# Admin Library Page Improvements - Implementation Plan

## Overview
Four improvements to the `/admin/library` page to fix bugs and add missing functionality.

## Issues Addressed

### Issue 1: Folder List Display Bugs
**Current State:** Folders can be added but disappear after adding; delete button doesn't work.

**Root Causes:**
1. Toggle logic bug - clicking "Folders" again hides instead of refreshing
2. DELETE API missing request body - backend requires `{"folder_path": "..."}` but frontend doesn't send it

**Files to Modify:**
- `web/src/api.ts` - Add optional data parameter to `apiDelete()`
- `web/src/library.ts` - Fix toggle logic and DELETE call

---

### Issue 2: Folder Path Browse Button
**Current State:** User must manually type server paths.

**Solution:** Add server-side folder browser (like Audiobookshelf, Jellyfin, Sonarr, etc.)

**Type:** Full-stack (requires backend + frontend)

**Files to Modify:**

**Backend:**
- `internal/services/library_service.go` - Add `BrowseDirectories()` function
- `internal/handlers/library.go` - Add `BrowseDirectories` handler
- `internal/router/library.go` - Register route
- `internal/services/library_service_test.go` - Unit tests
- `cmd/server/tests/library_browse_test.go` - Integration tests
- `bruno/library/browse-folders.yml` - Bruno test (manual API contract verification)
- `docs/developer/api/libraries/browse-folders.md` - API documentation
- `docs/user/admin-library-management.md` - User documentation

**Frontend:**
- `web/src/library.ts` - Add folder browser functions
- `templates/admin_library.templ` - Add folder browser modal + Browse button

**Security:**
- Path traversal protection (block `..`)
- Only list directories, not files
- Admin-only access

---

### Issue 3: Edit Library Button
**Current State:** Edit button shows "coming soon" toast.

**Solution:** Reuse "Create Library" modal, populate with existing data, switch between create/edit mode.

**Files to Modify:**
- `web/src/library.ts` - Implement `editLibrary()`, modify form handler
- `templates/admin_library.templ` - Add hidden input, data attributes to Edit button

**No backend changes needed** - `PUT /api/libraries/:id` already exists.

---

### Issue 4: Delete Library Confirmation
**Current State:** Basic confirmation, doesn't clarify what gets deleted.

**Solution:** Improve message to explicitly state book files on disk are NOT deleted.

**Files to Modify:**
- `web/src/library.ts` - Update confirmation message

---

## Detailed Implementation

### Issue 1: Folder List Bug Fixes

#### 1.1 Modify `web/src/api.ts`

**Location:** Line 37

**Current:**
```typescript
async function apiDelete(url: string): Promise<Response> {
    return fetch(`/api${url}`, {
        method: 'DELETE',
        headers: {
            'Authorization': getAuthHeader()
        }
    });
}
```

**Replace With:**
```typescript
async function apiDelete<T extends object>(url: string, data?: T): Promise<Response> {
    return fetch(`/api${url}`, {
        method: 'DELETE',
        headers: {
            'Authorization': getAuthHeader(),
            'Content-Type': 'application/json'
        },
        body: data ? JSON.stringify(data) : undefined
    });
}
```

**Rationale:** Generic type parameter provides type safety - TypeScript will enforce that request bodies match the expected object structure (e.g., `{ folder_path: string }`), preventing runtime errors from malformed requests. 100% backward compatible (optional parameter), only 2 callers exist in codebase.

**Type Safety Note:** The generic `<T extends object>` constraint ensures that:
1. Only objects can be passed (not primitives like strings/numbers)
2. TypeScript infers the literal type from the call site
3. If we wanted explicit type definitions, we could define:
   ```typescript
   interface DeleteFolderRequest {
       folder_path: string;
   }
   ```
   And call with explicit type: `apiDelete<DeleteFolderRequest>(url, data)`
   But inference is cleaner and equally type-safe.

---

#### 1.2 Fix Toggle Logic in `web/src/library.ts`

**Location:** Lines 196-228

**Current Problem:**
```typescript
if (container.classList.contains('hidden')) {
    // load and show folders
} else {
    container.classList.add('hidden');  // <-- HIDES on second click!
}
```

