Merge feat/ui-lab: Add browser-only UI Lab

- Adds a Vite UI Lab mode that boots the real Phokus frontend with mocked
  Tauri APIs.
- Introduces deterministic mock backend scenarios for rich, empty, busy,
  duplicate, album, error, and large-library states.
- Adds fixture media plus a mediaSrc helper so browser previews and Tauri file
  URLs share one rendering path.
- Documents the UI Lab workflow and exposes it through pnpm dev:ui.

README.md

@@ -109,6 +109,9 @@ pnpm dev:app
 # Frontend only
 pnpm dev:vite
 
+# Browser-only UI Lab with mocked Tauri APIs
+pnpm dev:ui
+
 # Production build (CPU)
 pnpm build:app:cpu
 
@@ -119,6 +122,9 @@ pnpm build:app:cuda
 pnpm build:vite
 ```
 
+For visual frontend work without launching Tauri or the Rust backend, see
+[Phokus UI Lab](docs/ui-lab.md).
+
 ## How it works
 
 1. Add a folder from the sidebar — the Rust indexer walks it recursively.

docs/ui-lab.md

@@ -0,0 +1,182 @@
+# Phokus UI Lab
+
+Phokus UI Lab is a browser-only development mode for visual work on the real
+Phokus frontend. It runs the same `App.tsx`, Zustand store, components, and CSS
+as the Tauri app, but installs Tauri JavaScript mocks before the app imports.
+
+This gives UI agents and contributors a stable browser target without launching
+the Rust backend or a Tauri window.
+
+## Run It
+
+```bash
+pnpm dev:ui
+```
+
+Then open:
+
+```text
+http://127.0.0.1:1422
+```
+
+The script runs Vite in the custom `ui` mode:
+
+```bash
+vite --mode ui --host 127.0.0.1 --port 1422 --strictPort --open
+```
+
+The normal app development commands are unchanged:
+
+```bash
+pnpm dev:app   # Tauri app + Rust backend
+pnpm dev:vite  # frontend dev server for Tauri dev
+```
+
+## Scenarios
+
+UI Lab reads `?scenario=` from the URL. If no scenario is provided, it uses
+`rich`.
+
+| URL | Purpose |
+| --- | --- |
+| `/?scenario=rich` | Default realistic library with folders, albums, ratings, favorites, tags, images, and videos |
+| `/?scenario=empty` | First-run state with no folders or media |
+| `/?scenario=busy` | Background workers with pending thumbnail, metadata, embedding, caption, and tagging jobs |
+| `/?scenario=duplicates` | Duplicate Finder opened with duplicate groups already available |
+| `/?scenario=album` | Gallery opened directly into an album |
+| `/?scenario=errors` | Broken thumbnails, folder scan errors, failed embeddings, failed tagging, and metadata issues |
+| `/?scenario=huge` | Large mock library for virtualization and layout checks |
+
+Examples:
+
+```text
+http://127.0.0.1:1422/?scenario=duplicates
+http://127.0.0.1:1422/?scenario=errors
+http://127.0.0.1:1422/?scenario=huge
+```
+
+## How It Works
+
+`src/main.tsx` bootstraps the app asynchronously. In `ui` mode it imports
+`src/dev/setupMockTauri.ts` first, then imports the real `App`.
+
+That order matters because static imports are hoisted. The Tauri mocks must be
+installed before `App`, the store, the title bar, or visual components import
+Tauri APIs.
+
+The mock setup installs:
+
+- `mockWindows("main")` for window APIs used by the title bar
+- `mockConvertFileSrc("windows")` as a baseline Tauri file URL mock
+- `mockIPC(..., { shouldMockEvents: true })` for `invoke`, `listen`, and `emit`
+
+The in-memory backend lives in:
+
+```text
+src/dev/mockBackend.ts
+src/dev/mockFixtures.ts
+src/dev/mockScenarios.ts
+src/dev/applyMockScenario.ts
+```
+
+Happy-path fixture media is generated from existing onboarding images and
+website screenshots into:
+
+```text
+public/dev-media/fixture-*.webp
+```
+
+The pack is deliberately small and deterministic, but varied enough for browser
+screenshots: square, portrait, landscape, monochrome, tinted, framed, and
+interface-like crops. Synthetic or deliberately broken fixture paths can still
+use the `mock://` scheme described below.
+
+## Mock Media
+
+Visual components should use `mediaSrc(...)` instead of calling
+`convertFileSrc(...)` directly:
+
+```ts
+import { mediaSrc } from "../lib/mediaSrc";
+
+const src = mediaSrc(image.thumbnail_path);
+```
+
+In normal Tauri modes, `mediaSrc` delegates to `convertFileSrc`. In UI Lab,
+root-relative asset URLs such as `/dev-media/fixture-01.webp` are returned
+as-is. Paths beginning with `mock://` are also served from `public/dev-media`:
+
+```text
+mock://thumb-1.svg -> /dev-media/thumb-1.svg
+```
+
+Use `mediaSrc` when adding components that render thumbnails, album covers,
+preview images, or video posters.
+
+## Adding A Mock Command
+
+If the browser console logs an unmocked command, add it to
+`src/dev/mockBackend.ts`.
+
+Prefer returning realistic data for commands that affect visible UI. For actions
+that would touch the machine, return a safe no-op:
+
+```ts
+case "open_app_data_folder":
+  return null;
+```
+
+When adding fixture data, keep it shaped like the real store/Rust contracts.
+Most frontend-facing types are exported from `src/store.ts`, so the mocks can
+stay type-checked against the real UI.
+
+## Adding A Scenario
+
+1. Add the scenario name to `MockScenario` and `SCENARIOS` in
+   `src/dev/mockScenarios.ts`.
+2. Adjust fixture creation in `src/dev/mockFixtures.ts`.
+3. If the scenario should open a specific view, add that behavior in
+   `src/dev/applyMockScenario.ts`.
+4. Visit `http://127.0.0.1:1422/?scenario=your-scenario` and check for console
+   errors.
