Harden renderer account IPC boundary

Move secret-bearing account and settings state behind main-process boundaries for Task 1B. Renderer snapshots now expose RendererSettings plus safe account metadata instead of full AppSettings, with provider tokens, passwords, API keys, archive passwords, and notification URLs excluded from renderer-bound state. Add write-only account create, replace, update-secret, and delete IPC commands, validate renderer settings updates against the safe shape, and keep account command results limited to safe settings, safe accounts, and stable account IDs.

Preserve existing account behavior while removing renderer secret access: blank replace secrets retain stored main-process secrets, Mega-Debrid API/Web pools stay mode-specific, Debrid-Link key metadata migrates by stable key ID, and delete/enable operations target stable account or provider identities. Remove obsolete renderer-side account status helpers from the old settings snapshot flow.

Add focused coverage for all supported renderer account kinds, secret-free UiSnapshot serialization, preload account command forwarding, malformed payload error sanitization, Mega-Debrid preferApi preservation, Debrid-Link key metadata migration, account edit safety, settings UI, debug server settings payloads, link export, and visual fixtures.

src/main/main.ts

@@ -1,7 +1,7 @@
 import fs from "node:fs";
 import path from "node:path";
 import { app, BrowserWindow, clipboard, dialog, ipcMain, IpcMainInvokeEvent, Menu, safeStorage, shell, Tray } from "electron";
-import { AddLinksPayload, AppSettings, DebridProvider, EnableRemoteDiagnosticsInput, UpdateInstallProgress } from "../shared/types";
+import { AddLinksPayload, AppSettings, DebridProvider, EnableRemoteDiagnosticsInput, RendererSettingsUpdate, UpdateInstallProgress } from "../shared/types";
 import { AppController } from "./app-controller";
 import { IPC_CHANNELS } from "../shared/ipc";
 import { getLogFilePath, logger } from "./logger";
@@ -15,6 +15,9 @@ import { DEV_SERVER_URL } from "./dev-server-url";
 import { resolveAppIconPath } from "./app-icon";
 import { configureCredentialProtector } from "./credential-protection";
 import { isMdd2Backup } from "./backup-crypto";
+import { validateAccountCommand, validateAccountCredentialCheckInput } from "./account-commands";
+import { createRendererSettings } from "./renderer-state";
+import { validateRendererSettingsUpdate } from "./renderer-settings";
 
 function validateString(value: unknown, name: string): string {
   if (typeof value !== "string") {
@@ -358,28 +361,52 @@ function registerIpcHandlers(): void {
       return false;
     }
   });
-  ipcMain.handle(IPC_CHANNELS.UPDATE_SETTINGS, (_event: IpcMainInvokeEvent, partial: Partial<AppSettings>) => {
-    const validated = validatePlainObject(partial ?? {}, "partial");
-    const result = controller.updateSettings(validated as Partial<AppSettings>);
-    updateClipboardWatcher();
-    updateTray();
-    armScheduledStart(result.scheduledStartEpochMs || 0, { startOnPast: true });
-    return result;
-  });
+  ipcMain.handle(IPC_CHANNELS.UPDATE_SETTINGS, (_event: IpcMainInvokeEvent, partial: RendererSettingsUpdate) => {
+    const validated = validateRendererSettingsUpdate(partial ?? {}, controller.getSettings());
+    const result = controller.updateSettings(validated as Partial<AppSettings>);
+    updateClipboardWatcher();
+    updateTray();
+    armScheduledStart(result.scheduledStartEpochMs || 0, { startOnPast: true });
+    return createRendererSettings(result);
+  });
   ipcMain.handle(IPC_CHANNELS.RESET_PROVIDER_DAILY_USAGE, (_event: IpcMainInvokeEvent, provider: string) => {
     const validatedProvider = validateString(provider, "provider") as DebridProvider;
     if (!RESETTABLE_PROVIDER_KEYS.has(validatedProvider)) {
       throw new Error("provider ist ungültig");
     }
-    return controller.resetProviderDailyUsage(validatedProvider);
+    return createRendererSettings(controller.resetProviderDailyUsage(validatedProvider));
   });
   ipcMain.handle(IPC_CHANNELS.RESET_DEBRID_LINK_API_KEY_DAILY_USAGE, (_event: IpcMainInvokeEvent, keyId: string) => {
     const validatedKeyId = validateString(keyId, "keyId").trim();
     if (!validatedKeyId) {
       throw new Error("keyId ist ungültig");
     }
-    return controller.resetDebridLinkApiKeyDailyUsage(validatedKeyId);
-  });
+    return createRendererSettings(controller.resetDebridLinkApiKeyDailyUsage(validatedKeyId));
+  });
+
+  ipcMain.handle(IPC_CHANNELS.CREATE_ACCOUNT, (_event: IpcMainInvokeEvent, rawCommand: unknown) => {
+    const command = validateAccountCommand(rawCommand);
+    if (command.action !== "create") throw new Error("Account-Payload ist ungültig");
+    return controller.executeAccountCommand(command);
+  });
+
+  ipcMain.handle(IPC_CHANNELS.REPLACE_ACCOUNT, (_event: IpcMainInvokeEvent, rawCommand: unknown) => {
+    const command = validateAccountCommand(rawCommand);
+    if (command.action !== "replace") throw new Error("Account-Payload ist ungültig");
+    return controller.executeAccountCommand(command);
+  });
+
+  ipcMain.handle(IPC_CHANNELS.UPDATE_ACCOUNT_SECRET, (_event: IpcMainInvokeEvent, rawCommand: unknown) => {
+    const command = validateAccountCommand(rawCommand);
+    if (command.action !== "update-secret") throw new Error("Account-Payload ist ungültig");
+    return controller.executeAccountCommand(command);
+  });
+
+  ipcMain.handle(IPC_CHANNELS.DELETE_ACCOUNT, (_event: IpcMainInvokeEvent, rawCommand: unknown) => {
+    const command = validateAccountCommand(rawCommand);
+    if (command.action !== "delete") throw new Error("Account-Payload ist ungültig");
+    return controller.executeAccountCommand(command);
+  });
   ipcMain.handle(IPC_CHANNELS.ADD_LINKS, (_event: IpcMainInvokeEvent, payload: AddLinksPayload) => {
     validatePlainObject(payload ?? {}, "payload");
     validateString(payload?.rawText, "rawText");
@@ -761,13 +788,13 @@ function registerIpcHandlers(): void {
     return controller.getDebridLinkHostLimits();
   });
 
-  ipcMain.handle(IPC_CHANNELS.CHECK_DEBRID_ACCOUNTS, async (_event, settings?: AppSettings, persistValidOverride = false, expectedAccountId?: string) => {
-    return controller.checkDebridAccounts(settings, persistValidOverride === true, expectedAccountId);
+  ipcMain.handle(IPC_CHANNELS.CHECK_DEBRID_ACCOUNTS, async () => {
+    return controller.checkDebridAccounts();
+  });
+
+  ipcMain.handle(IPC_CHANNELS.CHECK_ACCOUNT_CREDENTIALS, async (_event, rawInput: unknown) => {
+    return controller.checkAccountCredentials(validateAccountCredentialCheckInput(rawInput));
   });
-
-  ipcMain.handle(IPC_CHANNELS.CHECK_MEGA_DEBRID_ACCOUNT, async (_event, login: string, password: string) => {
-    return controller.checkSingleMegaDebridAccount(String(login || ""), String(password || ""));
-  });
 
   ipcMain.handle(IPC_CHANNELS.SELECT_BACKUP_IMPORT, async () => {
     pendingBackupImport = null;