# Frontend Hooks Reference

Complete documentation for all custom React hooks in the Tour Builder Platform frontend.

---

## Navigation

### Quick Links

| Category | Hooks |
|----------|-------|
| [Redux Integration](#redux-integration-hooks) | [useAppDispatch & useAppSelector](#useappdispatch--useappselector) |
| [Data Management](#data-management-hooks) | [useFormSync](#useformsync) · [useEditPageSync](#useeditpagesync) · [useDashboardCounts](#usedashboardcounts) · [useEntityTable](#useentitytable) · [useCSVHandling](#usecsvhandling) · [useFilterItems](#usefilteritems) · [useElementSettingsForm](#useelementsettingsform) |
| [Offline & Caching](#offline--caching-hooks) | [useOfflineMode](#useofflinemode) · [useStorageQuota](#usestoragequota) |
| [Preloading](#preloading-hooks) | [usePreloadOrchestrator](#usepreloadorchestrator) · [useNeighborGraph](#useneighborgraph) · [useNetworkAware](#usenetworkaware) · [usePWAPreload](#usepwapreload) · [usePreloadProgress](#usepreloadprogress) |
| [Media Playback](#media-playback-hooks) | [useReversePlayback](#usereverseplayback) · [useTransitionPlayback](#usetransitionplayback) · [useBackgroundTransition](#usebackgroundtransition) · [usePageDataLoader](#usepagedataloader) · [useElementEffects](#useelementeffects) |
| [Navigation](#navigation-hooks) | [usePageSwitch](#usepageswitch) · [usePageNavigation](#usepagenavigation) |
| [Asset Upload](#asset-upload-hooks) | [useAssetUploader](#useassetuploader) |
| [Constructor](#constructor-hooks) | [useConstructorElements](#useconstructorelements) · [useConstructorPageActions](#useconstructorpageactions) · [useTransitionPreview](#usetransitionpreview) · [useCanvasElapsedTime](#usecanvaselapsedtime) · [useCanvasElementDrag](#usecanvaselementdrag) · [useIconPreload](#useiconpreload) · [useMediaDurationProbe](#usemediadurationprobe) |
| [Utility](#utility-hooks) | [useDevCompilationStatus](#usedevcompilationstatus) · [useOutsideClick](#useoutsideclick) · [useDraggable](#usedraggable) |

### All Hooks (A-Z)

| Hook | Category | Used By | Description |
|------|----------|---------|-------------|
| [useAppDispatch](#useappdispatch--useappselector) | Redux | All | Type-safe Redux dispatch |
| [useAppSelector](#useappdispatch--useappselector) | Redux | All | Type-safe Redux state selection |
| [useAssetUploader](#useassetuploader) | Upload | Constructor | Batch asset uploads with progress |
| [useBackgroundTransition](#usebackgroundtransition) | Media | Runtime, Constructor | Background fade transition effects |
| [useCanvasElapsedTime](#usecanvaselapsedtime) | Constructor | Constructor | Elapsed time for element visibility |
| [useCanvasElementDrag](#usecanvaselementdrag) | Constructor | Constructor | Element drag with % positioning |
| [useConstructorElements](#useconstructorelements) | Constructor | Constructor | Element CRUD operations |
| [useConstructorPageActions](#useconstructorpageactions) | Constructor | Constructor | Page save/create/publish |
| [useCSVHandling](#usecsvhandling) | Data | List Pages | CSV import/export |
| [useDashboardCounts](#usedashboardcounts) | Data | Dashboard | Dashboard entity counts |
| [useDevCompilationStatus](#usedevcompilationstatus) | Utility | _app | Next.js dev compilation status |
| [useDraggable](#usedraggable) | Utility | Constructor | Draggable panel management |
| [useEditPageSync](#useeditpagesync) | Data | Edit Pages | Edit page data sync |
| [useElementEffects](#useelementeffects) | Media | Runtime | Element hover/focus/active effects |
| [useElementSettingsForm](#useelementsettingsform) | Data | Constructor | Element settings form state |
| [useEntityTable](#useentitytable) | Data | Table Pages | Complete table management |
| [useFilterItems](#usefilteritems) | Data | List Pages | Filter state management |
| [useFormSync](#useformsync) | Data | Edit Pages | Form sync with Redux entities |
| [useIconPreload](#useiconpreload) | Constructor | Constructor | Icon image preloading |
| [useMediaDurationProbe](#usemediadurationprobe) | Constructor | Constructor | Media duration probing |
| [useNeighborGraph](#useneighborgraph) | Preload | (internal) | Navigation graph building |
| [useNetworkAware](#usenetworkaware) | Preload | (internal) | Network condition monitoring |
| [useOfflineMode](#useofflinemode) | Offline | OfflineToggle | Project offline download |
| [useOutsideClick](#useoutsideclick) | Utility | Constructor | Click outside detection |
| [usePageDataLoader](#usepagedataloader) | Media | Runtime, Constructor | Project/page data loading |
| [usePageNavigation](#usepagenavigation) | Navigation | Runtime, Constructor | Page state with history |
| [usePageSwitch](#usepageswitch) | Navigation | Runtime, Constructor | Smooth page switching |
| [usePreloadOrchestrator](#usepreloadorchestrator) | Preload | Runtime, Constructor | Asset preload with blob URLs |
| [usePreloadProgress](#usepreloadprogress) | Preload | OfflineToggle | Preload job tracking |
| [usePWAPreload](#usepwapreload) | Preload | OfflineToggle | PWA asset caching |
| [useReversePlayback](#usereverseplayback) | Media | (internal) | Reverse video playback |
| [useStorageQuota](#usestoragequota) | Offline | OfflineToggle | Storage quota monitoring |
| [useTransitionPlayback](#usetransitionplayback) | Media | Runtime, Constructor | Transition video management |
| [useTransitionPreview](#usetransitionpreview) | Constructor | Constructor | Transition video preview |

**Legend:** Runtime = `RuntimePresentation.tsx`, Constructor = `constructor.tsx`, (internal) = used by other hooks

### Presentation Components Hook Usage

**RuntimePresentation.tsx** (public tour viewer):
```
usePageDataLoader ──→ usePreloadOrchestrator ──→ usePageSwitch
                              │
                              ▼
                    useTransitionPlayback ──→ useBackgroundTransition
```

**constructor.tsx** (tour editor):
```
usePageDataLoader ──→ usePreloadOrchestrator ──→ usePageSwitch
        │                     │
        ▼                     ▼
useConstructorElements   useTransitionPlayback ──→ useBackgroundTransition
        │                     │
        ▼                     ▼
useConstructorPageActions useTransitionPreview
        │
        ▼
useCanvasElementDrag, useCanvasElapsedTime, useIconPreload, useMediaDurationProbe
```

---

## Overview

The platform provides a comprehensive set of custom hooks organized into categories:

- **Redux Integration** - Type-safe store access
- **Data Management** - Form sync, table management, CSV handling
- **Offline & Caching** - PWA offline mode, storage quota
- **Preloading** - Asset preloading, neighbor graph, network awareness
- **Media Playback** - Video transitions, reverse playback
- **Navigation** - Page navigation with history
- **Asset Upload** - Batch upload with progress tracking
- **Constructor** - Element management, page actions, transitions, dragging
- **Utility** - Outside click detection, draggable panels

**Important: Blob URL Rendering**

Preloading hooks (`usePreloadOrchestrator`, `usePageSwitch`) return blob URLs for cached assets. When rendering these URLs as images, use native `<img>` tags instead of Next.js `<Image>`:

- **Next.js Image re-fetches on every render** - even with `unoptimized` prop
- **Blob URLs don't benefit from optimization** - already in-memory
- **Use conditional rendering**: native `<img>` for `blob:` URLs, Next.js Image for regular URLs

See `usePageSwitch` documentation for implementation example.

```
┌─────────────────────────────────────────────────────────────────────────────┐
│                         Frontend Hooks Architecture                          │
│                                                                              │
│  ┌────────────────────────────────────────────────────────────────────────┐ │
│  │                         Redux Layer                                     │ │
│  │                                                                         │ │
│  │   useAppDispatch ←──────────────────────────────→ useAppSelector       │ │
│  │         │                                               │               │ │
│  │         ▼                                               ▼               │ │
│  │   ┌─────────────┐                               ┌─────────────┐        │ │
│  │   │ Entity      │                               │ Entity      │        │ │
│  │   │ Slices      │                               │ State       │        │ │
│  │   └─────────────┘                               └─────────────┘        │ │
│  └────────────────────────────────────────────────────────────────────────┘ │
│                                    │                                         │
│                    ┌───────────────┼───────────────┐                        │
│                    ▼               ▼               ▼                        │
│  ┌──────────────────┐  ┌──────────────────┐  ┌──────────────────┐          │
│  │   useFormSync    │  │  useEntityTable  │  │  useCSVHandling  │          │
│  │                  │  │                  │  │                  │          │
│  │  Form ↔ Entity   │  │  Table + CRUD    │  │  Import/Export   │          │
│  └──────────────────┘  └──────────────────┘  └──────────────────┘          │
│                                                                              │
│  ┌────────────────────────────────────────────────────────────────────────┐ │
│  │                      Offline & Preload Layer                           │ │
│  │                                                                         │ │
│  │   useOfflineMode ──→ useStorageQuota                                   │ │
│  │         │                                                               │ │
│  │         ▼                                                               │ │
│  │   usePreloadOrchestrator ──→ useNeighborGraph                          │ │
│  │         │    (getReadyBlobUrl)     │                                    │ │
│  │         │                          ▼                                    │ │
│  │         ├──→ useNetworkAware    usePWAPreload                          │ │
│  │         ▼                                                               │ │
│  │   usePageSwitch (blob URL resolution + transitions)                    │ │
│  └────────────────────────────────────────────────────────────────────────┘ │
│                                                                              │
│  ┌────────────────────────────────────────────────────────────────────────┐ │
│  │                         Media Layer                                     │ │
│  │                                                                         │ │
│  │   useTransitionPlayback ──→ useReversePlayback                         │ │
│  │         │                                                               │ │
│  │         ▼                                                               │ │
│  │   useBackgroundTransition ──→ usePageDataLoader                        │ │
│  │                                                                         │ │
│  └────────────────────────────────────────────────────────────────────────┘ │
│                                                                              │
│  ┌────────────────────────────────────────────────────────────────────────┐ │
│  │                     Constructor Layer                                   │ │
│  │                                                                         │ │
│  │   useConstructorElements ──→ useConstructorPageActions                 │ │
│  │         │                            │                                  │ │
│  │         ▼                            ▼                                  │ │
│  │   useCanvasElementDrag        useTransitionPreview                     │ │
│  │         │                            │                                  │ │
│  │         ▼                            ▼                                  │ │
│  │   useCanvasElapsedTime    useIconPreload, useMediaDurationProbe        │ │
│  │                                                                         │ │
│  └────────────────────────────────────────────────────────────────────────┘ │
│                                                                              │
│  ┌────────────────────────────────────────────────────────────────────────┐ │
│  │                       Utility Layer                                     │ │
│  │                                                                         │ │
│  │   useDraggable ──→ useOutsideClick ──→ useElementEffects               │ │
│  │                                                                         │ │
│  └────────────────────────────────────────────────────────────────────────┘ │
└─────────────────────────────────────────────────────────────────────────────┘
```

