diff --git a/electron/database/LocalSystem.ts b/electron/database/LocalSystem.ts
new file mode 100644
index 0000000..24e226a
--- /dev/null
+++ b/electron/database/LocalSystem.ts
@@ -0,0 +1,282 @@
+import type { IpcMainInvokeEvent } from 'electron';
+import Store from 'electron-store';
+
+// Electron store instance for session management
+const store = new Store({
+    encryptionKey: 'eritors-scribe-secure-key'
+});
+
+// ============================================================
+// SESSION MANAGEMENT - Retrieve userId and lang from store
+// ============================================================
+
+/**
+ * Get userId from electron-store
+ * Set during login via 'login-success' event
+ */
+function getUserIdFromSession(): string | null {
+    return store.get('userId', null) as string | null;
+}
+
+/**
+ * Get lang from electron-store
+ * Set via 'set-lang' handler, defaults to 'fr'
+ */
+function getLangFromSession(): 'fr' | 'en' {
+    return store.get('userLang', 'fr') as 'fr' | 'en';
+}
+
+// ============================================================
+// LEGACY HANDLERS - Manual userId injection, lang must be passed
+// Keep these for backward compatibility
+// Updated to support Promises
+// ============================================================
+
+export function createDbHandler<TReturn>(
+    handler: (userId: string) => TReturn | Promise<TReturn>
+): (event: IpcMainInvokeEvent) => Promise<TReturn> {
+    return async function(event: IpcMainInvokeEvent): Promise<TReturn> {
+        const userId = getUserIdFromSession();
+
+        if (!userId) {
+            throw new Error('User not authenticated');
+        }
+
+        try {
+            return await handler(userId);
+        } catch (error: unknown) {
+            if (error instanceof Error) {
+                console.error(`[DB] ${error.message}`);
+                throw error;
+            }
+            throw new Error('An unknown error occurred.');
+        }
+    };
+}
+
+export function createDbHandler1<T1, TReturn>(
+    handler: (userId: string, arg1: T1) => TReturn | Promise<TReturn>
+): (event: IpcMainInvokeEvent, arg1: T1) => Promise<TReturn> {
+    return async function(event: IpcMainInvokeEvent, arg1: T1): Promise<TReturn> {
+        const userId = getUserIdFromSession();
+
+        if (!userId) {
+            throw new Error('User not authenticated');
+        }
+
+        try {
+            return await handler(userId, arg1);
+        } catch (error: unknown) {
+            if (error instanceof Error) {
+                console.error(`[DB] ${error.message}`);
+                throw error;
+            }
+            throw new Error('An unknown error occurred.');
+        }
+    };
+}
+
+export function createDbHandler2<T1, T2, TReturn>(
+    handler: (userId: string, arg1: T1, arg2: T2) => TReturn | Promise<TReturn>
+): (event: IpcMainInvokeEvent, arg1: T1, arg2: T2) => Promise<TReturn> {
+    return async function(event: IpcMainInvokeEvent, arg1: T1, arg2: T2): Promise<TReturn> {
+        const userId = getUserIdFromSession();
+
+        if (!userId) {
+            throw new Error('User not authenticated');
+        }
+
+        try {
+            return await handler(userId, arg1, arg2);
+        } catch (error: unknown) {
+            if (error instanceof Error) {
+                console.error(`[DB] ${error.message}`);
+                throw error;
+            }
+            throw new Error('An unknown error occurred.');
+        }
+    };
+}
+
+export function createDbHandler3<T1, T2, T3, TReturn>(
+    handler: (userId: string, arg1: T1, arg2: T2, arg3: T3) => TReturn | Promise<TReturn>
+): (event: IpcMainInvokeEvent, arg1: T1, arg2: T2, arg3: T3) => Promise<TReturn> {
+    return async function(event: IpcMainInvokeEvent, arg1: T1, arg2: T2, arg3: T3): Promise<TReturn> {
+        const userId = getUserIdFromSession();
+
+        if (!userId) {
+            throw new Error('User not authenticated');
+        }
+
+        try {
+            return await handler(userId, arg1, arg2, arg3);
+        } catch (error: unknown) {
+            if (error instanceof Error) {
+                console.error(`[DB] ${error.message}`);
+                throw error;
+            }
+            throw new Error('An unknown error occurred.');
+        }
+    };
+}
+
+// ============================================================