+
+## What UI Lab Is For
+
+UI Lab is intended for:
+
+- visual iteration on the real app shell
+- layout and responsive checks
+- state-heavy views like Explore, Timeline, Duplicates, albums, and Settings
+- AI-agent screenshot/browser inspection
+- safe UI work without filesystem or Rust-side effects
+
+It is not a replacement for Tauri app testing. Validate native behavior with
+`pnpm dev:app` when touching:
+
+- file or folder pickers
+- filesystem permissions
+- real thumbnail/video loading
+- window drag, minimize, maximize, or close behavior
+- Rust backend performance
+- updater installation
+- WebView2-specific behavior
+
+## Verification
+
+Useful checks after changing UI Lab:
+
+```bash
+pnpm exec tsc --noEmit
+pnpm build:vite
+pnpm dev:ui
+```
+
+Then smoke-test at least:
+
+```text
+http://127.0.0.1:1422/?scenario=rich
+http://127.0.0.1:1422/?scenario=empty
+http://127.0.0.1:1422/?scenario=duplicates
+http://127.0.0.1:1422/?scenario=errors
+http://127.0.0.1:1422/?scenario=huge
+```

package.json

@@ -13,6 +13,7 @@
     "clean:app": "cd src-tauri && cargo clean",
     "dev:app": "tauri dev",
     "dev:app:cpu": "tauri dev -- --no-default-features",
+    "dev:ui": "vite --mode ui --host 127.0.0.1 --port 1422 --strictPort --open",
     "dev:vite": "vite",
     "dev:web": "cd website && pnpm dev",
     "format:app": "cd src-tauri && cargo fmt",

src/App.tsx

@@ -48,12 +48,16 @@ export default function App() {
     if (import.meta.env.PROD) {
       void checkForUpdates({ quiet: true });
     }
-    loadFolders().then(() => {
+    loadFolders().then(async () => {
       void loadBackgroundJobProgress();
       void loadCaptionModelStatus();
       void loadDuplicateScanCache();
-      void loadAlbums();
-      return loadImages(true);
+      await loadAlbums();
+      await loadImages(true);
+      if (import.meta.env.MODE === "ui") {
+        const { applyMockScenario } = await import("./dev/applyMockScenario");
+        applyMockScenario();
+      }
     });
     let unlisten: (() => void) | undefined;
     subscribeToProgress().then((fn) => {

src/components/DuplicateFinder.tsx

@@ -1,8 +1,8 @@
 import { useRef, useState } from "react";
 import { useVirtualizer } from "@tanstack/react-virtual";
-import { convertFileSrc } from "@tauri-apps/api/core";
 import { DuplicateGroup, useGalleryStore } from "../store";
 import { FolderScopeDropdown } from "./FolderScopeDropdown";
+import { mediaSrc } from "../lib/mediaSrc";
 
 function formatBytes(bytes: number): string {
   if (bytes >= 1_073_741_824) return `${(bytes / 1_073_741_824).toFixed(1)} GB`;
@@ -68,7 +68,7 @@ function DuplicateGroupCard({ group }: { group: DuplicateGroup }) {
       <div className="flex flex-wrap gap-3">
         {group.images.map((image) => {
           const isSelected = selectedIds.has(image.id);
-          const src = image.thumbnail_path ? convertFileSrc(image.thumbnail_path) : null;
+          const src = mediaSrc(image.thumbnail_path);
           return (
             <button
               key={image.id}

src/components/Gallery.tsx

@@ -1,9 +1,9 @@
 import { useEffect, useLayoutEffect, useRef, useCallback, useMemo, useState } from "react";
 import { useVirtualizer } from "@tanstack/react-virtual";
-import { convertFileSrc } from "@tauri-apps/api/core";
 import { ImageRecord, parseSearchValue, tileSizeForZoom, useGalleryStore } from "../store";
 import { BulkActionBar } from "./BulkActionBar";
 import { Tooltip } from "./Tooltip";
+import { mediaSrc } from "../lib/mediaSrc";
 
 const GAP = 6;
 
@@ -123,7 +123,7 @@ export function ImageTile({
   const toggleGallerySelected = useGalleryStore((state) => state.toggleGallerySelected);
   const canFindSimilar = image.embedding_status === "ready";
 
-  const src = image.thumbnail_path ? convertFileSrc(image.thumbnail_path) : null;
+  const src = mediaSrc(image.thumbnail_path);
 
   return (
     <Tooltip label={image.filename} delay={500} block followCursor>

src/components/Lightbox.tsx

@@ -1,9 +1,10 @@
 import { useEffect, useCallback, useRef, useState } from "react";
 import { motion, AnimatePresence } from "framer-motion";
-import { convertFileSrc, invoke } from "@tauri-apps/api/core";
+import { invoke } from "@tauri-apps/api/core";
 import { revealItemInDir } from "@tauri-apps/plugin-opener";
 import { useGalleryStore, ImageTag, ImageExif, AiRating } from "../store";
 import { VideoPlayer } from "./VideoPlayer";
+import { mediaSrc } from "../lib/mediaSrc";
 
 function formatBytes(bytes: number): string {
   if (bytes < 1024) return `${bytes} B`;
@@ -475,12 +476,12 @@ export function Lightbox() {
                     transition={{ duration: 0.12 }}
                   >
                     {selectedImage.media_kind === "video" ? (
-                      <VideoPlayer src={convertFileSrc(selectedImage.path)} />
+                      <VideoPlayer src={mediaSrc(selectedImage.path) ?? ""} />
                     ) : (
                       <>
                         <img
                           ref={imgRef}
-                          src={convertFileSrc(selectedImage.path)}
+                          src={mediaSrc(selectedImage.path) ?? ""}
                           alt={selectedImage.filename}
                           className="max-w-full rounded-2xl shadow-2xl"
                           draggable={false}

src/components/Sidebar.tsx

@@ -1,9 +1,9 @@
 import { useEffect, useMemo, useRef, useState } from "react";
