feat(profile): sign-in methods matrix — email add/change, provider link/unlink

Profile shows the account's sign-in methods for guests and durable accounts alike:
add or change email, link Telegram on the web (login widget), and unlink a linked
provider. Email is never unlinked (it is changed); unlink is offered only when
another identity remains, and a change to an address owned by another account shows
the non-disclosing 'check the address or contact support'. Add-VK-on-web stays
deferred (no VK OAuth).

Wires linkUnlink / changeEmailRequest / changeEmailConfirm through the client,
transport, mock and codec (encodeLinkUnlink + LinkResult 'unlinked'/'changed'
statuses); codec wire tests; ru/en i18n.

ui/src/lib/client.ts

@@ -177,6 +177,14 @@ export interface GatewayClient {
   linkEmailMerge(email: string, code: string): Promise<LinkResult>;
   linkTelegram(data: string): Promise<LinkResult>;
   linkTelegramMerge(data: string): Promise<LinkResult>;
+  /** Detach a platform identity (kind 'telegram' | 'vk') from the account; email is never
+   *  unlinked. Returns the refreshed link result (status 'unlinked'). */
+  linkUnlink(kind: string): Promise<LinkResult>;
+  /** Change the account's confirmed email: mail a code to the new address, then confirm
+   *  to atomically switch (status 'changed'). A new address owned by another account is
+   *  refused without disclosure. */
+  changeEmailRequest(email: string): Promise<void>;
+  changeEmailConfirm(email: string, code: string): Promise<LinkResult>;
 
   // --- live stream ---
   subscribe(onEvent: (e: PushEvent) => void, onError?: (err: unknown) => void): Unsubscribe;

ui/src/lib/codec.test.ts

@@ -28,6 +28,7 @@ import {
   encodeExchange,
   encodeExportUrlRequest,
   encodeGuestLogin,
+  encodeLinkUnlink,
   encodeStateRequest,
   encodeSubmitPlay,
   encodeTarget,
@@ -458,6 +459,22 @@ describe('codec', () => {
     });
   });
 
+  it('encodes an unlink request carrying the provider kind', () => {
+    const r = fb.LinkUnlinkRequest.getRootAsLinkUnlinkRequest(new ByteBuffer(encodeLinkUnlink('telegram')));
+    expect(r.kind()).toBe('telegram');
+  });
+
+  it('passes an unlinked / changed LinkResult status straight through', () => {
+    for (const status of ['unlinked', 'changed'] as const) {
+      const b = new Builder(64);
+      const s = b.createString(status);
+      fb.LinkResult.startLinkResult(b);
+      fb.LinkResult.addStatus(b, s);
+      b.finish(fb.LinkResult.endLinkResult(b));
+      expect(decodeLinkResult(b.asUint8Array()).status).toBe(status);
+    }
+  });
+
   it('decodes a merged LinkResult carrying a switched session', () => {
     const b = new Builder(128);
     const token = b.createString('tok-9');

ui/src/lib/codec.ts

@@ -731,6 +731,14 @@ export function encodeLinkTelegram(data: string): Uint8Array {
   return finish(b, fb.LinkTelegramRequest.endLinkTelegramRequest(b));
 }
 
+export function encodeLinkUnlink(kind: string): Uint8Array {
+  const b = new Builder(64);
+  const k = b.createString(kind);
+  fb.LinkUnlinkRequest.startLinkUnlinkRequest(b);
+  fb.LinkUnlinkRequest.addKind(b, k);
+  return finish(b, fb.LinkUnlinkRequest.endLinkUnlinkRequest(b));
+}
+
 export function decodeLinkResult(buf: Uint8Array): LinkResult {
   const r = fb.LinkResult.getRootAsLinkResult(new ByteBuffer(buf));
   const sess = r.session();

ui/src/lib/i18n/en.ts

@@ -179,6 +179,15 @@ export const en = {
   'profile.mergeBody': 'This identity already belongs to “{name}” ({games} games, {friends} friends).',
   'profile.mergeIrreversible': 'Merging combines both accounts into this one and cannot be undone.',
   'profile.mergeConfirm': 'Merge',
+  'profile.accountsTitle': 'Sign-in methods',
+  'profile.changeEmail': 'Change',
+  'profile.newEmailPlaceholder': 'New email address',
+  'profile.emailChanged': 'Email updated.',
+  'profile.emailChangeTaken': 'Check the address or contact support.',
+  'profile.unlink': 'Unlink',
+  'profile.unlinked': 'Account unlinked.',
+  'profile.unlinkTitle': 'Unlink account?',
+  'profile.unlinkBody': 'Remove {provider} as a sign-in method? You can link it again later.',
 
