Try to implement VK ID

Signed-off-by: denis0001-dev <denis0001.dev@ya.ru>

app/android/src/main/AndroidManifest.xml

@@ -54,6 +54,15 @@
                     android:host="oauth"
                     android:pathPrefix="/yandex" />
             </intent-filter>
+            <intent-filter>
+                <action android:name="android.intent.action.VIEW" />
+                <category android:name="android.intent.category.DEFAULT" />
+                <category android:name="android.intent.category.BROWSABLE" />
+                <data
+                    android:scheme="fromchat"
+                    android:host="oauth"
+                    android:pathPrefix="/vk" />
+            </intent-filter>
         </activity>
         <service
             android:name=".fcm.FromChatFirebaseMessagingService"

app/shared/src/androidMain/kotlin/ru/fromchat/ui/auth/oauth/OAuthWebView.android.kt

@@ -1,4 +1,4 @@
-package ru.fromchat.ui.auth.yandex
+package ru.fromchat.ui.auth.oauth
 
 import android.annotation.SuppressLint
 import android.app.Activity
@@ -57,12 +57,10 @@ import kotlinx.coroutines.delay
 import kotlinx.coroutines.isActive
 import kotlinx.coroutines.suspendCancellableCoroutine
 import ru.fromchat.Logger
-import ru.fromchat.auth.yandex.YANDEX_OAUTH_REDIRECT_URI
-import ru.fromchat.auth.yandex.extractOAuthCode
 import ru.fromchat.ui.components.PredictiveBackHandler
 import kotlin.coroutines.resume
 
-private const val LOG_TAG = "YandexOAuthWV"
+private const val LOG_TAG = "OAuthWebView"
 private const val LOADING_FADE_MS = 250
 private const val LOADING_HIDE_DELAY_MS = 500L
 private const val TOP_ROW_SAMPLE_INTERVAL_MS = 50L
@@ -135,15 +133,18 @@ private const val PAGE_SCROLL_Y_JS = """
 @OptIn(ExperimentalMaterial3Api::class, ExperimentalMaterial3ExpressiveApi::class)
 @SuppressLint("SetJavaScriptEnabled")
 @Composable
-actual fun YandexOAuthWebView(
+actual fun OAuthWebView(
     authorizeUrl: String,
     languageTag: String,
     darkTheme: Boolean,
     fallbackColor: Color,
+    redirectUriPrefix: String,
+    isAuthNavigation: (url: String) -> Boolean,
     clearCookies: Boolean,
+    themeCookieHosts: List<String>,
     onPageBackgroundColor: (Color) -> Unit,
     onHistoryBackAvailabilityChanged: (Boolean) -> Unit,
-    onCode: (String) -> Unit,
+    onRedirectUrl: (String) -> Unit,
     onError: (String) -> Unit,
     onCancel: () -> Unit,
 ) {
@@ -158,8 +159,10 @@ actual fun YandexOAuthWebView(
     val scheme = if (darkTheme) "dark" else "light"
     val onHistoryBackAvailabilityChangedState = rememberUpdatedState(onHistoryBackAvailabilityChanged)
     val onPageBackgroundColorState = rememberUpdatedState(onPageBackgroundColor)
-    val onCodeState = rememberUpdatedState(onCode)
+    val onRedirectUrlState = rememberUpdatedState(onRedirectUrl)
     val onErrorState = rememberUpdatedState(onError)
+    val isAuthNavigationState = rememberUpdatedState(isAuthNavigation)
+    val redirectUriPrefixState = rememberUpdatedState(redirectUriPrefix)
     val onCancelState = rememberUpdatedState(onCancel)
     val lifecycleOwner = LocalLifecycleOwner.current
     val instanceId = remember { Integer.toHexString(System.identityHashCode(Any())) }
@@ -193,7 +196,7 @@ actual fun YandexOAuthWebView(
         }
     }
 
-    ApplyYandexWebViewSystemBars(
+    ApplyOAuthWebViewSystemBars(
         chromeColor = chromeColor,
         darkTheme = darkTheme,
         restoreSurfaceColor = fallbackColor,
@@ -269,7 +272,7 @@ actual fun YandexOAuthWebView(
         onCancel = { },
     )
 
-    val client = remember(authorizeUrl, lang, darkTheme) {
+    val client = remember(authorizeUrl, lang, darkTheme, redirectUriPrefix) {
         Logger.i(
             LOG_TAG,
             "WebViewClient create id=$instanceId darkTheme=$darkTheme lang=$lang " +
@@ -278,17 +281,16 @@ actual fun YandexOAuthWebView(
         object : WebViewClient() {
             private fun handleSpecialUrl(view: WebView?, url: String?): Boolean {
                 if (url.isNullOrBlank()) return false
-                if (url.startsWith("fromchat://", ignoreCase = true)) {
+                val redirectPrefix = redirectUriPrefixState.value
+                // Intercept trusted HTTPS callback (and fromchat:// deep links) before any page paint.
+                if (url.startsWith(redirectPrefix, ignoreCase = true) ||
+                    url.startsWith("fromchat://", ignoreCase = true)
+                ) {
                     Logger.i(LOG_TAG, "intercept redirect url=${shortUrl(url)} id=$instanceId")
-                    val code = extractOAuthCode(url)
-                    if (code != null) {
-                        onCodeState.value(code)
-                    } else {
-                        onErrorState.value("")
-                    }
+                    onRedirectUrlState.value(url)
                     return true
                 }
-                if (!isYandexAuthNavigation(url)) {
+                if (!isAuthNavigationState.value(url)) {
                     Logger.d(LOG_TAG, "external nav url=${shortUrl(url)} id=$instanceId")
                     view?.context?.let { ctx ->
                         runCatching {
@@ -327,7 +329,11 @@ actual fun YandexOAuthWebView(
                         "wv=${view?.let { Integer.toHexString(System.identityHashCode(it)) }} " +
                         "canGoBack=${view?.canGoBack()} stack=${Throwable().stackTraceToString().lineSequence().take(8).joinToString(" ← ")}",
                 )
-                if (url != null && url.startsWith(YANDEX_OAUTH_REDIRECT_URI, ignoreCase = true)) {
+                if (url != null && (
+                    url.startsWith(redirectUriPrefixState.value, ignoreCase = true) ||
+                        url.startsWith("fromchat://", ignoreCase = true)
+                    )
+                ) {
                     handleSpecialUrl(view, url)
                 }
                 pageLoading = true
@@ -374,16 +380,16 @@ actual fun YandexOAuthWebView(
                         "stack=${Throwable().stackTraceToString().lineSequence().drop(1).take(10).joinToString(" ← ")}",
                 )
                 if (clearCookies) {
-                    clearYandexWebViewCookies()
+                    clearOAuthWebViewCookies()
                 }
-                seedYandexThemeCookies(darkTheme)
+                seedOAuthThemeCookies(darkTheme, themeCookieHosts)
                 WebView(activity).apply {
                     setBackgroundColor(fallbackColor.toArgb())
                     settings.javaScriptEnabled = true
                     settings.domStorageEnabled = true
                     settings.javaScriptCanOpenWindowsAutomatically = true
                     settings.setSupportMultipleWindows(true)
-                    applyYandexDarkSettingsIfNeeded(this, darkTheme)
+                    applyOAuthDarkSettingsIfNeeded(this, darkTheme)
                     webViewClient = client
                     webChromeClient = object : WebChromeClient() {
                         override fun onCreateWindow(
@@ -394,14 +400,14 @@ actual fun YandexOAuthWebView(
                         ): Boolean {
                             val transport = resultMsg?.obj as? WebView.WebViewTransport ?: return false
                             val temp = WebView(activity).apply {
-                                applyYandexDarkSettingsIfNeeded(this, darkTheme)
+                                applyOAuthDarkSettingsIfNeeded(this, darkTheme)
                                 webViewClient = object : WebViewClient() {
                                     override fun shouldOverrideUrlLoading(
                                         v: WebView?,
                                         request: WebResourceRequest?,
                                     ): Boolean {
                                         val url = request?.url?.toString() ?: return false
-                                        if (!isYandexAuthNavigation(url)) {
+                                        if (!isAuthNavigationState.value(url)) {
                                             runCatching {
                                                 context.startActivity(
                                                     Intent(Intent.ACTION_VIEW, Uri.parse(url)),
@@ -451,7 +457,7 @@ actual fun YandexOAuthWebView(
             update = { wv ->
                 val clientChanged = wv.webViewClient !== client
                 val darkBefore = wv.getTag(TAG_APPLIED_DARK_THEME) as? Boolean
-                applyYandexDarkSettingsIfNeeded(wv, darkTheme)
+                applyOAuthDarkSettingsIfNeeded(wv, darkTheme)
                 if (clientChanged) {
                     Logger.i(
                         LOG_TAG,
@@ -500,7 +506,7 @@ actual fun YandexOAuthWebView(
 }
 
 @Composable
-private fun ApplyYandexWebViewSystemBars(
+private fun ApplyOAuthWebViewSystemBars(
     chromeColor: Color,
     darkTheme: Boolean,
     restoreSurfaceColor: Color,
@@ -557,26 +563,19 @@ private fun Context.findActivity(): Activity? {
     return null
 }
 
-private fun clearYandexWebViewCookies() {
+private fun clearOAuthWebViewCookies() {
     val cookieManager = CookieManager.getInstance()
     cookieManager.setAcceptCookie(true)
     cookieManager.removeAllCookies(null)
     cookieManager.flush()
-    Logger.i(LOG_TAG, "cleared all WebView cookies for Yandex re-auth")
+    Logger.i(LOG_TAG, "cleared all WebView cookies for OAuth re-auth")
 }
 