+// AUTO HANDLERS - Automatically inject userId AND lang
+// Use these for new handlers - no need to pass lang from frontend
+// ============================================================
+
+/**
+ * Auto-handler with 0 parameters
+ * Automatically injects: userId, lang
+ *
+ * @example
+ * ipcMain.handle('db:user:get', createAutoHandler<UserProps>(
+ *     function(userId: string, lang: 'fr' | 'en') {
+ *         return User.getUser(userId, lang);
+ *     }
+ * ));
+ *
+ * // Frontend call (no params needed):
+ * const user = await window.electron.invoke('db:user:get');
+ */
+export function createAutoHandler<TReturn>(
+    handler: (userId: string, lang: 'fr' | 'en') => TReturn | Promise<TReturn>
+): (event: IpcMainInvokeEvent) => Promise<TReturn> {
+    return async function(event: IpcMainInvokeEvent): Promise<TReturn> {
+        const userId = getUserIdFromSession();
+        const lang = getLangFromSession();
+
+        if (!userId) {
+            throw new Error('User not authenticated');
+        }
+
+        try {
+            return await handler(userId, lang);
+        } catch (error: unknown) {
+            if (error instanceof Error) {
+                console.error(`[DB] ${error.message}`);
+                throw error;
+            }
+            throw new Error('An unknown error occurred.');
+        }
+    };
+}
+
+/**
+ * Auto-handler with 1 parameter
+ * Automatically injects: userId, lang
+ *
+ * @example
+ * ipcMain.handle('db:book:get', createAutoHandler1<string, BookProps>(
+ *     function(userId: string, bookId: string, lang: 'fr' | 'en') {
+ *         return Book.getBook(bookId, userId, lang);
+ *     }
+ * ));
+ *
+ * // Frontend call (only bookId needed):
+ * const book = await window.electron.invoke('db:book:get', bookId);
+ */
+export function createAutoHandler1<T1, TReturn>(
+    handler: (userId: string, arg1: T1, lang: 'fr' | 'en') => TReturn | Promise<TReturn>
+): (event: IpcMainInvokeEvent, arg1: T1) => Promise<TReturn> {
+    return async function(event: IpcMainInvokeEvent, arg1: T1): Promise<TReturn> {
+        const userId = getUserIdFromSession();
+        const lang = getLangFromSession();
+
+        if (!userId) {
+            throw new Error('User not authenticated');
+        }
+
+        try {
+            return await handler(userId, arg1, lang);
+        } catch (error: unknown) {
+            if (error instanceof Error) {
+                console.error(`[DB] ${error.message}`);
+                throw error;
+            }
+            throw new Error('An unknown error occurred.');
+        }
+    };
+}
+
+/**
+ * Auto-handler with 2 parameters
+ * Automatically injects: userId, lang
+ *
+ * @example
+ * ipcMain.handle('db:book:create', createAutoHandler1<CreateBookData, string>(
+ *     function(userId: string, data: CreateBookData, lang: 'fr' | 'en') {
+ *         return Book.addBook(null, userId, data.title, ..., lang);
+ *     }
+ * ));
+ *
+ * // Frontend call (only data needed):
+ * const bookId = await window.electron.invoke('db:book:create', bookData);
+ */
+export function createAutoHandler2<T1, T2, TReturn>(
+    handler: (userId: string, arg1: T1, arg2: T2, lang: 'fr' | 'en') => TReturn | Promise<TReturn>
+): (event: IpcMainInvokeEvent, arg1: T1, arg2: T2) => Promise<TReturn> {
+    return async function(event: IpcMainInvokeEvent, arg1: T1, arg2: T2): Promise<TReturn> {
+        const userId = getUserIdFromSession();
+        const lang = getLangFromSession();
+
+        if (!userId) {
+            throw new Error('User not authenticated');
+        }
+
+        try {
+            return await handler(userId, arg1, arg2, lang);
+        } catch (error: unknown) {
+            if (error instanceof Error) {
+                console.error(`[DB] ${error.message}`);
+                throw error;
+            }
+            throw new Error('An unknown error occurred.');
+        }
+    };
+}
+
+/**
+ * Auto-handler with 3 parameters
+ * Automatically injects: userId, lang
+ *
+ * @example
+ * ipcMain.handle('db:book:cover:update', createAutoHandler2<string, string, boolean>(
+ *     function(userId: string, bookId: string, coverImageName: string, lang: 'fr' | 'en') {
+ *         return Book.updateBookCover(userId, bookId, coverImageName, lang);
+ *     }
+ * ));
+ *
+ * // Frontend call (bookId and coverImageName needed):