## Redux Integration Hooks

### useAppDispatch & useAppSelector

**Source:** `frontend/src/stores/hooks.ts`

Type-safe Redux hooks for accessing store and dispatching actions.

```typescript
import { useDispatch, useSelector } from 'react-redux';
import type { TypedUseSelectorHook } from 'react-redux';
import type { RootState, AppDispatch } from './store';

export const useAppDispatch: () => AppDispatch = useDispatch;
export const useAppSelector: TypedUseSelectorHook<RootState> = useSelector;
```

**Usage:**

```typescript
import { useAppDispatch, useAppSelector } from '../stores/hooks';
import { fetch, update } from '../stores/users/usersSlice';

function UserList() {
  const dispatch = useAppDispatch();
  const users = useAppSelector((state) => state.users.users);
  const loading = useAppSelector((state) => state.users.loading);

  useEffect(() => {
    dispatch(fetch({ query: '?limit=100' }));
  }, [dispatch]);

  return loading ? <Spinner /> : <Table data={users} />;
}
```

**Benefits:**
- Full TypeScript support for state shape
- Autocomplete for state paths
- Type-checked dispatch payloads

---

## Data Management Hooks

### useFormSync

**Source:** `frontend/src/hooks/useFormSync.ts`

Synchronizes form state with Redux entity data, eliminating boilerplate in edit pages.

**Signature:**

```typescript
function useFormSync<T extends BaseEntity, TFormValues extends Record<string, unknown>>(
  options: UseFormSyncOptions<T, TFormValues>
): UseFormSyncReturn<TFormValues>
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| entitySelector | `(state: RootState) => T \| T[] \| undefined` | Redux state selector |
| fetchAction | `AsyncThunk` | Thunk to fetch entity |
| initialValues | `TFormValues` | Default form values |
| transformEntity | `(entity: T) => TFormValues` | Optional field mapper |

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| formValues | `TFormValues` | Current form state |
| setFormValues | `(values: TFormValues) => void` | Update form |
| isLoading | `boolean` | Fetch in progress |
| entityId | `string \| undefined` | ID from router |
| resetForm | `() => void` | Reset to initial values |

**Example:**

```typescript
const { formValues, setFormValues, isLoading, entityId } = useFormSync({
  entitySelector: (state) => state.projects.projects,
  fetchAction: fetchProjects,
  initialValues: {
    name: '',
    slug: '',
    description: '',
  },
  transformEntity: (project) => ({
    name: project.name,
    slug: project.slug,
    description: project.description || '',
  }),
});

// In Formik
<Formik
  initialValues={formValues}
  enableReinitialize
  onSubmit={handleSubmit}
>
  {/* form fields */}
</Formik>
```

**Key Features:**
- Extracts entity ID from Next.js router query
- Handles both single entity and array state shapes
- Auto-fetches when ID is available
- Optional transform for field name mapping

---

### useEditPageSync

**Source:** `frontend/src/hooks/useEditPageSync.ts`

Simplified hook for edit pages that syncs form state with Redux entity data. Reduces ~50 lines of boilerplate code per edit page.

**Signature:**

```typescript
function useEditPageSync<T extends Record<string, unknown>>(
  options: UseEditPageSyncOptions<T>
): UseEditPageSyncReturn<T>
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| entitySelector | `(state: RootState) => unknown` | Redux selector for entity |
| fetchAction | `AsyncThunk` | Thunk to fetch entity |
| initialValues | `T` | Default form values |
| postProcess | `(entity: T, initial: T) => T` | Optional post-processing |
| idOverride | `string` | Optional ID override (defaults to router.query.id) |

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| values | `T` | Current form values |
| setValues | `React.Dispatch<SetStateAction<T>>` | Update form values |
| id | `string \| null` | Entity ID from router |
| isLoading | `boolean` | Fetch in progress |
| isFound | `boolean` | Entity was found |

**Example:**

```typescript
const initVals = { name: '', permissions: [] };

const EditRolesPage = () => {
  const { values, id, isLoading } = useEditPageSync({
    entitySelector: (state) => state.roles.roles,
    fetchAction: fetch,
    initialValues: initVals,
  });

  const handleSubmit = async (data) => {
    await dispatch(update({ id, data }));
    router.push('/roles/roles-list');
  };

  return (
    <Formik enableReinitialize initialValues={values} onSubmit={handleSubmit}>
      ...
    </Formik>
  );
};
```

**Simplified Variant:**

```typescript
// Returns [values, setValues] tuple for drop-in replacement
const [initialValues, setInitialValues] = useEditPageSyncSimple({
  entitySelector: (state) => state.roles.roles,
  fetchAction: fetch,
  initialValues: initVals,
});
```

---

### useDashboardCounts

**Source:** `frontend/src/hooks/useDashboardCounts.ts`

Fetches entity counts for the dashboard with permission-based filtering. Uses `Promise.allSettled` for resilience.

**Signature:**

```typescript
function useDashboardCounts(currentUser: User | null): UseDashboardCountsReturn
```

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| counts | `Record<string, number \| string \| null>` | Entity counts |
| loading | `boolean` | Fetch in progress |
| error | `Error \| null` | Error if failed |
| refetch | `() => Promise<void>` | Manual refetch |
| getCount | `(key: string) => EntityCountValue` | Get count for entity |
| getVisibleEntities | `() => EntityConfig[]` | Get permitted entities |

**Example:**

```typescript
const { counts, loading, getVisibleEntities, getCount } = useDashboardCounts(currentUser);

const entities = getVisibleEntities();
const userCount = getCount('users'); // number | 'Loading...' | null

return (
  <DashboardCards>
    {entities.map((entity) => (
      <Card key={entity.key} count={getCount(entity.key)} />
    ))}
  </DashboardCards>
);
```

**Entity Configuration:** Uses `DASHBOARD_ENTITIES` constant with 13 entities (users, roles, permissions, projects, etc.), each with permission requirements.

---

### useEntityTable

**Source:** `frontend/src/hooks/useEntityTable.ts`

Complete table state management including pagination, sorting, filtering, selection, and CRUD.

**Signature:**

```typescript
function useEntityTable<T extends BaseEntity>(
  options: UseEntityTableOptions<T>
): UseEntityTableReturn<T>
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| entityName | `string` | Entity identifier |
| sliceSelector | `(state: RootState) => EntitySliceState<T>` | Redux slice selector |
| fetchAction | `AsyncThunk` | Fetch thunk |
| updateAction | `AsyncThunk` | Update thunk (optional) |
| deleteAction | `AsyncThunk` | Delete single item thunk |
| deleteByIdsAction | `AsyncThunk` | Batch delete thunk (optional) |
| setRefetchAction | `(value: boolean) => Action` | Trigger refetch |
| loadColumnsFunction | `Function` | Column config loader |
| filters | `Filter[]` | Available filters |
| perPage | `number` | Items per page (default: 10) |

**Returns:**

```typescript
interface UseEntityTableReturn<T> {
  // Data
  data: T[];
  columns: GridColDef[];
  loading: boolean;
  count: number;

  // Pagination
  currentPage: number;
  setCurrentPage: (page: number) => void;
  numPages: number;

  // Sorting
  sortModel: GridSortModel;
  setSortModel: (model: GridSortModel) => void;

  // Selection
  selectedRows: string[];
  setSelectedRows: (ids: string[]) => void;

  // Filters
  filterItems: FilterItem[];
  setFilterItems: (items: FilterItem[]) => void;
  filterRequest: string;
  handleFilterSubmit: () => void;
  handleFilterReset: () => void;

  // Delete operations
  isDeleteModalActive: boolean;
  deleteTargetId: string | null;
  handleDeleteClick: (id: string) => void;
  handleDeleteConfirm: () => Promise<void>;
  handleDeleteCancel: () => void;
  handleDeleteSelected: () => Promise<void>;

  // Table operations
  handleRowUpdate: (id: string, data: Partial<T>) => Promise<void>;
  loadData: (page?: number, request?: string) => void;
}
```

**Example:**