 import { Reorder, useDragControls } from "framer-motion";
 import { open } from "@tauri-apps/plugin-dialog";
-import { convertFileSrc } from "@tauri-apps/api/core";
 import { useGalleryStore, Folder, Album, IndexProgress } from "../store";
 import { ThemedDropdown } from "./ThemedDropdown";
+import { mediaSrc } from "../lib/mediaSrc";
 
 interface ContextMenuState {
   folderId: number;
@@ -445,7 +445,7 @@ function AlbumItem({
     setRenaming(false);
   };
 
-  const cover = album.cover_thumbnail_path ? convertFileSrc(album.cover_thumbnail_path) : null;
+  const cover = mediaSrc(album.cover_thumbnail_path);
 
   const row = (
     <div

src/components/TagCloud.tsx

@@ -1,9 +1,9 @@
 import { useEffect, useLayoutEffect, useMemo, useRef, useState } from "react";
 import { motion, useReducedMotion } from "framer-motion";
-import { convertFileSrc } from "@tauri-apps/api/core";
 import { ExploreTagEntry, TagCloudEntry, useGalleryStore } from "../store";
 import { FolderScopeDropdown } from "./FolderScopeDropdown";
 import { Tooltip } from "./Tooltip";
+import { mediaSrc } from "../lib/mediaSrc";
 
 const ACCENTS = [
   "#60a5fa",
@@ -148,7 +148,7 @@ function buildCloud(entries: TagCloudEntry[], containerW: number, containerH: nu
 }
 
 function CloudCard({ node, onOpen, animated }: { node: PlacedNode; onOpen: (imageIds: number[]) => void; animated: boolean }) {
-  const src = node.entry.thumbnail_path ? convertFileSrc(node.entry.thumbnail_path) : null;
+  const src = mediaSrc(node.entry.thumbnail_path);
   const { w, h, accent } = node;
   const driftTransition = {
     duration: node.driftDuration,

src/dev/applyMockScenario.ts

@@ -0,0 +1,17 @@
+import { useGalleryStore } from "../store";
+import { getMockScenario } from "./mockScenarios";
+
+export function applyMockScenario() {
+  const scenario = getMockScenario();
+  const store = useGalleryStore.getState();
+
+  if (scenario === "album") {
+    const albumId = store.albums[0]?.id;
+    if (albumId !== undefined) store.viewAlbum(albumId);
+    return;
+  }
+
+  if (scenario === "duplicates") {
+    store.setView("duplicates");
+  }
+}

src/dev/mockBackend.ts

@@ -0,0 +1,403 @@
+import { emit } from "@tauri-apps/api/event";
+import type { Album, Folder, ImageRecord, ImageTag, SortOrder } from "../store";
+import { compareImages, createMockDb, mockExif } from "./mockFixtures";
+import { getMockScenario } from "./mockScenarios";
+
+const db = createMockDb(getMockScenario());
+let nextFolderId = 100;
+let nextAlbumId = 100;
+let nextTagId = 10_000;
+
+type AnyPayload = Record<string, any> | undefined;
+
+function params(payload: unknown): Record<string, any> {
+  if (!payload || typeof payload !== "object") return {};
+  const record = payload as Record<string, any>;
+  return record.params && typeof record.params === "object" ? record.params : record;
+}
+
+function page<T>(items: T[], offset = 0, limit = 200) {
+  return {
+    images: items.slice(offset, offset + limit),
+    total: items.length,
+    offset,
+    limit,
+  };
+}
+
+function filterImages(input: ImageRecord[], payload: unknown): ImageRecord[] {
+  const p = params(payload);
+  const query = String(p.search ?? p.query ?? "").trim().toLowerCase();
+  return input.filter((image) => {
+    if (p.folder_id !== undefined && p.folder_id !== null && image.folder_id !== p.folder_id) return false;
+    if (p.media_kind && image.media_kind !== p.media_kind) return false;
+    if (p.favorites_only && !image.favorite) return false;
+    if (p.rating_min !== undefined && p.rating_min !== null && image.rating < p.rating_min) return false;
+    if (p.embedding_failed_only && image.embedding_status !== "failed") return false;
+    if (p.tagging_failed_only && !image.ai_tagger_error) return false;
+    if (query && !image.filename.toLowerCase().includes(query)) return false;
+    return true;
+  });
+}
+
+function getImages(payload: unknown) {
+  const p = params(payload);
+  const sort = (p.sort ?? "date_desc") as SortOrder;
+  return page(
+    filterImages(db.images, payload).sort(compareImages(sort)),
+    Number(p.offset ?? 0),
+    Number(p.limit ?? 200),
+  );
+}
+
+function searchTags(payload: unknown) {
+  const p = params(payload);
+  const query = String(p.query ?? "").trim().toLowerCase();
+  const matchingIds = new Set(
+    Object.entries(db.tagsByImageId)
+      .filter(([, tags]) => tags.some((tag) => tag.tag.toLowerCase().includes(query)))
+      .map(([imageId]) => Number(imageId)),
+  );
+  const images = filterImages(db.images, payload)
+    .filter((image) => matchingIds.has(image.id))
+    .sort(compareImages((p.sort ?? "date_desc") as SortOrder));
+  return page(images, Number(p.offset ?? 0), Number(p.limit ?? 200));
+}
+
+function semanticSearch(payload: unknown): ImageRecord[] {
+  const p = params(payload);
+  const query = String(p.query ?? "").toLowerCase();
+  const scored = filterImages(db.images, payload)
+    .map((image, index) => ({
+      image,
+      score:
+        (image.generated_caption?.toLowerCase().includes(query) ? 0 : 20) +
+        (image.filename.toLowerCase().includes(query) ? 0 : 10) +
+        (index % 9),
+    }))
+    .sort((left, right) => left.score - right.score)
+    .slice(0, Number(p.limit ?? 200))
+    .map((entry) => entry.image);
+  return scored.length ? scored : filterImages(db.images, payload).slice(0, Number(p.limit ?? 200));
+}
+
+function albumImages(payload: unknown) {