**Fix:** Remove toggle, always reload and show:
```typescript
async function showLibraryFolders(libraryId: string): Promise<void> {
    const container = document.getElementById(`library-folders-${libraryId}`);
    if (!container) return;

    // Always reload content
    try {
        const response = await (window as any).api.get(`/libraries/${libraryId}/folders`);
        const folders = await (window as any).api.handleResponse(response) as LibraryFolder[];

        container.innerHTML = folders.map((folder: LibraryFolder) =>
            '<div class="flex justify-between items-center p-2 rounded" style="background-color: var(--bg-secondary); border-color: var(--border)">' +
                `<span class="text-sm" style="color: var(--text-primary)">${escapeHtmlLocal(folder.folder_path)}</span>` +
                `<button data-library-id="${libraryId}" data-folder-path="${escapeHtmlLocal(folder.folder_path)}" data-action="remove-folder" ` +
                    'class="text-xs text-red-500">Remove</button>' +
            '</div>'
        ).join('');

        // Add folder input with browse button (Issue 2 will add Browse button)
        container.innerHTML += '<div class="mt-2 flex space-x-2">' +
            `<input type="text" id="folder-path-${libraryId}" placeholder="Add folder path" ` +
                'class="flex-1 px-2 py-1 text-sm border rounded" style="background-color: var(--bg-primary); color: var(--text-primary); border-color: var(--border)">' +
            `<button data-library-id="${libraryId}" data-action="add-folder" ` +
                'class="btn-primary px-2 py-1 text-xs rounded">Add</button>' +
        '</div>';

        container.classList.remove('hidden');
    } catch (error) {
        (window as any).api.handleError(error, 'Failed to load folders');
    }
}
```

---

#### 1.3 Fix DELETE Request Body in `removeLibraryFolder()`

**File:** `web/src/library.ts` (modify `removeLibraryFolder` function, around line 259)

**Add interface at top of file (with other interfaces around line 14):**
```typescript
interface DeleteFolderRequest {
    folder_path: string;
}
```

**Current (broken):**
```typescript
async function removeLibraryFolder(libraryId: string, folderPath: string): Promise<void> {
    if (!confirm(`Remove folder "${folderPath}" from the library?`)) {
        return;
    }

    try {
        const response = await (window as any).api.delete(`/libraries/${libraryId}/folders`);
        await (window as any).api.handleVoidResponse(response);

        if ((window as any).showToast?.success) {
            (window as any).showToast.success('Folder removed successfully');
        }

        void showLibraryFolders(libraryId); // Refresh
    } catch (error) {
        (window as any).api.handleError(error, 'Failed to remove folder');
    }
}
```

**Replace With:**
```typescript
async function removeLibraryFolder(libraryId: string, folderPath: string): Promise<void> {
    if (!confirm(`Remove folder "${folderPath}" from the library?`)) {
        return;
    }

    try {
        const response = await (window as any).api.delete<DeleteFolderRequest>(
            `/libraries/${libraryId}/folders`,
            { folder_path: folderPath }
        );
        await (window as any).api.handleVoidResponse(response);

        if ((window as any).showToast?.success) {
            (window as any).showToast.success('Folder removed successfully');
        }

        void showLibraryFolders(libraryId); // Refresh
    } catch (error) {
        (window as any).api.handleError(error, 'Failed to remove folder');
    }
}
```

**Rationale:** Backend `DeleteLibraryFolder` handler (library.go:237) reuses `AddLibraryFolderRequest` struct and requires `{ "folder_path": "..." }` in request body. The `c.Bind()` call fails with "invalid request" error when body is missing, causing folder removal to silently fail. Using explicit `DeleteFolderRequest` interface provides type safety and prevents passing incorrect request shapes.

---

### Issue 2: Folder Browser (Full-Stack)

#### 2.1 Backend - Service Layer

**File:** `internal/services/library_service.go`

**Add Import:**
```go
import (
    "os"  // Add this import for os.Stat, os.IsNotExist, os.ReadDir
)
```

**Add Function:**
```go
// BrowseDirectories lists directories at a given path for folder browser UI
// Returns: (directories, currentPath, parentPath, error)
func (s *LibraryService) BrowseDirectories(ctx context.Context, path string) ([]string, string, string, error) {
    // Security: path traversal protection
    if strings.Contains(path, "..") {
        return nil, "", "", fmt.Errorf("path traversal not allowed")
    }

    cleanPath := filepath.Clean(path)

    // Check if path exists and is accessible
    fileInfo, err := os.Stat(cleanPath)
    if err != nil {
        if os.IsNotExist(err) {
            return nil, "", "", fmt.Errorf("path does not exist")
        }
        return nil, "", "", fmt.Errorf("path not accessible: %w", err)
    }

    if !fileInfo.IsDir() {
        return nil, "", "", fmt.Errorf("not a directory")
    }

    // Read directory contents
    entries, err := os.ReadDir(cleanPath)
    if err != nil {
        return nil, "", "", fmt.Errorf("failed to read directory: %w", err)
    }

    // Filter only directories
    var dirs []string
    for _, entry := range entries {
        if entry.IsDir() {
            dirs = append(dirs, entry.Name())
        }
    }

    // Get parent path for navigation
    parentPath := filepath.Dir(cleanPath)
    if parentPath == cleanPath {
        parentPath = "" // At root
    }

    return dirs, cleanPath, parentPath, nil
}
```

