feat(profile): account-deletion flow + terminal deleted screen

Profile gains a Delete-account control (durable accounts) opening a step-up dialog: a
mailed code for an email account, or the typed DELETE phrase for a platform-only one.
On success the app swaps to a terminal AccountDeleted screen ('Учётная запись удалена')
with a Close that closes the host Mini App (telegramClose / vkClose; web = no close).
Wires deleteRequest/deleteConfirm through client/transport/mock/codec; ru/en i18n;
codec wire test + Chromium/WebKit e2e.

ui/src/lib/app.svelte.ts

@@ -13,6 +13,7 @@ import { startLocalEvalMetrics } from './localeval-metrics';
 import { applyReduceMotion, applyTelegramTheme, applyTheme, type ThemePref, type TelegramThemeParams } from './theme';
 import {
   insideTelegram,
+  telegramClose,
   collectTelegramDiag,
   type TelegramDiag,
   onTelegramPath,
@@ -32,7 +33,7 @@ import {
   telegramCloudGet,
   telegramCloudSet,
 } from './telegram';
-import { onVKPath, insideVK, vkInit, vkDisableSwipeBack, vkLaunchParams, vkUserName, vkStartParam, vkOnScheme, vkOnInsets, vkSetViewSettings, appearanceForBg } from './vk';
+import { onVKPath, insideVK, vkInit, vkClose, vkDisableSwipeBack, vkLaunchParams, vkUserName, vkStartParam, vkOnScheme, vkOnInsets, vkSetViewSettings, appearanceForBg } from './vk';
 import { haptic } from './haptics';
 import { CLOUD_PREFS_KEY, decodeClientPrefs, encodeClientPrefs } from './cloudprefs';
 import { parseStartParam } from './deeplink';
@@ -92,6 +93,9 @@ export const app = $state<{
   /** The caller's active manual block, or null. When set, App.svelte replaces every screen with
    *  the terminal blocked screen and all push/poll is stopped. */
   blocked: BlockStatus | null;
+  /** Set once the account has been deleted: App.svelte shows the terminal "account deleted"
+   *  screen and all push/poll is stopped. Reopening the app just creates a fresh account. */
+  accountDeleted: boolean;
   toast: Toast | null;
   lastEvent: PushEvent | null;
   theme: ThemePref;
@@ -140,6 +144,7 @@ export const app = $state<{
   session: null,
   profile: null,
   blocked: null,
+  accountDeleted: false,
   toast: null,
   lastEvent: null,
   theme: 'auto',
@@ -544,6 +549,39 @@ export async function applyLinkResult(r: LinkResult): Promise<void> {
   void persistLanguageToServer(app.locale);
 }
 
+/**
+ * requestDeleteAccount starts account deletion and reports which step-up the account uses:
+ * 'email' (a code was mailed) or 'phrase' (type the confirmation phrase).
+ */
+export async function requestDeleteAccount(): Promise<'email' | 'phrase'> {
+  return (await gateway.deleteRequest()).method;
+}
+
+/**
+ * confirmDeleteAccount confirms deletion with the mailed code or the typed phrase. On
+ * success it switches to the terminal "account deleted" screen and stops all push/poll; it
+ * throws on a bad code/phrase so the caller can let the user retry.
+ */
+export async function confirmDeleteAccount(code: string, phrase: string): Promise<void> {
+  await gateway.deleteConfirm(code, phrase);
+  closeStream();
+  app.accountDeleted = true;
+}
+
+/**
+ * closeDeletedApp closes the host Mini App from the terminal deleted screen (Telegram / VK).
+ * A plain browser has nothing to close, so it is a no-op there — the terminal screen stays.
+ */
+export function closeDeletedApp(): void {
+  if (insideTelegram()) {
+    telegramClose();
+    return;
+  }
+  if (insideVK()) {
+    void vkClose();
+  }
+}
+
 /**
  * syncTelegramChrome paints Telegram's header/background/bottom bar from the app's live
  * theme tokens, so the surrounding chrome matches the UI. Called after the theme is applied.