+  const p = params(payload);
+  const albumId = Number(p.album_id);
+  const ids = new Set(db.albumImageIds[albumId] ?? []);
+  const sort = (p.sort ?? "date_desc") as SortOrder;
+  return page(
+    db.images.filter((image) => ids.has(image.id)).sort(compareImages(sort)),
+    Number(p.offset ?? 0),
+    Number(p.limit ?? 200),
+  );
+}
+
+function similarImages(payload: unknown) {
+  const p = params(payload);
+  const source = db.images.find((image) => image.id === p.image_id);
+  let images = db.images.filter((image) => image.id !== p.image_id && image.embedding_status === "ready");
+  if (p.album_id !== undefined && p.album_id !== null) {
+    const ids = new Set(db.albumImageIds[Number(p.album_id)] ?? []);
+    images = images.filter((image) => ids.has(image.id));
+  } else if (p.folder_id !== undefined && p.folder_id !== null) {
+    images = images.filter((image) => image.folder_id === p.folder_id);
+  }
+  const ordered = images.sort((left, right) => {
+    const leftScore = Math.abs(left.rating - (source?.rating ?? 0)) + (left.folder_id === source?.folder_id ? 0 : 2);
+    const rightScore = Math.abs(right.rating - (source?.rating ?? 0)) + (right.folder_id === source?.folder_id ? 0 : 2);
+    return leftScore - rightScore;
+  });
+  const offset = Number(p.offset ?? 0);
+  const limit = Number(p.limit ?? 200);
+  return {
+    images: ordered.slice(offset, offset + limit),
+    offset,
+    limit,
+    has_more: offset + limit < ordered.length,
+  };
+}
+
+function updateImages(ids: number[], updates: { favorite?: boolean | null; rating?: number | null }) {
+  const changed: ImageRecord[] = [];
+  for (const image of db.images) {
+    if (!ids.includes(image.id)) continue;
+    if (updates.favorite !== null && updates.favorite !== undefined) image.favorite = updates.favorite;
+    if (updates.rating !== null && updates.rating !== undefined) image.rating = updates.rating;
+    changed.push({ ...image });
+  }
+  return changed;
+}
+
+function refreshAlbumCounts() {
+  for (const album of db.albums) {
+    const ids = db.albumImageIds[album.id] ?? [];
+    album.image_count = ids.length;
+    album.cover_image_id = ids[0] ?? null;
+    album.cover_thumbnail_path = db.images.find((image) => image.id === ids[0])?.thumbnail_path ?? null;
+    album.updated_at = new Date().toISOString();
+  }
+}
+
+function createAlbum(name: string): Album {
+  const album: Album = {
+    id: nextAlbumId++,
+    name,
+    cover_image_id: null,
+    cover_thumbnail_path: null,
+    image_count: 0,
+    sort_order: db.albums.length + 1,
+    created_at: new Date().toISOString(),
+    updated_at: new Date().toISOString(),
+  };
+  db.albums.push(album);
+  db.albumImageIds[album.id] = [];
+  return album;
+}
+
+function addFolder(path: string): Folder {
+  const parts = path.split(/[\\/]/).filter(Boolean);
+  const name = parts[parts.length - 1] ?? "New Folder";
+  const folder: Folder = {
+    id: nextFolderId++,
+    path,
+    name,
+    image_count: 0,
+    indexed_at: new Date().toISOString(),
+    scan_error: null,
+    sort_order: db.folders.length + 1,
+  };
+  db.folders.push(folder);
+  return folder;
+}
+
+function safeFallback(cmd: string, payload: AnyPayload): unknown {
+  if (cmd.includes("app|version")) return "0.1.1-ui";
+  if (cmd.includes("path|resolve_directory")) return "C:\\Users\\phokus\\AppData\\Roaming\\Phokus";
+  if (cmd.includes("path|join")) {
+    const paths = payload?.paths ?? payload?.args ?? [];
+    return Array.isArray(paths) ? paths.join("\\") : "C:\\Users\\phokus\\AppData\\Roaming\\Phokus";
+  }
+  if (cmd.includes("notification|is_permission_granted")) return false;
+  if (cmd.includes("notification|request_permission")) return "denied";
+  if (cmd.includes("dialog|open")) return null;
+  if (cmd.includes("window|is_maximized")) return false;
+  if (cmd.includes("window|minimize")) return null;
+  if (cmd.includes("window|toggle_maximize")) return null;
+  if (cmd.includes("window|close")) return null;
+  if (cmd.includes("opener|reveal_item_in_dir")) return null;
+  if (cmd.includes("opener|open")) return null;
+  if (cmd.includes("process|relaunch")) return null;
+  console.warn("[Phokus UI Lab] Unmocked command:", cmd, payload);
+  return null;
+}
+
+export async function handleMockCommand(cmd: string, payload?: unknown): Promise<unknown> {
+  const p = params(payload);
+
+  switch (cmd) {
+    case "get_folders":
+      return db.folders;
+    case "add_folder":
+      addFolder(String(p.path ?? "C:\\Users\\phokus\\Pictures\\NewFolder"));
+      return null;
+    case "add_folders":
+      return (p.paths ?? []).map((path: string) => ({ status: "added", data: addFolder(path) }));
+    case "remove_folder":
+      db.folders = db.folders.filter((folder) => folder.id !== p.folderId);
+      return null;
+    case "rename_folder": {
+      const folder = db.folders.find((entry) => entry.id === p.folderId);
+      if (folder) folder.name = String(p.newName ?? folder.name);
+      return null;
+    }
+    case "update_folder_path": {
+      const folder = db.folders.find((entry) => entry.id === p.folderId);
+      if (folder) folder.path = String(p.newPath ?? folder.path);
+      return null;
+    }
+    case "reindex_folder":
+    case "reorder_folders":
+      return null;
+    case "list_directories":
+      return {
+        current: p.path ?? null,
+        parent: p.path ? "C:\\Users\\phokus" : null,
