diff --git a/apps/backend/src/app.module.ts b/apps/backend/src/app.module.ts
index d2cb4ed..9f66edf 100644
--- a/apps/backend/src/app.module.ts
+++ b/apps/backend/src/app.module.ts
@@ -1,3 +1,4 @@
+import { TradeAssistantModule } from './application/trade-assistant/trade-assistant.module';
 import { Module } from '@nestjs/common';
 import { ConfigModule, ConfigService } from '@nestjs/config';
 import { TypeOrmModule } from '@nestjs/typeorm';
@@ -76,6 +77,9 @@ import { CustomThrottlerGuard } from './application/guards/throttle.guard';
         SMTP_FROM: Joi.string().email().default('noreply@xpeditis.com'),
         SMTP_SECURE: Joi.boolean().default(false),
         // Stripe Configuration (optional for development)
+        OPENAI_API_KEY: Joi.string().allow('').optional(),
+        OPENAI_MODEL: Joi.string().default('gpt-4.1-mini'),
+        OPENAI_EMBEDDING_MODEL: Joi.string().default('text-embedding-3-small'),
         STRIPE_SECRET_KEY: Joi.string().optional(),
         STRIPE_WEBHOOK_SECRET: Joi.string().optional(),
         STRIPE_SILVER_MONTHLY_PRICE_ID: Joi.string().optional(),
@@ -188,6 +192,7 @@ import { CustomThrottlerGuard } from './application/guards/throttle.guard';
     AdminModule,
     BlogModule,
     SubscriptionsModule,
+    TradeAssistantModule,
     ApiKeysModule,
     LogsModule,
   ],
diff --git a/apps/backend/src/application/trade-assistant/trade-assistant.controller.ts b/apps/backend/src/application/trade-assistant/trade-assistant.controller.ts
new file mode 100644
index 0000000..025e1d1
--- /dev/null
+++ b/apps/backend/src/application/trade-assistant/trade-assistant.controller.ts
@@ -0,0 +1,97 @@
+import {
+  Body,
+  Controller,
+  Delete,
+  Get,
+  HttpCode,
+  Param,
+  ParseUUIDPipe,
+  Patch,
+  Post,
+} from '@nestjs/common';
+import { Transform } from 'class-transformer';
+import { IsIn, IsOptional, IsString, IsUUID, Length } from 'class-validator';
+import { ApiBearerAuth, ApiTags } from '@nestjs/swagger';
+import { CurrentUser, UserPayload } from '../decorators/current-user.decorator';
+import { TradeActor, TradeAssistantService } from './trade-assistant.service';
+
+const trim = ({ value }: { value: unknown }) => (typeof value === 'string' ? value.trim() : value);
+
+export class AskTradeAssistantDto {
+  @Transform(trim)
+  @IsString()
+  @Length(1, 2000)
+  question: string;
+
+  @IsIn(['fr', 'en'])
+  language: string = 'fr';
+
+  /** Absent : la question ouvre une nouvelle conversation. */
+  @IsOptional()
+  @IsUUID()
+  conversationId?: string;
+}
+
+export class RenameConversationDto {
+  @Transform(trim)
+  @IsString()
+  @Length(1, 60)
+  title: string;
+}
+
+// The global JWT guard validates the active account. No paid-feature gate:
+// Bronze users and all dashboard roles also have access.
+@ApiTags('Trade assistant')
+@ApiBearerAuth()
+@Controller('trade-assistant')
+export class TradeAssistantController {
+  constructor(private readonly service: TradeAssistantService) {}
+
+  @Get('quota')
+  status(@CurrentUser() user: UserPayload) {
+    return this.service.status(actorOf(user));
+  }
+
+  @Get('conversations')
+  list(@CurrentUser() user: UserPayload) {
+    return this.service.list(user.id);
+  }
+
+  @Get('conversations/:id')
+  messages(@CurrentUser() user: UserPayload, @Param('id', ParseUUIDPipe) id: string) {
+    return this.service.messages(user.id, id);
+  }
+
+  @Patch('conversations/:id')
+  @HttpCode(204)
+  async rename(
+    @CurrentUser() user: UserPayload,
+    @Param('id', ParseUUIDPipe) id: string,
+    @Body() dto: RenameConversationDto
+  ) {
+    await this.service.rename(user.id, id, dto.title);
+  }
+
+  @Delete('conversations/:id')
+  @HttpCode(204)
+  async remove(@CurrentUser() user: UserPayload, @Param('id', ParseUUIDPipe) id: string) {
+    await this.service.remove(user.id, id);
+  }
+
+  @Post('questions')
+  @HttpCode(200)
+  ask(@CurrentUser() user: UserPayload, @Body() dto: AskTradeAssistantDto) {
+    return this.service.ask(actorOf(user), dto.question, dto.language, dto.conversationId);
+  }
+}
+
+/**
+ * L'offre effective depend du role : il vient de la session validee, jamais du
+ * corps de requete.