-private fun seedYandexThemeCookies(darkTheme: Boolean) {
+private fun seedOAuthThemeCookies(darkTheme: Boolean, hosts: List<String>) {
+    if (hosts.isEmpty()) return
     val theme = if (darkTheme) "dark" else "light"
     val cookieManager = CookieManager.getInstance()
     cookieManager.setAcceptCookie(true)
-    val hosts = listOf(
-        "https://yandex.ru",
-        "https://yandex.com",
-        "https://passport.yandex.ru",
-        "https://passport.yandex.com",
-        "https://oauth.yandex.ru",
-        "https://oauth.yandex.com",
-    )
     for (host in hosts) {
         cookieManager.setCookie(host, "color_scheme=$theme; path=/")
         cookieManager.setCookie(host, "theme=$theme; path=/")
@@ -590,7 +589,7 @@ private fun seedYandexThemeCookies(darkTheme: Boolean) {
  * Re-applying the same force-dark value can reload the page and wipe in-progress OAuth UI.
  */
 @Suppress("DEPRECATION")
-private fun applyYandexDarkSettingsIfNeeded(webView: WebView, darkTheme: Boolean) {
+private fun applyOAuthDarkSettingsIfNeeded(webView: WebView, darkTheme: Boolean) {
     val previous = webView.getTag(TAG_APPLIED_DARK_THEME) as? Boolean
     if (previous == darkTheme) return
     Logger.w(
@@ -671,36 +670,3 @@ private suspend fun sampleTopRowColor(webView: WebView): Color? {
         }
     }
 }
-
-/**
- * Keep Yandex ID / OAuth / captcha flows in the WebView; open everything else externally.
- */
-internal fun isYandexAuthNavigation(url: String): Boolean {
-    if (url.startsWith("fromchat://", ignoreCase = true)) return true
-    val uri = Uri.parse(url)
-    val host = uri.host?.lowercase() ?: return false
-    val path = uri.path.orEmpty().lowercase()
-
-    if (host == "yandex.ru" || host == "www.yandex.ru" || host == "ya.ru" || host == "www.ya.ru") {
-        return path.contains("captcha") ||
-            path.startsWith("/auth") ||
-            path.startsWith("/showcaptcha") ||
-            path.startsWith("/checkcaptcha")
-    }
-
-    return host == "oauth.yandex.com" ||
-        host == "oauth.yandex.ru" ||
-        host.endsWith(".oauth.yandex.com") ||
-        host.endsWith(".oauth.yandex.ru") ||
-        host == "passport.yandex.ru" ||
-        host == "passport.yandex.com" ||
-        host.endsWith(".passport.yandex.ru") ||
-        host.endsWith(".passport.yandex.com") ||
-        host.startsWith("auth.yandex.") ||
-        host.startsWith("login.yandex.") ||
-        host.startsWith("id.yandex.") ||
-        host == "sso.passport.yandex.ru" ||
-        host == "captcha.yandex.net" ||
-        host.endsWith(".captcha.yandex.net") ||
-        (host.contains("captcha") && host.contains("yandex"))
-}

app/shared/src/commonMain/composeResources/drawable/ic_vk.xml

@@ -0,0 +1,10 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="48"
+    android:viewportHeight="48">
+    <!-- VK Compact Logo (2021–present) letter mark only; brand blue background removed for tintable icons. -->
+    <path
+        android:fillColor="#FFFFFFFF"
+        android:pathData="M25.54,34.5801C14.6,34.5801 8.3601,27.0801 8.1001,14.6001H13.5801C13.7601,23.7601 17.8,27.6401 21,28.4401V14.6001H26.1602V22.5001C29.3202,22.1601 32.6398,18.5601 33.7598,14.6001H38.9199C38.0599,19.4801 34.4599,23.0801 31.8999,24.5601C34.4599,25.7601 38.5601,28.9001 40.1201,34.5801H34.4399C33.2199,30.7801 30.1802,27.8401 26.1602,27.4401V34.5801H25.54Z" />
+</vector>

app/shared/src/commonMain/composeResources/values-ru/strings.xml

@@ -55,9 +55,14 @@
     <string name="auth_step_yandex_title">Войдите через Яндекс ID</string>
     <string name="auth_step_yandex_body">Так мы боремся с вредоносными ботами и соблюдаем требования российских законов. От Яндекса мы получаем только email — и мы его не сохраняем: вход нужен лишь для защиты.</string>
     <string name="auth_step_yandex_cta">Продолжить через Яндекс ID</string>
+    <string name="auth_step_verify_title">Подтвердите аккаунт</string>
+    <string name="auth_step_verify_body">Выберите Яндекс ID или VK ID. Мы используем это только против ботов и для соблюдения законов — email и профиль этих сервисов не сохраняем.</string>
+    <string name="auth_step_vk_cta">Продолжить через VK ID</string>
     <string name="auth_yandex_webview_title">Яндекс ID</string>
     <string name="auth_yandex_client_mismatch">Сервер вернул неожиданный идентификатор приложения Яндекса. Обновите приложение или обратитесь в поддержку.</string>
     <string name="auth_yandex_failed">Вход через Яндекс ID отменён или не удался.</string>
+    <string name="auth_vk_client_mismatch">Сервер вернул неожиданный идентификатор приложения VK. Обновите приложение или обратитесь в поддержку.</string>
+    <string name="auth_vk_failed">Вход через VK ID отменён или не удался.</string>
     <string name="chats">Чаты</string>
     <string name="contacts">Контакты</string>
     <string name="profile">Профиль</string>
@@ -433,6 +438,13 @@
     <string name="settings_yandex_step_confirm_cta">Продолжить</string>
     <string name="settings_yandex_step_done_title">Яндекс ID обновлён</string>
     <string name="settings_yandex_step_done_body">Аккаунт теперь привязан к Яндекс ID, с которым вы только что вошли.</string>
+    <string name="settings_account_change_vk">Сменить VK ID</string>
+    <string name="settings_account_change_vk_d">Привязать другой аккаунт VK</string>
+    <string name="settings_vk_step_confirm_title">Сменить VK ID?</string>
+    <string name="settings_vk_step_confirm_body">Это не удаляет ваш аккаунт FromChat. Предыдущий VK ID будет освобождён, а вместо него привяжется тот, с которым вы войдёте.</string>
+    <string name="settings_vk_step_confirm_cta">Продолжить</string>
+    <string name="settings_vk_step_done_title">VK ID обновлён</string>
+    <string name="settings_vk_step_done_body">Аккаунт теперь привязан к VK ID, с которым вы только что вошли.</string>
     <string name="settings_done">Готово</string>
     <string name="settings_account_delete_confirm_title">Удалить аккаунт?</string>
     <string name="settings_account_delete_confirm_body">Это нельзя отменить.</string>

app/shared/src/commonMain/composeResources/values/strings.xml

@@ -62,9 +62,14 @@
     <string name="auth_step_yandex_title">Sign in with Yandex ID</string>
     <string name="auth_step_yandex_body">This helps us fight malicious bots and meet Russian legal requirements. From Yandex we only get your email — and we don’t store it; sign-in is only used for security reasons.</string>
     <string name="auth_step_yandex_cta">Continue with Yandex ID</string>
+    <string name="auth_step_verify_title">Verify your account</string>
+    <string name="auth_step_verify_body">Choose Yandex ID or VK ID. We only use this to fight bots and meet legal requirements — we don’t store your email or profile from these providers.</string>
+    <string name="auth_step_vk_cta">Continue with VK ID</string>
     <string name="auth_yandex_webview_title">Yandex ID</string>
     <string name="auth_yandex_client_mismatch">This server returned an unexpected Yandex app id. Update the app or contact support.</string>
     <string name="auth_yandex_failed">Yandex sign-in was cancelled or failed.</string>
+    <string name="auth_vk_client_mismatch">This server returned an unexpected VK app id. Update the app or contact support.</string>
+    <string name="auth_vk_failed">VK sign-in was cancelled or failed.</string>
     <!-- Main Screen -->
     <string name="chats">Chats</string>
     <string name="contacts">Contacts</string>
@@ -461,6 +466,13 @@
     <string name="settings_yandex_step_confirm_cta">Continue</string>
     <string name="settings_yandex_step_done_title">Yandex ID updated</string>
     <string name="settings_yandex_step_done_body">Your account is now linked to the Yandex ID you just signed in with.</string>
+    <string name="settings_account_change_vk">Change VK ID</string>
+    <string name="settings_account_change_vk_d">Link a different VK account</string>
+    <string name="settings_vk_step_confirm_title">Change VK ID?</string>
+    <string name="settings_vk_step_confirm_body">This does not delete your FromChat account. Your previous VK ID will be freed, and the new one you sign in with will be linked instead.</string>
+    <string name="settings_vk_step_confirm_cta">Continue</string>
+    <string name="settings_vk_step_done_title">VK ID updated</string>
+    <string name="settings_vk_step_done_body">Your account is now linked to the VK ID you just signed in with.</string>
     <string name="settings_done">Done</string>
     <string name="settings_account_delete_confirm_title">Delete account?</string>
     <string name="settings_account_delete_confirm_body">This cannot be undone.</string>

app/shared/src/commonMain/kotlin/ru/fromchat/api/ApiClient.kt

@@ -107,13 +107,19 @@ import ru.fromchat.api.schema.user.VerifyPasswordRequest
 import ru.fromchat.api.schema.user.auth.AuthPasswordStepRequest
 import ru.fromchat.api.schema.user.auth.AuthUsernameStepRequest
 import ru.fromchat.api.schema.user.auth.AuthUsernameStepResponse
+import ru.fromchat.api.schema.user.auth.AccountVkResponse
 import ru.fromchat.api.schema.user.auth.AccountYandexResponse
+import ru.fromchat.api.schema.user.auth.ChangeVkRequest
+import ru.fromchat.api.schema.user.auth.ChangeVkResponse
 import ru.fromchat.api.schema.user.auth.ChangeYandexRequest
 import ru.fromchat.api.schema.user.auth.ChangeYandexResponse
 import ru.fromchat.api.schema.user.auth.CheckAuthResponse
 import ru.fromchat.api.schema.user.auth.CheckUsernameResponse
 import ru.fromchat.api.schema.user.auth.LoginResponse
 import ru.fromchat.api.schema.user.auth.RegisterConfirmRequest
+import ru.fromchat.api.schema.user.auth.VkExchangeRequest
+import ru.fromchat.api.schema.user.auth.VkExchangeResponse
+import ru.fromchat.api.schema.user.auth.VkOAuthParams
 import ru.fromchat.api.schema.user.auth.YandexExchangeRequest
 import ru.fromchat.api.schema.user.auth.YandexExchangeResponse
 import ru.fromchat.api.schema.user.auth.YandexOAuthParams
@@ -493,8 +499,9 @@ object ApiClient {
     sealed interface AuthPasswordStepOutcome {
         data class LoggedIn(val response: LoginResponse) : AuthPasswordStepOutcome
         data class NeedsRegister(
-            val yandexRequired: Boolean,
+            val verificationRequired: Boolean,
             val yandex: YandexOAuthParams?,
+            val vk: VkOAuthParams?,
         ) : AuthPasswordStepOutcome
     }
 