+        entries: db.folders.map((folder) => ({ name: folder.name, path: folder.path, has_children: false })),
+      };
+    case "get_background_job_progress":
+      return db.backgroundJobs;
+    case "get_images":
+      return getImages(payload);
+    case "semantic_search_images":
+      return semanticSearch(payload);
+    case "search_images_by_tag":
+      return searchTags(payload);
+    case "get_images_by_ids":
+      return (p.image_ids ?? []).map((id: number) => db.images.find((image) => image.id === id)).filter(Boolean);
+    case "find_similar_images":
+    case "find_similar_by_region":
+      return similarImages(payload);
+    case "get_tag_cloud":
+      return db.scenario === "empty" ? [] : db.tagCloud;
+    case "get_explore_tags":
+      return db.scenario === "empty" ? [] : db.exploreTags.slice(0, Number(p.limit ?? 48));
+    case "suggest_image_tags":
+      return ["select", "warm light"];
+    case "rename_tag":
+    case "delete_tag":
+      return cmd === "delete_tag" ? 6 : null;
+    case "get_image_tags":
+      return db.tagsByImageId[p.image_id] ?? [];
+    case "add_user_tag": {
+      const tag: ImageTag = { id: nextTagId++, image_id: p.image_id, tag: p.tag, source: "user", ai_model: null, confidence: null, created_at: new Date().toISOString() };
+      db.tagsByImageId[p.image_id] = [...(db.tagsByImageId[p.image_id] ?? []), tag];
+      return tag;
+    }
+    case "remove_tag":
+      for (const [imageId, imageTags] of Object.entries(db.tagsByImageId)) {
+        db.tagsByImageId[Number(imageId)] = imageTags.filter((tag) => tag.id !== p.tag_id);
+      }
+      return null;
+    case "get_image_exif":
+      return mockExif(Number(p.image_id));
+    case "update_image_details":
+      return updateImages([Number(p.image_id)], { favorite: p.favorite, rating: p.rating })[0];
+    case "bulk_update_details":
+      return updateImages(p.image_ids ?? [], { favorite: p.favorite, rating: p.rating });
+    case "bulk_add_tags":
+    case "bulk_remove_tag":
+      return null;
+    case "delete_images_from_disk":
+      return p.image_ids ?? [];
+    case "list_albums":
+      refreshAlbumCounts();
+      return db.albums;
+    case "create_album":
+      return createAlbum(String(p.name ?? "Untitled Album"));
+    case "rename_album": {
+      const album = db.albums.find((entry) => entry.id === p.album_id);
+      if (album) album.name = String(p.new_name ?? album.name);
+      return null;
+    }
+    case "delete_album":
+      db.albums = db.albums.filter((album) => album.id !== p.album_id);
+      delete db.albumImageIds[p.album_id];
+      return null;
+    case "delete_albums":
+      db.albums = db.albums.filter((album) => !(p.album_ids ?? []).includes(album.id));
+      for (const id of p.album_ids ?? []) delete db.albumImageIds[id];
+      return null;
+    case "reorder_albums":
+      return null;
+    case "add_images_to_album": {
+      const existing = new Set(db.albumImageIds[p.album_id] ?? []);
+      for (const id of p.image_ids ?? []) existing.add(id);
+      db.albumImageIds[p.album_id] = [...existing];
+      refreshAlbumCounts();
+      return p.image_ids?.length ?? 0;
+    }
+    case "remove_images_from_album":
+      db.albumImageIds[p.album_id] = (db.albumImageIds[p.album_id] ?? []).filter((id) => !(p.image_ids ?? []).includes(id));
+      refreshAlbumCounts();
+      return null;
+    case "get_album_images":
+      return albumImages(payload);
+    case "load_duplicate_scan_cache":
+      return db.duplicateScannedAt ? { groups: db.duplicateGroups, scanned_at: db.duplicateScannedAt } : null;
+    case "find_duplicates":
+      await emit("duplicate_scan_progress", { phase: "hashing", processed: Math.floor(db.images.length * 0.6), total: db.images.length, skipped: db.scenario === "errors" ? 3 : 0 });
+      db.duplicateScannedAt = Math.floor(Date.now() / 1000);
+      return {
+        groups: db.duplicateGroups,
+        scanned_files: db.images.length,
+        candidate_files: db.duplicateGroups.flatMap((group) => group.images).length,
+        skipped_files: db.scenario === "errors" ? 3 : 0,
+      };
+    case "invalidate_duplicate_scan_cache":
+      return null;
+    case "get_caption_model_status":
+      return { model_id: "Salesforce/blip-image-captioning-base", model_name: "BLIP Base", local_dir: "mock://models/caption", ready: true, missing_files: [] };
+    case "get_caption_acceleration":
+    case "set_caption_acceleration":
+      return p.acceleration ?? "auto";
+    case "get_caption_detail":
+    case "set_caption_detail":
+      return p.detail ?? "paragraph";
+    case "prepare_caption_model":
+    case "delete_caption_model":
+      return { model_id: "Salesforce/blip-image-captioning-base", model_name: "BLIP Base", local_dir: "mock://models/caption", ready: true, missing_files: [] };
+    case "probe_caption_runtime":
+      return { ready: true, acceleration: "auto", detail: "paragraph", tokenizer_vocab_size: 30522, sessions: [] };
+    case "probe_caption_image":
+      return { input_shape: [1, 3, 384, 384], output_shape: [1, 768], output_values: 768, acceleration: "auto" };
+    case "generate_caption_for_image": {
+      const image = db.images.find((entry) => entry.id === p.image_id);
+      if (image) image.generated_caption = `Generated in UI Lab for ${image.filename}.`;
+      return image;
+    }
+    case "queue_caption_jobs":