+ * const success = await window.electron.invoke('db:book:cover:update', bookId, coverImageName);
+ */
+export function createAutoHandler3<T1, T2, T3, TReturn>(
+    handler: (userId: string, arg1: T1, arg2: T2, arg3: T3, lang: 'fr' | 'en') => TReturn | Promise<TReturn>
+): (event: IpcMainInvokeEvent, arg1: T1, arg2: T2, arg3: T3) => Promise<TReturn> {
+    return async function(event: IpcMainInvokeEvent, arg1: T1, arg2: T2, arg3: T3): Promise<TReturn> {
+        const userId = getUserIdFromSession();
+        const lang = getLangFromSession();
+
+        if (!userId) {
+            throw new Error('User not authenticated');
+        }
+
+        try {
+            return await handler(userId, arg1, arg2, arg3, lang);
+        } catch (error: unknown) {
+            if (error instanceof Error) {
+                console.error(`[DB] ${error.message}`);
+                throw error;
+            }
+            throw new Error('An unknown error occurred.');
+        }
+    };
+}
+
+export function createUniqueId(): string {
+    return crypto.randomUUID();
+}
+
+export function getCurrentDate(): string {
+    return new Date().toISOString();
+}
diff --git a/electron/database/System.ts b/electron/database/System.ts
new file mode 100644
index 0000000..b5bb0bb
--- /dev/null
+++ b/electron/database/System.ts
@@ -0,0 +1,66 @@
+import { getDatabaseService } from './database.service.js';
+import { encryptDataWithUserKey, decryptDataWithUserKey, hashElement } from './encryption.js';
+import type { Database } from 'node-sqlite3-wasm';
+import crypto from 'crypto';
+
+export default class System {
+    public static getDb(): Database {
+        const db: Database | null = getDatabaseService().getDb();
+        if (!db) {
+            throw new Error('Database not initialized');
+        }
+        return db;
+    }
+    
+    public static encryptDataWithUserKey(data: string, userKey: string): string {
+        return encryptDataWithUserKey(data, userKey);
+    }
+    
+    public static decryptDataWithUserKey(encryptedData: string, userKey: string): string {
+        return decryptDataWithUserKey(encryptedData, userKey);
+    }
+    
+    public static createUniqueId(): string {
+        return crypto.randomUUID();
+    }
+    
+    static htmlToText(htmlNode: string): string {
+        let text: string = htmlNode
+            .replace(/<\/?p[^>]*>/gi, '\n')
+            .replace(/<br\s*\/?>/gi, '\n')
+            .replace(/<\/?(span|h[1-6])[^>]*>/gi, '');
+        text = text
+            .replace(/&apos;/g, "'")
+            .replace(/&quot;/g, '"')
+            .replace(/&amp;/g, '&')
+            .replace(/&lt;/g, '<')
+            .replace(/&gt;/g, '>')
+            .replace(/&#39;/g, "'");
+        text = text.replace(/\r?\n\s*\n/g, '\n');
+        text = text.replace(/[ \t]+/g, ' ');
+        
+        return text.trim();
+    }
+    
+    public static getCurrentDate(): string {
+        return new Date().toISOString();
+    }
+    
+    static dateToMySqlDate(isoDateString: string): string {
+        const dateObject: Date = new Date(isoDateString);
+        
+        function padWithZeroes(value: number): string {
+            return value.toString().padStart(2, '0');
+        }
+        
+        const year: number = dateObject.getFullYear();
+        const month: string = padWithZeroes(dateObject.getMonth() + 1);
+        const day: string = padWithZeroes(dateObject.getDate());
+        
+        return `${year}-${month}-${day}`;
+    }
+    
+    public static hashElement(element: string): string {
+        return hashElement(element);
+    }
+}
\ No newline at end of file
diff --git a/electron/ipc/book.ipc.ts b/electron/ipc/book.ipc.ts
new file mode 100644
index 0000000..3be3ff2
--- /dev/null
+++ b/electron/ipc/book.ipc.ts
@@ -0,0 +1,507 @@
+import { ipcMain } from 'electron';
+import {
+    createDbHandler2,
+    // Auto-handlers: automatically inject userId AND lang
+    createAutoHandler,
+    createAutoHandler1
+} from '../database/LocalSystem.js';
+import Book from '../database/models/Book.js';
+import type { BookProps, GuideLine, GuideLineAI, Act, Issue, WorldProps } from '../database/models/Book.js';
+
+ipcMain.handle(
+    'db:book:getAll',
+    createAutoHandler<BookProps[]>(
+        async function(userId: string, lang: 'fr' | 'en') {
+            return await Book.getBooks(userId, lang);
+        }
+    )
+);
+
+ipcMain.handle(
+    'db:book:get',