@@ -513,8 +520,9 @@ object ApiClient {
         val status = raw["status"]?.jsonPrimitive?.contentOrNull
         return when (status) {
             "needs_register" -> AuthPasswordStepOutcome.NeedsRegister(
-                yandexRequired = raw["yandex_required"]?.jsonPrimitive?.booleanOrNull == true,
+                verificationRequired = raw["verification_required"]?.jsonPrimitive?.booleanOrNull == true,
                 yandex = raw["yandex"]?.let { json.decodeFromJsonElement(YandexOAuthParams.serializer(), it) },
+                vk = raw["vk"]?.let { json.decodeFromJsonElement(VkOAuthParams.serializer(), it) },
             )
             else -> AuthPasswordStepOutcome.LoggedIn(json.decodeFromJsonElement(LoginResponse.serializer(), raw))
         }
@@ -528,6 +536,26 @@ object ApiClient {
             }
             .body()
 
+    suspend fun authVkExchange(
+        code: String,
+        codeVerifier: String,
+        deviceId: String,
+        state: String,
+    ): VkExchangeResponse =
+        httpProbe
+            .post("${ServerConfig.apiBaseUrl}/auth/vk/exchange") {
+                contentType(ContentType.Application.Json)
+                setBody(
+                    VkExchangeRequest(
+                        code = code,
+                        code_verifier = codeVerifier,
+                        device_id = deviceId,
+                        state = state,
+                    ),
+                )
+            }
+            .body()
+
     suspend fun authRegisterConfirm(request: RegisterConfirmRequest): LoginResponse =
         httpProbe
             .post("${ServerConfig.apiBaseUrl}/auth/steps/register/confirm") {
@@ -1542,6 +1570,19 @@ object ApiClient {
             }
             .body()
 
+    suspend fun getAccountVk(): AccountVkResponse =
+        http
+            .get("${ServerConfig.apiBaseUrl}/account/vk")
+            .body()
+
+    suspend fun changeAccountVk(registrationProof: String): ChangeVkResponse =
+        http
+            .post("${ServerConfig.apiBaseUrl}/account/vk") {
+                contentType(ContentType.Application.Json)
+                setBody(ChangeVkRequest(registration_proof = registrationProof))
+            }
+            .body()
+
     suspend fun verifyPasswordDerived(passwordDerived: String) {
         http.post("${ServerConfig.apiBaseUrl}/verify-password") {
             contentType(ContentType.Application.Json)

app/shared/src/commonMain/kotlin/ru/fromchat/api/schema/user/auth/AuthSteps.kt

@@ -27,11 +27,20 @@ data class YandexOAuthParams(
     val scope: String,
 )
 
+@Serializable
+data class VkOAuthParams(
+    val client_id: String,
+    val redirect_uri: String,
+    val authorize_url: String,
+    val scope: String,
+)
+
 @Serializable
 data class AuthNeedsRegisterResponse(
     val status: String,
-    val yandex_required: Boolean = false,
+    val verification_required: Boolean = false,
     val yandex: YandexOAuthParams? = null,
+    val vk: VkOAuthParams? = null,
 )
 
 @Serializable
@@ -45,6 +54,19 @@ data class YandexExchangeResponse(
     val registration_proof: String,
 )
 
+@Serializable
+data class VkExchangeRequest(
+    val code: String,
+    val code_verifier: String,
+    val device_id: String,
+    val state: String,
+)
+
+@Serializable
+data class VkExchangeResponse(
+    val registration_proof: String,
+)
+
 @Serializable
 data class AccountYandexResponse(
     val linked: Boolean = false,
@@ -62,6 +84,23 @@ data class ChangeYandexResponse(
     val unchanged: Boolean = false,
 )
 
+@Serializable
+data class AccountVkResponse(
+    val linked: Boolean = false,
+    val vk: VkOAuthParams? = null,
+)
+
+@Serializable
+data class ChangeVkRequest(
+    val registration_proof: String,
+)
+
+@Serializable
+data class ChangeVkResponse(
+    val status: String? = null,
+    val unchanged: Boolean = false,
+)
+
 @Serializable
 data class RegisterConfirmRequest(
     val username: String,
@@ -70,4 +109,5 @@ data class RegisterConfirmRequest(
     val confirm_password: String,
     val bio: String? = null,
     val registration_proof: String? = null,
+    val vk_registration_proof: String? = null,
 )

app/shared/src/commonMain/kotlin/ru/fromchat/auth/vk/VkAuthNavigation.kt

@@ -0,0 +1,36 @@
+package ru.fromchat.auth.vk
+
+/**
+ * Keep VK ID / OAuth / captcha flows in the WebView; open everything else externally.
+ */
+internal fun isVkAuthNavigation(url: String): Boolean {
+    if (url.startsWith("fromchat://", ignoreCase = true)) return true
+    val withoutScheme = url.substringAfter("://", missingDelimiterValue = "")
+    val host = withoutScheme.substringBefore('/').substringBefore('?').substringBefore('#').lowercase()
+
+    return host == "id.vk.ru" ||
+        host == "id.vk.com" ||
+        host.endsWith(".id.vk.ru") ||
+        host.endsWith(".id.vk.com") ||
+        host == "login.vk.ru" ||
+        host == "login.vk.com" ||
+        host == "oauth.vk.com" ||
+        host == "oauth.vk.ru" ||
+        host == "m.vk.ru" ||
+        host == "m.vk.com" ||
+        host == "vk.ru" ||
+        host == "vk.com" ||
+        host == "www.vk.ru" ||
+        host == "www.vk.com" ||
+        host == "api.fromchat.ru" ||
+        (host.contains("captcha") && host.contains("vk"))
+}
+
+internal val VK_OAUTH_THEME_COOKIE_HOSTS = listOf(
+    "https://id.vk.ru",
+    "https://id.vk.com",
+    "https://vk.ru",
+    "https://vk.com",
+    "https://login.vk.ru",
+    "https://oauth.vk.com",
+)