```typescript
const {
  data,
  columns,
  loading,
  currentPage,
  setCurrentPage,
  numPages,
  sortModel,
  setSortModel,
  filterItems,
  setFilterItems,
  handleFilterSubmit,
  handleDeleteConfirm,
  isDeleteModalActive,
} = useEntityTable({
  entityName: 'assets',
  sliceSelector: (state) => state.assets,
  fetchAction: fetchAssets,
  deleteAction: deleteAsset,
  deleteByIdsAction: deleteAssetsByIds,
  setRefetchAction: setRefetch,
  loadColumnsFunction: configureAssetsCols,
  filters: assetFilters,
  perPage: 25,
});

return (
  <>
    <FilterBar
      filters={filters}
      filterItems={filterItems}
      setFilterItems={setFilterItems}
      onSubmit={handleFilterSubmit}
    />
    <DataGrid
      rows={data}
      columns={columns}
      loading={loading}
      sortModel={sortModel}
      onSortModelChange={setSortModel}
      paginationModel={{ page: currentPage, pageSize: 25 }}
      onPaginationModelChange={({ page }) => setCurrentPage(page)}
      rowCount={count}
    />
    <DeleteModal
      isActive={isDeleteModalActive}
      onConfirm={handleDeleteConfirm}
      onCancel={handleDeleteCancel}
    />
  </>
);
```

---

### useCSVHandling

**Source:** `frontend/src/hooks/useCSVHandling.ts`

Manages CSV import and export operations for bulk data handling.

**Signature:**

```typescript
function useCSVHandling(options: UseCSVHandlingOptions): UseCSVHandlingReturn
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| endpoint | `string` | API endpoint (e.g., 'users') |
| uploadAction | `AsyncThunk` | CSV upload thunk |
| setRefetchAction | `(value: boolean) => Action` | Trigger data reload |
| fileName | `string` | Export filename (optional) |

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| csvFile | `File \| null` | Selected file |
| setCsvFile | `(file: File \| null) => void` | Set file |
| isModalActive | `boolean` | Import modal visible |
| setIsModalActive | `(active: boolean) => void` | Toggle modal |
| isUploading | `boolean` | Upload in progress |
| isDownloading | `boolean` | Download in progress |
| downloadCSV | `() => Promise<void>` | Trigger export |
| uploadCSV | `() => Promise<void>` | Trigger import |
| error | `string \| null` | Error message |

**Example:**

```typescript
const {
  csvFile,
  setCsvFile,
  isUploading,
  isDownloading,
  downloadCSV,
  uploadCSV,
  error,
} = useCSVHandling({
  endpoint: 'users',
  uploadAction: uploadUsersCsv,
  setRefetchAction: setRefetch,
  fileName: 'users-export.csv',
});

return (
  <>
    <Button onClick={downloadCSV} disabled={isDownloading}>
      Export CSV
    </Button>
    <input
      type="file"
      accept=".csv"
      onChange={(e) => setCsvFile(e.target.files?.[0] || null)}
    />
    <Button onClick={uploadCSV} disabled={isUploading || !csvFile}>
      Import CSV
    </Button>
    {error && <Alert severity="error">{error}</Alert>}
  </>
);
```

---

### useFilterItems

**Source:** `frontend/src/hooks/useFilterItems.ts`

Manages filter state for data tables with support for range and enum filters.

**Signature:**

```typescript
function useFilterItems(filters: Filter[]): UseFilterItemsReturn
```

**Filter Definition:**

```typescript
interface Filter {
  title: string;      // Field name
  label: string;      // Display label
  number?: boolean;   // Range filter (numbers)
  date?: boolean;     // Range filter (dates)
  type?: 'enum';      // Enum filter
  options?: string[]; // Enum options
}
```

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| filterItems | `FilterItem[]` | Active filters |
| setFilterItems | `(items: FilterItem[]) => void` | Replace filters |
| addFilter | `() => void` | Add new filter row |
| removeFilter | `(id: string) => void` | Remove filter |
| updateFilter | `(id: string, fields: Partial<FilterFields>) => void` | Update filter |
| resetFilters | `() => void` | Clear all filters |
| generateFilterRequest | `() => string` | Build query string |
| filterRequest | `FilterRequest` | Filter object |

**Example:**

```typescript
const filters: Filter[] = [
  { title: 'name', label: 'Name' },
  { title: 'created_at', label: 'Created', date: true },
  { title: 'environment', label: 'Environment', type: 'enum', options: ['dev', 'stage', 'production'] },
];

const {
  filterItems,
  addFilter,
  removeFilter,
  updateFilter,
  generateFilterRequest,
  resetFilters,
} = useFilterItems(filters);

// Generate query: "&name=test&created_atRange=2024-01-01&created_atRange=2024-12-31"
const queryString = generateFilterRequest();
```

---

### useElementSettingsForm

**Source:** `frontend/src/components/ElementSettings/useElementSettingsForm.ts`

Form state management hook for element settings across global defaults, project defaults, and constructor pages.

**Signature:**

```typescript
function useElementSettingsForm(
  options: UseElementSettingsFormOptions
): UseElementSettingsFormReturn

interface UseElementSettingsFormOptions {
  elementType: CanvasElementType | string;
}
```

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| state | `FormState` | Current form state (all settings) |
| setField | `(field, value) => void` | Update single field |
| setFields | `(updates) => void` | Update multiple fields |
| applySettings | `(json) => void` | Load settings from JSON |
| getStyleValues | `() => ElementStyleProperties` | Get CSS style values |
| buildSettingsJson | `() => Record<string, unknown>` | Serialize to JSON for saving |
| isNavigationType | `boolean` | Element is navigation_next/prev |
| isTooltipType | `boolean` | Element is tooltip |
| isDescriptionType | `boolean` | Element is description |
| isGalleryType | `boolean` | Element is gallery |
| isCarouselType | `boolean` | Element is carousel |
| isMediaType | `boolean` | Element is video/audio player |
| addGalleryCard | `() => void` | Add gallery card |
| removeGalleryCard | `(id) => void` | Remove gallery card |
| updateGalleryCard | `(id, field, value) => void` | Update gallery card |
| addCarouselSlide | `() => void` | Add carousel slide |
| removeCarouselSlide | `(id) => void` | Remove carousel slide |
| updateCarouselSlide | `(id, field, value) => void` | Update carousel slide |

**FormState includes:**
- Common: label, xPercent, yPercent, appearDelaySec, appearDurationSec
- CSS: width, height, margin, padding, fontSize, border, borderRadius, opacity, etc.
- Navigation: iconUrl, navLabel, navType, targetPageSlug, transitionVideoUrl, etc.
- Tooltip: tooltipTitle, tooltipText
- Description: descriptionTitle, descriptionText, typography settings
- Media: mediaUrl, mediaAutoplay, mediaLoop, mediaMuted
- Gallery: galleryCards array
- Carousel: carouselSlides array, prev/next icons

**Example:**

```typescript
const form = useElementSettingsForm({ elementType: 'navigation_next' });

// Load existing settings
useEffect(() => {
  if (item?.settings_json) {
    form.applySettings(item.settings_json);
  }
}, [item]);

// Update field
form.setField('navLabel', 'Next Page');

// Save
const handleSave = async () => {
  const settings = form.buildSettingsJson();
  await axios.put(`/project-element-defaults/${id}`, {
    data: { settings_json: settings },
  });
};

// Render type-specific sections
{form.isNavigationType && (
  <NavigationSettingsSection
    navLabel={form.state.navLabel}
    onChange={(field, value) => form.setField(field, value)}
  />
)}
```

**Key Features:**
- Type-aware: Shows/hides fields based on element type
- Bidirectional: `applySettings()` loads JSON, `buildSettingsJson()` serializes
- Validation: Clamps position to 0-100, normalizes CSS units
- Array management: Gallery cards and carousel slides with add/remove/update

---

## Offline & Caching Hooks

### useOfflineMode

**Source:** `frontend/src/hooks/useOfflineMode.ts`

Manages offline mode state and project download functionality with progress tracking.

**Signature:**

```typescript
function useOfflineMode(options: UseOfflineModeOptions): UseOfflineModeResult
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| projectId | `string \| null` | Project to download |
| projectSlug | `string` | Project slug (optional) |
| projectName | `string` | Display name (optional) |
| enabled | `boolean` | Enable hook (default: true) |

**Returns:**

```typescript
interface UseOfflineModeResult {
  // Status
  isOfflineCapable: boolean;    // Browser supports offline
  isDownloaded: boolean;        // Project fully cached
  isDownloading: boolean;       // Download in progress
  status: ProjectOfflineStatus; // 'not_downloaded' | 'downloading' | 'downloaded' | 'error' | 'outdated'
  progress: number;             // 0-100
  downloadedAssets: number;
  totalAssets: number;
  downloadedBytes: number;
  totalBytes: number;
  error: string | null;

  // Actions
  startDownload: () => Promise<void>;
  pauseDownload: () => void;
  resumeDownload: () => void;
  cancelDownload: () => void;
  deleteOfflineData: () => Promise<void>;
  checkForUpdates: () => Promise<boolean>;

  // Info
  projectInfo: OfflineProject | null;
  estimatedSize: number;
  formatSize: (bytes: number) => string;
}
```

**Example:**

```typescript
const {
  isOfflineCapable,
  status,
  progress,
  downloadedAssets,
  totalAssets,
  startDownload,
  deleteOfflineData,
  formatSize,
  downloadedBytes,
} = useOfflineMode({
  projectId: project?.id,
  projectSlug: project?.slug,
  enabled: true,
});

return (
  <div>
    {status === 'not_downloaded' && (
      <Button onClick={startDownload}>
        Download for Offline ({formatSize(estimatedSize)})
      </Button>
    )}
    {status === 'downloading' && (
      <ProgressBar value={progress}>
        {downloadedAssets}/{totalAssets} assets
      </ProgressBar>
    )}
    {status === 'downloaded' && (
      <Button onClick={deleteOfflineData}>Remove Offline Data</Button>
    )}
  </div>
);
```

**Key Features:**
- Checks Service Worker and Cache API support
- Uses frontend asset discovery (same as online preload) - no backend manifest
- Requires `pages` prop for asset discovery
- Priority-based downloads (images: 100, videos: 50, audio: 75)
- Progress via IndexedDB and DownloadEventBus
- Storage quota validation before download
- Handles partial → full download upgrades for offline completeness

---

### useStorageQuota

**Source:** `frontend/src/hooks/useStorageQuota.ts`

Monitors storage quota and usage for offline assets.

**Signature:**

