Lock download client type after creation (#831)

code/backend/Cleanuparr.Api.Tests/Features/DownloadClient/DownloadClientControllerTests.cs

@@ -302,6 +302,30 @@ public class DownloadClientControllerTests : IDisposable
             () => _controller.UpdateDownloadClientConfig(client.Id, request));
     }
 
+    [Fact]
+    public async Task UpdateDownloadClientConfig_ChangedTypeName_PropagatesValidationException()
+    {
+        // Arrange
+        DownloadClientConfig client = NewClient("orig", DownloadClientTypeName.qBittorrent);
+        _dataContext.DownloadClients.Add(client);
+        await _dataContext.SaveChangesAsync();
+
+        UpdateDownloadClientRequest request = new()
+        {
+            Name = "renamed",
+            Host = "http://newhost:9090",
+            TypeName = DownloadClientTypeName.rTorrent,
+        };
+
+        // Act / Assert
+        Cleanuparr.Domain.Exceptions.ValidationException exception = await Should.ThrowAsync<Cleanuparr.Domain.Exceptions.ValidationException>(
+            () => _controller.UpdateDownloadClientConfig(client.Id, request));
+        exception.Message.ShouldContain("cannot be changed");
+
+        DownloadClientConfig saved = await _dataContext.DownloadClients.AsNoTracking().FirstAsync(c => c.Id == client.Id);
+        saved.TypeName.ShouldBe(DownloadClientTypeName.qBittorrent);
+    }
+
     [Fact]
     public async Task DeleteDownloadClientConfig_ExistingClient_RemovesAndUnregistersHttpClient()
     {

code/backend/Cleanuparr.Api/Features/DownloadClient/Controllers/DownloadClientController.cs

@@ -5,6 +5,7 @@ using Cleanuparr.Api.Extensions;
 using Cleanuparr.Api.Features.DownloadClient.Contracts.Requests;
 using Cleanuparr.Api.Features.DownloadClient.Contracts.Responses;
 using Cleanuparr.Domain.Enums;
+using Cleanuparr.Domain.Exceptions;
 using Cleanuparr.Infrastructure.Features.DownloadClient;
 using Cleanuparr.Infrastructure.Http.DynamicHttpClientSystem;
 using Cleanuparr.Persistence;
@@ -101,6 +102,11 @@ public sealed class DownloadClientController : ControllerBase
                 return this.ProblemResult(StatusCodes.Status404NotFound, $"Download client with ID {id} not found");
             }
 
+            if (updatedClient.TypeName != existingClient.TypeName)
+            {
+                throw new ValidationException("Download client type cannot be changed");
+            }
+
             var clientToPersist = updatedClient.ApplyTo(existingClient);
             clientToPersist.Validate();
 

code/frontend/src/app/features/settings/download-clients/download-clients.component.spec.ts

@@ -116,12 +116,15 @@ function hintFor(fixture: ComponentFixture<DownloadClientsComponent>, label: str
   return field?.querySelector('.input-hint')?.textContent!.trim() ?? '';
 }
 
+function clientTypeTrigger(fixture: ComponentFixture<DownloadClientsComponent>): HTMLButtonElement {
+  return fixture.nativeElement.querySelector('.select-trigger') as HTMLButtonElement;
+}
+
 function chooseClientType(
   fixture: ComponentFixture<DownloadClientsComponent>,
   label: string,
 ): void {
-  const trigger = fixture.nativeElement.querySelector('.select-trigger') as HTMLButtonElement;
-  trigger.click();
+  clientTypeTrigger(fixture).click();
   fixture.detectChanges();
 
   const option = Array.from(fixture.nativeElement.querySelectorAll('.select-option')).find(
@@ -417,6 +420,22 @@ describe('DownloadClientsComponent', () => {
     expect(fixture.nativeElement.textContent).toContain('Edit Client');
   });
 
+  it('locks the client type while editing and unlocks it when adding', () => {
+    const { fixture, component } = setup();
+
+    component.openEditModal(QBIT);
+    fixture.detectChanges();
+
+    expect(component.clientForm.typeName().disabled()).toBe(true);
+    expect(clientTypeTrigger(fixture).disabled).toBe(true);
+
+    component.openAddModal();
+    fixture.detectChanges();
+
+    expect(component.clientForm.typeName().disabled()).toBe(false);
+    expect(clientTypeTrigger(fixture).disabled).toBe(false);
+  });
+
   it('creates a client from the modal values and reloads the list', () => {
     const { fixture, component, api, toast } = setup();
 

code/frontend/src/app/features/settings/download-clients/download-clients.component.ts

@@ -1,6 +1,6 @@
 import { Component, ChangeDetectionStrategy, inject, signal, computed } from '@angular/core';
 import { forkJoin } from 'rxjs';
-import { form, required, FormField } from '@angular/forms/signals';
+import { form, required, disabled, FormField } from '@angular/forms/signals';
 import { PageHeaderComponent } from '@layout/page-header/page-header.component';
 import {
   CardComponent, ButtonComponent, InputComponent, ToggleComponent,
@@ -114,6 +114,7 @@ export class DownloadClientsComponent implements HasPendingChanges {
       when: ({ valueOf }) => valueOf(p.typeName) === DownloadClientTypeName.Sabnzbd,
       message: 'API key is required',
     });
+    disabled(p.typeName, () => this.editingClient() !== null);
   });
 
   readonly hasModalErrors = computed(() => this.clientForm().invalid());

e2e/tests/download-client/download-client-crud.api.spec.ts

@@ -137,6 +137,25 @@ test.describe('DownloadClient: invalid type validation', () => {
 
     await api.downloadClient.delete(created.id);
   });
+
+  test('update changing typeName returns 400 and keeps the original type', async ({ api }) => {
+    const payload = buildDownloadClientPayload('qbittorrent', {
+      name: 'base-for-type-change',
+      host: TEST_CONFIG.mocks.downloadClientUrl,
+      username: 'admin',
+      password: 'admin',
+    });
+    const created = await (await api.downloadClient.create(payload)).json();
+
+    const res = await api.downloadClient.update(created.id, { ...payload, typeName: 'rTorrent' });
+    expect(res.status).toBe(400);
+
+    const list = await (await api.downloadClient.list()).json();
+    const stored = list.clients.find((c: { id: string }) => c.id === created.id);
+    expect(stored.typeName.toLowerCase()).toBe(payload.typeName?.toLowerCase());
+
+    await api.downloadClient.delete(created.id);
+  });
 });
 
 test.describe('DownloadClient: API key validation', () => {