app/shared/src/commonMain/kotlin/ru/fromchat/auth/vk/VkOAuth.kt

@@ -0,0 +1,150 @@
+package ru.fromchat.auth.vk
+
+import kotlin.random.Random
+import ru.fromchat.auth.yandex.PkcePair
+import ru.fromchat.auth.yandex.generatePkcePair
+import ru.fromchat.auth.yandex.isOfficialApiHost
+
+/**
+ * Prod VK OAuth client id (identity-only app). When non-empty and the API host is
+ * [OFFICIAL_API_HOST], the server-supplied client_id must match this value.
+ */
+internal const val OFFICIAL_VK_OAUTH_CLIENT_ID = ""
+
+internal const val VK_OAUTH_REDIRECT_URI = "https://api.fromchat.ru/oauth/vk"
+internal const val VK_OAUTH_DEEP_LINK = "fromchat://oauth/vk"
+
+private const val OAUTH_STATE_ALPHABET = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_-"
+
+/**
+ * Returns the client_id to use, or null if the official host sent a mismatched id.
+ */
+internal fun resolveVkClientId(serverClientId: String, serverIp: String): String? {
+    val trimmed = serverClientId.trim()
+    if (trimmed.isEmpty()) return null
+    if (!isOfficialApiHost(serverIp)) return trimmed
+    val pinned = OFFICIAL_VK_OAUTH_CLIENT_ID.trim()
+    if (pinned.isEmpty()) return trimmed
+    return if (pinned == trimmed) trimmed else null
+}
+
+internal fun generateOAuthState(length: Int = 43): String {
+    require(length >= 32)
+    val bytes = ByteArray(length).also { Random.Default.nextBytes(it) }
+    return buildString(length) {
+        for (b in bytes) {
+            append(OAUTH_STATE_ALPHABET[(b.toInt() and 0x7f) % OAUTH_STATE_ALPHABET.length])
+        }
+    }
+}
+
+internal fun buildVkAuthorizeUrl(
+    authorizeUrl: String,
+    clientId: String,
+    redirectUri: String,
+    scope: String,
+    codeChallenge: String,
+    state: String,
+    languageTag: String = "en",
+    darkTheme: Boolean = false,
+): String {
+    val lang = languageTag.substringBefore('-').lowercase().ifBlank { "en" }
+    val langId = if (lang == "ru") "0" else "3"
+    val scheme = if (darkTheme) "dark" else "light"
+    val base = authorizeUrl.trim().trimEnd('?')
+    val params = buildList {
+        add("response_type" to "code")
+        add("client_id" to clientId)
+        add("redirect_uri" to redirectUri)
+        if (scope.isNotBlank()) {
+            add("scope" to scope.trim())
+        }
+        add("code_challenge" to codeChallenge)
+        add("code_challenge_method" to "S256")
+        add("state" to state)
+        add("lang_id" to langId)
+        add("scheme" to scheme)
+    }.joinToString("&") { (k, v) ->
+        "${encodeUrl(k)}=${encodeUrl(v)}"
+    }
+    return "$base?$params"
+}
+
+private fun encodeUrl(value: String): String = buildString(value.length) {
+    for (ch in value) {
+        when {
+            ch.isLetterOrDigit() || ch in "-_.~" -> append(ch)
+            else -> {
+                val bytes = ch.toString().encodeToByteArray()
+                for (b in bytes) {
+                    append('%')
+                    append(((b.toInt() shr 4) and 0xf).toString(16).uppercase())
+                    append((b.toInt() and 0xf).toString(16).uppercase())
+                }
+            }
+        }
+    }
+}
+
+data class VkOAuthRedirect(
+    val code: String,
+    val deviceId: String,
+    val state: String,
+)
+
+internal fun extractVkOAuthRedirect(redirectUrl: String, redirectUri: String = VK_OAUTH_REDIRECT_URI): VkOAuthRedirect? {
+    val uri = redirectUrl.trim()
+    val expectedHttps = redirectUri.trim().ifBlank { VK_OAUTH_REDIRECT_URI }
+    val matchesPrefix = uri.startsWith(expectedHttps, ignoreCase = true) ||
+        uri.startsWith(VK_OAUTH_DEEP_LINK, ignoreCase = true) ||
+        uri.contains("/oauth/vk?", ignoreCase = true) ||
+        uri.substringBefore('?', missingDelimiterValue = uri).endsWith("/oauth/vk", ignoreCase = true)
+    if (!matchesPrefix) return null
+    val query = uri.substringAfter('?', missingDelimiterValue = "")
+    if (query.isEmpty()) return null
+    var code: String? = null
+    var deviceId: String? = null
+    var state: String? = null
+    for (part in query.split('&')) {
+        val key = part.substringBefore('=')
+        val raw = part.substringAfter('=', missingDelimiterValue = "")
+        if (raw.isEmpty()) continue
+        val decoded = decodeUrl(raw)
+        when (key) {
+            "code" -> code = decoded
+            "device_id" -> deviceId = decoded
+            "state" -> state = decoded
+        }
+    }
+    val c = code ?: return null
+    val d = deviceId ?: return null
+    val s = state ?: return null
+    return VkOAuthRedirect(code = c, deviceId = d, state = s)
+}
+
+private fun decodeUrl(value: String): String {
+    val bytes = ArrayList<Byte>()
+    var i = 0
+    while (i < value.length) {
+        val c = value[i]
+        when {
+            c == '+' -> {
+                bytes.add(' '.code.toByte())
+                i++
+            }
+            c == '%' && i + 2 < value.length -> {
+                val hex = value.substring(i + 1, i + 3)
+                bytes.add(hex.toInt(16).toByte())
+                i += 3
+            }
+            else -> {
+                bytes.add(c.code.toByte())
+                i++
+            }
+        }
+    }
+    return bytes.toByteArray().decodeToString()
+}
+
+// Re-export PKCE helpers used by VK flows (same module as Yandex).
+internal fun generateVkPkcePair(): PkcePair = generatePkcePair()

app/shared/src/commonMain/kotlin/ru/fromchat/auth/yandex/YandexAuthNavigation.kt

@@ -0,0 +1,44 @@
+package ru.fromchat.auth.yandex
+
+/**
+ * Keep Yandex ID / OAuth / captcha flows in the WebView; open everything else externally.
+ */
+internal fun isYandexAuthNavigation(url: String): Boolean {
+    if (url.startsWith("fromchat://", ignoreCase = true)) return true
+    val withoutScheme = url.substringAfter("://", missingDelimiterValue = "")
+    val hostAndPath = withoutScheme.substringBefore('#').substringBefore('?')
+    val host = hostAndPath.substringBefore('/').lowercase()
+    val path = hostAndPath.substringAfter('/', missingDelimiterValue = "").lowercase().let { "/$it" }
+
+    if (host == "yandex.ru" || host == "www.yandex.ru" || host == "ya.ru" || host == "www.ya.ru") {
+        return path.contains("captcha") ||
+            path.startsWith("/auth") ||
+            path.startsWith("/showcaptcha") ||
+            path.startsWith("/checkcaptcha")
+    }
+
+    return host == "oauth.yandex.com" ||
+        host == "oauth.yandex.ru" ||
+        host.endsWith(".oauth.yandex.com") ||
+        host.endsWith(".oauth.yandex.ru") ||
+        host == "passport.yandex.ru" ||
+        host == "passport.yandex.com" ||
+        host.endsWith(".passport.yandex.ru") ||
+        host.endsWith(".passport.yandex.com") ||
+        host.startsWith("auth.yandex.") ||
+        host.startsWith("login.yandex.") ||
+        host.startsWith("id.yandex.") ||
+        host == "sso.passport.yandex.ru" ||
+        host == "captcha.yandex.net" ||
+        host.endsWith(".captcha.yandex.net") ||
+        (host.contains("captcha") && host.contains("yandex"))
+}
+
+internal val YANDEX_OAUTH_THEME_COOKIE_HOSTS = listOf(
+    "https://yandex.ru",
+    "https://yandex.com",
+    "https://passport.yandex.ru",
+    "https://passport.yandex.com",
+    "https://oauth.yandex.ru",
+    "https://oauth.yandex.com",
+)

app/shared/src/commonMain/kotlin/ru/fromchat/ui/App.kt

@@ -79,6 +79,8 @@ import ru.fromchat.legal.DocumentScreen
 import ru.fromchat.legal.DocumentType
 import ru.fromchat.notifications.NotificationLaunchCoordinator
 import ru.fromchat.ui.auth.AuthScreen
+import ru.fromchat.ui.auth.vk.VkOAuthNav
+import ru.fromchat.ui.auth.vk.VkOAuthScreen
 import ru.fromchat.ui.auth.yandex.YandexOAuthNav
 import ru.fromchat.ui.auth.yandex.YandexOAuthScreen
 import ru.fromchat.ui.calls.CallOverlay
@@ -103,6 +105,9 @@ import ru.fromchat.ui.main.settings.account.changepassword.ChangePasswordScreen
 import ru.fromchat.ui.main.settings.account.changeyandex.ChangeYandexConfirmScreen
 import ru.fromchat.ui.main.settings.account.changeyandex.ChangeYandexDoneScreen
 import ru.fromchat.ui.main.settings.account.changeyandex.ChangeYandexOAuthScreen
+import ru.fromchat.ui.main.settings.account.changevk.ChangeVkConfirmScreen
+import ru.fromchat.ui.main.settings.account.changevk.ChangeVkDoneScreen
+import ru.fromchat.ui.main.settings.account.changevk.ChangeVkOAuthScreen
 import ru.fromchat.ui.main.settings.account.delete.DeleteAccountScreen
 import ru.fromchat.ui.main.settings.server.ServerConfigScreen
 import ru.fromchat.ui.profile.EditProfileFocusField
@@ -466,6 +471,10 @@ fun App(
                                 YandexOAuthScreen()
                             }
 
+                            composable(VkOAuthNav.ROUTE) {
+                                VkOAuthScreen()
+                            }
+
                             composable("chat") {
                                 MainScreen(
                                     sharedTransitionScope = this@SharedTransitionLayout,
@@ -699,6 +708,26 @@ fun App(
                                 )
                             }
 
+                            settingsComposable(SettingsRoutes.AccountVkFlow) {
+                                ChangeVkConfirmScreen(
+                                    onBack = { navController.navigateUp() },
+                                )
+                            }
+
+                            settingsComposable(SettingsRoutes.AccountVkOAuth) {
+                                ChangeVkOAuthScreen(
+                                    onBack = { navController.navigateUp() },
+                                )
+                            }
+
+                            settingsComposable(SettingsRoutes.AccountVkDone) {
+                                ChangeVkDoneScreen(
+                                    onDone = {
+                                        navController.popBackStack(SettingsRoutes.Account, inclusive = false)
+                                    },
+                                )
+                            }
+
                             settingsComposable(SettingsRoutes.Account) {
                                 AccountScreen(
                                     onBack = { navController.navigateUp() },
@@ -709,6 +738,7 @@ fun App(
                                     },
                                     onChangePassword = { navController.navigate(SettingsRoutes.SecurityPasswordFlow) },
                                     onChangeYandexId = { navController.navigate(SettingsRoutes.AccountYandexFlow) },
+                                    onChangeVkId = { navController.navigate(SettingsRoutes.AccountVkFlow) },
                                     onDeleteAccount = { navController.navigate(SettingsRoutes.AccountDeleteFlow) },
                                 )
                             }

app/shared/src/commonMain/kotlin/ru/fromchat/ui/auth/AuthRegisterDraft.kt

@@ -1,9 +1,10 @@
 package ru.fromchat.ui.auth
 
+import ru.fromchat.api.schema.user.auth.VkOAuthParams
 import ru.fromchat.api.schema.user.auth.YandexOAuthParams
 
