diff --git a/src/components/TitleBar.tsx b/src/components/TitleBar.tsx
index 1ab5728..e2e888f 100644
--- a/src/components/TitleBar.tsx
+++ b/src/components/TitleBar.tsx
@@ -147,6 +147,7 @@ export function TitleBar() {
         <Tooltip label="Settings (right-click to switch theme)" anchorToCursor>
         <button
           ref={settingsBtnRef}
+          aria-label="Settings"
           onClick={() => setSettingsOpen(true)}
           onContextMenu={handleSettingsContextMenu}
           className="group flex h-full w-10 items-center justify-center text-gray-600 transition-colors duration-100 hover:bg-white/6 hover:text-gray-300"
diff --git a/src/dev/mockBackend.ts b/src/dev/mockBackend.ts
index d55ac27..540cfa7 100644
--- a/src/dev/mockBackend.ts
+++ b/src/dev/mockBackend.ts
@@ -1,5 +1,15 @@
 import { emit } from "@tauri-apps/api/event";
-import type { Album, ExploreTagEntry, Folder, ImageRecord, ImageTag, SortOrder } from "../store";
+import type {
+  Album,
+  ExploreTagEntry,
+  Folder,
+  ImageRecord,
+  ImageTag,
+  SortOrder,
+  TaggerModel,
+  TaggerModelStatus,
+  TaggerRuntimeProbe,
+} from "../store";
 import { compareImages, createMockDb, mockExif } from "./mockFixtures";
 import { getMockScenario } from "./mockScenarios";
 
@@ -7,6 +17,8 @@ const db = createMockDb(getMockScenario());
 let nextFolderId = 100;
 let nextAlbumId = 100;
 let nextTagId = 10_000;
+let mockTaggerModel: TaggerModel = db.scenario === "joytag-unready" ? "joytag" : "wd";
+let mockTaggerReady = db.scenario !== "unready" && db.scenario !== "joytag-unready";
 
 type AnyPayload = Record<string, any> | undefined;
 type Rgb = [number, number, number];
@@ -55,6 +67,42 @@ function page<T>(items: T[], offset = 0, limit = 200) {
   };
 }
 
+function mockTaggerStatus(): TaggerModelStatus {
+  const modelInfo =
+    mockTaggerModel === "joytag"
+      ? {
+          model_id: "fancyfeast/joytag",
+          model_name: "JoyTag",
+          local_dir: "mock://models/joytag",
+          label_file: "top_tags.txt",
+        }
+      : {
+          model_id: "SmilingWolf/wd-swinv2-tagger-v3",
+          model_name: "wd-swinv2-tagger-v3",
+          local_dir: "mock://models/wd-swinv2-tagger-v3",
+          label_file: "selected_tags.csv",
+        };
+
+  return {
+    model_id: modelInfo.model_id,
+    model_name: modelInfo.model_name,
+    local_dir: modelInfo.local_dir,
+    ready: mockTaggerReady,
+    missing_files: mockTaggerReady ? [] : ["model.onnx", modelInfo.label_file],
+  };
+}
+
+function mockTaggerRuntimeProbe(): TaggerRuntimeProbe {
+  if (!mockTaggerReady) {
+    throw new Error(`${mockTaggerStatus().model_name} is missing required model files`);
+  }
+  return {
+    ready: true,
+    acceleration: "auto",
+    session: { file: "model.onnx", inputs: ["input"], outputs: ["tags"] },
+  };
+}
+
 function filterImages(input: ImageRecord[], payload: unknown): ImageRecord[] {
   const p = params(payload);
   const query = String(p.search ?? p.query ?? "").trim().toLowerCase();
@@ -463,10 +511,19 @@ export async function handleMockCommand(cmd: string, payload?: unknown): Promise
       return reset;
     }
     case "get_tagger_model_status":
-      return { model_id: "SmilingWolf/wd-vit-tagger-v3", model_name: "WD ViT Tagger", local_dir: "mock://models/tagger", ready: true, missing_files: [] };
+      return mockTaggerStatus();
     case "get_tagger_model":
+      return mockTaggerModel;
     case "set_tagger_model":
-      return p.model ?? "wd";
+      mockTaggerModel = p.model ?? "wd";
+      mockTaggerReady = db.scenario !== "unready" && db.scenario !== "joytag-unready";
+      return mockTaggerModel;
+    case "prepare_tagger_model":
+      mockTaggerReady = true;
+      return mockTaggerStatus();
+    case "delete_tagger_model":
+      mockTaggerReady = false;
+      return mockTaggerStatus();
     case "get_tagger_acceleration":
     case "set_tagger_acceleration":
       return p.acceleration ?? "auto";
@@ -477,7 +534,7 @@ export async function handleMockCommand(cmd: string, payload?: unknown): Promise
     case "set_tagger_batch_size":
       return p.batch_size ?? 8;
     case "probe_tagger_runtime":
-      return { ready: true, acceleration: "auto", session: { file: "model.onnx", inputs: ["input"], outputs: ["tags"] } };
+      return mockTaggerRuntimeProbe();
     case "get_tagging_queue_scope":
       return "all";
     case "get_tagging_queue_folder_ids":
diff --git a/src/dev/mockScenarios.ts b/src/dev/mockScenarios.ts
index db7d36f..194295f 100644
--- a/src/dev/mockScenarios.ts
+++ b/src/dev/mockScenarios.ts
@@ -1,4 +1,14 @@
-export type MockScenario = "rich" | "empty" | "busy" | "duplicates" | "album" | "errors" | "huge" | "extreme";
+export type MockScenario =
+  | "rich"
+  | "empty"
+  | "busy"
+  | "duplicates"
+  | "album"
+  | "errors"
+  | "huge"
+  | "extreme"
+  | "unready"
+  | "joytag-unready";
 
 const SCENARIOS = new Set<MockScenario>([
   "rich",
@@ -9,6 +19,8 @@ const SCENARIOS = new Set<MockScenario>([
   "errors",
   "huge",
   "extreme",
+  "unready",
+  "joytag-unready",
 ]);
 
 export function getMockScenario(): MockScenario {