+    createAutoHandler1<string, BookProps>(
+        async function(userId: string, bookId: string, lang: 'fr' | 'en') {
+            return await Book.getBook(bookId, userId, lang);
+        }
+    )
+);
+// Frontend call: await window.electron.invoke('db:book:get', bookId);
+
+// ============================================================
+// 3. POST /book/basic-information
+// ============================================================
+interface UpdateBookBasicData {
+    title: string;
+    subTitle: string;
+    summary: string;
+    publicationDate: string;
+    wordCount: number;
+    bookId: string;
+}
+
+ipcMain.handle(
+    'db:book:updateBasicInformation',
+    createAutoHandler1<UpdateBookBasicData, boolean>(
+        function(userId: string, data: UpdateBookBasicData, lang: 'fr' | 'en') {
+            return Book.updateBookBasicInformation(
+                userId,
+                data.title,
+                data.subTitle,
+                data.summary,
+                data.publicationDate,
+                data.wordCount,
+                data.bookId,
+                lang
+            );
+        }
+    )
+);
+// Frontend call: await window.electron.invoke('db:book:updateBasicInformation', data);
+
+// ============================================================
+// 4. GET /book/guide-line
+// ============================================================
+ipcMain.handle(
+    'db:book:guideline:get',
+    createAutoHandler1<string, GuideLine | null>(
+        async function(userId: string, bookId: string, lang: 'fr' | 'en') {
+            return await Book.getGuideLine(userId, bookId, lang);
+        }
+    )
+);
+
+// ============================================================
+// 5. POST /book/guide-line
+// ============================================================
+interface UpdateGuideLineData {
+    bookId: string;
+    tone: string | null;
+    atmosphere: string | null;
+    writingStyle: string | null;
+    themes: string | null;
+    symbolism: string | null;
+    motifs: string | null;
+    narrativeVoice: string | null;
+    pacing: string | null;
+    keyMessages: string | null;
+    intendedAudience: string | null;
+}
+
+ipcMain.handle(
+    'db:book:guideline:update',
+    createAutoHandler1<UpdateGuideLineData, boolean>(
+        async function(userId: string, data: UpdateGuideLineData, lang: 'fr' | 'en') {
+            return await Book.updateGuideLine(
+                userId,
+                data.bookId,
+                data.tone,
+                data.atmosphere,
+                data.writingStyle,
+                data.themes,
+                data.symbolism,
+                data.motifs,
+                data.narrativeVoice,
+                data.pacing,
+                data.keyMessages,
+                data.intendedAudience,
+                lang
+            );
+        }
+    )
+);
+
+// ============================================================
+// 6. GET /book/story
+// ============================================================
+interface StoryData {
+    acts: Act[];
+    issues: Issue[];
+}
+
+ipcMain.handle(
+    'db:book:story:get',
+    createDbHandler2<string, 'fr' | 'en', StoryData>(
+        async function(userId: string, bookId: string, lang: 'fr' | 'en') {
+            const acts = await Book.getActsData(userId, bookId, lang);
+            const issues = await Book.getIssuesFromBook(userId, bookId, lang);
+            return {
+                acts,
+                issues
+            };
+        }
+    )
+);
+
+// ============================================================
+// 7. POST /book/story
+// TODO: Implement updateStory in Book.ts
+// ============================================================
+// interface StoryUpdateData {
+//     bookId: string;
+//     acts: Act[];
+//     mainChapters: ChapterProps[];
+// }
+//
+// ipcMain.handle(
+//     'db:book:story:update',
+//     createDbHandler2<StoryUpdateData, 'fr' | 'en', boolean>(
+//         function(userId: string, data: StoryUpdateData, lang: 'fr' | 'en') {
+//             return Book.updateStory(userId, data.bookId, data.acts, data.mainChapters, lang);
+//         }
+//     )
+// );
+
+// ============================================================
+// 8. POST /book/add
+// ============================================================
+interface CreateBookData {
+    title: string;