   'settings.title': 'Settings',
   'settings.theme': 'Theme',

ui/src/lib/i18n/ru.ts

@@ -179,6 +179,15 @@ export const ru: Record<MessageKey, string> = {
   'profile.mergeBody': 'Эта личность уже принадлежит «{name}» (игр: {games}, друзей: {friends}).',
   'profile.mergeIrreversible': 'Объединение сольёт оба аккаунта в этот и необратимо.',
   'profile.mergeConfirm': 'Объединить',
+  'profile.accountsTitle': 'Способы входа',
+  'profile.changeEmail': 'Изменить',
+  'profile.newEmailPlaceholder': 'Новый адрес e-mail',
+  'profile.emailChanged': 'E-mail изменён.',
+  'profile.emailChangeTaken': 'Проверьте правильность e-mail или обратитесь в поддержку.',
+  'profile.unlink': 'Отвязать',
+  'profile.unlinked': 'Аккаунт отвязан.',
+  'profile.unlinkTitle': 'Отвязать аккаунт?',
+  'profile.unlinkBody': 'Убрать {provider} как способ входа? Позже можно привязать снова.',
 
   'settings.title': 'Настройки',
   'settings.theme': 'Тема',

ui/src/lib/mock/client.ts

@@ -656,20 +656,37 @@ export class MockGateway implements GatewayClient {
       };
     }
     this.profile.isGuest = false;
+    this.profile.email = email;
     return emptyLinked();
   }
-  async linkEmailMerge(_email: string, _code: string): Promise<LinkResult> {
+  async linkEmailMerge(email: string, _code: string): Promise<LinkResult> {
     this.profile.isGuest = false;
+    this.profile.email = email;
     return { ...emptyLinked(), status: 'merged' };
   }
   async linkTelegram(_data: string): Promise<LinkResult> {
     this.profile.isGuest = false;
+    this.profile.telegramLinked = true;
     return emptyLinked();
   }
   async linkTelegramMerge(_data: string): Promise<LinkResult> {
     this.profile.isGuest = false;
+    this.profile.telegramLinked = true;
     return { ...emptyLinked(), status: 'merged' };
   }
+  async linkUnlink(kind: string): Promise<LinkResult> {
+    if (kind === 'telegram') this.profile.telegramLinked = false;
+    if (kind === 'vk') this.profile.vkLinked = false;
+    return { ...emptyLinked(), status: 'unlinked' };
+  }
+  async changeEmailRequest(_email: string): Promise<void> {}
+  async changeEmailConfirm(email: string, _code: string): Promise<LinkResult> {
+    // An address containing "taken" stands in for one confirmed by another account, so the
+    // mock can drive the non-disclosing refusal (never a merge).
+    if (email.includes('taken')) throw new GatewayError('email_taken');
+    this.profile.email = email;
+    return { ...emptyLinked(), status: 'changed' };
+  }
   async statsGet(): Promise<Stats> {
     return { ...this.stats };
   }

ui/src/lib/model.ts

@@ -346,13 +346,14 @@ export interface Session {
   displayName: string;
 }
 
-// LinkResult is the outcome of an account link/merge step. status is
+// LinkResult is the outcome of an account link/merge/unlink/change step. status is
 // 'linked' (bound to the current account), 'merge_required' (the identity belongs to
 // another account — the secondary* fields summarise it for the irreversible
-// confirmation) or 'merged'. session is set only when the active account switched
-// (a guest initiator whose durable counterpart won); the client adopts it.
+// confirmation), 'merged', 'unlinked' (a provider detached) or 'changed' (the email was
+// switched). session is set only when the active account switched (a guest initiator
+// whose durable counterpart won); the client adopts it.
 export interface LinkResult {
-  status: 'linked' | 'merge_required' | 'merged';
+  status: 'linked' | 'merge_required' | 'merged' | 'unlinked' | 'changed';
   secondaryUserId: string;
   secondaryDisplayName: string;
   secondaryGames: number;

ui/src/lib/transport.ts

@@ -268,6 +268,15 @@ export function createTransport(baseUrl: string): GatewayClient {
     async linkTelegramMerge(data) {
       return codec.decodeLinkResult(await exec('link.telegram.merge', codec.encodeLinkTelegram(data)));
     },
+    async linkUnlink(kind) {
+      return codec.decodeLinkResult(await exec('link.unlink', codec.encodeLinkUnlink(kind)));
+    },
+    async changeEmailRequest(email) {
+      await exec('link.email.change.request', codec.encodeLinkEmailRequest(email));
+    },
+    async changeEmailConfirm(email, code) {
+      return codec.decodeLinkResult(await exec('link.email.change.confirm', codec.encodeLinkEmailConfirm(email, code)));
+    },
     async statsGet() {
       return codec.decodeStats(await exec('stats.get', codec.empty()));
     },