+ */
+const actorOf = (user: UserPayload): TradeActor => ({
+  id: user.id,
+  organizationId: user.organizationId,
+  role: user.role,
+  email: user.email,
+});
diff --git a/apps/backend/src/application/trade-assistant/trade-assistant.module.ts b/apps/backend/src/application/trade-assistant/trade-assistant.module.ts
new file mode 100644
index 0000000..827929b
--- /dev/null
+++ b/apps/backend/src/application/trade-assistant/trade-assistant.module.ts
@@ -0,0 +1,31 @@
+import { Module } from '@nestjs/common';
+import { ConfigModule } from '@nestjs/config';
+import {
+  TRADE_AI,
+  TRADE_CONVERSATIONS,
+  TRADE_EMBEDDINGS,
+  TRADE_QUOTA,
+  TRADE_RETRIEVAL,
+} from '@domain/ports/out/trade-assistant.port';
+import { OpenAiEmbeddingAdapter } from '@infrastructure/ai/openai-embedding.adapter';
+import { OpenAiTradeAdapter } from '@infrastructure/ai/openai-trade.adapter';
+import { WikiRetriever } from '@infrastructure/ai/wiki-retriever';
+import { TypeOrmTradeConversationRepository } from '@infrastructure/persistence/typeorm/repositories/typeorm-trade-conversation.repository';
+import { TypeOrmTradeQuotaRepository } from '@infrastructure/persistence/typeorm/repositories/typeorm-trade-quota.repository';
+import { SubscriptionsModule } from '../subscriptions/subscriptions.module';
+import { TradeAssistantController } from './trade-assistant.controller';
+import { TradeAssistantService } from './trade-assistant.service';
+
+@Module({
+  // repond mais n'agit jamais.
+  controllers: [TradeAssistantController],
+  providers: [
+    TradeAssistantService,
+    { provide: TRADE_AI, useClass: OpenAiTradeAdapter },
+    { provide: TRADE_EMBEDDINGS, useClass: OpenAiEmbeddingAdapter },
+    { provide: TRADE_RETRIEVAL, useClass: WikiRetriever },
+    { provide: TRADE_QUOTA, useClass: TypeOrmTradeQuotaRepository },
+    { provide: TRADE_CONVERSATIONS, useClass: TypeOrmTradeConversationRepository },
+  ],
+})
+export class TradeAssistantModule {}
diff --git a/apps/backend/src/application/trade-assistant/trade-assistant.service.spec.ts b/apps/backend/src/application/trade-assistant/trade-assistant.service.spec.ts
new file mode 100644
index 0000000..72fd7ef
--- /dev/null
+++ b/apps/backend/src/application/trade-assistant/trade-assistant.service.spec.ts
@@ -0,0 +1,364 @@
+import { NotFoundException, ServiceUnavailableException } from '@nestjs/common';
+import { TradeAssistantService, truncateTitle } from './trade-assistant.service';
+import { SubscriptionRepository } from '@domain/ports/out/subscription.repository';
+import {
+  TradeAiPort,
+  TradeConversationRepository,
+  TradeMessage,
+  TradePassage,
+  TradeQuotaPort,
+  TradeRetrievalPort,
+} from '@domain/ports/out/trade-assistant.port';
+import { Subscription } from '@domain/entities/subscription.entity';
+import { SubscriptionPlan, SubscriptionPlanType } from '@domain/value-objects/subscription-plan.vo';
+import { AskTradeAssistantDto } from './trade-assistant.controller';
+import { plainToInstance } from 'class-transformer';
+import { validate } from 'class-validator';
+
+const answer = { text: 'Réponse', inputTokens: 100, outputTokens: 50 };
+
+/** Compte courant : role sans privilege, offre portee par l'organisation. */
+const actor = { id: 'user', organizationId: 'org', role: 'MANAGER' };
+const admin = { ...actor, role: 'ADMIN' };
+
+const passage = (topic: string, href: string): TradePassage => ({
+  id: `fr:${topic}:0`,
+  title: topic,
+  section: 'Section',
+  href,
+  text: 'Extrait du wiki.',
+  score: 0.8,
+});
+
+const conversation = {
+  id: 'c1',
+  title: 'Question',