+    subTitle: string | null;
+    summary: string | null;
+    type: string;
+    serieId: number | null;
+    desiredReleaseDate: string | null;
+    desiredWordCount: number | null;
+}
+
+ipcMain.handle(
+    'db:book:create',
+    createDbHandler2<CreateBookData, 'fr' | 'en', string>(
+        function(userId: string, data: CreateBookData, lang: 'fr' | 'en') {
+            return Book.addBook(
+                null,
+                userId,
+                data.title,
+                data.subTitle || '',
+                data.summary || '',
+                data.type,
+                data.serieId || 0,
+                data.desiredReleaseDate || '',
+                data.desiredWordCount || 0,
+                lang
+            );
+        }
+    )
+);
+
+// ============================================================
+// 9. POST /book/cover
+// ============================================================
+// TODO: Implement updateBookCover in Book.ts
+// ipcMain.handle(
+//     'db:book:cover:update',
+//     createDbHandler3<string, string, 'fr' | 'en', boolean>(
+//         function(userId: string, bookId: string, coverImageName: string, lang: 'fr' | 'en') {
+//             return Book.updateBookCover(userId, bookId, coverImageName, lang);
+//         }
+//     )
+// );
+
+// ============================================================
+// 10. POST /book/incident/new
+// ============================================================
+interface AddIncidentData {
+    bookId: string;
+    name: string;
+}
+
+ipcMain.handle(
+    'db:book:incident:add',
+    createDbHandler2<AddIncidentData, 'fr' | 'en', string>(
+        function(userId: string, data: AddIncidentData, lang: 'fr' | 'en') {
+            return Book.addNewIncident(userId, data.bookId, data.name, lang);
+        }
+    )
+);
+
+// ============================================================
+// 11. DELETE /book/incident/remove
+// ============================================================
+interface RemoveIncidentData {
+    bookId: string;
+    incidentId: string;
+}
+
+ipcMain.handle(
+    'db:book:incident:remove',
+    createDbHandler2<RemoveIncidentData, 'fr' | 'en', boolean>(
+        function(userId: string, data: RemoveIncidentData, lang: 'fr' | 'en') {
+            return Book.removeIncident(userId, data.bookId, data.incidentId, lang);
+        }
+    )
+);
+
+// ============================================================
+// 12. POST /book/plot/new
+// ============================================================
+interface AddPlotPointData {
+    bookId: string;
+    name: string;
+    incidentId: string;
+}
+
+ipcMain.handle(
+    'db:book:plot:add',
+    createDbHandler2<AddPlotPointData, 'fr' | 'en', string>(
+        function(userId: string, data: AddPlotPointData, lang: 'fr' | 'en') {
+            return Book.addNewPlotPoint(
+                userId,
+                data.bookId,
+                data.incidentId,
+                data.name,
+                lang
+            );
+        }
+    )
+);
+
+// ============================================================
+// 13. DELETE /book/plot/remove
+// ============================================================
+ipcMain.handle(
+    'db:book:plot:remove',
+    createDbHandler2<string, 'fr' | 'en', boolean>(
+        function(userId: string, plotPointId: string, lang: 'fr' | 'en') {
+            return Book.removePlotPoint(userId, plotPointId, lang);
+        }
+    )
+);
+
+// ============================================================
+// 14. POST /book/issue/add
+// ============================================================
+interface AddIssueData {
+    bookId: string;
+    name: string;
+}
+
+ipcMain.handle(
+    'db:book:issue:add',
+    createDbHandler2<AddIssueData, 'fr' | 'en', string>(
+        function(userId: string, data: AddIssueData, lang: 'fr' | 'en') {
+            return Book.addNewIssue(userId, data.bookId, data.name, lang);
+        }
+    )
+);
+
+// ============================================================
+// 15. DELETE /book/issue/remove
+// ============================================================
+ipcMain.handle(
+    'db:book:issue:remove',
+    createDbHandler2<string, 'fr' | 'en', boolean>(
+        function(userId: string, issueId: string, lang: 'fr' | 'en') {
+            return Book.removeIssue(userId, issueId, lang);
+        }