---

#### 2.2 Backend - Handler

**File:** `internal/handlers/library.go`

**Add Handler Function:**
```go
// BrowseDirectories returns directory listings for folder browser UI
func (h *LibraryHandler) BrowseDirectories(c echo.Context) error {
    path := c.QueryParam("path")
    if path == "" {
        path = "/" // Start from root
    }

    dirs, currentPath, parentPath, err := h.libraryService.BrowseDirectories(c.Request().Context(), path)
    if err != nil {
        return c.JSON(http.StatusBadRequest, map[string]string{"error": err.Error()})
    }

    return c.JSON(http.StatusOK, map[string]interface{}{
        "current_path": currentPath,
        "parent_path":  parentPath,
        "directories":  dirs,
    })
}
```

---

#### 2.3 Backend - Router

**File:** `internal/router/library.go`

**Add Route Registration (before line 31, before all /:id routes):**
```go
adminLibrary.GET("/browse", cfg.LibraryHandler.BrowseDirectories)
```

**CRITICAL:** Must come before `/:id` routes (line 31) to avoid route matching conflicts where `/libraries/browse` could be captured by `/:id`.

---

#### 2.4 Backend - Unit Tests

**File:** `internal/services/library_service_test.go` (create if doesn't exist)

```go
package services

import (
    "context"
    "testing"

    "github.com/stretchr/testify/assert"
)

func TestBrowseDirectories(t *testing.T) {
    // BrowseDirectories operates on filesystem only - no database needed
    service := &LibraryService{}

    t.Run("blocks path traversal with ..", func(t *testing.T) {
        _, _, _, err := service.BrowseDirectories(context.Background(), "/etc/../root")
        assert.Error(t, err)
        assert.Contains(t, err.Error(), "path traversal not allowed")
    })

    t.Run("returns error for non-existent path", func(t *testing.T) {
        _, _, _, err := service.BrowseDirectories(context.Background(), "/nonexistent/path")
        assert.Error(t, err)
        assert.Contains(t, err.Error(), "path does not exist")
    })

    t.Run("returns error when path is a file", func(t *testing.T) {
        _, _, _, err := service.BrowseDirectories(context.Background(), "/etc/passwd")
        assert.Error(t, err)
        assert.Contains(t, err.Error(), "not a directory")
    })

    t.Run("returns subdirectories for valid path", func(t *testing.T) {
        dirs, currentPath, parentPath, err := service.BrowseDirectories(context.Background(), "/tmp")
        assert.NoError(t, err)
        assert.NotEmpty(t, dirs)
        assert.Equal(t, "/tmp", currentPath)
        assert.Equal(t, "/", parentPath)
    })
}
```

---

#### 2.5 Backend - Integration Tests

**File:** `cmd/server/tests/library_browse_test.go` (create new file)

```go
package main

import (
    "encoding/json"
    "net/http"
    "net/http/httptest"
    "testing"

    "github.com/stretchr/testify/assert"
)

func TestBrowseLibraryFoldersEndpoint(t *testing.T) {
    setup := setupTestServer(t)

    t.Run("GET /api/libraries/browse - no authentication returns 401", func(t *testing.T) {
        req := httptest.NewRequest("GET", "/api/libraries/browse?path=/tmp", nil)
        rec := httptest.NewRecorder()
        setup.Server.Config.Handler.ServeHTTP(rec, req)
        assert.Equal(t, http.StatusUnauthorized, rec.Code)
    })

    t.Run("GET /api/libraries/browse - regular user returns 403 forbidden", func(t *testing.T) {
        req := httptest.NewRequest("GET", "/api/libraries/browse?path=/tmp", nil)
        req.Header.Set("Authorization", "Bearer "+setup.RegularToken)
        rec := httptest.NewRecorder()
        setup.Server.Config.Handler.ServeHTTP(rec, req)
        assert.Equal(t, http.StatusForbidden, rec.Code)
    })

    t.Run("GET /api/libraries/browse - admin can browse directories", func(t *testing.T) {
        req := httptest.NewRequest("GET", "/api/libraries/browse?path=/tmp", nil)
        req.Header.Set("Authorization", "Bearer "+setup.Token)
        rec := httptest.NewRecorder()
        setup.Server.Config.Handler.ServeHTTP(rec, req)
        assert.Equal(t, http.StatusOK, rec.Code)

        var data struct {
            CurrentPath string   `json:"current_path"`
            ParentPath  string   `json:"parent_path"`
            Directories []string `json:"directories"`
        }
        err := json.Unmarshal(rec.Body.Bytes(), &data)
        assert.NoError(t, err)
        assert.Equal(t, "/tmp", data.CurrentPath)
        assert.NotEmpty(t, data.Directories)
    })

    t.Run("GET /api/libraries/browse - blocks path traversal attempts", func(t *testing.T) {
        req := httptest.NewRequest("GET", "/api/libraries/browse?path=/etc/../root", nil)
        req.Header.Set("Authorization", "Bearer "+setup.Token)
        rec := httptest.NewRecorder()
        setup.Server.Config.Handler.ServeHTTP(rec, req)
        assert.Equal(t, http.StatusBadRequest, rec.Code)

        var errResp struct {
            Error string `json:"error"`
        }
        json.Unmarshal(rec.Body.Bytes(), &errResp)
        assert.Contains(t, errResp.Error, "path traversal not allowed")
    })
}
```