 /**
- * Survives [AuthScreen] leaving composition when navigating to the Yandex OAuth route.
+ * Survives [AuthScreen] leaving composition when navigating to an OAuth route.
  * Cleared on welcome / successful auth / explicit reset to username.
  */
 internal object AuthRegisterDraft {
@@ -12,9 +13,11 @@ internal object AuthRegisterDraft {
     var confirmPassword: String = ""
     var displayName: String = ""
     var bio: String = ""
-    var yandexRequired: Boolean = false
+    var verificationRequired: Boolean = false
     var yandexParams: YandexOAuthParams? = null
-    var registrationProof: String? = null
+    var vkParams: VkOAuthParams? = null
+    var yandexRegistrationProof: String? = null
+    var vkRegistrationProof: String? = null
     var page: Int = 0
 
     fun clear() {
@@ -23,9 +26,11 @@ internal object AuthRegisterDraft {
         confirmPassword = ""
         displayName = ""
         bio = ""
-        yandexRequired = false
+        verificationRequired = false
         yandexParams = null
-        registrationProof = null
+        vkParams = null
+        yandexRegistrationProof = null
+        vkRegistrationProof = null
         page = 0
     }
 }

app/shared/src/commonMain/kotlin/ru/fromchat/ui/auth/AuthScreen.kt

@@ -30,13 +30,13 @@ import ru.fromchat.api.instance.probeServer
 import ru.fromchat.api.schema.core.ErrorResponse
 import ru.fromchat.api.schema.user.auth.LoginResponse
 import ru.fromchat.api.schema.user.auth.RegisterConfirmRequest
+import ru.fromchat.api.schema.user.auth.VkOAuthParams
 import ru.fromchat.api.schema.user.auth.YandexOAuthParams
 import ru.fromchat.change_server
 import ru.fromchat.config.Settings
 import ru.fromchat.ui.LocalNavController
 import ru.fromchat.ui.auth.register.confirmPasswordStepPage
 import ru.fromchat.ui.auth.register.profileStepPage
-import ru.fromchat.ui.auth.yandex.yandexIdStepPage
 import ru.fromchat.ui.components.ExpressiveStepFlowScaffold
 import ru.fromchat.ui.components.Text
 import ru.fromchat.ui.components.TextCta
@@ -49,15 +49,16 @@ private enum class AuthFlowStep {
     Username,
     Password,
     ConfirmPassword,
-    YandexId,
+    IdentityVerify,
     Profile,
 }
 
 internal sealed interface PasswordStepResult {
     data object LoginSuccess : PasswordStepResult
     data class NeedsRegister(
-        val yandexRequired: Boolean,
+        val verificationRequired: Boolean,
         val yandex: YandexOAuthParams?,
+        val vk: VkOAuthParams?,
     ) : PasswordStepResult
     data class WrongPassword(val message: String) : PasswordStepResult
     data class RateLimited(val message: String) : PasswordStepResult
@@ -121,8 +122,9 @@ internal suspend fun authPasswordStep(
         }
 
         is ApiClient.AuthPasswordStepOutcome.NeedsRegister -> PasswordStepResult.NeedsRegister(
-            yandexRequired = outcome.yandexRequired,
+            verificationRequired = outcome.verificationRequired,
             yandex = outcome.yandex,
+            vk = outcome.vk,
         )
     }
 } catch (e: ClientRequestException) {
@@ -146,7 +148,8 @@ internal suspend fun register(
     displayName: String,
     password: String,
     bio: String,
-    registrationProof: String?,
+    yandexRegistrationProof: String?,
+    vkRegistrationProof: String?,
     unexpectedError: String,
 ) = try {
     fullLogin(username.trim(), password.trim()) {
@@ -158,7 +161,8 @@ internal suspend fun register(
                 password = derived,
                 confirm_password = derived,
                 bio = bio.trim().takeIf { it.isNotEmpty() },
-                registration_proof = registrationProof,
+                registration_proof = yandexRegistrationProof,
+                vk_registration_proof = vkRegistrationProof,
             ),
         )
     }
@@ -214,9 +218,11 @@ fun AuthScreen(
     var confirmPassword by remember { mutableStateOf(AuthRegisterDraft.confirmPassword) }
     var displayName by remember { mutableStateOf(AuthRegisterDraft.displayName) }
     var bio by remember { mutableStateOf(AuthRegisterDraft.bio) }
-    var yandexRequired by remember { mutableStateOf(AuthRegisterDraft.yandexRequired) }
+    var verificationRequired by remember { mutableStateOf(AuthRegisterDraft.verificationRequired) }
     var yandexParams by remember { mutableStateOf(AuthRegisterDraft.yandexParams) }
-    var registrationProof by remember { mutableStateOf(AuthRegisterDraft.registrationProof) }
+    var vkParams by remember { mutableStateOf(AuthRegisterDraft.vkParams) }
+    var yandexRegistrationProof by remember { mutableStateOf(AuthRegisterDraft.yandexRegistrationProof) }
+    var vkRegistrationProof by remember { mutableStateOf(AuthRegisterDraft.vkRegistrationProof) }
 
     fun persistDraft() {
         AuthRegisterDraft.username = username
@@ -224,9 +230,11 @@ fun AuthScreen(
         AuthRegisterDraft.confirmPassword = confirmPassword
         AuthRegisterDraft.displayName = displayName
         AuthRegisterDraft.bio = bio
-        AuthRegisterDraft.yandexRequired = yandexRequired
+        AuthRegisterDraft.verificationRequired = verificationRequired
         AuthRegisterDraft.yandexParams = yandexParams
-        AuthRegisterDraft.registrationProof = registrationProof
+        AuthRegisterDraft.vkParams = vkParams
+        AuthRegisterDraft.yandexRegistrationProof = yandexRegistrationProof
+        AuthRegisterDraft.vkRegistrationProof = vkRegistrationProof
         AuthRegisterDraft.page = flowState.pagerState.currentPage
     }
 
@@ -255,9 +263,11 @@ fun AuthScreen(
         confirmPassword = ""
         displayName = ""
         bio = ""
-        yandexRequired = false
+        verificationRequired = false
         yandexParams = null
-        registrationProof = null
+        vkParams = null
+        yandexRegistrationProof = null
+        vkRegistrationProof = null
         AuthRegisterDraft.clear()
         flowState.resetPredictiveState()
         scope.launch {
@@ -265,11 +275,27 @@ fun AuthScreen(
         }
     }
 
+    fun clearProofs() {
+        yandexRegistrationProof = null
+        vkRegistrationProof = null
+    }
+
     DisposableEffect(Unit) {
         onDispose { persistDraft() }
     }
 
-    LaunchedEffect(username, password, confirmPassword, displayName, bio, yandexRequired, yandexParams, registrationProof) {
+    LaunchedEffect(
+        username,
+        password,
+        confirmPassword,
+        displayName,
+        bio,
+        verificationRequired,
+        yandexParams,
+        vkParams,
+        yandexRegistrationProof,
+        vkRegistrationProof,
+    ) {
         persistDraft()
     }
 
@@ -284,7 +310,7 @@ fun AuthScreen(
         snapshotFlow { flowState.pagerState.currentPage }
             .collect { page ->
                 AuthRegisterDraft.page = page
-                if (page == AuthFlowStep.YandexId.ordinal && !yandexRequired) {
+                if (page == AuthFlowStep.IdentityVerify.ordinal && !verificationRequired) {
                     val target = if (page > settledPage) {
                         AuthFlowStep.Profile.ordinal
                     } else {
@@ -296,37 +322,27 @@ fun AuthScreen(
                 }
                 if (page < settledPage) {
                     when (page) {
-                        AuthFlowStep.Username.ordinal -> {
+                        AuthFlowStep.Username.ordinal,
+                        AuthFlowStep.Password.ordinal,
+                        -> {
                             password = ""
                             confirmPassword = ""
-                            yandexRequired = false
+                            verificationRequired = false
                             yandexParams = null
-                            registrationProof = null
+                            vkParams = null
+                            clearProofs()
                         }
 
-                        AuthFlowStep.Password.ordinal -> {
-                            password = ""
-                            confirmPassword = ""
-                            yandexRequired = false
-                            yandexParams = null
-                            registrationProof = null
-                        }
-
-                        AuthFlowStep.ConfirmPassword.ordinal -> {
-                            // Keep confirm password when returning from Yandex ID / OAuth.
-                            registrationProof = null
-                        }
-
-                        AuthFlowStep.YandexId.ordinal -> {
-                            registrationProof = null
-                        }
+                        AuthFlowStep.ConfirmPassword.ordinal,
+                        AuthFlowStep.IdentityVerify.ordinal,
+                        -> clearProofs()
                     }
                 }
                 settledPage = page
             }
     }
 
-    val yandexStep = yandexParams
+    val showVerify = verificationRequired && (yandexParams != null || vkParams != null)
     ExpressiveStepFlowScaffold(
         flowState = flowState,
         pages = listOf(
@@ -343,10 +359,11 @@ fun AuthScreen(
                 password = password,
                 onPasswordChange = { password = it },
                 onLoginSuccess = wrappedAuthSuccess,
-                onNeedsRegister = { required, params ->
-                    yandexRequired = required
-                    yandexParams = params
-                    registrationProof = null
+                onNeedsRegister = { required, yandex, vk ->
+                    verificationRequired = required
+                    yandexParams = yandex
+                    vkParams = vk
+                    clearProofs()
                     flowState.pagerState.animateScrollToPage(AuthFlowStep.ConfirmPassword.ordinal)
                 },
                 onSnackbar = ::snackbar,
@@ -356,19 +373,29 @@ fun AuthScreen(
                 onConfirmPasswordChange = { confirmPassword = it },
                 password = password,
                 onContinue = {
-                    if (yandexRequired && yandexParams != null) {
-                        flowState.pagerState.animateScrollToPage(AuthFlowStep.YandexId.ordinal)
+                    if (showVerify) {
+                        flowState.pagerState.animateScrollToPage(AuthFlowStep.IdentityVerify.ordinal)
                     } else {
                         flowState.pagerState.animateScrollToPage(AuthFlowStep.Profile.ordinal)
                     }
                 },
                 onSnackbar = ::snackbar,
             ),
-            if (yandexStep != null) {
-                yandexIdStepPage(
-                    yandex = yandexStep,
-                    onProof = { proof ->
-                        registrationProof = proof
+            if (showVerify) {
+                identityVerifyStepPage(
+                    yandex = yandexParams,
+                    vk = vkParams,
+                    onProof = { provider, proof ->
+                        when (provider) {
+                            IdentityProvider.Yandex -> {
+                                yandexRegistrationProof = proof
+                                vkRegistrationProof = null
+                            }
+                            IdentityProvider.Vk -> {
+                                vkRegistrationProof = proof
+                                yandexRegistrationProof = null
+                            }
+                        }
                         flowState.pagerState.animateScrollToPage(AuthFlowStep.Profile.ordinal)
                     },
                     onSnackbar = ::snackbar,
@@ -391,7 +418,8 @@ fun AuthScreen(
                 bio = bio,
                 onBioChange = { bio = it },
                 password = password,
-                registrationProof = registrationProof,
+                yandexRegistrationProof = yandexRegistrationProof,
+                vkRegistrationProof = vkRegistrationProof,
                 onRegisterSuccess = wrappedAuthSuccess,
                 onUsernameTaken = resetToUsername,
                 onSnackbar = ::snackbar,

