diff --git a/apps/frontend/src/app/features/auth/login/login.spec.ts b/apps/frontend/src/app/features/auth/login/login.spec.ts
index d39298d..d100e5e 100644
--- a/apps/frontend/src/app/features/auth/login/login.spec.ts
+++ b/apps/frontend/src/app/features/auth/login/login.spec.ts
@@ -1,28 +1,43 @@
 import { TestBed } from '@angular/core/testing';
 import { ReactiveFormsModule } from '@angular/forms';
-import { ActivatedRoute, Router } from '@angular/router';
+import { ActivatedRoute, convertToParamMap, Router } from '@angular/router';
 import { HttpErrorResponse, HttpHeaders } from '@angular/common/http';
 import { of, throwError } from 'rxjs';
 import { vi } from 'vitest';
 import { Login } from './login';
 import { AuthService } from '../../../core/services/auth.service';
+import { MOTIF_LIEN_RESET_INVALIDE } from '../../../shared/models/auth-redirect-reason';
+
+function configure(queryParams: Record<string, string> = {}) {
+  const authMock = { login: vi.fn() };
+  const routerMock = { navigate: vi.fn() };
+
+  return {
+    authMock,
+    routerMock,
+    testBed: TestBed.configureTestingModule({
+      imports: [Login, ReactiveFormsModule],
+      providers: [
+        { provide: AuthService, useValue: authMock },
+        { provide: Router, useValue: routerMock },
+        {
+          provide: ActivatedRoute,
+          useValue: { snapshot: { queryParamMap: convertToParamMap(queryParams) } },
+        },
+      ],
+    }),
+  };
+}
 
 describe('Login', () => {
   let authMock: { login: ReturnType<typeof vi.fn> };
   let routerMock: { navigate: ReturnType<typeof vi.fn> };
 
   beforeEach(async () => {
-    authMock = { login: vi.fn() };
-    routerMock = { navigate: vi.fn() };
-
-    await TestBed.configureTestingModule({
-      imports: [Login, ReactiveFormsModule],
-      providers: [
-        { provide: AuthService, useValue: authMock },
-        { provide: Router, useValue: routerMock },
-        { provide: ActivatedRoute, useValue: {} },
-      ],
-    }).compileComponents();
+    const attirail = configure();
+    authMock = attirail.authMock;
+    routerMock = attirail.routerMock;
+    await attirail.testBed.compileComponents();
   });
 
   it('ne soumet pas si le formulaire est invalide', () => {
@@ -85,6 +100,14 @@ describe('Login', () => {
     expect(errorEl?.textContent).toContain('30s');
   });
 
+  it('affiche le message standard quand on arrive avec ?motif=lien-expire', async () => {
+    const attirail = configure({ motif: MOTIF_LIEN_RESET_INVALIDE });
+    await attirail.testBed.compileComponents();
+    const fixture = TestBed.createComponent(Login);
+
+    expect(fixture.componentInstance.errorMessage()).toContain('expiré');
+  });
+
   it('désactive le bouton tant que le formulaire est invalide', () => {
     const fixture = TestBed.createComponent(Login);
     fixture.detectChanges();
diff --git a/apps/frontend/src/app/features/auth/login/login.ts b/apps/frontend/src/app/features/auth/login/login.ts
index 871e7cc..f9bd085 100644
--- a/apps/frontend/src/app/features/auth/login/login.ts
+++ b/apps/frontend/src/app/features/auth/login/login.ts
@@ -1,8 +1,9 @@
 import { Component, inject, signal } from '@angular/core';
 import { ReactiveFormsModule, FormBuilder, Validators } from '@angular/forms';
-import { Router, RouterLink } from '@angular/router';
+import { ActivatedRoute, Router, RouterLink } from '@angular/router';
 import { HttpErrorResponse } from '@angular/common/http';
 import { AuthService } from '../../../core/services/auth.service';
+import { MESSAGE_LIEN_RESET_INVALIDE, MOTIF_LIEN_RESET_INVALIDE } from '../../../shared/models/auth-redirect-reason';
 