+    )
+);
+
+// ============================================================
+// 16. GET /book/worlds
+// ============================================================
+ipcMain.handle(
+    'db:book:worlds:get',
+    createDbHandler2<string, 'fr' | 'en', WorldProps[]>(
+        function(userId: string, bookId: string, lang: 'fr' | 'en') {
+            return Book.getWorlds(userId, bookId, lang);
+        }
+    )
+);
+
+// ============================================================
+// 17. POST /book/world/add
+// ============================================================
+interface AddWorldData {
+    bookId: string;
+    worldName: string;
+}
+
+ipcMain.handle(
+    'db:book:world:add',
+    createDbHandler2<AddWorldData, 'fr' | 'en', string>(
+        function(userId: string, data: AddWorldData, lang: 'fr' | 'en') {
+            return Book.addNewWorld(userId, data.bookId, data.worldName, lang);
+        }
+    )
+);
+
+// ============================================================
+// 18. POST /book/world/element/add
+// ============================================================
+interface AddWorldElementData {
+    worldId: string;
+    elementName: string;
+    elementType: number;
+}
+
+ipcMain.handle(
+    'db:book:world:element:add',
+    createDbHandler2<AddWorldElementData, 'fr' | 'en', string>(
+        function(userId: string, data: AddWorldElementData, lang: 'fr' | 'en') {
+            return Book.addNewElementToWorld(
+                userId,
+                data.worldId,
+                data.elementName,
+                data.elementType.toString(),
+                lang
+            );
+        }
+    )
+);
+
+// ============================================================
+// 19. DELETE /book/world/element/delete
+// ============================================================
+ipcMain.handle(
+    'db:book:world:element:remove',
+    createDbHandler2<string, 'fr' | 'en', boolean>(
+        function(userId: string, elementId: string, lang: 'fr' | 'en') {
+            return Book.removeElementFromWorld(userId, elementId, lang);
+        }
+    )
+);
+
+// ============================================================
+// 20. PUT /book/world/update
+// TODO: Implement updateWorld in Book.ts
+// ============================================================
+// ipcMain.handle(
+//     'db:book:world:update',
+//     createDbHandler2<WorldProps, 'fr' | 'en', boolean>(
+//         function(userId: string, world: WorldProps, lang: 'fr' | 'en') {
+//             return Book.updateWorld(userId, world, lang);
+//         }
+//     )
+// );
+
+// ============================================================
+// 21. DELETE /book/cover/delete
+// TODO: Implement deleteCoverPicture in Book.ts
+// ============================================================
+// ipcMain.handle(
+//     'db:book:cover:delete',
+//     createDbHandler2<string, 'fr' | 'en', boolean>(
+//         function(userId: string, bookId: string, lang: 'fr' | 'en') {
+//             return Book.deleteCoverPicture(userId, bookId, lang);
+//         }
+//     )
+// );
+
+// ============================================================
+// 22. DELETE /book/delete
+// ============================================================
+ipcMain.handle(
+    'db:book:delete',
+    createDbHandler2<string, 'fr' | 'en', boolean>(
+        function(userId: string, bookId: string, lang: 'fr' | 'en') {
+            return Book.removeBook(userId, bookId, lang);
+        }
+    )
+);
+
+// ============================================================
+// 23. GET /book/ai/guideline
+// ============================================================
+ipcMain.handle(
+    'db:book:guideline:ai:get',
+    createDbHandler2<string, 'fr' | 'en', GuideLineAI>(
+        function(userId: string, bookId: string, lang: 'fr' | 'en') {
+            return Book.getGuideLineAI(bookId, userId, lang);
+        }
+    )
+);
+
+// ============================================================
+// 24. POST /book/ai/guideline (set)
+// ============================================================
+interface SetAIGuideLineData {
+    bookId: string;
+    narrativeType: number;
+    dialogueType: number;
+    globalResume: string;
+    atmosphere: string;
+    verbeTense: number;
+    langue: number;
+    themes: string;
+}
+
+ipcMain.handle(
+    'db:book:guideline:ai:set',