app/shared/src/commonMain/kotlin/ru/fromchat/ui/auth/IdentityVerifyStep.kt

@@ -0,0 +1,217 @@
+package ru.fromchat.ui.auth
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.VerifiedUser
+import androidx.compose.material3.ExperimentalMaterial3ExpressiveApi
+import androidx.compose.material3.MaterialShapes
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberUpdatedState
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.intl.Locale
+import androidx.compose.ui.unit.dp
+import org.jetbrains.compose.resources.stringResource
+import ru.fromchat.Res
+import ru.fromchat.api.schema.user.auth.VkOAuthParams
+import ru.fromchat.api.schema.user.auth.YandexOAuthParams
+import ru.fromchat.auth.vk.VK_OAUTH_REDIRECT_URI
+import ru.fromchat.auth.vk.buildVkAuthorizeUrl
+import ru.fromchat.auth.vk.generateOAuthState
+import ru.fromchat.auth.vk.generateVkPkcePair
+import ru.fromchat.auth.vk.resolveVkClientId
+import ru.fromchat.auth.yandex.YANDEX_OAUTH_REDIRECT_URI
+import ru.fromchat.auth.yandex.buildYandexAuthorizeUrl
+import ru.fromchat.auth.yandex.generatePkcePair
+import ru.fromchat.auth.yandex.resolveYandexClientId
+import ru.fromchat.auth_step_verify_body
+import ru.fromchat.auth_step_verify_title
+import ru.fromchat.auth_step_vk_cta
+import ru.fromchat.auth_step_yandex_cta
+import ru.fromchat.auth_vk_client_mismatch
+import ru.fromchat.auth_yandex_client_mismatch
+import ru.fromchat.config.Settings
+import ru.fromchat.error_unexpected
+import ru.fromchat.ui.LocalNavController
+import ru.fromchat.ui.auth.vk.VkOAuthNav
+import ru.fromchat.ui.auth.yandex.YandexOAuthNav
+import ru.fromchat.ui.components.ActionButton
+import ru.fromchat.ui.components.ExpressiveHeroSpec
+import ru.fromchat.ui.components.ExpressiveStepPage
+import ru.fromchat.ui.components.ExpressiveStepPageHeader
+import ru.fromchat.ui.components.Text
+import ru.fromchat.ui.isAppInDarkTheme
+
+enum class IdentityProvider {
+    Yandex,
+    Vk,
+}
+
+@OptIn(ExperimentalMaterial3ExpressiveApi::class)
+@Composable
+internal fun identityVerifyStepPage(
+    yandex: YandexOAuthParams?,
+    vk: VkOAuthParams?,
+    onProof: suspend (provider: IdentityProvider, proof: String) -> Unit,
+    onSnackbar: (String, Throwable?) -> Unit,
+): ExpressiveStepPage {
+    val navController = LocalNavController.current
+    val colorScheme = MaterialTheme.colorScheme
+    var busy by remember { mutableStateOf(false) }
+    val languageTag = Locale.current.toLanguageTag()
+    val darkTheme = isAppInDarkTheme()
+    val onProofState = rememberUpdatedState(onProof)
+    val onSnackbarState = rememberUpdatedState(onSnackbar)
+
+    val title = stringResource(Res.string.auth_step_verify_title)
+    val body = stringResource(Res.string.auth_step_verify_body)
+    val yandexCta = stringResource(Res.string.auth_step_yandex_cta)
+    val vkCta = stringResource(Res.string.auth_step_vk_cta)
+    val yandexMismatch = stringResource(Res.string.auth_yandex_client_mismatch)
+    val vkMismatch = stringResource(Res.string.auth_vk_client_mismatch)
+    val unexpected = stringResource(Res.string.error_unexpected)
+
+    LaunchedEffect(navController) {
+        val handle = navController.currentBackStackEntry?.savedStateHandle ?: return@LaunchedEffect
+        handle.getStateFlow<String?>(YandexOAuthNav.RESULT_PROOF, null).collect { proof ->
+            if (proof == null) return@collect
+            handle.remove<String>(YandexOAuthNav.RESULT_PROOF)
+            busy = true
+            try {
+                onProofState.value(IdentityProvider.Yandex, proof)
+            } finally {
+                busy = false
+            }
+        }
+    }
+    LaunchedEffect(navController) {
+        val handle = navController.currentBackStackEntry?.savedStateHandle ?: return@LaunchedEffect
+        handle.getStateFlow<String?>(YandexOAuthNav.RESULT_ERROR, null).collect { message ->
+            if (message == null) return@collect
+            handle.remove<String>(YandexOAuthNav.RESULT_ERROR)
+            onSnackbarState.value(message, null)
+        }
+    }
+    LaunchedEffect(navController) {
+        val handle = navController.currentBackStackEntry?.savedStateHandle ?: return@LaunchedEffect
+        handle.getStateFlow<String?>(VkOAuthNav.RESULT_PROOF, null).collect { proof ->
+            if (proof == null) return@collect
+            handle.remove<String>(VkOAuthNav.RESULT_PROOF)
+            busy = true
+            try {
+                onProofState.value(IdentityProvider.Vk, proof)
+            } finally {
+                busy = false
+            }
+        }
+    }
+    LaunchedEffect(navController) {
+        val handle = navController.currentBackStackEntry?.savedStateHandle ?: return@LaunchedEffect
+        handle.getStateFlow<String?>(VkOAuthNav.RESULT_ERROR, null).collect { message ->
+            if (message == null) return@collect
+            handle.remove<String>(VkOAuthNav.RESULT_ERROR)
+            onSnackbarState.value(message, null)
+        }
+    }
+
+    return ExpressiveStepPage(
+        hero = ExpressiveHeroSpec(
+            icon = Icons.Filled.VerifiedUser,
+            polygon = MaterialShapes.Cookie9Sided.normalized(),
+            containerColor = colorScheme.primaryContainer,
+            contentColor = colorScheme.onPrimaryContainer,
+        ),
+        content = {
+            ExpressiveStepPageHeader(title = title, body = body)
+        },
+        button = {
+            Column(
+                modifier = Modifier.fillMaxWidth(),
+                verticalArrangement = Arrangement.spacedBy(12.dp),
+            ) {
+                if (yandex != null) {
+                    ActionButton(
+                        onClick = {
+                            if (busy) return@ActionButton
+                            val serverIp = runCatching { Settings.serverConfig.serverIp }.getOrElse {
+                                onSnackbar(unexpected, it)
+                                return@ActionButton
+                            }
+                            val clientId = resolveYandexClientId(yandex.client_id, serverIp)
+                            if (clientId == null) {
+                                onSnackbar(yandexMismatch, null)
+                                return@ActionButton
+                            }
+                            val pkce = generatePkcePair()
+                            YandexOAuthNav.pending = YandexOAuthNav.Session(
+                                authorizeUrl = buildYandexAuthorizeUrl(
+                                    authorizeUrl = yandex.authorize_url,
+                                    clientId = clientId,
+                                    redirectUri = yandex.redirect_uri.ifBlank { YANDEX_OAUTH_REDIRECT_URI },
+                                    scope = yandex.scope,
+                                    codeChallenge = pkce.codeChallenge,
+                                    languageTag = languageTag,
+                                    darkTheme = darkTheme,
+                                ),
+                                codeVerifier = pkce.codeVerifier,
+                            )
+                            navController.navigate(YandexOAuthNav.ROUTE)
+                        },
+                        enabled = !busy,
+                        loading = busy,
+                        modifier = Modifier.fillMaxWidth(),
+                    ) {
+                        Text(yandexCta)
+                    }
+                }
+                if (vk != null) {
+                    ActionButton(
+                        onClick = {
+                            if (busy) return@ActionButton
+                            val serverIp = runCatching { Settings.serverConfig.serverIp }.getOrElse {
+                                onSnackbar(unexpected, it)
+                                return@ActionButton
+                            }
+                            val clientId = resolveVkClientId(vk.client_id, serverIp)
+                            if (clientId == null) {
+                                onSnackbar(vkMismatch, null)
+                                return@ActionButton
+                            }
+                            val pkce = generateVkPkcePair()
+                            val state = generateOAuthState()
+                            val redirectUri = vk.redirect_uri.ifBlank { VK_OAUTH_REDIRECT_URI }
+                            VkOAuthNav.pending = VkOAuthNav.Session(
+                                authorizeUrl = buildVkAuthorizeUrl(
+                                    authorizeUrl = vk.authorize_url,
+                                    clientId = clientId,
+                                    redirectUri = redirectUri,
+                                    scope = vk.scope,
+                                    codeChallenge = pkce.codeChallenge,
+                                    state = state,
+                                    languageTag = languageTag,
+                                    darkTheme = darkTheme,
+                                ),
+                                codeVerifier = pkce.codeVerifier,
+                                state = state,
+                                redirectUri = redirectUri,
+                            )
+                            navController.navigate(VkOAuthNav.ROUTE)
+                        },
+                        enabled = !busy,
+                        loading = busy,
+                        modifier = Modifier.fillMaxWidth(),
+                    ) {
+                        Text(vkCta)
+                    }
+                }
+            }
+        },
+    )
+}

app/shared/src/commonMain/kotlin/ru/fromchat/ui/auth/PasswordStep.kt

@@ -35,6 +35,7 @@ import ru.fromchat.login
 import ru.fromchat.password
 import ru.fromchat.password_length_error
 import ru.fromchat.show_password
+import ru.fromchat.api.schema.user.auth.VkOAuthParams
 import ru.fromchat.api.schema.user.auth.YandexOAuthParams
 import ru.fromchat.ui.components.ActionButton
 import ru.fromchat.ui.components.ExpressiveHeroSpec
@@ -54,7 +55,11 @@ internal fun passwordStepPage(
     password: String,
     onPasswordChange: (String) -> Unit,
     onLoginSuccess: () -> Unit,
-    onNeedsRegister: suspend (yandexRequired: Boolean, yandex: YandexOAuthParams?) -> Unit,
+    onNeedsRegister: suspend (
+        verificationRequired: Boolean,
+        yandex: YandexOAuthParams?,
+        vk: VkOAuthParams?,
+    ) -> Unit,
     onSnackbar: (String, Throwable?) -> Unit,
 ): ExpressiveStepPage {
     val scope = rememberCoroutineScope()
@@ -135,7 +140,11 @@ internal fun passwordStepPage(
                                 }
 