 @Component({
   selector: 'app-login',
@@ -15,8 +16,13 @@ export class Login {
   private fb = inject(FormBuilder);
   private auth = inject(AuthService);
   private router = inject(Router);
+  private route = inject(ActivatedRoute);
 
-  errorMessage = signal<string | null>(null);
+  errorMessage = signal<string | null>(
+    this.route.snapshot.queryParamMap.get('motif') === MOTIF_LIEN_RESET_INVALIDE
+      ? MESSAGE_LIEN_RESET_INVALIDE
+      : null,
+  );
   retryAfterSeconds = signal<number | null>(null);
   isLoading = signal(false);
 
diff --git a/apps/frontend/src/app/features/auth/reset-password/reset-password.html b/apps/frontend/src/app/features/auth/reset-password/reset-password.html
index eed77a8..57d202e 100644
--- a/apps/frontend/src/app/features/auth/reset-password/reset-password.html
+++ b/apps/frontend/src/app/features/auth/reset-password/reset-password.html
@@ -2,9 +2,7 @@
   <form class="auth-card" [formGroup]="form" (ngSubmit)="onSubmit()">
     <h1>Nouveau mot de passe</h1>
 
-    @if (!hasToken) {
-      <p class="auth-error">Ce lien est incomplet. Redemandez un lien de réinitialisation.</p>
-    } @else {
+    @if (hasToken) {
       <p class="auth-subtitle">Choisissez votre nouveau mot de passe</p>
 
       <label for="new_password">Nouveau mot de passe</label>
diff --git a/apps/frontend/src/app/features/auth/reset-password/reset-password.spec.ts b/apps/frontend/src/app/features/auth/reset-password/reset-password.spec.ts
index 7e212cd..a14cb78 100644
--- a/apps/frontend/src/app/features/auth/reset-password/reset-password.spec.ts
+++ b/apps/frontend/src/app/features/auth/reset-password/reset-password.spec.ts
@@ -6,6 +6,7 @@ import { of, throwError } from 'rxjs';
 import { vi } from 'vitest';
 import { ResetPassword } from './reset-password';
 import { AuthService } from '../../../core/services/auth.service';
+import { MOTIF_LIEN_RESET_INVALIDE } from '../../../shared/models/auth-redirect-reason';
 
 function configure(token: string | null) {
   return TestBed.configureTestingModule({
@@ -22,11 +23,17 @@ function configure(token: string | null) {
 }
 
 describe('ResetPassword', () => {
-  it("signale un lien incomplet quand le jeton est absent de l'URL", async () => {
+  it("redirige vers /login avec le motif standard quand le jeton est absent de l'URL", async () => {
     await configure(null);
     const fixture = TestBed.createComponent(ResetPassword);
+    const router = TestBed.inject(Router) as unknown as { navigate: ReturnType<typeof vi.fn> };
+
+    fixture.detectChanges();
 
     expect(fixture.componentInstance.hasToken).toBe(false);
+    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 () => {
@@ -59,16 +66,32 @@ describe('ResetPassword', () => {
     expect(router.navigate).toHaveBeenCalledWith(['/dashboard']);
   });
 
-  it('affiche un message dédié quand le lien est invalide ou expiré', async () => {
+  it('redirige vers /login avec le motif standard quand le lien est invalide ou expiré', async () => {
     await configure('un-secret-perime');
     const fixture = TestBed.createComponent(ResetPassword);
     const component = fixture.componentInstance;
     const auth = TestBed.inject(AuthService) as unknown as { resetPassword: ReturnType<typeof vi.fn> };
+    const router = TestBed.inject(Router) as unknown as { navigate: ReturnType<typeof vi.fn> };
     component.form.setValue({ new_password: 'Un-nouveau-mot-de-passe1!' });
     auth.resetPassword.mockReturnValue(throwError(() => new HttpErrorResponse({ status: 400 })));
 
     component.onSubmit();
 