+  createdAt: '2026-09-05T10:00:00.000Z',
+  updatedAt: '2026-09-05T10:00:00.000Z',
+  messageCount: 0,
+};
+
+const message = (role: 'user' | 'assistant', content: string): TradeMessage => ({
+  id: `${role}-1`,
+  role,
+  content,
+  sources: [],
+  actions: [],
+  createdAt: '2026-09-05T10:00:00.000Z',
+});
+
+describe('TradeAssistantService', () => {
+  let service: TradeAssistantService;
+  let subscriptions: jest.Mocked<SubscriptionRepository>;
+  let quota: jest.Mocked<TradeQuotaPort>;
+  let ai: jest.Mocked<TradeAiPort>;
+  let retrieval: jest.Mocked<TradeRetrievalPort>;
+  let conversations: jest.Mocked<TradeConversationRepository>;
+
+  beforeEach(() => {
+    subscriptions = {
+      findByOrganizationId: jest.fn().mockResolvedValue(null),
+      save: jest.fn(),
+      findById: jest.fn(),
+      findByStripeSubscriptionId: jest.fn(),
+      findByStripeCustomerId: jest.fn(),
+      findAll: jest.fn(),
+      delete: jest.fn(),
+    };
+    quota = {
+      get: jest
+        .fn()
+        .mockResolvedValue({ day: '2026-09-05', resetsAt: '2026-09-05T22:00:00.000Z', used: 0 }),
+      reserve: jest.fn().mockResolvedValue(true),
+      release: jest.fn().mockResolvedValue(undefined),
+      recordTokens: jest.fn().mockResolvedValue(undefined),
+    };
+    ai = {
+      isAvailable: jest.fn().mockReturnValue(true),
+      answer: jest.fn().mockResolvedValue(answer),
+    };
+    retrieval = { search: jest.fn().mockResolvedValue([]) };
+    conversations = {
+      list: jest.fn().mockResolvedValue([conversation]),
+      create: jest.fn().mockResolvedValue(conversation),
+      find: jest.fn().mockResolvedValue(conversation),
+      messages: jest.fn().mockResolvedValue([]),
+      addMessage: jest
+        .fn()
+        .mockImplementation((_id, role: 'user' | 'assistant', content: string) =>
+          Promise.resolve(message(role, content))
+        ),
+      rename: jest.fn().mockResolvedValue(undefined),
+      remove: jest.fn().mockResolvedValue(undefined),
+    };
+    service = new TradeAssistantService(subscriptions, quota, ai, retrieval, conversations);
+  });
+
+  /* ---------------------------------------------------------------------- */
+  /* Quota                                                                   */
+  /* ---------------------------------------------------------------------- */
+
+  const onPlan = (plan: SubscriptionPlanType) =>
+    subscriptions.findByOrganizationId.mockResolvedValue(
+      Subscription.create({
+        id: 's',
+        organizationId: 'org',
+        plan: SubscriptionPlan.fromString(plan),
+      })
+    );
+
+  it.each<[SubscriptionPlanType, number]>([
+    ['BRONZE', 3],
+    ['SILVER', 10],
+    ['GOLD', 15],
+    ['PLATINIUM', -1],
+  ])('enforces %s quota per user', async (plan, limit) => {
+    onPlan(plan);
+    const result = await service.ask(actor, 'Question', 'fr');
+    expect(result.quota.limit).toBe(limit);
+    expect(quota.reserve).toHaveBeenCalledWith('user', '2026-09-05', limit);
+    expect(subscriptions.findByOrganizationId).toHaveBeenCalledWith('org');
+    expect(quota.recordTokens).toHaveBeenCalledWith('user', '2026-09-05', answer);
+  });
+
+  it('never blocks Platinium, however many questions were already asked', async () => {
+    onPlan('PLATINIUM');
+    quota.get.mockResolvedValue({ day: '2026-09-05', resetsAt: '', used: 4200 });
+
+    const status = await service.status(actor);
+    expect(status.unlimited).toBe(true);
+    expect(status.limit).toBe(-1);
+    // `remaining` ne vaut pas 0 : cela se lirait comme un quota epuise.