+    createDbHandler2<SetAIGuideLineData, 'fr' | 'en', boolean>(
+        function(userId: string, data: SetAIGuideLineData, lang: 'fr' | 'en') {
+            return Book.setAIGuideLine(
+                data.bookId,
+                userId,
+                data.narrativeType,
+                data.dialogueType,
+                data.globalResume,
+                data.atmosphere,
+                data.verbeTense,
+                data.langue,
+                data.themes,
+                lang
+            );
+        }
+    )
+);
+
+// ============================================================
+// 25. GET /book/transform/epub
+// ============================================================
+// TODO: Implement transformToEpub in Book.ts
+// ipcMain.handle(
+//     'db:book:export:epub',
+//     createDbHandler2<string, 'fr' | 'en', ExportData>(
+//         function(userId: string, bookId: string, lang: 'fr' | 'en') {
+//             return Book.transformToEpub(userId, bookId, lang);
+//         }
+//     )
+// );
+
+// ============================================================
+// 26. GET /book/transform/pdf
+// ============================================================
+// TODO: Implement transformToPDF in Book.ts
+// ipcMain.handle(
+//     'db:book:export:pdf',
+//     createDbHandler2<string, 'fr' | 'en', ExportData>(
+//         function(userId: string, bookId: string, lang: 'fr' | 'en') {
+//             return Book.transformToPDF(userId, bookId, lang);
+//         }
+//     )
+// );
+
+// ============================================================
+// 27. GET /book/transform/docx
+// ============================================================
+// TODO: Implement transformToDOCX in Book.ts
+// ipcMain.handle(
+//     'db:book:export:docx',
+//     createDbHandler2<string, 'fr' | 'en', ExportData>(
+//         function(userId: string, bookId: string, lang: 'fr' | 'en') {
+//             return Book.transformToDOCX(userId, bookId, lang);
+//         }
+//     )
+// );
+
+// ============================================================
+// 28. GET /book/tags
+// TODO: Implement getTagsFromBook in Book.ts
+// ============================================================
+// interface BookTags {
+//     characters: Tag[];
+//     locations: Tag[];
+//     objects: Tag[];
+//     worldElements: Tag[];
+// }
+//
+// ipcMain.handle(
+//     'db:book:tags:get',
+//     createDbHandler2<string, 'fr' | 'en', BookTags>(
+//         function(userId: string, bookId: string, lang: 'fr' | 'en') {
+//             return Book.getTagsFromBook(userId, bookId, lang);
+//         }
+//     )
+// );
+
+console.log('[IPC] Book handlers registered');
diff --git a/electron/main.ts b/electron/main.ts
index 38771bc..eacf8fb 100644
--- a/electron/main.ts
+++ b/electron/main.ts
@@ -129,8 +129,19 @@ ipcMain.handle('remove-token', () => {
   return true;
 });
 
-ipcMain.on('login-success', (_event, token: string) => {
+// IPC Handlers pour la gestion de la langue
+ipcMain.handle('get-lang', () => {
+  return store.get('userLang', 'fr');
+});
+
+ipcMain.handle('set-lang', (_event, lang: 'fr' | 'en') => {
+  store.set('userLang', lang);
+  return true;
+});
+
+ipcMain.on('login-success', (_event, token: string, userId: string) => {
   store.set('authToken', token);
+  store.set('userId', userId);
 
   if (loginWindow) {
     loginWindow.close();
@@ -141,6 +152,8 @@ ipcMain.on('login-success', (_event, token: string) => {
 
 ipcMain.on('logout', () => {
   store.delete('authToken');
+  store.delete('userId');
+  store.delete('userLang');
 
   // Close database connection
   const db = getDatabaseService();
diff --git a/electron/preload.ts b/electron/preload.ts
index 50017b4..d39cafa 100644
--- a/electron/preload.ts
+++ b/electron/preload.ts
@@ -9,8 +9,12 @@ contextBridge.exposeInMainWorld('electron', {
   setToken: (token: string) => ipcRenderer.invoke('set-token', token),
   removeToken: () => ipcRenderer.invoke('remove-token'),
 
+  // Language management
+  getLang: () => ipcRenderer.invoke('get-lang'),
+  setLang: (lang: 'fr' | 'en') => ipcRenderer.invoke('set-lang', lang),
+
   // Auth events
-  loginSuccess: (token: string) => ipcRenderer.send('login-success', token),
+  loginSuccess: (token: string, userId: string) => ipcRenderer.send('login-success', token, userId),
   logout: () => ipcRenderer.send('logout'),
 
   // Database operations