---

#### 2.6 Bruno API Test (Manual Testing)

**File:** `bruno/library/browse-folders.yml` (create new file)

**Purpose:** Single manual test case for API contract verification and examples. Unit and integration tests cover all scenarios (no auth, user, admin, edge cases). Bruno provides a quick manual test for API contract validation.

```yaml
meta:
  name: Browse library folders
  type: http
  seq: 1
config:
  test:
    filter: "response.status == 200"
    assertions:
      - type: stddev
        target: response_time
        threshold: 1000
      - type: jsonpath
        expression: response.directories
        condition: exists
      - type: jsonpath
        expression: response.current_path
        condition: exists
      - type: jsonpath
        expression: response.parent_path
        condition: exists
req:
  method: GET
  url: "{{base_url}}/api/libraries/browse?path=/tmp"
  headers:
    Authorization: "Bearer {{ADMIN_TOKEN}}"
```

---

#### 2.7 User Documentation

**File:** `docs/user/admin-library-management.md` (create new file)

```markdown
# Admin Library Management

## Adding Library Folders

When creating or managing a library, you can add folders containing your media files (ebooks, comics, manga).

### Using the Folder Browser

The admin library page includes a folder browser to help you select folders on the server:

1. Navigate to **Admin → Library Management**
2. Find the library you want to manage
3. Click the **Folders** button
4. Click **Browse** next to "Add folder path"
5. Navigate through the server's filesystem
6. Select a folder by clicking **Select This Folder**

### Security

- The folder browser only shows directories (not files)
- Path traversal is protected (cannot access parent directories with `..`)
- Only admin users can browse the filesystem

### Manual Entry

Alternatively, you can manually type the full server path if you know it:

```
/home/user/books
/media/external/ebooks
/var/lib/manga
```
```

---

#### 2.8 Frontend - Folder Browser Functions

**File:** `web/src/library.ts` (add before `initializeLibraryAdmin()`)

```typescript
// Folder browser state
let currentBrowsePath = '';
let currentBrowseInputId = '';

// Show folder browser modal
function showFolderBrowser(inputId: string): void {
    currentBrowseInputId = inputId;
    currentBrowsePath = '/'; // Start at root

    const modal = document.getElementById('folder-browser-modal') as HTMLElement;
    if (modal) {
        modal.classList.remove('hidden');
        void loadBrowseDirectories(currentBrowsePath);
    }
}

// Load directories for browsing
async function loadBrowseDirectories(path: string): Promise<void> {
    try {
        const response = await (window as any).api.get(`/libraries/browse?path=${encodeURIComponent(path)}`);
        const data = await (window as any).api.handleResponse(response) as {
            current_path: string;
            parent_path: string;
            directories: string[];
        };

        currentBrowsePath = data.current_path;
        renderBrowseDirectories(data);
    } catch (error) {
        (window as any).api.handleError(error, 'Failed to load directories');
    }
}

// Render browse directories (uses event delegation via data-action attributes)
function renderBrowseDirectories(data: { current_path: string; parent_path: string; directories: string[] }): void {
    const container = document.getElementById('folder-browser-content');
    if (!container) return;

    let html = `
        <div class="flex items-center gap-2 mb-4">
            ${data.parent_path ?
                `<button type="button" data-action="browse-parent" data-path="${escapeHtmlLocal(data.parent_path)}" class="btn-secondary px-3 py-1 rounded">↑ Parent</button>`
                : ''}
            <span class="text-sm" style="color: var(--text-secondary)">${escapeHtmlLocal(data.current_path)}</span>
        </div>
        <div class="max-h-64 overflow-y-auto space-y-1">
    `;

    if (data.directories.length === 0) {
        html += '<p style="color: var(--text-secondary)" class="text-center py-4">No subdirectories</p>';
    } else {
        data.directories.forEach(dir => {
            const fullPath = data.current_path === '/' ? `/${dir}` : `${data.current_path}/${dir}`;
            html += `
                <div class="p-2 rounded cursor-pointer hover:opacity-80"
                     style="background-color: var(--bg-secondary); color: var(--text-primary)"
                     data-action="browse-navigate"
                     data-path="${escapeHtmlLocal(fullPath)}">
                    📁 ${escapeHtmlLocal(dir)}
                </div>
            `;
        });
    }

    html += `
        </div>
        <div class="mt-4 flex justify-end gap-2">
            <button type="button" data-action="browse-cancel" class="btn-secondary px-4 py-2 rounded">Cancel</button>
            <button type="button" data-action="browse-select" data-path="${escapeHtmlLocal(data.current_path)}" class="btn-primary px-4 py-2 rounded">Select This Folder</button>
        </div>
    `;

    container.innerHTML = html;
}

// Navigate to subdirectory
function navigateFolderBrowser(path: string): void {
    void loadBrowseDirectories(path);
}

// Select folder and close browser
function selectBrowseFolder(path: string): void {
    const input = document.getElementById(currentBrowseInputId) as HTMLInputElement;
    if (input) {
        input.value = path;
    }
    hideFolderBrowser();
}

// Hide folder browser modal
function hideFolderBrowser(): void {
    const modal = document.getElementById('folder-browser-modal') as HTMLElement;
    if (modal) {
        modal.classList.add('hidden');
    }
}

**NOTE:** Export the new folder browser functions by adding them to the existing window exports block at the end of library.ts (around line 380-387), not as a separate block:

```typescript
// Add these to the existing exports at lines 380-387:
(window as any).showFolderBrowser = showFolderBrowser;
(window as any).navigateFolderBrowser = navigateFolderBrowser;
(window as any).selectBrowseFolder = selectBrowseFolder;
(window as any).hideFolderBrowser = hideFolderBrowser;
```

---

#### 2.9 Frontend - Update Event Delegation Handler

**File:** `web/src/library.ts` (modify `handleLibraryListClick` function, around line 309)

**Add cases for folder browser actions:**

```typescript
function handleLibraryListClick(event: Event): void {
    const target = event.target as HTMLElement;
    const button = target.closest('button') as HTMLElement;
    if (!button) return;

    const action = button.dataset.action;
    const libraryId = button.dataset.libraryId;

    switch (action) {
        case 'show-folders':
            if (libraryId) showLibraryFolders(libraryId);
            break;
        case 'delete':
            if (libraryId) deleteLibrary(libraryId);
            break;
        case 'edit':
            if (libraryId) editLibrary(libraryId);
            break;
        case 'add-folder':
            if (libraryId) addLibraryFolder(libraryId);
            break;
        case 'remove-folder':
            if (libraryId && button.dataset.folderPath) {
                removeLibraryFolder(libraryId, button.dataset.folderPath);
            }
            break;
        case 'browse-folder':
            if (button.dataset.inputId) showFolderBrowser(button.dataset.inputId);
            break;
    }
}

function handleFolderBrowserClick(event: Event): void {
    const target = event.target as HTMLElement;
    const button = target.closest('button') as HTMLElement;
    const div = target.closest('div[data-action]') as HTMLElement;

    // Handle button clicks
    if (button) {
        const action = button.dataset.action;
        const path = button.dataset.path;

        switch (action) {
            case 'browse-parent':
                if (path) navigateFolderBrowser(path);
                break;
            case 'browse-cancel':
                hideFolderBrowser();
                break;
            case 'browse-select':
                if (path) selectBrowseFolder(path);
                break;
        }
    }

    // Handle directory div clicks
    if (div && div.dataset.action === 'browse-navigate') {
        const path = div.dataset.path;
        if (path) navigateFolderBrowser(path);
    }
}
```

**Update `initializeLibraryAdmin` to add folder browser event listener:**

```typescript
function initializeLibraryAdmin(): void {
    // Setup event listeners
    const librariesList = document.getElementById('libraries-list');
    if (librariesList) {
        librariesList.addEventListener('click', handleLibraryListClick);
    }

    const folderBrowserModal = document.getElementById('folder-browser-modal');
    if (folderBrowserModal) {
        folderBrowserModal.addEventListener('click', handleFolderBrowserClick);
    }

    document.addEventListener('click', handleGlobalClick);

