summarize"

config/locales/server.en.yml

@@ -25,6 +25,7 @@ en:
         description: "Periodic report based on a large language model"
   site_settings:
     discourse_ai_enabled: "Enable the discourse AI plugin."
+    ai_default_llm_model: "The default LLM model to use for all AI features"
     ai_artifact_security: "The AI artifact system generates IFRAMEs with runnable code. Strict mode forces an extra click to run code. Lax mode runs code immediately. Hybrid mode allows user to supply data-ai-artifact-autorun to show right away. Disabled mode disables the artifact system."
     ai_toxicity_enabled: "Enable the toxicity module."
     ai_toxicity_inference_service_api_endpoint: "URL where the API is running for the toxicity module"
@@ -582,7 +583,7 @@ en:
     llm:
       configuration:
         create_llm: "You need to setup an LLM before enabling this feature"
-        disable_module_first: "You have to disable %{setting} first."
+        disable_modules_first: "You must disable these modules first: %{settings}"
         set_llm_first: "Set %{setting} first"
         model_unreachable: "We couldn't get a response from this model. Check your settings first."
         invalid_seeded_model: "You can't use this model with this feature"

config/settings.yml

@@ -11,6 +11,12 @@ discourse_ai:
       - "lax"
       - "hybrid"
       - "strict"
+  ai_default_llm_model:
+    default: ""
+    type: enum
+    allow_any: false
+    enum: "DiscourseAi::Configuration::LlmEnumerator"
+    validator: "DiscourseAi::Configuration::LlmValidator"
 
   ai_sentiment_enabled:
     default: false
@@ -103,7 +109,7 @@ discourse_ai:
     default: false
     client: true
     area: "ai-features/ai_helper"
-  ai_helper_model:
+  ai_helper_model:  # Deprecated. TODO(keegan): Remove 2025-09-01
     default: ""
     allow_any: false
     type: enum
@@ -149,7 +155,7 @@ discourse_ai:
       - "context_menu"
       - "image_caption"
     area: "ai-features/ai_helper"
-  ai_helper_image_caption_model:
+  ai_helper_image_caption_model:  # Deprecated. TODO(keegan): Remove 2025-09-01
     default: ""
     type: enum
     enum: "DiscourseAi::Configuration::LlmVisionEnumerator"
@@ -260,12 +266,12 @@ discourse_ai:
     client: true
     validator: "DiscourseAi::Configuration::LlmDependencyValidator"
     area: "ai-features/embeddings"
-  ai_embeddings_semantic_search_hyde_model:
+  ai_embeddings_semantic_search_hyde_model:  # Deprecated. TODO(keegan): Remove 2025-09-01
+    hidden: true
     default: ""
     type: enum
     allow_any: false
     enum: "DiscourseAi::Configuration::LlmEnumerator"
-    validator: "DiscourseAi::Configuration::LlmValidator"
     area: "ai-features/embeddings"
   ai_embeddings_semantic_search_hyde_model_allowed_seeded_models:
     default: ""
@@ -316,12 +322,11 @@ discourse_ai:
     client: true
     validator: "DiscourseAi::Configuration::LlmDependencyValidator"
     area: "ai-features/summarization"
-  ai_summarization_model:
+  ai_summarization_model: # Deprecated. TODO(keegan): Remove 2025-09-01
     default: ""
     allow_any: false
     type: enum
     enum: "DiscourseAi::Configuration::LlmEnumerator"
-    validator: "DiscourseAi::Configuration::LlmValidator"
     hidden: true
   ai_summarization_persona:
     default: "-11"
@@ -483,12 +488,11 @@ discourse_ai:
     client: true
     validator: "DiscourseAi::Configuration::LlmDependencyValidator"
     area: "ai-features/translation"
-  ai_translation_model:
+  ai_translation_model: # Deprecated. TODO(keegan): Remove 2025-09-01
     default: ""
     type: enum
     allow_any: false
     enum: "DiscourseAi::Configuration::LlmEnumerator"
-    validator: "DiscourseAi::Configuration::LlmValidator"
     area: "ai-features/translation"
   ai_translation_locale_detector_persona:
     default: "-27"