+    case "clear_caption_jobs":
+    case "reset_generated_captions":
+    case "queue_tagging_jobs":
+    case "clear_tagging_jobs":
+      return 12;
+    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: [] };
+    case "get_tagger_acceleration":
+    case "set_tagger_acceleration":
+      return p.acceleration ?? "auto";
+    case "get_tagger_threshold":
+    case "set_tagger_threshold":
+      return p.threshold ?? 0.35;
+    case "get_tagger_batch_size":
+    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"] } };
+    case "get_tagging_queue_scope":
+      return "all";
+    case "get_tagging_queue_folder_ids":
+    case "get_muted_folder_ids":
+      return [];
+    case "set_tagging_queue_scope":
+    case "set_tagging_queue_folder_ids":
+    case "set_muted_folder_ids":
+    case "set_notifications_paused":
+    case "set_worker_paused":
+      return null;
+    case "get_notifications_paused":
+    case "get_onboarding_completed":
+      return db.scenario !== "empty";
+    case "set_onboarding_completed":
+    case "set_last_seen_version":
+      return null;
+    case "get_worker_states":
+      return (p.folderIds ?? []).map((folder_id: number) => ({ folder_id, thumbnail_paused: false, metadata_paused: false, embedding_paused: false, tagging_paused: false }));
+    case "get_build_variant":
+      return "cpu";
+    case "get_last_seen_version":
+      return "0.1.1-ui";
+    case "get_ffmpeg_status":
+      return { installed: true, downloading: false, failed: false };
+    case "retry_ffmpeg_download":
+    case "open_app_data_folder":
+    case "open_map_location":
+    case "open_changelog_url":
+      return null;
+    case "get_database_info":
+      return { size_mb: 14.2, reclaimable_mb: 1.8 };
+    case "vacuum_database":
+      return { before_mb: 14.2, after_mb: 12.4, freed_mb: 1.8 };
+    case "rebuild_semantic_index":
+      return db.images.length;
+    case "get_orphaned_thumbnails_info":
+      return { count: 9, size_mb: 3.4 };
+    case "cleanup_orphaned_thumbnails":
+      return { deleted_count: 9, freed_mb: 3.4 };
+    case "retry_failed_embeddings":
+      return null;
+    default:
+      return safeFallback(cmd, payload as AnyPayload);
+  }
+}

src/dev/mockFixtures.ts

@@ -0,0 +1,289 @@
+import type {
+  Album,
+  AiRating,
+  DuplicateGroup,
+  ExploreTagEntry,
+  Folder,
+  FolderJobProgress,
+  ImageExif,
+  ImageRecord,
+  ImageTag,
+  SortOrder,
+  TagCloudEntry,
+} from "../store";
+import type { MockScenario } from "./mockScenarios";
+import { fixtureMediaPath } from "./mockMedia";
+
+export interface MockDb {
+  scenario: MockScenario;
+  folders: Folder[];
+  images: ImageRecord[];
+  albums: Album[];
+  albumImageIds: Record<number, number[]>;
+  tagsByImageId: Record<number, ImageTag[]>;
+  tagCloud: TagCloudEntry[];
+  exploreTags: ExploreTagEntry[];
+  backgroundJobs: FolderJobProgress[];
+  duplicateGroups: DuplicateGroup[];
+  duplicateScannedAt: number | null;
+}
+
+const folderNames = ["Camera Roll", "Client Selects", "Video Archive"];
+const mediaNames = [
+  "alpine-lake",
+  "city-after-rain",
+  "coastal-walk",
+  "studio-portrait",
+  "market-neon",
+  "forest-floor",
+  "product-macro",
+  "golden-hour",
+  "night-drive",
+  "desk-flatlay",
+  "museum-hall",
+  "wildflower",
+];
+const tags = [
+  "landscape",
+  "portrait",
+  "street",
+  "travel",
+  "night",
+  "product",
+  "editorial",
+  "architecture",
+  "nature",
+  "warm light",
+  "blue hour",
+  "select",
+];
+const aiRatings: AiRating[] = ["general", "sensitive", "questionable"];
+
+function daysAgo(days: number): string {
+  return new Date(Date.now() - days * 86_400_000).toISOString();
+}
+
+function mockPath(folder: number, name: string, index: number, ext: string): string {
+  return `mock://full/${folder}-${name}-${index}.${ext}`;
+}
+
+function mockThumb(index: number): string {
+  return fixtureMediaPath(index);
+}
+
+function makeImage(index: number, folderId: number, scenario: MockScenario): ImageRecord {
+  const name = mediaNames[index % mediaNames.length];
+  const isVideo = index % 11 === 6;
+  const failedEmbedding = scenario === "errors" && index % 9 === 0;
+  const failedTagging = scenario === "errors" && index % 7 === 0;
+  const ext = isVideo ? "mp4" : "jpg";
+  return {
+    id: index + 1,
+    folder_id: folderId,
+    path: isVideo ? mockPath(folderId, name, index + 1, ext) : mockThumb(index),
+    filename: `${name}-${String(index + 1).padStart(3, "0")}.${ext}`,
+    thumbnail_path: scenario === "errors" && index % 10 === 3 ? "mock://missing-thumb.svg" : mockThumb(index),
+    width: isVideo ? 3840 : 3000 + (index % 5) * 180,
+    height: isVideo ? 2160 : 2000 + (index % 4) * 160,
+    file_size: 480_000 + index * 73_000,
+    created_at: daysAgo(index + 3),
+    modified_at: daysAgo(index + 1),
+    taken_at: daysAgo(index + 10),
+    mime_type: isVideo ? "video/mp4" : "image/jpeg",
+    media_kind: isVideo ? "video" : "image",
+    duration_ms: isVideo ? 42_000 + index * 1300 : null,
+    video_codec: isVideo ? "h264" : null,
+    audio_codec: isVideo ? "aac" : null,
+    metadata_updated_at: daysAgo(index),
+    metadata_error: scenario === "errors" && index % 8 === 2 ? "EXIF parse failed in UI fixture" : null,
+    favorite: index % 5 === 0,
+    rating: index % 6,
+    embedding_status: failedEmbedding ? "failed" : index % 13 === 0 ? "processing" : "ready",