    // ... rest of existing code
}
```

---

#### 2.10 Frontend - Add Browse Button

**File:** `web/src/library.ts` (modify `showLibraryFolders` function, around line 214)

**Current folder input:**
```typescript
container.innerHTML += '<div class="mt-2 flex space-x-2">' +
    `<input type="text" id="folder-path-${libraryId}" placeholder="Add folder path" ` +
        'class="flex-1 px-2 py-1 text-sm border rounded" style="background-color: var(--bg-primary); color: var(--text-primary); border-color: var(--border)">' +
    `<button data-library-id="${libraryId}" data-action="add-folder" ` +
        'class="btn-primary px-2 py-1 text-xs rounded">Add</button>' +
'</div>';
```

**Replace With:**
```typescript
container.innerHTML += '<div class="mt-2 flex space-x-2">' +
    `<input type="text" id="folder-path-${libraryId}" placeholder="Add folder path" ` +
        'class="flex-1 px-2 py-1 text-sm border rounded" style="background-color: var(--bg-primary); color: var(--text-primary); border-color: var(--border)">' +
    `<button data-action="browse-folder" data-input-id="folder-path-${libraryId}" ` +
        'class="btn-secondary px-2 py-1 text-xs rounded">Browse</button>' +
    `<button data-library-id="${libraryId}" data-action="add-folder" ` +
        'class="btn-primary px-2 py-1 text-xs rounded">Add</button>' +
'</div>';
```

---

#### 2.11 Frontend - Folder Browser Modal

**File:** `templates/admin_library.templ`

**Add after Create Library Modal (after line 147):**
```html
<!-- Folder Browser Modal -->
<div id="folder-browser-modal" class="hidden fixed inset-0 z-50 flex items-center justify-center" style="background-color: rgba(0, 0, 0, 0.7);">
    <div class="card rounded-lg p-6 w-full max-w-md mx-4" style="background-color: var(--bg-secondary); border-color: var(--border);">
        <div class="flex justify-between items-center mb-4">
            <h2 class="text-xl font-bold" style="color: var(--text-primary)">Browse Folders</h2>
            <button type="button" data-action="browse-cancel" class="p-2 hover:opacity-80 rounded" style="color: var(--text-primary)">✕</button>
        </div>
        <div id="folder-browser-content">
            <!-- Directory listings will be rendered here -->
        </div>
    </div>
</div>
```

---

### Issue 3: Edit Library Button

#### 3.1 Implement `editLibrary()` Function

**File:** `web/src/library.ts` (lines 278-284)

**Current (placeholder):**
```typescript
function editLibrary(libraryId: string): void {
    console.log('Edit library:', libraryId);
    if ((window as any).showToast?.info) {
        (window as any).showToast.info('Edit library functionality coming soon');
    }
}
```

**Replace With:**
```typescript
function editLibrary(libraryId: string): void {
    const library = libraries.find(l => l.id === libraryId);
    if (!library) {
        if ((window as any).showToast?.error) {
            (window as any).showToast.error('Library not found');
        }
        return;
    }

    // Populate form with existing data
    const form = document.getElementById('create-library-form') as HTMLFormElement;
    if (form) {
        const nameInput = form.querySelector('[name="name"]') as HTMLInputElement;
        const descInput = form.querySelector('[name="description"]') as HTMLTextAreaElement;
        const typeInput = form.querySelector('[name="type"]') as HTMLSelectElement;

        if (nameInput) nameInput.value = library.name;
        if (descInput) descInput.value = library.description || '';
        if (typeInput) typeInput.value = library.library_type_id;
    }

    // Update modal title
    const modalTitle = document.querySelector('#create-library-modal h2');
    if (modalTitle) {
        modalTitle.textContent = 'Edit Library';
    }

    // Store library ID for form submission
    const libraryIdInput = document.getElementById('library-id') as HTMLInputElement;
    if (libraryIdInput) {
        libraryIdInput.value = libraryId;
    }

    showCreateLibraryModal();
}
```

---

#### 3.2 Modify Form Handler

**File:** `web/src/library.ts` (lines 144-170)

**Current:**
```typescript
async function handleCreateLibrarySubmit(event: Event): Promise<void> {
    event.preventDefault();

    const form = event.target as HTMLFormElement;
    const formData = new FormData(form);

    const libraryData = {
        name: formData.get('name') as string,
        description: formData.get('description') as string,
        type: formData.get('type') as string
    };

    try {
        const response = await (window as any).api.post('/libraries', libraryData);
        await (window as any).api.handleResponse(response) as { data: Library };

        if ((window as any).showToast?.success) {
            (window as any).showToast.success('Library created successfully');
        }

        hideCreateLibraryModal();
        form.reset();
        void reloadLibraries();
    } catch (error) {
        (window as any).api.handleError(error, 'Failed to create library');
    }
}
```

**Replace With:**
```typescript
async function handleCreateLibrarySubmit(event: Event): Promise<void> {
    event.preventDefault();