                                 is PasswordStepResult.NeedsRegister -> {
-                                    onNeedsRegister(result.yandexRequired, result.yandex)
+                                    onNeedsRegister(
+                                        result.verificationRequired,
+                                        result.yandex,
+                                        result.vk,
+                                    )
                                 }
 
                                 is PasswordStepResult.WrongPassword -> {

app/shared/src/commonMain/kotlin/ru/fromchat/ui/auth/oauth/OAuthWebView.kt

@@ -0,0 +1,28 @@
+package ru.fromchat.ui.auth.oauth
+
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.graphics.Color
+
+/**
+ * Platform WebView for identity OAuth (Yandex, VK ID, …).
+ * Intercepts [redirectUriPrefix] and reports the full redirect URL via [onRedirectUrl].
+ *
+ * @param isAuthNavigation Keep matching hosts in-WebView; open everything else externally.
+ * @param themeCookieHosts Optional hosts that receive light/dark theme cookies before load.
+ */
+@Composable
+expect fun OAuthWebView(
+    authorizeUrl: String,
+    languageTag: String,
+    darkTheme: Boolean,
+    fallbackColor: Color,
+    redirectUriPrefix: String,
+    isAuthNavigation: (url: String) -> Boolean,
+    clearCookies: Boolean = false,
+    themeCookieHosts: List<String> = emptyList(),
+    onPageBackgroundColor: (Color) -> Unit = {},
+    onHistoryBackAvailabilityChanged: (Boolean) -> Unit = {},
+    onRedirectUrl: (String) -> Unit,
+    onError: (String) -> Unit,
+    onCancel: () -> Unit,
+)

app/shared/src/commonMain/kotlin/ru/fromchat/ui/auth/register/ProfileStep.kt

@@ -55,7 +55,8 @@ internal fun profileStepPage(
     bio: String,
     onBioChange: (String) -> Unit,
     password: String,
-    registrationProof: String?,
+    yandexRegistrationProof: String?,
+    vkRegistrationProof: String?,
     onRegisterSuccess: () -> Unit,
     onUsernameTaken: () -> Unit,
     onSnackbar: (String, Throwable?) -> Unit,
@@ -148,7 +149,8 @@ internal fun profileStepPage(
                                     displayName = displayName.trim(),
                                     password = password,
                                     bio = bio.trim(),
-                                    registrationProof = registrationProof,
+                                    yandexRegistrationProof = yandexRegistrationProof,
+                                    vkRegistrationProof = vkRegistrationProof,
                                     unexpectedError = unexpected,
                                 )
                             ) {

app/shared/src/commonMain/kotlin/ru/fromchat/ui/auth/vk/VkOAuthNav.kt

@@ -0,0 +1,41 @@
+package ru.fromchat.ui.auth.vk
+
+import androidx.compose.runtime.saveable.listSaver
+import kotlin.concurrent.Volatile
+
+/**
+ * Root [androidx.navigation.NavController] route for the VK OAuth WebView.
+ * Session is staged in [pending] before [navigate]; PKCE verifier and state must not go in the route.
+ * Prefer [SessionSaver] / rememberSaveable on the OAuth screen so pause/recreate keeps PKCE.
+ */
+internal object VkOAuthNav {
+    const val ROUTE = "vkOAuth"
+    const val RESULT_PROOF = "vk_registration_proof"
+    const val RESULT_ERROR = "vk_oauth_error"
+
+    data class Session(
+        val authorizeUrl: String,
+        val codeVerifier: String,
+        val state: String,
+        val redirectUri: String,
+    )
+
+    val SessionSaver = listSaver<Session?, String>(
+        save = { session ->
+            if (session == null) emptyList()
+            else listOf(session.authorizeUrl, session.codeVerifier, session.state, session.redirectUri)
+        },
+        restore = { saved ->
+            if (saved.size < 4) null
+            else Session(
+                authorizeUrl = saved[0],
+                codeVerifier = saved[1],
+                state = saved[2],
+                redirectUri = saved[3],
+            )
+        },
+    )
+
+    @Volatile
+    var pending: Session? = null
+}

app/shared/src/commonMain/kotlin/ru/fromchat/ui/auth/vk/VkOAuthScreen.kt

@@ -0,0 +1,180 @@
+package ru.fromchat.ui.auth.vk
+
+import androidx.compose.animation.AnimatedVisibility
+import androidx.compose.animation.fadeIn
+import androidx.compose.animation.fadeOut
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.safeDrawingPadding
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.automirrored.filled.ArrowBack
+import androidx.compose.material3.FilledIconButton
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButtonDefaults
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.runtime.saveable.rememberSaveable
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.intl.Locale
+import androidx.compose.ui.unit.dp
+import io.ktor.client.call.body
+import io.ktor.client.plugins.ClientRequestException
+import kotlinx.coroutines.launch
+import org.jetbrains.compose.resources.stringResource
+import ru.fromchat.Logger
+import ru.fromchat.Res
+import ru.fromchat.api.ApiClient
+import ru.fromchat.api.schema.core.ErrorResponse
+import ru.fromchat.auth_vk_failed
+import ru.fromchat.back
+import ru.fromchat.ui.auth.vk.VkOAuthWebView
+import ru.fromchat.ui.LocalNavController
+import ru.fromchat.ui.isAppInDarkTheme
+
+private const val LOG_TAG = "VkOAuthScreen"
+
+@Composable
+internal fun VkOAuthScreen() {
+    val navController = LocalNavController.current
+    val scope = rememberCoroutineScope()
+    var session by rememberSaveable(stateSaver = VkOAuthNav.SessionSaver) {
+        mutableStateOf(VkOAuthNav.pending)
+    }
+    val fallbackColor = MaterialTheme.colorScheme.background
+    var chromeColor by remember { mutableStateOf(fallbackColor) }
+    var busy by remember { mutableStateOf(false) }
+    var webViewCanGoBack by remember { mutableStateOf(false) }
+    val failedMessage = stringResource(Res.string.auth_vk_failed)
+    val backLabel = stringResource(Res.string.back)
+    val darkTheme = isAppInDarkTheme()
+    val screenId = remember { (100000..999999).random().toString(16) }
+
+    DisposableEffect(screenId) {
+        Logger.i(
+            LOG_TAG,
+            "compose enter id=$screenId sessionNull=${session == null} " +
+                "pendingNull=${VkOAuthNav.pending == null} darkTheme=$darkTheme " +
+                "route=${navController.currentBackStackEntry?.destination?.route}",
+        )
+        onDispose {
+            Logger.i(LOG_TAG, "compose dispose id=$screenId")
+        }
+    }
+
+    LaunchedEffect(session) {
+        if (session == null) {
+            Logger.w(LOG_TAG, "session null → popBackStack id=$screenId")
+            navController.popBackStack()
+        } else {
+            VkOAuthNav.pending = session
+            Logger.d(LOG_TAG, "session kept id=$screenId urlLen=${session!!.authorizeUrl.length}")
+        }
+    }
+
+    val active = session ?: return
+
+    fun finishWithProof(proof: String) {
+        Logger.i(LOG_TAG, "finishWithProof id=$screenId")
+        VkOAuthNav.pending = null
+        navController.previousBackStackEntry
+            ?.savedStateHandle
+            ?.set(VkOAuthNav.RESULT_PROOF, proof)
+        navController.popBackStack()
+    }
+
+    fun finishWithError(message: String) {
+        Logger.w(LOG_TAG, "finishWithError id=$screenId message=$message")
+        VkOAuthNav.pending = null
+        navController.previousBackStackEntry
+            ?.savedStateHandle
+            ?.set(VkOAuthNav.RESULT_ERROR, message)
+        navController.popBackStack()
+    }
+
+    fun cancel() {
+        if (busy) return
+        Logger.i(LOG_TAG, "cancel id=$screenId")
+        VkOAuthNav.pending = null
+        navController.popBackStack()
+    }
+
+    Box(
+        modifier = Modifier
+            .fillMaxSize()
+            .background(chromeColor),
+    ) {
+        VkOAuthWebView(
+            authorizeUrl = active.authorizeUrl,
+            redirectUri = active.redirectUri,
+            languageTag = Locale.current.toLanguageTag(),
+            darkTheme = darkTheme,
+            fallbackColor = fallbackColor,
+            onPageBackgroundColor = { chromeColor = it },
+            onHistoryBackAvailabilityChanged = { webViewCanGoBack = it },
+            onRedirect = { redirect ->
+                if (busy) return@VkOAuthWebView
+                if (redirect.state != active.state) {
+                    finishWithError(failedMessage)
+                    return@VkOAuthWebView
+                }
+                scope.launch {
+                    busy = true
+                    try {
+                        val proof = ApiClient.authVkExchange(
+                            code = redirect.code,
+                            codeVerifier = active.codeVerifier,
+                            deviceId = redirect.deviceId,
+                            state = redirect.state,
+                        ).registration_proof
+                        finishWithProof(proof)
+                    } catch (e: ClientRequestException) {
+                        val detail = if (e.response.status.value == 400) {
+                            runCatching { e.response.body<ErrorResponse>().detail }
+                                .getOrNull()
+                                ?.ifBlank { null }
+                        } else {
+                            null
+                        }
+                        finishWithError(detail ?: failedMessage)
+                    } catch (_: Exception) {
+                        finishWithError(failedMessage)
+                    } finally {
+                        busy = false
+                    }
+                }
+            },
+            onError = { finishWithError(it.ifBlank { failedMessage }) },
+            onCancel = { cancel() },
+        )
+
+        AnimatedVisibility(
+            visible = !webViewCanGoBack && !busy,
+            enter = fadeIn(),
+            exit = fadeOut(),
+            modifier = Modifier
+                .align(Alignment.TopStart)
+                .safeDrawingPadding()
+                .padding(start = 12.dp, top = 12.dp),
+        ) {
+            FilledIconButton(
+                onClick = { cancel() },
+                colors = IconButtonDefaults.filledIconButtonColors(
+                    containerColor = MaterialTheme.colorScheme.surfaceContainerHigh.copy(alpha = 0.92f),
+                    contentColor = MaterialTheme.colorScheme.onSurface,
+                ),
+            ) {
+                Icon(Icons.AutoMirrored.Filled.ArrowBack, contentDescription = backLabel)
+            }
+        }
+    }
+}