ui/src/lib/client.ts

@@ -185,6 +185,11 @@ export interface GatewayClient {
    *  refused without disclosure. */
   changeEmailRequest(email: string): Promise<void>;
   changeEmailConfirm(email: string, code: string): Promise<LinkResult>;
+  /** Start account deletion; the backend mails a code (method 'email') or asks for the
+   *  typed phrase (method 'phrase'). */
+  deleteRequest(): Promise<{ method: 'email' | 'phrase' }>;
+  /** Confirm and perform account deletion with the mailed code or the typed phrase. */
+  deleteConfirm(code: string, phrase: string): Promise<void>;
 
   // --- live stream ---
   subscribe(onEvent: (e: PushEvent) => void, onError?: (err: unknown) => void): Unsubscribe;

ui/src/lib/codec.test.ts

@@ -27,6 +27,8 @@ import {
   encodeEnqueue,
   encodeExchange,
   encodeExportUrlRequest,
+  encodeAccountDeleteConfirm,
+  decodeDeleteRequestResult,
   encodeGuestLogin,
   encodeLinkUnlink,
   encodeStateRequest,
@@ -464,6 +466,21 @@ describe('codec', () => {
     expect(r.kind()).toBe('telegram');
   });
 
+  it('round-trips the account-delete confirm + request-result wire', () => {
+    const c = fb.AccountDeleteConfirm.getRootAsAccountDeleteConfirm(
+      new ByteBuffer(encodeAccountDeleteConfirm('123456', 'DELETE')),
+    );
+    expect(c.code()).toBe('123456');
+    expect(c.phrase()).toBe('DELETE');
+
+    const b = new Builder(32);
+    const m = b.createString('email');
+    fb.AccountDeleteRequestResult.startAccountDeleteRequestResult(b);
+    fb.AccountDeleteRequestResult.addMethod(b, m);
+    b.finish(fb.AccountDeleteRequestResult.endAccountDeleteRequestResult(b));
+    expect(decodeDeleteRequestResult(b.asUint8Array()).method).toBe('email');
+  });
+
   it('passes an unlinked / changed LinkResult status straight through', () => {
     for (const status of ['unlinked', 'changed'] as const) {
       const b = new Builder(64);

ui/src/lib/codec.ts

@@ -739,6 +739,21 @@ export function encodeLinkUnlink(kind: string): Uint8Array {
   return finish(b, fb.LinkUnlinkRequest.endLinkUnlinkRequest(b));
 }
 
+export function encodeAccountDeleteConfirm(code: string, phrase: string): Uint8Array {
+  const b = new Builder(64);
+  const c = b.createString(code);
+  const p = b.createString(phrase);
+  fb.AccountDeleteConfirm.startAccountDeleteConfirm(b);
+  fb.AccountDeleteConfirm.addCode(b, c);
+  fb.AccountDeleteConfirm.addPhrase(b, p);
+  return finish(b, fb.AccountDeleteConfirm.endAccountDeleteConfirm(b));
+}
+
+export function decodeDeleteRequestResult(buf: Uint8Array): { method: 'email' | 'phrase' } {
+  const r = fb.AccountDeleteRequestResult.getRootAsAccountDeleteRequestResult(new ByteBuffer(buf));
+  return { method: (s(r.method()) || 'phrase') as 'email' | 'phrase' };
+}
+
 export function decodeLinkResult(buf: Uint8Array): LinkResult {
   const r = fb.LinkResult.getRootAsLinkResult(new ByteBuffer(buf));
   const sess = r.session();

ui/src/lib/i18n/en.ts

@@ -188,6 +188,15 @@ export const en = {
   'profile.unlinked': 'Account unlinked.',
   'profile.unlinkTitle': 'Unlink account?',
   'profile.unlinkBody': 'Remove {provider} as a sign-in method? You can link it again later.',
+  'profile.deleteAccount': 'Delete account',
+  'profile.deleteTitle': 'Delete your account?',
+  'profile.deleteWarn': 'This removes your account and frees your sign-in methods. It cannot be undone.',
+  'profile.deleteEmailPrompt': 'We sent a code to your email. Enter it to delete your account.',
+  'profile.deletePhrasePrompt': 'Type DELETE to confirm.',
+  'profile.deletePhrasePlaceholder': 'DELETE',
+  'profile.deleteConfirm': 'Delete permanently',
+  'deleted.title': 'Account deleted',
+  'deleted.body': 'Your account has been removed. Reopening the app just creates a new account.',
 