+    expect(status.remaining).toBe(-1);
+
+    const result = await service.ask(actor, 'Q', 'fr');
+    expect(result.mode).toBe('ai');
+    expect(ai.answer).toHaveBeenCalled();
+  });
+
+  it('still meters Platinium usage, for cost tracking', async () => {
+    onPlan('PLATINIUM');
+    await service.ask(actor, 'Q', 'fr');
+
+    expect(quota.reserve).toHaveBeenCalledWith('user', '2026-09-05', -1);
+    expect(quota.recordTokens).toHaveBeenCalledWith('user', '2026-09-05', answer);
+  });
+
+  it('gives an ADMIN the Platinium quota its own interface already shows', async () => {
+    // L'apercu d'abonnement affiche « Platinium » a tout compte ADMIN. Sans
+    // cette regle, l'assistant lisait l'abonnement de l'organisation — Bronze —
+    // et n'accordait que trois questions a un utilisateur a qui le produit
+    // annonçait partout l'offre illimitee.
+    onPlan('BRONZE');
+
+    const status = await service.status(admin);
+
+    expect(status.plan).toBe('PLATINIUM');
+    expect(status.unlimited).toBe(true);
+    expect((await service.ask(admin, 'Q', 'fr')).mode).toBe('ai');
+  });
+
+  it('keeps the organisation plan for every other role', async () => {
+    onPlan('BRONZE');
+    expect((await service.status({ ...actor, role: 'MANAGER' })).plan).toBe('BRONZE');
+    expect((await service.status({ ...actor, role: 'USER' })).plan).toBe('BRONZE');
+    expect((await service.status({ ...actor, role: undefined })).plan).toBe('BRONZE');
+  });
+
+  it('promotes an ADMIN even when the organisation subscription is inactive', async () => {
+    subscriptions.findByOrganizationId.mockResolvedValue({
+      isActive: () => false,
+      plan: SubscriptionPlan.fromString('SILVER'),
+    } as never);
+
+    expect((await service.status(actor)).plan).toBe('BRONZE');
+    expect((await service.status(admin)).plan).toBe('PLATINIUM');
+  });
+
+  it('falls back to the strictest plan when the stored plan is unknown', async () => {
+    // Une offre inconnue donnait `undefined`, puis « NaN/undefined » a l'ecran.