    const form = event.target as HTMLFormElement;
    const formData = new FormData(form);

    const libraryId = (document.getElementById('library-id') as HTMLInputElement)?.value;
    const isEdit = !!libraryId;

    const libraryData = {
        name: formData.get('name') as string,
        description: formData.get('description') as string,
        type: formData.get('type') as string
    };

    try {
        const url = isEdit ? `/libraries/${libraryId}` : '/libraries';
        const method = isEdit ? 'put' : 'post';

        const response = await (window as any).api[method](url, libraryData);

        if (isEdit) {
            await (window as any).api.handleVoidResponse(response);
        } else {
            await (window as any).api.handleResponse(response) as { data: Library };
        }

        if ((window as any).showToast?.success) {
            (window as any).showToast.success(isEdit ? 'Library updated successfully' : 'Library created successfully');
        }

        hideCreateLibraryModal();
        form.reset();

        // Clear library ID
        const libraryIdInput = document.getElementById('library-id') as HTMLInputElement;
        if (libraryIdInput) {
            libraryIdInput.value = '';
        }

        void reloadLibraries();
    } catch (error) {
        (window as any).api.handleError(error, isEdit ? 'Failed to update library' : 'Failed to create library');
    }
}
```

---

#### 3.3 Update Modal Title Reset

**File:** `web/src/library.ts` (lines 287-292)

**Current:**
```typescript
function showCreateLibraryModal(): void {
    const modal = document.getElementById('create-library-modal') as HTMLElement;
    if (modal) {
        modal.classList.remove('hidden');
    }
}
```

**Replace With:**
```typescript
function showCreateLibraryModal(): void {
    const modal = document.getElementById('create-library-modal') as HTMLElement;
    if (modal) {
        modal.classList.remove('hidden');

        // Reset modal title to "Create Library"
        const modalTitle = document.querySelector('#create-library-modal h2');
        if (modalTitle) {
            modalTitle.textContent = 'Create Library';
        }
    }
}
```

---

#### 3.4 Add Hidden Input to Template

**File:** `templates/admin_library.templ` (line 124, in form)

**Add at beginning of form:**
```html
<form id="create-library-form">
    <input type="hidden" id="library-id" name="id">
    <!-- rest of form unchanged -->
</form>
```

---

### Issue 4: Delete Library Clarification

#### 4.1 Update Confirmation Message

**File:** `web/src/library.ts` (line 177 in `deleteLibrary()`)

**Current:**
```typescript
if (!confirm(`Delete library "${library.name}"? This will permanently remove all associated media and cannot be undone.`)) {
    return;
}
```

**Replace With:**
```typescript
const message = `Are you sure you want to delete "${library.name}"?

This will remove:
• Library metadata from the database
• All folder references
• All book records from the database

⚠️ Book files on disk will NOT be deleted.

This action cannot be undone.`;

if (!confirm(message)) {
    return;
}
```

---

## Git Commit Structure

### Frontend Commits (Issues 3, 4, 1)

```
feat(frontend): implement library edit functionality

- Reuse Create Library modal for edit mode
- Add hidden library-id input to track create vs edit
- Update handleCreateLibrarySubmit to detect mode and use PUT vs POST
- Implement editLibrary() to populate modal with existing data
- Pass library data to Edit button via data attributes
- Reset modal title when opening for create mode

Fixes: Issue 3

---

fix(frontend): clarify library delete confirmation message

- Explicitly state book files on disk are NOT deleted
- List what gets removed (database records only)
- Improve user understanding of delete operation
- Use multi-line format for better readability

Fixes: Issue 4

---

fix(frontend): resolve folder list display bugs

- Fix toggle logic that hid folders on second click
- Remove toggle behavior, always reload and show folders
- Add data parameter support to apiDelete() in api.ts
- Fix DELETE /api/libraries/:id/folders to include request body
- 100% backward compatible (optional parameter)

Fixes: Issue 1
```

### Full-Stack Commits (Issue 2)

```
feat(backend): add server-side directory browsing API

- Add BrowseDirectories() to library service with path traversal protection
- Add BrowseDirectories handler with proper error handling
- Register GET /api/libraries/browse endpoint (admin-only)
- Returns current path, parent path, and list of subdirectories
- Security: blocks "..", validates path exists, checks is directory

Fixes: Issue 2 (backend)

---

test(backend): add unit and integration tests for folder browsing

- Add unit tests in internal/services/library_service_test.go
  - Test path traversal protection
  - Test non-existent path handling
  - Test file vs directory validation
  - Test successful directory listing
- Add integration tests in cmd/server/tests/library_browse_test.go
  - Use setupTestServer() helper from test_helpers.go
  - Test no authentication returns 401
  - Test regular user returns 403 forbidden
  - Test admin can browse directories
  - Test path traversal blocking
- All tests use table-driven approach with t.Run()

