fix(settings): harden settings and diagnostic controls

src/store/useDownloadStore.test.ts

@@ -200,6 +200,9 @@ describe('useDownloadStore', () => {
     expect(normalizeCustomProxy(' socks5://127.0.0.1 ', 1080)).toBeNull();
     expect(normalizeCustomProxy('https://proxy.local', 8443)).toBeNull();
     expect(normalizeCustomProxy('127.0.0.1', NaN)).toBeNull();
+    expect(normalizeCustomProxy('127.0.0.1:9000', 8080)).toBeNull();
+    expect(normalizeCustomProxy('127.0.0.1/path', 8080)).toBeNull();
+    expect(normalizeCustomProxy('[::1]', 8080)).toBe('http://[::1]:8080');
 
     expect(await getProxyArgs({
       proxyMode: 'none',

src/store/useDownloadStore.ts

@@ -276,6 +276,7 @@ export const normalizeCustomProxy = (host: string, port: number): string | null
     try {
       const parsed = new URL(trimmedHost);
       if (parsed.protocol !== 'http:') return null;
+      if (!parsed.hostname) return null;
       if (!parsed.port) parsed.port = String(normalizedPort);
       return parsed.toString().replace(/\/$/, '');
     } catch {
@@ -283,7 +284,24 @@ export const normalizeCustomProxy = (host: string, port: number): string | null
     }
   }
 
-  return `http://${trimmedHost}:${normalizedPort}`;
+  try {
+    const parsed = new URL(`http://${trimmedHost}:${normalizedPort}`);
+    if (
+      !parsed.hostname
+      || parsed.username
+      || parsed.password
+      || parsed.pathname !== '/'
+      || parsed.search
+      || parsed.hash
+      || (parsed.port && Number(parsed.port) !== normalizedPort)
+      || (!parsed.port && normalizedPort !== 80)
+    ) {
+      return null;
+    }
+    return `http://${trimmedHost}:${normalizedPort}`;
+  } catch {
+    return null;
+  }
 };
 
 export const getProxyArgs = async (settings: ReturnType<typeof useSettingsStore.getState>) => {

src/store/useSettingsStore.test.ts

@@ -1,5 +1,5 @@
 import { beforeEach, describe, expect, it, vi } from 'vitest';
-import { useSettingsStore } from './useSettingsStore';
+import { subscribeToSettingsPersistenceErrors, useSettingsStore } from './useSettingsStore';
 import * as ipc from '../ipc';
 
 vi.mock('../ipc', () => ({
@@ -66,3 +66,26 @@ describe('useSettingsStore credential-store startup flow', () => {
     expect(useSettingsStore.getState().keychainPromptDismissed).toBe(true);
   });
 });
+
+describe('useSettingsStore persistence failures', () => {
+  it('reports a database save failure and retries the next settings update', async () => {
+    vi.clearAllMocks();
+    await new Promise(resolve => setTimeout(resolve, 0));
+
+    const onPersistenceError = vi.fn();
+    const unsubscribe = subscribeToSettingsPersistenceErrors(onPersistenceError);
+    vi.mocked(ipc.invokeCommand).mockRejectedValueOnce(new Error('database unavailable'));
+
+    useSettingsStore.setState({ theme: 'dark' });
+    await new Promise(resolve => setTimeout(resolve, 0));
+
+    expect(onPersistenceError).toHaveBeenCalledTimes(1);
+
+    vi.mocked(ipc.invokeCommand).mockResolvedValueOnce(undefined);
+    useSettingsStore.setState({ theme: 'light' });
+    await new Promise(resolve => setTimeout(resolve, 0));
+
+    expect(onPersistenceError).toHaveBeenCalledTimes(1);
+    unsubscribe();
+  });
+});

src/store/useSettingsStore.ts

@@ -20,9 +20,29 @@ import {
 import { normalizeSpeedLimitForBackend } from '../utils/downloads';
 
 let settingsSave = Promise.resolve();
+const settingsPersistenceErrorListeners = new Set<() => void>();
+let settingsPersistenceFailed = false;
 const DEFAULT_SCHEDULER_QUEUE_ID = '00000000-0000-0000-0000-000000000001';
 export const DEFAULT_SPEED_LIMIT_PRESET_VALUES = [1, 5, 10];
 
+export const subscribeToSettingsPersistenceErrors = (listener: () => void): (() => void) => {
+  settingsPersistenceErrorListeners.add(listener);
+  if (settingsPersistenceFailed) listener();
+  return () => settingsPersistenceErrorListeners.delete(listener);
+};
+
+const notifySettingsPersistenceError = () => {
+  if (settingsPersistenceFailed) return;
+  settingsPersistenceFailed = true;
+  for (const listener of settingsPersistenceErrorListeners) {
+    try {
+      listener();
+    } catch (error) {
+      console.error('Settings persistence error listener failed', error);
+    }
+  }
+};
+
 const THEME_VALUES = ['system', 'light', 'dark', 'dracula', 'nord'] as const;
 const APP_FONT_SIZE_VALUES = ['small', 'standard', 'large'] as const;
 const LIST_ROW_DENSITY_VALUES = ['compact', 'standard', 'relaxed'] as const;
@@ -83,9 +103,13 @@ const tauriStorage: StateStorage = {
   setItem: async (name: string, value: string): Promise<void> => {
     if (name === 'firelink-settings') {
       settingsSave = settingsSave
+        .catch(() => undefined)
         .then(() => invoke('db_save_settings', { data: value }))
-        .catch(e => {
-          console.error("Failed to save settings to DB", e);
+        .then(() => {
+          settingsPersistenceFailed = false;
+        }, () => {
+          console.error('Failed to save settings to DB');
+          notifySettingsPersistenceError();
         });
       await settingsSave;
     }