```typescript
function useStorageQuota(): UseStorageQuotaResult
```

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| usage | `number` | Bytes used |
| quota | `number \| Infinity` | Total available |
| percentUsed | `number` | Usage percentage |
| available | `number` | Bytes remaining |
| isLoading | `boolean` | Fetching quota |
| error | `string \| null` | Error message |
| refresh | `() => Promise<void>` | Manual refresh |
| requestPersistence | `() => Promise<boolean>` | Request persistent storage |
| isPersisted | `boolean` | Storage is persistent |
| isWarning | `boolean` | >= 80% used |
| isCritical | `boolean` | >= 95% used |
| formatSize | `(bytes: number) => string` | Format bytes |
| canStore | `(bytes: number) => boolean` | Check if fits |

**Example:**

```typescript
const {
  usage,
  quota,
  percentUsed,
  isWarning,
  isCritical,
  formatSize,
  requestPersistence,
  isPersisted,
} = useStorageQuota();

return (
  <StorageIndicator>
    <span>{formatSize(usage)} / {formatSize(quota)}</span>
    {isWarning && <WarningIcon />}
    {isCritical && <CriticalIcon />}
    {!isPersisted && (
      <Button onClick={requestPersistence}>
        Enable Persistent Storage
      </Button>
    )}
  </StorageIndicator>
);
```

---

## Preloading Hooks

### usePreloadOrchestrator

**Source:** `frontend/src/hooks/usePreloadOrchestrator.ts`

**Used by:** `RuntimePresentation.tsx`, `constructor.tsx`

Main coordinator for online mode asset preloading with priority queue management. Downloads assets from S3 presigned URLs, stores in Cache API/IndexedDB, and provides instant blob URL lookup for smooth page transitions.

**Signature:**

```typescript
function usePreloadOrchestrator(
  options: UsePreloadOrchestratorOptions
): UsePreloadOrchestratorResult
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| pages | `PreloadPage[]` | All pages (filtered by environment) |
| pageLinks | `PreloadPageLink[]` | Navigation links (from `extractPageLinksAndElements`) |
| elements | `PreloadElement[]` | Page elements |
| currentPageId | `string \| null` | Active page |
| pageHistory | `string[]` | Navigation history |
| enabled | `boolean` | Enable preloading (default: true) |
| maxNeighborDepth | `number` | BFS depth limit (default: 1, immediate neighbors only) |

**Environment Isolation:** Pages, pageLinks, and elements should be filtered by environment (`dev`, `stage`, `production`) before passing to this hook. This prevents preloading assets from other environments.

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| isPreloading | `boolean` | Downloads active |
| preloadedUrls | `Set<string>` | Cached URLs |
| queueLength | `number` | Pending downloads |
| preloadAsset | `(url: string, priority?: number) => void` | Manual preload |
| clearQueue | `() => void` | Cancel pending |
| getCachedBlobUrl | `(url: string) => Promise<string \| null>` | Get cached blob (creates new blob URL) |
| isUrlPreloaded | `(url: string) => Promise<boolean>` | Check cache |
| getReadyBlobUrl | `(url: string) => string \| null` | Instant lookup - decoded blob URL (O(1)) |

**Example:**

```typescript
const {
  isPreloading,
  preloadedUrls,
  getCachedBlobUrl,
  getReadyBlobUrl,
  preloadAsset,
} = usePreloadOrchestrator({
  pages,
  pageLinks,
  elements,
  currentPageId,
  enabled: !isOffline,
});

// Instant blob URL lookup (O(1), already decoded, ready to display)
const readyUrl = getReadyBlobUrl(videoUrl);
if (readyUrl) {
  videoRef.current.src = readyUrl;
}

// Fallback: async cached blob (creates new blob URL, may need decode)
const blobUrl = await getCachedBlobUrl(videoUrl);
videoRef.current.src = blobUrl || videoUrl;

// Manual high-priority preload
preloadAsset('https://example.com/important.mp4', 200);
```

**S3 Presigned URL Flow with Storage Key Mapping:**
```
1. POST /api/file/presign { urls: [asset1, asset2, ...] }  // Max 50 per batch
2. Download from presigned URLs (1-hour expiry)
3. Store in Cache API (keyed by both download URL and storage key)
4. Create blob URL: URL.createObjectURL(blob)
5. Decode if image
6. Store in readyBlobUrlsRef Map:
   - keyed by download URL (presigned URL)
   - keyed by storage key (canonical path, e.g., "assets/project-123/video.mp4")
   - keyed by proxy URL (for fallback compatibility)
```

**Storage Key Mapping:**
The orchestrator maps downloaded blobs to multiple keys for reliable cache hits:
| Key Type | Example | Purpose |
|----------|---------|---------|
| Download URL | `https://s3...?X-Amz-Signature=ABC` | Original presigned URL |
| Storage Key | `assets/project-123/video.mp4` | Canonical path (most reliable) |
| Proxy URL | `/api/file/download?privateUrl=...` | Fallback compatibility |

This ensures lookups succeed regardless of which URL is used, since presigned URL signatures change on each resolution but the storage key remains constant.

---

### useNeighborGraph

**Source:** `frontend/src/hooks/useNeighborGraph.ts`

Builds navigation graph from page links to determine which pages are neighbors and should have their assets preloaded.

**Signature:**

```typescript
function useNeighborGraph(options: UseNeighborGraphOptions): NeighborGraphResult
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| pages | `PreloadPage[]` | All pages (should be filtered by environment first) |
| pageLinks | `PreloadPageLink[]` | Navigation links with `from_pageId` and `to_pageId` |
| elements | `PreloadElement[]` | Page elements (for asset extraction) |
| maxDepth | `number` | BFS depth (default: 1, immediate neighbors only) |

**Note:** Page links are extracted from `ui_schema_json` navigation elements using `extractPageLinksAndElements()` and passed as `PreloadPageLink[]` with resolved page IDs.

**Environment Filtering:** Pages and elements should be filtered by environment (`dev`, `stage`, or `production`) before passing to this hook to ensure preloading respects environment isolation.

**Returns:**

| Method | Signature | Description |
|--------|-----------|-------------|
| getNeighbors | `(pageId: string, depth?: number) => PreloadNeighborInfo[]` | Get neighbor pages |
| getAssetsForPages | `(pageIds: string[]) => PreloadAssetInfo[]` | Get page assets |
| getPrioritizedAssets | `(pageId: string, depth?: number) => PreloadAssetInfo[]` | Prioritized assets |
| adjacencyList | `Map<string, string[]>` | Raw graph (debugging) |

**Example:**

```typescript
const { getNeighbors, getPrioritizedAssets } = useNeighborGraph({
  pages,
  pageLinks,  // Links with from_pageId, to_pageId
  elements,   // Elements with content_json for asset extraction
  maxDepth: 1,
});

// Get neighbors within 1 hop
const neighbors = getNeighbors(currentPageId);
// Returns: [{pageId: 'page-2', distance: 1}]

// Get prioritized assets for preloading
const assets = getPrioritizedAssets(currentPageId);
// Sorted by priority: current page (1000) > neighbor (100/distance) + type bonus
```

---

### useNetworkAware

**Source:** `frontend/src/hooks/useNetworkAware.ts`

Monitors network conditions and adapts preloading strategy.

**Signature:**

```typescript
function useNetworkAware(): UseNetworkAwareResult
```

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| networkInfo | `NetworkInfo` | Connection details |
| shouldPreloadAggressively | `boolean` | Good connection |
| preferLowQuality | `boolean` | Slow connection |
| recommendedConcurrency | `number` | Parallel downloads |
| suggestOfflineMode | `boolean` | Very slow connection |

**NetworkInfo:**

```typescript
interface NetworkInfo {
  isOnline: boolean;
  effectiveType: 'slow-2g' | '2g' | '3g' | '4g' | undefined;
  downlink: number | undefined;     // Mbps
  rtt: number | undefined;          // Round-trip time ms
  saveData: boolean;
}
```

**Example:**

```typescript
const {
  networkInfo,
  shouldPreloadAggressively,
  recommendedConcurrency,
  preferLowQuality,
  suggestOfflineMode,
} = useNetworkAware();

// Adapt preloading
const concurrency = recommendedConcurrency; // 1 for 2g, 2 for 3g, 3 for 4g

// Show offline suggestion
if (suggestOfflineMode) {
  showToast('Connection is slow. Consider downloading for offline use.');
}

// Select asset quality
const videoUrl = preferLowQuality ? video.lowRes : video.highRes;
```

---

### usePWAPreload

**Source:** `frontend/src/hooks/usePWAPreload.ts`

PWA asset preloading with progress tracking.

**Signature:**

```typescript
function usePWAPreload(options: UsePWAPreloadOptions): PreloadState
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| assets | `AssetToPreload[]` | Assets to preload |
| onComplete | `() => void` | Completion callback |
| onError | `(errors: string[]) => void` | Error callback |
| skipIfCached | `boolean` | Skip if already cached (default: true) |

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| isPreloading | `boolean` | In progress |
| progress | `number` | 0-100 |
| loadedCount | `number` | Completed assets |
| totalCount | `number` | Total assets |
| errors | `string[]` | Failed URLs |
| startPreload | `() => Promise<void>` | Manual trigger |
| isCached | `boolean` | All cached |

**Example:**

```typescript
const { isPreloading, progress, loadedCount, totalCount, startPreload } = usePWAPreload({
  assets: [
    { url: '/images/bg.jpg', type: 'image' },
    { url: '/videos/intro.mp4', type: 'video' },
  ],
  onComplete: () => setShowOverlay(false),
  skipIfCached: true,
});

return isPreloading ? (
  <LoadingOverlay>
    Loading {loadedCount}/{totalCount} ({Math.round(progress)}%)
  </LoadingOverlay>
) : null;
```

---

### usePreloadProgress

**Source:** `frontend/src/hooks/usePreloadProgress.ts`

Tracks preload job progress via DownloadEventBus with auto-cleanup.