+    subscriptions.findByOrganizationId.mockResolvedValue({
+      isActive: () => true,
+      plan: { value: 'LEGACY_TIER' },
+    } as never);
+
+    const status = await service.status(actor);
+    expect(status.limit).toBe(3);
+    expect(status.remaining).toBe(3);
+    expect(status.unlimited).toBe(false);
+  });
+
+  it('defaults an unsubscribed dashboard account to Bronze', async () => {
+    expect((await service.status(actor)).limit).toBe(3);
+  });
+
+  it('does not call OpenAI when quota is exhausted', async () => {
+    quota.get.mockResolvedValue({ day: '2026-09-05', resetsAt: '', used: 3 });
+    expect((await service.ask(actor, 'Q', 'fr')).mode).toBe('guided');
+    expect(quota.reserve).not.toHaveBeenCalled();
+    expect(ai.answer).not.toHaveBeenCalled();
+  });
+
+  it('handles a concurrent request taking the last slot', async () => {
+    quota.reserve.mockResolvedValue(false);
+    expect((await service.ask(actor, 'Q', 'fr')).mode).toBe('guided');
+    expect(ai.answer).not.toHaveBeenCalled();
+  });
+
+  it('does not consume quota without an API key', async () => {
+    ai.isAvailable.mockReturnValue(false);
+    expect((await service.ask(actor, 'Q', 'fr')).mode).toBe('unavailable');
+    expect(quota.reserve).not.toHaveBeenCalled();
+  });
+
+  it('refunds provider failures on the original day', async () => {
+    ai.answer.mockRejectedValue(new Error('timeout'));
+    await expect(service.ask(actor, 'Q', 'fr')).rejects.toThrow(ServiceUnavailableException);
+    expect(quota.release).toHaveBeenCalledWith('user', '2026-09-05');
+    expect(quota.recordTokens).not.toHaveBeenCalled();
+  });
+
+  it('never refunds a successful answer on accounting failure', async () => {
+    quota.recordTokens.mockRejectedValue(new Error('database unavailable'));
+    expect((await service.ask(actor, 'Q', 'fr')).mode).toBe('ai');
+    expect(quota.release).not.toHaveBeenCalled();
+  });
+
+  it('returns a fresh quota when the answer crosses midnight', async () => {
+    quota.get
+      .mockResolvedValueOnce({ day: '2026-09-05', resetsAt: '', used: 0 })
+      .mockResolvedValueOnce({ day: '2026-09-06', resetsAt: '', used: 0 });
+    expect((await service.ask(actor, 'Q', 'fr')).quota.day).toBe('2026-09-06');
+    expect(quota.reserve).toHaveBeenCalledWith('user', '2026-09-05', 3);
+  });
+
+  /* ---------------------------------------------------------------------- */
+  /* Conversations                                                           */
+  /* ---------------------------------------------------------------------- */
+
+  it('opens a conversation titled after the first question', async () => {
+    const result = await service.ask(actor, '  Quels documents pour un LCL ?  ', 'fr');
+
+    expect(conversations.create).toHaveBeenCalledWith('user', 'Quels documents pour un LCL ?');
+    expect(result.mode).toBe('ai');
+    expect(result.conversationId).toBe('c1');
+    expect(conversations.addMessage.mock.calls.map(call => call[1])).toEqual(['user', 'assistant']);
+  });
+
+  it('replays the existing turns when continuing a conversation', async () => {
+    conversations.messages.mockResolvedValue([
+      message('user', 'Première question'),
+      message('assistant', 'Première réponse'),
+    ]);
+
+    await service.ask(actor, 'Et pour le FCL ?', 'fr', 'c1');
+
+    expect(conversations.create).not.toHaveBeenCalled();
+    expect(ai.answer).toHaveBeenCalledWith(
+      expect.objectContaining({
+        question: 'Et pour le FCL ?',
+        history: [
+          { role: 'user', content: 'Première question' },
+          { role: 'assistant', content: 'Première réponse' },
+        ],
+      })
+    );
+  });
+
+  it('rejects a conversation owned by someone else before spending a question', async () => {
+    conversations.find.mockResolvedValue(null);
+
+    await expect(service.ask(actor, 'Q', 'fr', 'other')).rejects.toThrow(NotFoundException);
+    expect(quota.reserve).not.toHaveBeenCalled();
+    expect(ai.answer).not.toHaveBeenCalled();
+  });
+
+  it('does not leave an empty conversation behind when the provider fails', async () => {
+    ai.answer.mockRejectedValue(new Error('timeout'));
+
+    await expect(service.ask(actor, 'Q', 'fr')).rejects.toThrow(ServiceUnavailableException);
+    expect(conversations.remove).toHaveBeenCalledWith('user', 'c1');
+  });
+
+  it('keeps an existing conversation when the provider fails', async () => {