+    embedding_model: failedEmbedding ? null : "clip-vit-b-32",
+    embedding_updated_at: failedEmbedding ? null : daysAgo(index),
+    embedding_error: failedEmbedding ? "Fixture embedding failure" : null,
+    generated_caption: `Fixture caption for ${name.replace(/-/g, " ")}.`,
+    caption_model: "blip-base",
+    caption_updated_at: daysAgo(index),
+    caption_error: null,
+    ai_rating: aiRatings[index % aiRatings.length],
+    ai_tagger_model: failedTagging ? null : "wd-vit-tagger-v3",
+    ai_tagged_at: failedTagging ? null : daysAgo(index),
+    ai_tagger_error: failedTagging ? "Fixture tagger failure" : null,
+  };
+}
+
+function makeFolders(scenario: MockScenario): Folder[] {
+  if (scenario === "empty") return [];
+  return folderNames.map((name, index) => ({
+    id: index + 1,
+    path: `C:\\Users\\phokus\\Pictures\\${name.replace(/ /g, "")}`,
+    name,
+    image_count: 0,
+    indexed_at: daysAgo(index + 1),
+    scan_error: scenario === "errors" && index === 1 ? "Folder moved or permission denied" : null,
+    sort_order: index + 1,
+  }));
+}
+
+function makeImages(scenario: MockScenario, folders: Folder[]): ImageRecord[] {
+  if (scenario === "empty") return [];
+  const count = scenario === "huge" ? 720 : scenario === "errors" ? 54 : 72;
+  const images = Array.from({ length: count }, (_, index) => makeImage(index, folders[index % folders.length].id, scenario));
+  for (const folder of folders) {
+    folder.image_count = images.filter((image) => image.folder_id === folder.id).length;
+  }
+  return images;
+}
+
+function makeTags(images: ImageRecord[]): Record<number, ImageTag[]> {
+  return Object.fromEntries(
+    images.map((image, index) => [
+      image.id,
+      [0, 1, 2].map((offset) => ({
+        id: image.id * 10 + offset,
+        image_id: image.id,
+        tag: tags[(index + offset) % tags.length],
+        source: offset === 0 ? "user" : "ai",
+        ai_model: offset === 0 ? null : "wd-vit-tagger-v3",
+        confidence: offset === 0 ? null : 0.72 + offset * 0.07,
+        created_at: daysAgo(index + offset),
+      })),
+    ]),
+  );
+}
+
+function makeAlbums(images: ImageRecord[], scenario: MockScenario): { albums: Album[]; albumImageIds: Record<number, number[]> } {
+  if (scenario === "empty") return { albums: [], albumImageIds: {} };
+  const selects = images.filter((image) => image.rating >= 4).slice(0, 36).map((image) => image.id);
+  const motion = images.filter((image) => image.media_kind === "video").map((image) => image.id);
+  const favorites = images.filter((image) => image.favorite).slice(0, 40).map((image) => image.id);
+  const albumImageIds = { 1: selects, 2: motion, 3: favorites };
+  const albums: Album[] = [
+    { id: 1, name: "Portfolio Shortlist", cover_image_id: selects[0] ?? null, cover_thumbnail_path: images.find((image) => image.id === selects[0])?.thumbnail_path ?? null, image_count: selects.length, sort_order: 1, created_at: daysAgo(40), updated_at: daysAgo(2) },
+    { id: 2, name: "Motion Tests", cover_image_id: motion[0] ?? null, cover_thumbnail_path: images.find((image) => image.id === motion[0])?.thumbnail_path ?? null, image_count: motion.length, sort_order: 2, created_at: daysAgo(38), updated_at: daysAgo(3) },
+    { id: 3, name: "Favorites", cover_image_id: favorites[0] ?? null, cover_thumbnail_path: images.find((image) => image.id === favorites[0])?.thumbnail_path ?? null, image_count: favorites.length, sort_order: 3, created_at: daysAgo(20), updated_at: daysAgo(1) },
+  ];
+  return { albums, albumImageIds };
+}
+
+function makeProgress(folders: Folder[], scenario: MockScenario): FolderJobProgress[] {
+  return folders.map((folder, index) => ({
+    folder_id: folder.id,
+    thumbnail_pending: scenario === "busy" ? 18 - index * 3 : 0,
+    metadata_pending: scenario === "busy" ? 12 - index * 2 : 0,
+    embedding_pending: scenario === "busy" ? 36 - index * 4 : scenario === "errors" ? 4 : 0,
+    embedding_ready: Math.max(0, folder.image_count - (scenario === "busy" ? 20 : 2)),
+    embedding_failed: scenario === "errors" ? 3 + index : 0,
+    caption_pending: scenario === "busy" ? 24 - index * 2 : 0,
+    caption_ready: Math.max(0, Math.floor(folder.image_count * 0.5)),
+    caption_failed: scenario === "errors" ? 2 : 0,
+    tagging_pending: scenario === "busy" ? 30 - index * 5 : 0,
+    tagging_ready: Math.max(0, Math.floor(folder.image_count * 0.65)),
+    tagging_failed: scenario === "errors" ? 4 : 0,
+  }));
+}
+
+function makeTagCloud(images: ImageRecord[]): TagCloudEntry[] {
+  return tags.slice(0, 10).map((_, index) => {
+    const group = images.filter((image) => image.id % (index + 2) === 0).slice(0, 28);
+    const representative = group[0] ?? images[index];
+    return {
+      count: Math.max(group.length, 1),
+      representative_image_id: representative?.id ?? index + 1,
+      thumbnail_path: representative?.thumbnail_path ?? null,
+      image_ids: group.length ? group.map((image) => image.id) : [representative?.id ?? 1],
+    };
+  });
+}
+
+function makeExploreTags(images: ImageRecord[]): ExploreTagEntry[] {
+  return tags.map((tag, index) => {
+    const representative = images[index % Math.max(images.length, 1)];
+    return {
+      tag,
+      count: Math.max(3, Math.round(images.length / (index + 3))),
+      representative_image_id: representative?.id ?? index + 1,
+      thumbnail_path: representative?.thumbnail_path ?? null,
+    };
+  });
+}
+