**Signature:**

```typescript
function usePreloadProgress(): UsePreloadProgressResult
```

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| jobs | `PreloadJob[]` | All tracked jobs |
| activeCount | `number` | Downloading/queued jobs |
| completedCount | `number` | Completed jobs |
| errorCount | `number` | Failed jobs |
| totalProgress | `number` | Overall progress 0-100 |
| isActive | `boolean` | Any active downloads |
| clearJob | `(id: string) => void` | Remove specific job |
| clearAllCompleted | `() => void` | Clear completed jobs |
| clearAllErrors | `() => void` | Clear errored jobs |

**PreloadJob:**

```typescript
interface PreloadJob {
  id: string;
  assetId: string;
  url: string;
  filename: string;
  progress: number;
  status: 'queued' | 'downloading' | 'completed' | 'error';
  bytesLoaded: number;
  totalBytes: number;
  addedAt: number;
  startedAt?: number;
  completedAt?: number;
  error?: string;
}
```

**Example:**

```typescript
const {
  jobs,
  activeCount,
  totalProgress,
  isActive,
  clearAllCompleted,
} = usePreloadProgress();

return isActive ? (
  <PreloadIndicator>
    <span>{activeCount} downloads in progress ({totalProgress}%)</span>
    {jobs.map((job) => (
      <JobProgress key={job.id} job={job} />
    ))}
  </PreloadIndicator>
) : null;
```

**Key Features:**
- Listens to DownloadEventBus for preload events
- Auto-removes completed jobs after configurable delay
- Auto-removes error jobs after longer delay
- Byte-based progress calculation when available

---

## Media Playback Hooks

### useReversePlayback

**Source:** `frontend/src/hooks/useReversePlayback.ts`

Handles reverse video playback with fallback strategies.

**Signature:**

```typescript
function useReversePlayback(options: UseReversePlaybackOptions): UseReversePlaybackResult
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| videoRef | `RefObject<HTMLVideoElement>` | Video element ref |
| onComplete | `() => void` | Completion callback |
| preloadedUrls | `Set<string>` | Cached URLs (optional) |
| videoUrl | `string` | Current video URL (optional) |
| getCachedBlobUrl | `(url: string) => Promise<string \| null>` | Blob URL getter (optional) |

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| startReverse | `() => Promise<void>` | Start reverse playback |
| stopReverse | `() => void` | Stop playback |
| isReversing | `boolean` | Playback active |
| isBuffering | `boolean` | Buffering video |
| canUseNativeReverse | `boolean` | Browser supports native reverse |

**Example:**

```typescript
const videoRef = useRef<HTMLVideoElement>(null);

const { startReverse, stopReverse, isReversing, isBuffering } = useReversePlayback({
  videoRef,
  onComplete: () => navigateBack(),
  getCachedBlobUrl,
});

// Trigger reverse when back button clicked
const handleBack = async () => {
  await startReverse();
};

return (
  <div>
    <video ref={videoRef} src={transitionUrl} />
    {isBuffering && <Spinner />}
  </div>
);
```

**Playback Strategies:**
1. **Native:** `playbackRate = -1` (modern browsers)
2. **Frame-stepping:** Fallback seeking (15-30 FPS based on cache status)

---

### useTransitionPlayback

**Source:** `frontend/src/hooks/useTransitionPlayback.ts`

**Used by:** `RuntimePresentation.tsx`, `constructor.tsx`

Manages complex transition video playback with forward/reverse support. Handles blob URL resolution from preload cache for smooth seeking during reverse playback.

**Signature:**

```typescript
function useTransitionPlayback(
  options: UseTransitionPlaybackOptions
): UseTransitionPlaybackResult
```

**Parameters:**

```typescript
interface UseTransitionPlaybackOptions {
  videoRef: RefObject<HTMLVideoElement | null>;
  transition: TransitionConfig | null;
  onComplete: (targetPageId?: string) => void;
  onError?: (reason: string) => void;

  timeouts?: {
    playbackStartMs?: number;   // Default: 3000
    durationBufferMs?: number;  // Default: 200
    hardTimeoutMs?: number;     // Default: 45000
  };

  features?: {
    useBlobUrl?: boolean;
    preDecodeImages?: boolean;
    getTargetPageImages?: () => string[];
  };

  preload?: {
    preloadedUrls?: Set<string>;
    getCachedBlobUrl?: (url: string) => Promise<string | null>;
    getReadyBlobUrl?: (url: string) => string | null;  // Instant O(1) lookup
  };
}

interface TransitionConfig {
  videoUrl: string;           // Resolved URL (presigned or proxy) for playback
  storageKey?: string;        // Raw storage path for cache lookup (e.g., "assets/project-123/video.mp4")
  reverseMode: 'none' | 'reverse' | 'separate';
  reverseVideoUrl?: string;   // For 'separate' mode
  reverseStorageKey?: string; // Storage key for reverse video
  durationSec?: number;
  targetPageId?: string;      // Resolved from targetPageSlug at navigation time
  displayName?: string;
}
```

**Note:** Navigation elements store `targetPageSlug` in `ui_schema_json`. At navigation time, the slug is resolved to a page ID before being passed to this hook.

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| phase | `PlaybackPhase` | Current phase |
| isBuffering | `boolean` | Loading video |
| isReversing | `boolean` | Reverse playback |
| cancel | `() => void` | Cancel transition |
| forceComplete | `() => void` | Skip to end |

**PlaybackPhase:** `'idle' | 'preparing' | 'playing' | 'reversing' | 'finishing' | 'completed'`

**Example:**

```typescript
const videoRef = useRef<HTMLVideoElement>(null);

const { phase, isBuffering, cancel } = useTransitionPlayback({
  videoRef,
  transition: {
    videoUrl: resolveAssetPlaybackUrl(transitionPath),  // Resolved URL
    storageKey: transitionPath,  // Raw storage path for cache lookup
    reverseMode: 'reverse',
    durationSec: 1.5,
    targetPageId: 'page-gallery',
  },
  onComplete: (targetPageId) => {
    setCurrentPage(targetPageId);
  },
  features: {
    preDecodeImages: true,
    getTargetPageImages: () => getPageImages(targetPageId),
  },
  preload: {
    preloadedUrls: preloadOrchestrator.preloadedUrls,
    getCachedBlobUrl: preloadOrchestrator.getCachedBlobUrl,
    getReadyBlobUrl: preloadOrchestrator.getReadyBlobUrl,  // Instant lookup
  },
});

return (
  <TransitionOverlay visible={phase !== 'idle'}>
    <video ref={videoRef} muted autoPlay playsInline />
    {isBuffering && <LoadingIndicator />}
    <Button onClick={cancel}>Skip</Button>
  </TransitionOverlay>
);
```

**Reverse Modes:**
- `none`: Forward playback only
- `reverse`: Play forward, then reverse same video
- `separate`: Play forward video, then separate reverse video

**Storage Key Lookup Priority:**
The hook uses `storageKey` for reliable cache hits across presigned URL regeneration:
1. `getReadyBlobUrl(storageKey)` - instant O(1) in-memory lookup
2. `getCachedBlobUrl(storageKey)` - Cache API lookup (post-refresh)
3. `getReadyBlobUrl(videoUrl)` - fallback by resolved URL
4. `getCachedBlobUrl(videoUrl)` - fallback by resolved URL
5. Network fetch - final fallback

---

### useBackgroundTransition

**Source:** `frontend/src/hooks/useBackgroundTransition.ts`

**Used by:** `RuntimePresentation.tsx`, `constructor.tsx`

Manages background transition effects when switching pages. Handles fade-out animation of transition video overlay and coordinates with page switch hook.

**Signature:**

```typescript
function useBackgroundTransition(
  options: UseBackgroundTransitionOptions
): UseBackgroundTransitionResult
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| pageSwitch | `PageSwitchInterface` | Page switch hook instance |
| fadeOut | `FadeOutConfig` | Optional fade-out configuration |

**FadeOutConfig (for RuntimePresentation):**

```typescript
interface FadeOutConfig {
  pendingTransitionComplete: boolean;  // Video finished, waiting for bg ready
  isBackgroundReady: boolean;          // New background loaded
  transitionVideoRef: RefObject<HTMLVideoElement>;
  onTransitionCleanup: () => void;
}
```

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| isOverlayFadingOut | `boolean` | Overlay currently fading |
| resetFadeOut | `() => void` | Reset fade state |

**Example:**

```typescript
// Full mode with fade-out (RuntimePresentation)
const { isOverlayFadingOut, resetFadeOut } = useBackgroundTransition({
  pageSwitch,
  fadeOut: {
    pendingTransitionComplete,
    isBackgroundReady,
    transitionVideoRef,
    onTransitionCleanup: () => {
      setTransitionPreview(null);
      setPendingTransitionComplete(false);
    },
  },
});

// Simple mode - direct navigation only (constructor)
useBackgroundTransition({ pageSwitch });
```

**Modes:**
- **Full mode** (RuntimePresentation): Fade-out animation + direct navigation clearing
- **Simple mode** (constructor): Direct navigation clearing only

---

### usePageDataLoader

**Source:** `frontend/src/hooks/usePageDataLoader.ts`

**Used by:** `RuntimePresentation.tsx`, `constructor.tsx`

Unified hook for loading project and page data in presentation components. Handles both public access (by slug) and authenticated access (by ID).

