feat(auth): verifie le lien de reset des le chargement, sans le consommer

Ajoute GET /auth/reset-password/validate (lecture seule, sans rate
limit : le jeton est un secret de 256 bits non brute-forcable) pour que
la page reset-password redirige immediatement vers /login si le lien
est invalide ou expire, plutot que d'attendre la soumission du
formulaire. La verification a la soumission (confirm_password_reset)
reste la seule source de verite atomique.

apps/frontend/src/app/core/services/auth.service.spec.ts

@@ -83,4 +83,17 @@ describe('AuthService', () => {
 
   expect(result).toEqual(tokenResponse.principal);
 });
+
+  it('vérifie la validité du jeton de reset via GET /auth/reset-password/validate', () => {
+    let result: { valid: boolean } | undefined;
+    service.validateResetToken('un-secret-opaque').subscribe((r) => (result = r));
+
+    const req = httpMock.expectOne(
+      `${environment.apiUrl}/auth/reset-password/validate?token=un-secret-opaque`
+    );
+    expect(req.request.method).toBe('GET');
+    req.flush({ valid: true });
+
+    expect(result).toEqual({ valid: true });
+  });
 });

apps/frontend/src/app/core/services/auth.service.ts

@@ -83,4 +83,10 @@ export class AuthService {
       .post<TokenResponse>(`${environment.apiUrl}/auth/reset-password`, payload, { withCredentials: true })
       .pipe(tap((response) => this.setSession(response)));
   }
+
+  validateResetToken(token: string): Observable<{ valid: boolean }> {
+    return this.http.get<{ valid: boolean }>(`${environment.apiUrl}/auth/reset-password/validate`, {
+      params: { token },
+    });
+  }
 }

apps/frontend/src/app/features/auth/reset-password/reset-password.html

@@ -2,7 +2,7 @@
   <form class="auth-card" [formGroup]="form" (ngSubmit)="onSubmit()">
     <h1>Nouveau mot de passe</h1>
 
-    @if (hasToken) {
+    @if (hasToken && !isCheckingToken()) {
       <p class="auth-subtitle">Choisissez votre nouveau mot de passe</p>
 
       <label for="new_password">Nouveau mot de passe</label>
@@ -23,6 +23,10 @@
       </button>
     }
 
+    @if (hasToken && isCheckingToken()) {
+      <p class="auth-subtitle">Vérification du lien...</p>
+    }
+
     <p class="auth-link"><a routerLink="/forgot-password">Redemander un lien</a></p>
   </form>
 </div>

apps/frontend/src/app/features/auth/reset-password/reset-password.spec.ts

@@ -12,7 +12,13 @@ function configure(token: string | null) {
   return TestBed.configureTestingModule({
     imports: [ResetPassword, ReactiveFormsModule],
     providers: [
-      { provide: AuthService, useValue: { resetPassword: vi.fn() } },
+      {
+        provide: AuthService,
+        useValue: {
+          resetPassword: vi.fn(),
+          validateResetToken: vi.fn().mockReturnValue(of({ valid: true })),
+        },
+      },
       { provide: Router, useValue: { navigate: vi.fn() } },
       {
         provide: ActivatedRoute,
@@ -36,6 +42,32 @@ describe('ResetPassword', () => {
     });
   });
 
+  it('vérifie le jeton sans le consommer dès le chargement de la page', async () => {
+    await configure('un-secret-opaque');
+    const fixture = TestBed.createComponent(ResetPassword);
+    const auth = TestBed.inject(AuthService) as unknown as { validateResetToken: ReturnType<typeof vi.fn> };
+
+    fixture.detectChanges();
+
+    expect(auth.validateResetToken).toHaveBeenCalledWith('un-secret-opaque');
+    expect(fixture.componentInstance.isCheckingToken()).toBe(false);
+  });
+
+  it('redirige immédiatement vers /login si la vérification signale un jeton invalide', async () => {
+    await configure('un-secret-perime');
+    TestBed.overrideProvider(AuthService, {
+      useValue: { resetPassword: vi.fn(), validateResetToken: vi.fn().mockReturnValue(of({ valid: false })) },
+    });
+    const fixture = TestBed.createComponent(ResetPassword);
+    const router = TestBed.inject(Router) as unknown as { navigate: ReturnType<typeof vi.fn> };
+
+    fixture.detectChanges();
+
+    expect(router.navigate).toHaveBeenCalledWith(['/login'], {
+      queryParams: { motif: MOTIF_LIEN_RESET_INVALIDE },
+    });
+  });
+
   it('ne soumet pas si le mot de passe ne respecte pas la politique de complexité', async () => {
     await configure('un-secret-opaque');
     const fixture = TestBed.createComponent(ResetPassword);

apps/frontend/src/app/features/auth/reset-password/reset-password.ts

@@ -33,11 +33,23 @@ export class ResetPassword implements OnInit {
   });
 
   password = toSignal(this.form.controls.new_password.valueChanges, { initialValue: '' });
+  isCheckingToken = signal(this.hasToken);
 
   ngOnInit(): void {
     if (!this.hasToken) {
       this.redirigeVersLoginLienInvalide();
+      return;
     }
+
+    this.auth.validateResetToken(this.token).subscribe({
+      next: ({ valid }) => {
+        this.isCheckingToken.set(false);
+        if (!valid) {
+          this.redirigeVersLoginLienInvalide();
+        }
+      },
+      error: () => this.isCheckingToken.set(false),
+    });
   }
 
   onSubmit(): void {