+    ai.answer.mockRejectedValue(new Error('timeout'));
+
+    await expect(service.ask(actor, 'Q', 'fr', 'c1')).rejects.toThrow(ServiceUnavailableException);
+    expect(conversations.remove).not.toHaveBeenCalled();
+  });
+
+  it.each(['messages', 'rename', 'remove'] as const)('guards %s by owner', async method => {
+    conversations.find.mockResolvedValue(null);
+    const call =
+      method === 'rename'
+        ? service.rename('user', 'c1', 'Titre')
+        : method === 'remove'
+          ? service.remove('user', 'c1')
+          : service.messages('user', 'c1');
+
+    await expect(call).rejects.toThrow(NotFoundException);
+  });
+
+  /* ---------------------------------------------------------------------- */
+  /* Recherche documentaire                                                  */
+  /* ---------------------------------------------------------------------- */
+
+  it('passes the retrieved passages to the model and cites each page once', async () => {
+    retrieval.search.mockResolvedValue([
+      passage('Douanes', '/dashboard/wiki/douanes'),
+      passage('Douanes', '/dashboard/wiki/douanes'),
+      passage('Incoterms', '/dashboard/wiki/incoterms'),
+    ]);
+
+    const result = await service.ask(actor, 'Code SH ?', 'fr');
+
+    expect(retrieval.search).toHaveBeenCalledWith('Code SH ?', 'fr');
+    expect(ai.answer).toHaveBeenCalledWith(
+      expect.objectContaining({ passages: expect.arrayContaining([expect.any(Object)]) })
+    );
+    expect(result.sources).toEqual([
+      { title: 'Douanes', section: 'Section', href: '/dashboard/wiki/douanes' },
+      { title: 'Incoterms', section: 'Section', href: '/dashboard/wiki/incoterms' },
+    ]);
+  });
+
+  it('still answers when the knowledge search fails', async () => {
+    retrieval.search.mockRejectedValue(new Error('redis down'));
+
+    const result = await service.ask(actor, 'Q', 'fr');
+
+    expect(result.mode).toBe('ai');
+    expect(ai.answer).toHaveBeenCalledWith(expect.objectContaining({ passages: [] }));
+  });
+});
+
+describe('truncateTitle', () => {
+  it('keeps a short question untouched', () => {
+    expect(truncateTitle('  LCL ou   FCL ?  ')).toBe('LCL ou FCL ?');
+  });
+
+  it('cuts long questions on a word boundary', () => {
+    const title = truncateTitle(`Quels documents ${'très '.repeat(20)}précisément ?`);
+    expect(title.length).toBeLessThanOrEqual(60);
+    expect(title).not.toMatch(/\s$/);
+    expect(title.endsWith('trè')).toBe(false);
+  });
+});
+
+describe('AskTradeAssistantDto', () => {
+  it.each(['   ', 'a'.repeat(2001), 42, null])('rejects invalid question %p', async question => {
+    const dto = plainToInstance(AskTradeAssistantDto, { question });
+    expect((await validate(dto)).length).toBeGreaterThan(0);
+  });
+
+  it('accepts a trimmed question and default language', async () => {
+    const dto = plainToInstance(AskTradeAssistantDto, { question: '  LCL ?  ' });
+    expect(await validate(dto)).toEqual([]);
+    expect(dto.question).toBe('LCL ?');
+  });
+
+  it('rejects a conversation id that is not a uuid', async () => {
+    const dto = plainToInstance(AskTradeAssistantDto, { question: 'Q', conversationId: 'nope' });
+    expect((await validate(dto)).length).toBeGreaterThan(0);
+  });
+});
diff --git a/apps/backend/src/application/trade-assistant/trade-assistant.service.ts b/apps/backend/src/application/trade-assistant/trade-assistant.service.ts
new file mode 100644
index 0000000..6550418
--- /dev/null
+++ b/apps/backend/src/application/trade-assistant/trade-assistant.service.ts
@@ -0,0 +1,239 @@
+import {
+  Inject,
+  Injectable,
+  Logger,
+  NotFoundException,
+  ServiceUnavailableException,
+} from '@nestjs/common';
+import {
+  SUBSCRIPTION_REPOSITORY,
+  SubscriptionRepository,
+} from '@domain/ports/out/subscription.repository';
+import {
+  TRADE_AI,
+  TRADE_CONVERSATIONS,
+  TRADE_QUOTA,
+  TRADE_RETRIEVAL,
+  TradeAiPort,
+  TradeConversationRepository,
+  TradeConversationSummary,
+  TradeMessage,
+  TradePassage,
+  TradeQuotaPort,
+  TradeRetrievalPort,
+  TradeSource,
+} from '@domain/ports/out/trade-assistant.port';
+import {
+  TRADE_SUPPORT_EMAIL,
+  isUnlimitedTradeQuota,
+  tradeDailyLimit,
+} from '@domain/services/trade-assistant-policy';
+import { effectivePlan } from '@domain/services/subscription-access';
+
+/**
+ * L'utilisateur qui interroge l'assistant.