**Signature:**

```typescript
function usePageDataLoader(
  options: UsePageDataLoaderOptions
): UsePageDataLoaderResult
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| projectId | `string` | Project ID (constructor mode) |
| projectSlug | `string` | Project slug (runtime mode) |
| environment | `'dev' \| 'stage' \| 'production'` | Environment filter |
| enabled | `boolean` | Enable loading (default: true) |
| apiHeaders | `Record<string, string>` | Custom API headers |
| initialPageId | `string` | Initial page ID from route |

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| project | `RuntimeProject \| null` | Loaded project |
| pages | `RuntimePage[]` | Filtered and sorted pages |
| isLoading | `boolean` | Loading in progress |
| error | `string` | Error message |
| reload | `(preservePageId?) => Promise<void>` | Reload data |
| initialPageId | `string` | Selected initial page ID |

**Example:**

```typescript
// Runtime mode (public presentation)
const { project, pages, isLoading, error } = usePageDataLoader({
  projectSlug: 'my-project',
  environment: 'production',
});

// Constructor mode (authenticated)
const { project, pages, isLoading, error, reload } = usePageDataLoader({
  projectId: 'uuid-here',
  environment: 'dev',
  enabled: isAuthReady,
});
```

**Features:**
- Loads by slug (runtime) or ID (constructor)
- Filters pages by environment
- Sorts pages by sort_order
- Handles authentication errors
- Supports page preservation on reload

---

### useElementEffects

**Source:** `frontend/src/hooks/useElementEffects.ts`

Manages element interactive effects (hover, focus, active) at runtime. Since CSS pseudo-classes don't work with inline styles, this hook handles state-based style application via JavaScript events.

**Signature:**

```typescript
function useElementEffects(
  effects: Partial<ElementEffectProperties>
): UseElementEffectsResult
```

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| effectStyle | `CSSProperties` | Style to merge with base element style |
| eventHandlers | `object` | Event handlers for the element |

**Event Handlers:**
- `onMouseEnter`, `onMouseLeave` - Hover effects
- `onFocus`, `onBlur` - Focus effects
- `onMouseDown`, `onMouseUp` - Active/pressed effects

**Example:**

```typescript
const { effectStyle, eventHandlers } = useElementEffects({
  hoverScale: 1.1,
  hoverOpacity: 0.8,
  activeScale: 0.95,
  transitionDuration: '0.2s',
});

return (
  <button
    style={{ ...baseStyle, ...effectStyle }}
    {...eventHandlers}
  >
    {content}
  </button>
);
```

**Effect Priority:** active > focus > hover > base (highest wins)

---

## Navigation Hooks

### usePageSwitch

**Source:** `frontend/src/hooks/usePageSwitch.ts`

**Used by:** `RuntimePresentation.tsx`, `constructor.tsx`

Unified page switching hook that eliminates white flashes during page transitions by using preloaded blob URLs and keeping previous background visible until new one is ready.

**Signature:**

```typescript
function usePageSwitch(options?: UsePageSwitchOptions): UsePageSwitchResult
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| preloadCache | `PreloadCacheProvider` | Optional preload cache provider |

**PreloadCacheProvider Interface:**

```typescript
interface PreloadCacheProvider {
  /** Instant lookup - returns decoded blob URL ready to display (O(1)) */
  getReadyBlobUrl?: (url: string) => string | null;
  /** Fallback: async blob URL from cache (creates new blob URL) */
  getCachedBlobUrl?: (url: string) => Promise<string | null>;
  preloadedUrls?: Set<string>;
}
```

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| currentBgImageUrl | `string` | Current background image URL |
| currentBgVideoUrl | `string` | Current background video URL |
| currentBgAudioUrl | `string` | Current background audio URL |
| previousBgImageUrl | `string` | Previous background for overlay |
| isSwitching | `boolean` | Page switch in progress |
| isNewBgReady | `boolean` | New background ready to display |
| switchToPage | `(page, onSwitched?) => Promise<void>` | Switch to page with transition |
| setBackgroundsDirectly | `(img, vid, aud) => void` | Direct set without transition |
| markBackgroundReady | `() => void` | Mark background as loaded |
| clearPreviousBackground | `() => void` | Clear overlay after fade |

**Example:**

```typescript
const pageSwitch = usePageSwitch({
  preloadCache: {
    getReadyBlobUrl: preloadOrchestrator.getReadyBlobUrl,  // Instant O(1) lookup
    getCachedBlobUrl: preloadOrchestrator.getCachedBlobUrl,  // Fallback
    preloadedUrls: preloadOrchestrator.preloadedUrls,
  },
});

// Switch to a page with smooth transition
await pageSwitch.switchToPage(targetPage, () => {
  setActivePageId(targetPage.id);
});

// In render - previous background overlay fades out
{pageSwitch.previousBgImageUrl && (
  <div
    className='absolute inset-0 transition-opacity duration-200'
    style={{
      backgroundImage: `url("${pageSwitch.previousBgImageUrl}")`,
      opacity: pageSwitch.isNewBgReady ? 0 : 1,
    }}
  />
)}

// Current background with onLoad handler
<NextImage
  src={pageSwitch.currentBgImageUrl}
  onLoad={pageSwitch.markBackgroundReady}
/>
```

**Key Features:**
- Instant blob URL lookup via `getReadyBlobUrl()` (O(1), already decoded)
- Fallback to `getCachedBlobUrl()` if ready URL not available
- Presigned URL fallback with automatic retry via proxy on CORS failure
- Keeps previous background visible until new one is painted
- Double RAF (requestAnimationFrame) ensures browser has painted before fade
- Automatic blob URL cleanup to prevent memory leaks

**White Flash Prevention Strategy with Storage Key Priority:**
1. Before switching, save current background as "previous"
2. Try `getReadyBlobUrl(storagePath)` - instant O(1) lookup by storage key
3. Try `getCachedBlobUrl(storagePath)` - Cache API lookup by storage key
4. Resolve to playback URL and try `getReadyBlobUrl(resolvedUrl)`
5. Try `getCachedBlobUrl(resolvedUrl)` by resolved URL
6. Fallback: load with presigned URL (retries with proxy on CORS failure)
7. Set new background and wait for Image onLoad
8. Fade out previous background overlay after paint confirmed

**Storage Key Lookup:**
The hook prioritizes storage key lookups (e.g., `assets/project-123/bg.jpg`) over resolved URLs because:
- Storage keys are canonical and don't change
- Presigned URL signatures change on each resolution
- Storage key mapping ensures cache hits across URL regenerations

**Image Rendering for Blob URLs:**
When rendering images from blob URLs, use native `<img>` tags instead of Next.js `<Image>`:
```tsx
// Background image example
{backgroundImageUrl.startsWith('blob:') ? (
  <img
    src={backgroundImageUrl}
    alt=""
    className="absolute inset-0 w-full h-full object-cover"
    onLoad={() => pageSwitch.markBackgroundReady()}
  />
) : (
  <NextImage
    src={backgroundImageUrl}
    fill
    sizes="100vw"
    className="object-cover"
    onLoad={() => pageSwitch.markBackgroundReady()}
  />
)}
```

**Why conditional rendering:**
- Next.js Image re-fetches `src` on every component re-render
- Pages with frequent state updates (e.g., 100ms timers) cause thousands of requests
- Blob URLs are already in-memory and don't benefit from Next.js optimization
- Native `<img>` with blob URLs is cached by browser and doesn't re-fetch

---

### usePageNavigation

**Source:** `frontend/src/hooks/usePageNavigation.ts`

Page navigation state with optional history tracking.

**Signature:**

```typescript
function usePageNavigation<TPage extends NavigablePage>(
  options: UsePageNavigationOptions<TPage>
): UsePageNavigationResult<TPage>
```

**Parameters:**

```typescript
interface NavigablePage {
  id: string;
  sort_order?: number;
  slug?: string;
}

interface UsePageNavigationOptions<TPage> {
  pages: TPage[];
  defaultPageId?: string;
  trackHistory?: boolean;  // Default: true
  onPageChange?: (pageId: string, isBack: boolean) => void;
}
```

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| currentPageId | `string \| null` | Active page ID |
| currentPage | `TPage \| null` | Active page object |
| pageHistory | `string[]` | Navigation history |
| previousPageId | `string \| null` | Previous page ID |
| defaultPage | `TPage \| null` | Initial page |
| setCurrentPageId | `(pageId: string) => void` | Navigate (no history) |
| applyPageSelection | `(pageId: string, isBack?: boolean) => void` | Navigate with history |
| isBackNavigation | `(pageId: string) => boolean` | Check if back nav |
| goBack | `() => boolean` | Go to previous page |
| resetHistory | `() => void` | Clear history |

**Example - Runtime with History:**

```typescript
const nav = usePageNavigation({
  pages,
  trackHistory: true,
  onPageChange: (pageId, isBack) => {
    analytics.track('page_view', { pageId, isBack });
  },
});

// Navigate forward
nav.applyPageSelection('page-gallery');

// Navigate back
if (nav.previousPageId) {
  nav.goBack();
}

// Check direction
const transitionDirection = nav.isBackNavigation(targetPageId)
  ? 'reverse'
  : 'forward';
```

**Example - Editor without History:**

```typescript
const nav = usePageNavigation({
  pages,
  defaultPageId: firstPageId,
  trackHistory: false,
});

// Simple navigation
nav.setCurrentPageId('page-2');
```

---

## Asset Upload Hooks

### useAssetUploader

**Source:** `frontend/src/components/Assets/useAssetUploader.ts`

Batch asset uploads with concurrent workers and progress tracking.