   'settings.title': 'Settings',
   'settings.theme': 'Theme',

ui/src/lib/i18n/ru.ts

@@ -188,6 +188,15 @@ export const ru: Record<MessageKey, string> = {
   'profile.unlinked': 'Аккаунт отвязан.',
   'profile.unlinkTitle': 'Отвязать аккаунт?',
   'profile.unlinkBody': 'Убрать {provider} как способ входа? Позже можно привязать снова.',
+  'profile.deleteAccount': 'Удалить аккаунт',
+  'profile.deleteTitle': 'Удалить аккаунт?',
+  'profile.deleteWarn': 'Аккаунт будет удалён, а способы входа освобождены. Отменить нельзя.',
+  'profile.deleteEmailPrompt': 'Мы отправили код на вашу почту. Введите его, чтобы удалить аккаунт.',
+  'profile.deletePhrasePrompt': 'Введите DELETE для подтверждения.',
+  'profile.deletePhrasePlaceholder': 'DELETE',
+  'profile.deleteConfirm': 'Удалить навсегда',
+  'deleted.title': 'Учётная запись удалена',
+  'deleted.body': 'Аккаунт удалён. Если снова откроете приложение — будет создан новый аккаунт.',
 
   'settings.title': 'Настройки',
   'settings.theme': 'Тема',

ui/src/lib/mock/client.ts

@@ -687,6 +687,10 @@ export class MockGateway implements GatewayClient {
     this.profile.email = email;
     return { ...emptyLinked(), status: 'changed' };
   }
+  async deleteRequest(): Promise<{ method: 'email' | 'phrase' }> {
+    return { method: this.profile.email ? 'email' : 'phrase' };
+  }
+  async deleteConfirm(_code: string, _phrase: string): Promise<void> {}
   async statsGet(): Promise<Stats> {
     return { ...this.stats };
   }

ui/src/lib/telegram.ts

@@ -36,6 +36,7 @@ interface TelegramWebApp {
   contentSafeAreaInset?: { top: number; bottom: number; left: number; right: number };
   ready?: () => void;
   expand?: () => void;
+  close?: () => void;
   openTelegramLink?: (url: string) => void;
   openLink?: (url: string) => void;
   onEvent?: (event: string, handler: () => void) => void;
@@ -84,6 +85,12 @@ export function insideTelegram(): boolean {
   return !!w && typeof w.initData === 'string' && w.initData.length > 0;
 }
 
+/** telegramClose closes the Mini App (Telegram.WebApp.close), used on the terminal
+ *  account-deleted screen. A no-op outside Telegram. */
+export function telegramClose(): void {
+  webApp()?.close?.();
+}
+
 // The ?NN suffix pins the Bot API SDK version Telegram serves (and busts the cache); keep it at the
 // version the official Mini Apps page currently recommends so newer client features (fullscreen,
 // safe-area insets, vertical-swipe guard, …) are available. Bump it when Telegram bumps theirs.

ui/src/lib/transport.ts

@@ -277,6 +277,12 @@ export function createTransport(baseUrl: string): GatewayClient {
     async changeEmailConfirm(email, code) {
       return codec.decodeLinkResult(await exec('link.email.change.confirm', codec.encodeLinkEmailConfirm(email, code)));
     },
+    async deleteRequest() {
+      return codec.decodeDeleteRequestResult(await exec('account.delete.request', codec.empty()));
+    },
+    async deleteConfirm(code, phrase) {
+      await exec('account.delete.confirm', codec.encodeAccountDeleteConfirm(code, phrase));
+    },
     async statsGet() {
       return codec.decodeStats(await exec('stats.get', codec.empty()));
     },

ui/src/lib/vk.ts

@@ -52,6 +52,18 @@ export async function vkInit(): Promise<void> {
   }
 }
 
+/**
+ * vkClose closes the VK Mini App (VKWebAppClose), used on the terminal account-deleted
+ * screen. Best-effort: a no-op outside VK.
+ */
+export async function vkClose(): Promise<void> {
+  try {
+    await (await bridge()).send('VKWebAppClose', { status: 'success' });
+  } catch {
+    // Outside VK there is no client to receive it.
+  }
+}
+
 /**
  * vkUserName fetches the launching user's display name via VKWebAppGetUserInfo, since VK omits it
  * from the signed launch params. Returns '' on any failure or outside VK, so the backend falls back