+ *
+ * Le role en fait partie : sans lui, l'assistant appliquait le quota de
+ * l'abonnement brut a un administrateur a qui le reste du produit affiche
+ * l'offre Platinium.
+ */
+export interface TradeActor {
+  id: string;
+  organizationId: string;
+  role?: string;
+  /** Reporte dans le journal d'audit des capacites invoquees. */
+  email?: string;
+  /** Offre effective, resolue par `status()` et reinjectee pour les outils. */
+  plan?: string;
+}
+
+/** Un titre trop long deborde de la liste laterale sans rien apprendre. */
+const TITLE_MAX_LENGTH = 60;
+
+@Injectable()
+export class TradeAssistantService {
+  private readonly logger = new Logger(TradeAssistantService.name);
+
+  constructor(
+    @Inject(SUBSCRIPTION_REPOSITORY) private readonly subscriptions: SubscriptionRepository,
+    @Inject(TRADE_QUOTA) private readonly quota: TradeQuotaPort,
+    @Inject(TRADE_AI) private readonly ai: TradeAiPort,
+    @Inject(TRADE_RETRIEVAL) private readonly retrieval: TradeRetrievalPort,
+    @Inject(TRADE_CONVERSATIONS) private readonly conversations: TradeConversationRepository
+  ) {}
+
+  async status(actor: TradeActor) {
+    const subscription = await this.subscriptions.findByOrganizationId(actor.organizationId);
+    // Un abonnement inactif ne porte plus son offre ; le role, lui, peut la
+    // remplacer (voir `effectivePlan`).
+    const active = subscription?.isActive() ? subscription.plan : null;
+    const plan = effectivePlan(actor.role, active).value;
+    const usage = await this.quota.get(actor.id);
+    const limit = tradeDailyLimit(plan);
+    const unlimited = isUnlimitedTradeQuota(limit);
+    return {
+      ...usage,
+      plan,
+      limit,
+      unlimited,
+      // `-1` plutot que 0 : une offre illimitee n'a pas de reste a decompter,
+      // et 0 se lirait comme un quota epuise partout ou la valeur circule.
+      remaining: unlimited ? -1 : Math.max(0, limit - usage.used),
+      available: this.ai.isAvailable(),
+      supportEmail: TRADE_SUPPORT_EMAIL,
+    };
+  }
+
+  /* ------------------------------------------------------------------------ */
+  /* Conversations                                                             */
+  /* ------------------------------------------------------------------------ */
+
+  list(userId: string): Promise<TradeConversationSummary[]> {
+    return this.conversations.list(userId);
+  }
+
+  async messages(userId: string, conversationId: string): Promise<TradeMessage[]> {
+    await this.mine(userId, conversationId);
+    return this.conversations.messages(userId, conversationId);
+  }
+
+  async rename(userId: string, conversationId: string, title: string): Promise<void> {
+    await this.mine(userId, conversationId);
+    await this.conversations.rename(userId, conversationId, truncateTitle(title));
+  }
+
+  async remove(userId: string, conversationId: string): Promise<void> {
+    await this.mine(userId, conversationId);
+    await this.conversations.remove(userId, conversationId);
+  }
+
+  private async mine(userId: string, conversationId: string): Promise<TradeConversationSummary> {
+    const conversation = await this.conversations.find(userId, conversationId);
+    // Meme reponse qu'une conversation inexistante : appartenir a quelqu'un
+    // d'autre ne doit pas etre distinguable de ne pas exister.
+    if (!conversation) throw new NotFoundException('Conversation introuvable.');
+    return conversation;
+  }
+
+  /* ------------------------------------------------------------------------ */
+  /* Question                                                                  */
+  /* ------------------------------------------------------------------------ */
+
+  /**
+   * Pose une question dans une conversation, en la creant au besoin.
+   *
+   * Le quota est reserve avant l'appel au modele et rendu si celui-ci echoue :
+   * une panne du fournisseur ne consomme pas la question de l'utilisateur.