Fixes: Issue 2 (tests)

---

docs(api): document library folder browsing endpoint

- Add docs/developer/api/libraries/browse-folders.md
- Document security features (path traversal protection, admin-only)
- Include usage examples and error responses
- Clarify browses server filesystem, not client's

docs(user): add admin library folder browser documentation

- Add docs/user/admin-library-management.md
- Document how to use the folder browser UI
- Include security notes and manual entry instructions
- Explain server filesystem browsing behavior

Fixes: Issue 2 (documentation)

---

test(bruno): add manual API contract test for folder browsing

- Create bruno/library/browse-folders.yml
- Single manual test case for admin context
- Unit/integration tests cover all scenarios (no auth, user, admin)
- Bruno provides quick manual API contract verification

Fixes: Issue 2 (manual testing)

---

feat(frontend): add folder browser UI for library management

- Add folder browser modal to admin/library page
- Implement directory navigation in library.ts
- Add Browse button next to folder path input
- Connect to backend /api/libraries/browse endpoint
- Support parent directory navigation and path selection

Fixes: Issue 2 (frontend)
```

---

## Verification Steps

After each commit:

```bash
# 1. Verify Go compilation
go build ./...

# 2. Run tests
go test ./... -v

# 3. Run verification script
bash scripts/verify-guidelines.sh

# 4. Review git diff
git diff

# 5. Rebuild container for testing
podman compose up --build -d
```

---

## Testing Checklist

### Issue 1: Folder List Bugs
- [ ] Click "Folders" button - folder list appears
- [ ] Click "Folders" again - list refreshes (doesn't hide)
- [ ] Add new folder - folder appears in list
- [ ] Click "Remove" on folder - confirmation dialog appears
- [ ] Confirm removal - folder removed from list
- [ ] Check browser console - no errors

### Issue 2: Folder Browser
- [ ] Click "Browse" button - folder browser modal opens
- [ ] See list of directories starting at root (/)
- [ ] Click on directory - navigate into it
- [ ] Click "↑ Parent" - navigate to parent directory
- [ ] Click "Select This Folder" - path entered in input field
- [ ] Modal closes after selection
- [ ] Test path traversal protection (try URL with "..") - should error
- [ ] Test with non-existent path - should show error
- [ ] Check browser console - no errors

### Issue 3: Edit Library
- [ ] Click "Edit" button on library - modal opens with library data
- [ ] Modal title shows "Edit Library"
- [ ] Form is pre-filled with existing library data
- [ ] Modify name/description/type
- [ ] Click "Create" button - library updates
- [ ] Success toast appears
- [ ] Library list refreshes with updated data
- [ ] Open modal again - shows "Create Library" title
- [ ] Create new library - still works

### Issue 4: Delete Clarification
- [ ] Click "Delete" button on library
- [ ] See improved confirmation message
- [ ] Message explicitly states book files NOT deleted
- [ ] Message lists what WILL be deleted
- [ ] Cancel - nothing happens
- [ ] Confirm - library deleted, success toast shown

---

## Files Summary

### Frontend Only
- `web/src/api.ts` - Add data parameter to apiDelete
- `web/src/library.ts` - All frontend logic (Issues 1, 3, 4, and part of 2)
- `templates/admin_library.templ` - HTML changes (Issues 2, 3)

### Backend Only (Issue 2)
- `internal/services/library_service.go` - BrowseDirectories function
- `internal/handlers/library.go` - BrowseDirectories handler
- `internal/router/library.go` - Route registration

### Tests (Issue 2)
- `internal/services/library_service_test.go` - Unit tests for BrowseDirectories
- `cmd/server/tests/library_browse_test.go` - Integration tests (no auth, user, admin contexts)

### Documentation (Issue 2)
- `docs/developer/api/libraries/browse-folders.md` - API reference documentation
- `docs/user/admin-library-management.md` - User-facing documentation for folder browser

### Manual API Testing (Issue 2)
- `bruno/library/browse-folders.yml` - Single Bruno test for manual API contract verification

---

## Notes

- All TypeScript files are in `web/src/` - these are the source files
- JS files in `web/static/` are compiled artifacts, not manually edited
- Build process: `npm run build:ts` compiles TS → JS, or use container rebuild
- Following PROJECT_GUIDELINES.md throughout
- No OOP - procedural/imperative style only
- TailwindCSS only - no custom CSS
- All business logic in service layer
- Progressive enhancement - pages work without JavaScript