+function makeDuplicateGroups(images: ImageRecord[], scenario: MockScenario): DuplicateGroup[] {
+  if (scenario === "empty") return [];
+  const candidates = images.filter((image) => image.media_kind === "image");
+  const groups = [0, 1, 2, 3].map((groupIndex) => ({
+    file_hash: `fixture-hash-${groupIndex}`,
+    file_size: candidates[groupIndex]?.file_size ?? 1_200_000,
+    images: candidates.slice(groupIndex * 4, groupIndex * 4 + (groupIndex === 1 ? 3 : 2)),
+  })).filter((group) => group.images.length > 1);
+  return scenario === "duplicates" ? groups.concat(groups.map((group, index) => ({
+    ...group,
+    file_hash: `${group.file_hash}-extra`,
+    images: candidates.slice(20 + index * 3, 23 + index * 3),
+  })).filter((group) => group.images.length > 1)) : groups;
+}
+
+export function createMockDb(scenario: MockScenario): MockDb {
+  const folders = makeFolders(scenario);
+  const images = makeImages(scenario, folders);
+  const { albums, albumImageIds } = makeAlbums(images, scenario);
+  return {
+    scenario,
+    folders,
+    images,
+    albums,
+    albumImageIds,
+    tagsByImageId: makeTags(images),
+    tagCloud: makeTagCloud(images),
+    exploreTags: makeExploreTags(images),
+    backgroundJobs: makeProgress(folders, scenario),
+    duplicateGroups: makeDuplicateGroups(images, scenario),
+    duplicateScannedAt: scenario === "duplicates" ? Math.floor(Date.now() / 1000) - 420 : null,
+  };
+}
+
+export function compareImages(sort: SortOrder): (left: ImageRecord, right: ImageRecord) => number {
+  return (left, right) => {
+    switch (sort) {
+      case "name_asc":
+        return left.filename.localeCompare(right.filename);
+      case "name_desc":
+        return right.filename.localeCompare(left.filename);
+      case "size_asc":
+        return left.file_size - right.file_size;
+      case "size_desc":
+        return right.file_size - left.file_size;
+      case "rating_asc":
+        return left.rating - right.rating;
+      case "rating_desc":
+        return right.rating - left.rating;
+      case "duration_asc":
+        return (left.duration_ms ?? 0) - (right.duration_ms ?? 0);
+      case "duration_desc":
+        return (right.duration_ms ?? 0) - (left.duration_ms ?? 0);
+      case "date_asc":
+      case "taken_asc":
+        return Date.parse(left.taken_at ?? left.created_at ?? "") - Date.parse(right.taken_at ?? right.created_at ?? "");
+      case "date_desc":
+      case "taken_desc":
+      default:
+        return Date.parse(right.taken_at ?? right.created_at ?? "") - Date.parse(left.taken_at ?? left.created_at ?? "");
+    }
+  };
+}
+
+export function mockExif(imageId: number): ImageExif {
+  return {
+    make: "Phokus Fixture Co.",
+    model: `MockCam ${100 + imageId}`,
+    lens: "35mm f/1.8",
+    iso: String(100 + (imageId % 8) * 100),
+    f_number: "f/4",
+    exposure_time: "1/250",
+    focal_length: "35mm",
+    datetime_original: daysAgo(imageId),
+    gps_lat: imageId % 2 === 0 ? 51.5072 : null,
+    gps_lon: imageId % 2 === 0 ? -0.1276 : null,
+  };
+}

src/dev/mockMedia.ts

@@ -0,0 +1,8 @@
+const fixtureMedia = Array.from(
+  { length: 48 },
+  (_, index) => `/dev-media/fixture-${String(index + 1).padStart(2, "0")}.webp`,
+);
+
+export function fixtureMediaPath(index: number): string {
+  return fixtureMedia[index % fixtureMedia.length];
+}

src/dev/mockScenarios.ts

@@ -0,0 +1,17 @@
+export type MockScenario = "rich" | "empty" | "busy" | "duplicates" | "album" | "errors" | "huge";
+
+const SCENARIOS = new Set<MockScenario>([
+  "rich",
+  "empty",
+  "busy",
+  "duplicates",
+  "album",
+  "errors",
+  "huge",
+]);
+
+export function getMockScenario(): MockScenario {
+  if (typeof window === "undefined") return "rich";
+  const value = new URLSearchParams(window.location.search).get("scenario");
+  return value && SCENARIOS.has(value as MockScenario) ? (value as MockScenario) : "rich";
+}

src/dev/setupMockTauri.ts

@@ -0,0 +1,11 @@
+import { mockConvertFileSrc, mockIPC, mockWindows } from "@tauri-apps/api/mocks";
+import { handleMockCommand } from "./mockBackend";
+
+mockWindows("main");
+mockConvertFileSrc("windows");
+
+mockIPC((cmd, payload) => handleMockCommand(cmd, payload), {
+  shouldMockEvents: true,
+});
+
+console.info("[Phokus UI Lab] Mock Tauri backend installed.");

src/lib/mediaSrc.ts

@@ -0,0 +1,17 @@
+import { convertFileSrc } from "@tauri-apps/api/core";
+
+const MOCK_MEDIA_PREFIX = "mock://";
+
+export function mediaSrc(path: string | null): string | null {
+  if (!path) return null;
+
+  if (import.meta.env.MODE === "ui" && (path.startsWith("/") || path.startsWith("http"))) {
+    return path;
+  }
+
+  if (import.meta.env.MODE === "ui" && path.startsWith(MOCK_MEDIA_PREFIX)) {
+    return `/dev-media/${path.slice(MOCK_MEDIA_PREFIX.length)}`;
+  }
+
+  return convertFileSrc(path);
+}

src/main.tsx

@@ -1,10 +1,19 @@
 import React from "react";
 import ReactDOM from "react-dom/client";
-import App from "./App";
 import "./index.css";
 
-ReactDOM.createRoot(document.getElementById("root") as HTMLElement).render(
+async function bootstrap() {
+  if (import.meta.env.MODE === "ui") {
+    await import("./dev/setupMockTauri");
+  }
+
+  const { default: App } = await import("./App");
+
+  ReactDOM.createRoot(document.getElementById("root") as HTMLElement).render(
     <React.StrictMode>
       <App />
     </React.StrictMode>,
-);
+  );
+}
+
+void bootstrap();