+   */
+  async ask(actor: TradeActor, question: string, language: string, conversationId?: string) {
+    const userId = actor.id;
+    const status = await this.status(actor);
+    if (!status.available) return { mode: 'unavailable' as const, quota: status };
+
+    // La conversation est verifiee avant la reservation : une conversation
+    // inexistante ne doit pas couter une question.
+    if (conversationId) await this.mine(userId, conversationId);
+
+    // Une offre illimitee ne teste pas de reste, mais reserve quand meme : le
+    // decompte reste la base du suivi de consommation et de cout.
+    const outOfQuota = !status.unlimited && status.remaining <= 0;
+    if (outOfQuota || !(await this.quota.reserve(userId, status.day, status.limit))) {
+      return { mode: 'guided' as const, quota: await this.status(actor) };
+    }
+
+    const conversation = conversationId
+      ? await this.mine(userId, conversationId)
+      : await this.conversations.create(userId, truncateTitle(question));
+
+    const history = conversationId
+      ? (await this.conversations.messages(userId, conversation.id)).map(message => ({
+          role: message.role,
+          content: message.content,
+        }))
+      : [];
+
+    const passages = await this.retrieve(question, language);
+
+    let answer;
+    try {
+      answer = await this.ai.answer({ question, language, history, passages });
+    } catch {
+      // Le remboursement vise le jour reserve, meme si la reponse a franchi minuit.
+      await this.quota.release(userId, status.day);
+      if (!conversationId) await this.conversations.remove(userId, conversation.id);
+      throw new ServiceUnavailableException(
+        'Assistant indisponible. Votre question n’a pas été décomptée. Contactez support@xpeditis.com.'
+      );
+    }
+
+    // Un echec de comptabilite ne doit pas rembourser une reponse deja facturee.
+    try {
+      await this.quota.recordTokens(userId, status.day, answer);
+    } catch {
+      this.logger.warn('Could not record assistant token usage');
+    }
+
+    const sources = toSources(passages);
+    const userMessage = await this.conversations.addMessage(conversation.id, 'user', question);
+    const assistantMessage = await this.conversations.addMessage(
+      conversation.id,
+      'assistant',
+      answer.text,
+      sources,
+      answer.actions ?? []
+    );
+
+    return {
+      mode: 'ai' as const,
+      conversationId: conversation.id,
+      conversationTitle: conversation.title,
+      messages: [userMessage, assistantMessage],
+      answer: answer.text,
+      sources,
+      actions: answer.actions ?? [],
+      quota: await this.status(actor),
+    };
+  }
+
+  /**
+   * La recherche documentaire ne doit jamais empecher une reponse : sans
+   * extrait, le modele repond sur ses connaissances generales.
+   */
+  private async retrieve(question: string, language: string): Promise<TradePassage[]> {
+    try {
+      return await this.retrieval.search(question, language);
+    } catch (error) {
+      this.logger.warn(
+        `Knowledge search failed: ${error instanceof Error ? error.message : String(error)}`
+      );
+      return [];
+    }
+  }
+}
+
+/* -------------------------------------------------------------------------- */
+
+/** Une meme page wiki citee deux fois n'apporte rien de plus a la lecture. */
+function toSources(passages: TradePassage[]): TradeSource[] {
+  const seen = new Map<string, TradeSource>();
+  for (const passage of passages) {
+    if (!seen.has(passage.href)) {
+      seen.set(passage.href, {
+        title: passage.title,
+        section: passage.section,
+        href: passage.href,
+      });
+    }
+  }
+  return [...seen.values()];
+}
+
+/** Coupe sur un mot entier plutot qu'au milieu, et sans points de suspension. */
+export function truncateTitle(text: string): string {
+  const clean = text.replace(/\s+/g, ' ').trim();
+  if (clean.length <= TITLE_MAX_LENGTH) return clean;
+
+  const cut = clean.slice(0, TITLE_MAX_LENGTH);
+  const lastSpace = cut.lastIndexOf(' ');
+  return (lastSpace > TITLE_MAX_LENGTH / 2 ? cut.slice(0, lastSpace) : cut).trim();
+}