db/migrate/20250710173803_seed_ai_default_llm_model.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+class SeedAiDefaultLlmModel < ActiveRecord::Migration[7.2]
+  def up
+    return if DB.query_single("SELECT 1 FROM llm_models LIMIT 1").empty?
+
+    last_model_id = DB.query_single("SELECT id FROM llm_models ORDER BY id DESC LIMIT 1").first
+
+    if last_model_id.present?
+      execute "UPDATE site_settings SET value = '#{last_model_id}' WHERE name = 'ai_default_llm_model' AND (value IS NULL OR value = '');"
+    end
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20250710180401_copy_ai_summarization_model_to_persona_default.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+class CopyAiSummarizationModelToPersonaDefault < ActiveRecord::Migration[7.2]
+  def up
+    ai_summarization_model =
+      DB.query_single("SELECT value FROM site_settings WHERE name = 'ai_summarization_model'").first
+
+    if ai_summarization_model.present? && ai_summarization_model.start_with?("custom:")
+      # Extract the model ID from the setting value (e.g., "custom:-5" -> "-5")
+      model_id = ai_summarization_model.split(":").last
+
+      # Update the summarization personas (IDs -11 and -12) with the extracted model ID
+      execute(<<~SQL)
+        UPDATE ai_personas
+        SET default_llm_id = #{model_id}
+        WHERE id IN (-11, -12) AND default_llm_id IS NULL
+      SQL
+    end
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20250710181656_copy_ai_helper_model_to_persona_default.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+class CopyAiHelperModelToPersonaDefault < ActiveRecord::Migration[7.2]
+  def up
+    ai_helper_model =
+      DB.query_single("SELECT value FROM site_settings WHERE name = 'ai_helper_model'").first
+
+    if ai_helper_model.present? && ai_helper_model.start_with?("custom:")
+      # Extract the model ID from the setting value (e.g., "custom:1" -> "1")
+      model_id = ai_helper_model.split(":").last
+
+      # Update the helper personas with the extracted model ID
+      execute(<<~SQL)
+        UPDATE ai_personas
+        SET default_llm_id = #{model_id}
+        WHERE id IN (-18, -19, -20, -21, -22, -23, -24, -25) AND default_llm_id IS NULL
+      SQL
+    end
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20250710215720_copy_hyde_model_to_persona.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+class CopyHydeModelToPersona < ActiveRecord::Migration[7.2]
+  def up
+    hyde_model =
+      DB.query_single("SELECT value FROM site_settings WHERE name = 'ai_embeddings_semantic_search_hyde_model'").first
+
+    if hyde_model.present? && hyde_model.start_with?("custom:")
+      # Extract the model ID from the setting value (e.g., "custom:1" -> "1")
+      model_id = hyde_model.split(":").last
+
+      # Update the hyde persona with the extracted model ID
+      execute(<<~SQL)
+        UPDATE ai_personas
+        SET default_llm_id = #{model_id}
+        WHERE id IN (-32) AND default_llm_id IS NULL
+      SQL
+    end
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20250716005451_copy_translation_model_to_persona.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+class CopyTranslationModelToPersona < ActiveRecord::Migration[7.2]
+  def up
+    ai_translation_model =
+      DB.query_single("SELECT value FROM site_settings WHERE name = 'ai_translation_model'").first
+
+    if ai_translation_model.present? && ai_translation_model.start_with?("custom:")
+      # Extract the model ID from the setting value (e.g., "custom:-5" -> "-5")
+      model_id = ai_translation_model.split(":").last
+
+      # Update the translation personas (IDs -27, -28, -29, -30) with the extracted model ID
+      execute(<<~SQL)
+        UPDATE ai_personas
+        SET default_llm_id = #{model_id}
+        WHERE id IN (-27, -28, -29, -30) AND default_llm_id IS NULL
+      SQL
+    end
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end