**Signature:**

```typescript
function useAssetUploader(options: UseAssetUploaderOptions): UseAssetUploaderReturn
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| selectedProjectId | `string` | Target project |
| onUploadComplete | `() => void` | Completion callback |

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| uploadingSections | `string[]` | Sections with active uploads |
| uploadQueues | `Record<string, UploadQueueItem[]>` | Per-section queues |
| runBatchUpload | `(section: AssetSection, files: File[]) => Promise<void>` | Start upload |

**UploadQueueItem:**

```typescript
interface UploadQueueItem {
  id: string;
  fileName: string;
  progress: number;  // 0-100
  status: 'queued' | 'uploading' | 'saving' | 'success' | 'error';
  error?: string;
}
```

**Example:**

```typescript
const { uploadingSections, uploadQueues, runBatchUpload } = useAssetUploader({
  selectedProjectId: project?.id,
  onUploadComplete: () => {
    toast.success('Upload complete!');
    refreshAssets();
  },
});

const handleFileSelect = (files: File[]) => {
  runBatchUpload(
    { key: 'images', label: 'Images', assetFormat: 'image', assetCategory: 'general' },
    files
  );
};

return (
  <div>
    <FileDropzone onDrop={handleFileSelect} />
    {uploadQueues['images']?.map((item) => (
      <UploadProgress key={item.id} item={item} />
    ))}
  </div>
);
```

**Features:**
- Max 2 concurrent uploads
- 5 MB chunk size, 3 retries
- Media duration probing (video/audio)
- Automatic metadata submission

---

## Constructor Hooks

Hooks specifically designed for the visual tour builder (constructor.tsx). These manage element CRUD, page actions, transitions, dragging, and timing.

### useConstructorElements

**Source:** `frontend/src/hooks/useConstructorElements.ts`

Manages element CRUD operations with defaults merging. Core hook for element management in the constructor.

**Signature:**

```typescript
function useConstructorElements(
  options: UseConstructorElementsOptions
): UseConstructorElementsResult
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| initialElements | `CanvasElement[]` | Starting elements |
| elementDefaultsByType | `Record<CanvasElementType, Partial<CanvasElement>>` | Project defaults |
| allowedNavigationTypes | `NavigationElementType[]` | Allowed nav types |
| onElementsChange | `(elements) => void` | Change callback |
| initialSelectedElementId | `string` | Initial selection from route |
| onElementSelected | `(id) => void` | Selection callback |
| onSelectionCleared | `() => void` | Clear selection callback |
| onElementAdded | `(element) => void` | Add callback |
| onElementRemoved | `(id) => void` | Remove callback |

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| elements | `CanvasElement[]` | Current elements |
| setElements | `Dispatch<SetStateAction>` | Set elements directly |
| selectedElementId | `string` | Selected element ID |
| selectedElement | `CanvasElement \| null` | Selected element |
| selectElement | `(id) => void` | Select element |
| clearSelection | `() => void` | Clear selection |
| addElement | `(type) => void` | Add new element |
| updateSelectedElement | `(patch) => void` | Update selected |
| updateElement | `(id, patch) => void` | Update by ID |
| removeSelectedElement | `() => void` | Remove selected |
| removeElement | `(id) => void` | Remove by ID |
| galleryCards | `{add, update, remove}` | Gallery operations |
| carouselSlides | `{add, update, remove}` | Carousel operations |
| updateElementPosition | `(id, x, y) => void` | Update position |
| normalizeNavigationType | `(el, type) => CanvasElement` | Normalize nav type |

**Example:**

```typescript
const {
  elements,
  selectedElement,
  selectElement,
  addElement,
  updateSelectedElement,
  removeSelectedElement,
} = useConstructorElements({
  initialElements: parsedElements,
  elementDefaultsByType: projectDefaults,
  allowedNavigationTypes: ['navigation_next', 'navigation_prev'],
});

// Add new element
addElement('hotspot');

// Update selected element
updateSelectedElement({ label: 'New Label', xPercent: 50 });
```

---

### useConstructorPageActions

**Source:** `frontend/src/hooks/useConstructorPageActions.ts`

Handles page create/save/publish operations in the constructor.

**Signature:**

```typescript
function useConstructorPageActions(
  options: UseConstructorPageActionsOptions
): UseConstructorPageActionsResult
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| projectId | `string` | Current project ID |
| pages | `TourPage[]` | All pages |
| activePage | `TourPage \| null` | Current page |
| activePageId | `string` | Current page ID |
| elements | `CanvasElement[]` | Current elements |
| backgroundImageUrl | `string` | Background image |
| backgroundVideoUrl | `string` | Background video |
| backgroundAudioUrl | `string` | Background audio |
| onReload | `(preservePageId?) => Promise<void>` | Reload callback |
| onSetActivePageId | `(id) => void` | Set active page |
| onSetMenuOpen | `(open) => void` | Set menu open |
| onError | `(message) => void` | Error callback |
| onSuccess | `(message) => void` | Success callback |

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| isSaving | `boolean` | Save in progress |
| isSavingToStage | `boolean` | Stage save in progress |
| isCreatingPage | `boolean` | Page creation in progress |
| isCreatingTransition | `boolean` | Transition creation in progress |
| saveConstructor | `() => Promise<void>` | Save current state |
| saveToStage | `() => Promise<void>` | Save dev → stage |
| createPage | `() => Promise<void>` | Create new page |
| createTransition | `(params) => Promise<void>` | Create transition (legacy) |

**Example:**

```typescript
const {
  isSaving,
  saveConstructor,
  createPage,
  isCreatingPage,
} = useConstructorPageActions({
  projectId,
  pages,
  activePage,
  activePageId,
  elements,
  backgroundImageUrl,
  backgroundVideoUrl,
  backgroundAudioUrl,
  onReload: loadData,
  onSetActivePageId: setActivePageId,
  onError: setErrorMessage,
  onSuccess: setSuccessMessage,
});

// Save changes
await saveConstructor();

// Create new page
await createPage();
```

---

### useTransitionPreview

**Source:** `frontend/src/hooks/useTransitionPreview.ts`

Manages transition video preview state in the constructor. Used to preview forward and reverse transitions before navigation.

**Signature:**

```typescript
function useTransitionPreview(
  options: UseTransitionPreviewOptions
): UseTransitionPreviewResult
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| isNavigationElementType | `(type) => boolean` | Type checker |
| onError | `(message) => void` | Error callback |

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| preview | `TransitionPreviewState \| null` | Current preview |
| pendingPageId | `string` | Target page ID |
| openPreview | `(element, direction) => void` | Open preview |
| openPreviewWithTarget | `(element, direction, pageId) => void` | Open with target |
| closePreview | `() => void` | Close preview |
| isActive | `boolean` | Preview active |

**TransitionPreviewState:**

```typescript
interface TransitionPreviewState {
  videoUrl: string;
  storageKey: string;
  reverseMode: 'none' | 'reverse' | 'separate';
  reverseVideoUrl?: string;
  reverseStorageKey?: string;
  durationSec?: number;
  title: string;
}
```

**Example:**

```typescript
const {
  preview,
  pendingPageId,
  openPreviewWithTarget,
  closePreview,
  isActive,
} = useTransitionPreview({
  isNavigationElementType,
  onError: setErrorMessage,
});

// Open preview when clicking element
const handleClick = () => {
  openPreviewWithTarget(element, 'forward', targetPage.id);
};

// Use with useTransitionPlayback
useTransitionPlayback({
  transition: preview,
  onComplete: (targetId) => {
    switchToPage(targetId);
    closePreview();
  },
});
```

---

### useCanvasElapsedTime

**Source:** `frontend/src/hooks/useCanvasElapsedTime.ts`

Tracks elapsed time since page load for element visibility timing.

**Signature:**

```typescript
function useCanvasElapsedTime(
  options: UseCanvasElapsedTimeOptions
): UseCanvasElapsedTimeResult
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| pageId | `string` | Current page ID (resets timer) |
| enabled | `boolean` | Timer active (default: true) |
| intervalMs | `number` | Update interval (default: 100ms) |

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| elapsedSec | `number` | Elapsed time in seconds |
| reset | `() => void` | Reset to zero |
| startedAt | `number` | Start timestamp |

**Example:**

```typescript
const { elapsedSec } = useCanvasElapsedTime({
  pageId: activePageId,
  enabled: !isLoading,
});

// Check if element should be visible
const isVisible = elapsedSec >= element.appearDelaySec;
```

**Helper Function:**

```typescript
import { isElementVisibleAtTime } from '../hooks/useCanvasElapsedTime';

const visible = isElementVisibleAtTime(
  elapsedSec,
  element.appearDelaySec,      // delay before appearing
  element.appearDurationSec,   // duration visible (null = infinite)
);
```

---

### useCanvasElementDrag

**Source:** `frontend/src/hooks/useCanvasElementDrag.ts`

Handles dragging of canvas elements with percentage-based positioning.

**Signature:**

```typescript
function useCanvasElementDrag(
  options: UseCanvasElementDragOptions
): UseCanvasElementDragResult
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| canvasRef | `RefObject<HTMLElement>` | Canvas container ref |
| onPositionChange | `(id, x, y) => void` | Position update callback |
| enabled | `boolean` | Dragging enabled (default: true) |

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| onElementDragStart | `(event, id, x, y) => void` | Start drag handler |
| isDragging | `boolean` | Currently dragging |
| draggedElementId | `string \| null` | Dragged element ID |
| cancelDrag | `() => void` | Cancel drag |

**Example:**

```typescript
const { onElementDragStart, isDragging } = useCanvasElementDrag({
  canvasRef,
  onPositionChange: (id, x, y) => {
    elementsHook.updateElementPosition(id, x, y);
  },
  enabled: isEditMode,
});

return (
  <button
    onMouseDown={(e) => onElementDragStart(
      e, element.id, element.xPercent, element.yPercent
    )}
  >
    {element.label}
  </button>
);
```

---

### useIconPreload

**Source:** `frontend/src/hooks/useIconPreload.ts`

Preloads icon images for smooth rendering without flash.