+    expect(router.navigate).toHaveBeenCalledWith(['/login'], {
+      queryParams: { motif: MOTIF_LIEN_RESET_INVALIDE },
+    });
+  });
+
+  it('affiche un message générique sur une erreur inattendue (pas 400)', async () => {
+    await configure('un-secret-opaque');
+    const fixture = TestBed.createComponent(ResetPassword);
+    const component = fixture.componentInstance;
+    const auth = TestBed.inject(AuthService) as unknown as { resetPassword: ReturnType<typeof vi.fn> };
+    component.form.setValue({ new_password: 'Un-nouveau-mot-de-passe1!' });
+    auth.resetPassword.mockReturnValue(throwError(() => new HttpErrorResponse({ status: 500 })));
+
+    component.onSubmit();
+
     expect(component.errorMessage()).toContain('invalide');
   });
 });
diff --git a/apps/frontend/src/app/features/auth/reset-password/reset-password.ts b/apps/frontend/src/app/features/auth/reset-password/reset-password.ts
index 6754fa7..3fa56fa 100644
--- a/apps/frontend/src/app/features/auth/reset-password/reset-password.ts
+++ b/apps/frontend/src/app/features/auth/reset-password/reset-password.ts
@@ -1,9 +1,10 @@
-import { Component, inject, signal } from '@angular/core';
+import { Component, OnInit, inject, signal } from '@angular/core';
 import { ReactiveFormsModule, FormBuilder } from '@angular/forms';
 import { ActivatedRoute, Router, RouterLink } from '@angular/router';
 import { HttpErrorResponse } from '@angular/common/http';
 import { AuthService } from '../../../core/services/auth.service';
 import { passwordValidators, PASSWORD_HINT } from '../../../shared/validators/password.validator';
+import { MOTIF_LIEN_RESET_INVALIDE } from '../../../shared/models/auth-redirect-reason';
 
 @Component({
   selector: 'app-reset-password',
@@ -12,7 +13,7 @@ import { passwordValidators, PASSWORD_HINT } from '../../../shared/validators/pa
   templateUrl: './reset-password.html',
   styleUrl: './reset-password.scss',
 })
-export class ResetPassword {
+export class ResetPassword implements OnInit {
   private fb = inject(FormBuilder);
   private auth = inject(AuthService);
   private router = inject(Router);
@@ -29,6 +30,12 @@ export class ResetPassword {
     new_password: ['', passwordValidators],
   });
 
+  ngOnInit(): void {
+    if (!this.hasToken) {
+      this.redirigeVersLoginLienInvalide();
+    }
+  }
+
   onSubmit(): void {
     if (this.form.invalid || !this.hasToken) return;
 
@@ -42,11 +49,15 @@ export class ResetPassword {
       error: (error: HttpErrorResponse) => {
         this.isLoading.set(false);
         if (error.status === 400) {
-          this.errorMessage.set('Ce lien est invalide, déjà utilisé, ou a expiré. Redemandez-en un.');
+          this.redirigeVersLoginLienInvalide();
           return;
         }
         this.errorMessage.set(`Nouveau mot de passe invalide (${this.passwordHint}).`);
       },
     });
   }
+
+  private redirigeVersLoginLienInvalide(): void {
+    this.router.navigate(['/login'], { queryParams: { motif: MOTIF_LIEN_RESET_INVALIDE } });
+  }
 }
diff --git a/apps/frontend/src/app/shared/models/auth-redirect-reason.ts b/apps/frontend/src/app/shared/models/auth-redirect-reason.ts
new file mode 100644
index 0000000..7feb0de
--- /dev/null
+++ b/apps/frontend/src/app/shared/models/auth-redirect-reason.ts
@@ -0,0 +1,3 @@
+export const MOTIF_LIEN_RESET_INVALIDE = 'lien-expire';
+export const MESSAGE_LIEN_RESET_INVALIDE =
+  'Ce lien de réinitialisation est invalide ou a expiré. Connectez-vous ou redemandez-en un.';