**Signature:**

```typescript
function useIconPreload(
  options: UseIconPreloadOptions
): UseIconPreloadResult
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| iconUrls | `string[]` | URLs to preload |
| enabled | `boolean` | Preloading enabled (default: true) |

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| preloadedUrlMap | `Record<string, boolean>` | Preload status map |
| isPreloaded | `(url) => boolean` | Check if URL preloaded |
| pendingCount | `number` | Icons being preloaded |
| allPreloaded | `boolean` | All icons ready |

**Example:**

```typescript
const iconUrls = elements
  .filter(el => el.iconUrl)
  .map(el => resolveAssetPlaybackUrl(el.iconUrl));

const { isPreloaded } = useIconPreload({ iconUrls });

// Only render element if icon is ready
if (element.iconUrl && !isPreloaded(element.iconUrl)) return null;
```

**Helper Function:**

```typescript
import { buildIconPreloadTargets } from '../hooks/useIconPreload';

const targets = buildIconPreloadTargets(elements, {
  isNavigationElementType,
  isTooltipElementType,
  isDescriptionElementType,
});
```

---

### useMediaDurationProbe

**Source:** `frontend/src/hooks/useMediaDurationProbe.ts`

Probes media durations with caching and deduplication.

**Signature:**

```typescript
function useMediaDurationProbe(
  options: UseMediaDurationProbeOptions
): UseMediaDurationProbeResult
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| targets | `DurationProbeTarget[]` | Media sources to probe |

**DurationProbeTarget:**

```typescript
interface DurationProbeTarget {
  source: string;
  mediaType: 'video' | 'audio';
}
```

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| durationBySource | `Record<string, number \| null>` | Duration map |
| getDuration | `(source) => number \| null` | Get duration |
| getDurationNote | `(source) => string` | Get formatted note |
| isProbing | `boolean` | Probes in progress |

**Example:**

```typescript
const { getDurationNote, getDuration } = useMediaDurationProbe({
  targets: [
    { source: backgroundVideoUrl, mediaType: 'video' },
    { source: backgroundAudioUrl, mediaType: 'audio' },
  ],
});

return <p>{getDurationNote(backgroundVideoUrl)}</p>; // "1:30" or ""
```

**Helper Function:**

```typescript
import { buildDurationProbeTargets } from '../hooks/useMediaDurationProbe';

const targets = buildDurationProbeTargets({
  backgroundVideoUrl,
  backgroundAudioUrl,
  selectedElement,
  elements,
  isMediaElementType,
  isVideoPlayerElementType,
  isNavigationElementType,
});
```

---

## Utility Hooks

### useDevCompilationStatus

**Source:** `frontend/src/hooks/useDevCompilationStatus.ts`

Tracks Next.js compilation status in development mode.

**Signature:**

```typescript
function useDevCompilationStatus(): CompilationStatus
```

**Returns:** `'ready' | 'compiling' | 'error' | 'initial'`

**Example:**

```typescript
const status = useDevCompilationStatus();

return (
  <div>
    {status === 'compiling' && <TopLoadingBar />}
    {status === 'error' && <CompilationErrorBanner />}
    <MainContent />
  </div>
);
```

**Note:** Returns `'ready'` in production mode.

---

### useOutsideClick

**Source:** `frontend/src/hooks/useOutsideClick.ts`

Detects clicks outside specified elements to clear selection. Useful for closing panels, deselecting elements, etc.

**Signature:**

```typescript
function useOutsideClick(options: UseOutsideClickOptions): void
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| containerRef | `RefObject<HTMLElement>` | Element whose outside clicks to detect |
| ignoreRefs | `RefObject<HTMLElement>[]` | Additional refs to ignore |
| ignoreDataAttribute | `string` | Data attribute to check |
| selectedValue | `string` | Current selected value |
| onOutsideClick | `() => void` | Click outside callback |
| enabled | `boolean` | Hook active (default: true) |

**Example:**

```typescript
useOutsideClick({
  containerRef: panelRef,
  ignoreRefs: [buttonRef],
  onOutsideClick: () => setSelectedId(''),
  enabled: !!selectedId,
});
```

**With Data Attribute:**

```typescript
useOutsideClick({
  containerRef: canvasRef,
  ignoreDataAttribute: 'data-element-id',
  selectedValue: selectedElementId,
  onOutsideClick: () => clearSelection(),
  enabled: !!selectedElementId,
});

// In element render
<button data-element-id={element.id}>...</button>
```

---

### useDraggable

**Source:** `frontend/src/hooks/useDraggable.ts`

Generic draggable panel management with pointer tracking. Used for draggable controls, menus, and editor panels.

**Signature:**

```typescript
function useDraggable(options?: UseDraggableOptions): UseDraggableResult
```

**Parameters:**

| Option | Type | Description |
|--------|------|-------------|
| initialPosition | `Position` | Starting position |
| minX | `number` | Minimum x (default: 0) |
| minY | `number` | Minimum y (default: 0) |
| maxX | `number` | Maximum x (auto-calculated from window) |
| maxY | `number` | Maximum y (auto-calculated from window) |
| elementWidth | `number` | Element width for bounds |
| elementHeight | `number` | Element height for bounds |

**Returns:**

| Property | Type | Description |
|----------|------|-------------|
| position | `Position` | Current position {x, y} |
| setPosition | `(pos) => void` | Set position directly |
| isDragging | `boolean` | Currently dragging |
| onDragStart | `(event) => void` | Drag start handler |
| onDragStartIgnoreButtons | `(event) => void` | Drag start (ignores buttons) |

**Example:**

```typescript
const { position, onDragStart, isDragging } = useDraggable({
  initialPosition: { x: 20, y: 20 },
  elementWidth: 400,
});

return (
  <div
    style={{
      position: 'fixed',
      left: position.x,
      top: position.y,
    }}
  >
    <div
      className="drag-handle"
      onMouseDown={onDragStart}
    >
      Drag Handle
    </div>
    <div>Content</div>
  </div>
);
```

**With Button Ignore:**

```typescript
// Prevent drag when clicking buttons inside the drag handle
<div onMouseDown={onDragStartIgnoreButtons}>
  <span>Title</span>
  <button>Close</button>  {/* Clicking this won't start drag */}
</div>
```

---

## Quick Reference Table

| Hook | Category | Primary Use Case |
|------|----------|------------------|
| `useAppDispatch` | Redux | Type-safe dispatch |
| `useAppSelector` | Redux | Type-safe state selection |
| `useFormSync` | Data | Sync forms with entities |
| `useEditPageSync` | Data | Edit page data sync |
| `useDashboardCounts` | Data | Dashboard entity counts |
| `useEntityTable` | Data | Complete table management |
| `useCSVHandling` | Data | CSV import/export |
| `useFilterItems` | Data | Filter state management |
| `useElementSettingsForm` | Data | Element settings form state |
| `useOfflineMode` | Offline | Project offline download |
| `useStorageQuota` | Offline | Storage monitoring |
| `usePreloadOrchestrator` | Preload | Asset preload with ready blob URLs |
| `useNeighborGraph` | Preload | Navigation graph building |
| `useNetworkAware` | Preload | Network condition monitoring |
| `usePWAPreload` | Preload | PWA asset caching |
| `usePreloadProgress` | Preload | Preload job tracking |
| `useReversePlayback` | Media | Reverse video playback |
| `useTransitionPlayback` | Media | Transition video management |
| `useBackgroundTransition` | Media | Background fade transition |
| `usePageDataLoader` | Media | Project/page data loading |
| `useElementEffects` | Media | Element interactive effects |
| `usePageSwitch` | Navigation | Smooth page switching without flash |
| `usePageNavigation` | Navigation | Page state with history |
| `useAssetUploader` | Upload | Batch asset uploads |
| `useConstructorElements` | Constructor | Element CRUD operations |
| `useConstructorPageActions` | Constructor | Page save/create/publish |
| `useTransitionPreview` | Constructor | Transition video preview |
| `useCanvasElapsedTime` | Constructor | Elapsed time tracking |
| `useCanvasElementDrag` | Constructor | Element drag positioning |
| `useIconPreload` | Constructor | Icon image preloading |
| `useMediaDurationProbe` | Constructor | Media duration probing |
| `useDevCompilationStatus` | Utility | Dev mode compilation |
| `useOutsideClick` | Utility | Click outside detection |
| `useDraggable` | Utility | Draggable panel management |

---

## File Structure

```
frontend/src/
├── hooks/
│   ├── index.ts                    # Central exports
│   │
│   │ # Data Management
│   ├── useFormSync.ts
│   ├── useEditPageSync.ts          # Edit page data sync
│   ├── useDashboardCounts.ts       # Dashboard entity counts
│   ├── useEntityTable.ts
│   ├── useCSVHandling.ts
│   ├── useFilterItems.ts
│   │
│   │ # Offline & Caching
│   ├── useOfflineMode.ts
│   ├── useStorageQuota.ts
│   │
│   │ # Preloading
│   ├── usePreloadOrchestrator.ts
│   ├── useNeighborGraph.ts
│   ├── useNetworkAware.ts
│   ├── usePWAPreload.ts
│   ├── usePreloadProgress.ts
│   │
│   │ # Media Playback
│   ├── useReversePlayback.ts
│   ├── useTransitionPlayback.ts
│   ├── useBackgroundTransition.ts  # Background fade transition
│   ├── usePageDataLoader.ts        # Project/page loading
│   ├── useElementEffects.ts        # Interactive effects
│   │
│   │ # Navigation
│   ├── usePageSwitch.ts
│   ├── usePageNavigation.ts
│   │
│   │ # Constructor-Specific
│   ├── useConstructorElements.ts   # Element CRUD
│   ├── useConstructorPageActions.ts # Page save/create/publish
│   ├── useTransitionPreview.ts     # Transition video preview
│   ├── useCanvasElapsedTime.ts     # Elapsed time tracking
│   ├── useCanvasElementDrag.ts     # Element drag positioning
│   ├── useIconPreload.ts           # Icon image preloading
│   ├── useMediaDurationProbe.ts    # Media duration probing
│   │
│   │ # Utility
│   ├── useDevCompilationStatus.ts
│   ├── useOutsideClick.ts          # Click outside detection
│   └── useDraggable.ts             # Draggable panel management
│
├── stores/
│   └── hooks.ts  (useAppDispatch, useAppSelector)
│
└── components/
    ├── Assets/
    │   └── useAssetUploader.ts
    └── ElementSettings/
        └── useElementSettingsForm.ts
```

---

## Related Documentation

| Document | Description |
|----------|-------------|
| [runtime-presentation.md](./runtime-presentation.md) | RuntimePresentation component - public tour viewer with transitions and offline support |
| [constructor-page-editor.md](./constructor-page-editor.md) | Constructor page - visual tour builder with element editing |
| [assets-preloading.md](../../documentation/assets-preloading.md) | Asset preloading architecture and S3 direct download flow |
| [page-transitions.md](../../documentation/page-transitions.md) | Video transitions stored on navigation elements |
| [offline-pwa-mode.md](../../documentation/offline-pwa-mode.md) | PWA offline capabilities and caching |