app/shared/src/commonMain/kotlin/ru/fromchat/ui/auth/vk/VkOAuthWebView.kt

@@ -0,0 +1,50 @@
+package ru.fromchat.ui.auth.vk
+
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.graphics.Color
+import ru.fromchat.auth.vk.VK_OAUTH_REDIRECT_URI
+import ru.fromchat.auth.vk.VK_OAUTH_THEME_COOKIE_HOSTS
+import ru.fromchat.auth.vk.VkOAuthRedirect
+import ru.fromchat.auth.vk.extractVkOAuthRedirect
+import ru.fromchat.auth.vk.isVkAuthNavigation
+import ru.fromchat.ui.auth.oauth.OAuthWebView
+
+/**
+ * VK-specific wrapper around [OAuthWebView].
+ *
+ * @param redirectUri Trusted HTTPS redirect from the server (must match VK ID cabinet).
+ */
+@Composable
+internal fun VkOAuthWebView(
+    authorizeUrl: String,
+    redirectUri: String,
+    languageTag: String,
+    darkTheme: Boolean,
+    fallbackColor: Color,
+    clearCookies: Boolean = false,
+    onPageBackgroundColor: (Color) -> Unit = {},
+    onHistoryBackAvailabilityChanged: (Boolean) -> Unit = {},
+    onRedirect: (VkOAuthRedirect) -> Unit,
+    onError: (String) -> Unit,
+    onCancel: () -> Unit,
+) {
+    val resolvedRedirect = redirectUri.trim().ifBlank { VK_OAUTH_REDIRECT_URI }
+    OAuthWebView(
+        authorizeUrl = authorizeUrl,
+        languageTag = languageTag,
+        darkTheme = darkTheme,
+        fallbackColor = fallbackColor,
+        redirectUriPrefix = resolvedRedirect,
+        isAuthNavigation = ::isVkAuthNavigation,
+        clearCookies = clearCookies,
+        themeCookieHosts = VK_OAUTH_THEME_COOKIE_HOSTS,
+        onPageBackgroundColor = onPageBackgroundColor,
+        onHistoryBackAvailabilityChanged = onHistoryBackAvailabilityChanged,
+        onRedirectUrl = { url ->
+            val redirect = extractVkOAuthRedirect(url, resolvedRedirect)
+            if (redirect != null) onRedirect(redirect) else onError("")
+        },
+        onError = onError,
+        onCancel = onCancel,
+    )
+}

app/shared/src/commonMain/kotlin/ru/fromchat/ui/auth/yandex/YandexIdStep.kt

@@ -1,130 +0,0 @@
-package ru.fromchat.ui.auth.yandex
-
-import androidx.compose.foundation.layout.fillMaxWidth
-import androidx.compose.material3.ExperimentalMaterial3ExpressiveApi
-import androidx.compose.material3.MaterialShapes
-import androidx.compose.material3.MaterialTheme
-import androidx.compose.runtime.Composable
-import androidx.compose.runtime.LaunchedEffect
-import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.remember
-import androidx.compose.runtime.rememberUpdatedState
-import androidx.compose.runtime.setValue
-import androidx.compose.ui.Modifier
-import androidx.compose.ui.text.intl.Locale
-import org.jetbrains.compose.resources.stringResource
-import org.jetbrains.compose.resources.vectorResource
-import ru.fromchat.Res
-import ru.fromchat.api.schema.user.auth.YandexOAuthParams
-import ru.fromchat.auth.yandex.YANDEX_OAUTH_REDIRECT_URI
-import ru.fromchat.auth.yandex.buildYandexAuthorizeUrl
-import ru.fromchat.auth.yandex.generatePkcePair
-import ru.fromchat.auth.yandex.resolveYandexClientId
-import ru.fromchat.auth_step_yandex_body
-import ru.fromchat.auth_step_yandex_cta
-import ru.fromchat.auth_step_yandex_title
-import ru.fromchat.auth_yandex_client_mismatch
-import ru.fromchat.config.Settings
-import ru.fromchat.error_unexpected
-import ru.fromchat.ic_yandex
-import ru.fromchat.ui.LocalNavController
-import ru.fromchat.ui.components.ActionButton
-import ru.fromchat.ui.components.ExpressiveHeroSpec
-import ru.fromchat.ui.components.ExpressiveStepPage
-import ru.fromchat.ui.components.ExpressiveStepPageHeader
-import ru.fromchat.ui.components.Text
-import ru.fromchat.ui.isAppInDarkTheme
-
-@OptIn(ExperimentalMaterial3ExpressiveApi::class)
-@Composable
-internal fun yandexIdStepPage(
-    yandex: YandexOAuthParams,
-    onProof: suspend (String) -> Unit,
-    onSnackbar: (String, Throwable?) -> Unit,
-): ExpressiveStepPage {
-    val navController = LocalNavController.current
-    val colorScheme = MaterialTheme.colorScheme
-    var busy by remember { mutableStateOf(false) }
-    val languageTag = Locale.current.toLanguageTag()
-    val darkTheme = isAppInDarkTheme()
-    val onProofState = rememberUpdatedState(onProof)
-    val onSnackbarState = rememberUpdatedState(onSnackbar)
-    val yandexIcon = vectorResource(Res.drawable.ic_yandex)
-
-    val title = stringResource(Res.string.auth_step_yandex_title)
-    val body = stringResource(Res.string.auth_step_yandex_body)
-    val cta = stringResource(Res.string.auth_step_yandex_cta)
-    val clientMismatch = stringResource(Res.string.auth_yandex_client_mismatch)
-    val unexpected = stringResource(Res.string.error_unexpected)
-
-    LaunchedEffect(navController) {
-        val handle = navController.currentBackStackEntry?.savedStateHandle ?: return@LaunchedEffect
-        handle.getStateFlow<String?>(YandexOAuthNav.RESULT_PROOF, null).collect { proof ->
-            if (proof == null) return@collect
-            handle.remove<String>(YandexOAuthNav.RESULT_PROOF)
-            busy = true
-            try {
-                onProofState.value(proof)
-            } finally {
-                busy = false
-            }
-        }
-    }
-
-    LaunchedEffect(navController) {
-        val handle = navController.currentBackStackEntry?.savedStateHandle ?: return@LaunchedEffect
-        handle.getStateFlow<String?>(YandexOAuthNav.RESULT_ERROR, null).collect { message ->
-            if (message == null) return@collect
-            handle.remove<String>(YandexOAuthNav.RESULT_ERROR)
-            onSnackbarState.value(message, null)
-        }
-    }
-
-    return ExpressiveStepPage(
-        hero = ExpressiveHeroSpec(
-            icon = yandexIcon,
-            polygon = MaterialShapes.Cookie9Sided.normalized(),
-            containerColor = colorScheme.primaryContainer,
-            contentColor = colorScheme.onPrimaryContainer,
-        ),
-        content = {
-            ExpressiveStepPageHeader(title = title, body = body)
-        },
-        button = {
-            ActionButton(
-                onClick = {
-                    if (busy) return@ActionButton
-                    val serverIp = runCatching { Settings.serverConfig.serverIp }.getOrElse {
-                        onSnackbar(unexpected, it)
-                        return@ActionButton
-                    }
-                    val clientId = resolveYandexClientId(yandex.client_id, serverIp)
-                    if (clientId == null) {
-                        onSnackbar(clientMismatch, null)
-                        return@ActionButton
-                    }
-                    val pkce = generatePkcePair()
-                    YandexOAuthNav.pending = YandexOAuthNav.Session(
-                        authorizeUrl = buildYandexAuthorizeUrl(
-                            authorizeUrl = yandex.authorize_url,
-                            clientId = clientId,
-                            redirectUri = yandex.redirect_uri.ifBlank { YANDEX_OAUTH_REDIRECT_URI },
-                            scope = yandex.scope,
-                            codeChallenge = pkce.codeChallenge,
-                            languageTag = languageTag,
-                            darkTheme = darkTheme,
-                        ),
-                        codeVerifier = pkce.codeVerifier,
-                    )
-                    navController.navigate(YandexOAuthNav.ROUTE)
-                },
-                enabled = !busy,
-                loading = busy,
-                modifier = Modifier.fillMaxWidth(),
-            ) {
-                Text(cta)
-            }
-        },
-    )
-}

app/shared/src/commonMain/kotlin/ru/fromchat/ui/auth/yandex/YandexOAuthWebView.kt

@@ -2,19 +2,17 @@ package ru.fromchat.ui.auth.yandex
 
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.graphics.Color
+import ru.fromchat.auth.yandex.YANDEX_OAUTH_REDIRECT_URI
+import ru.fromchat.auth.yandex.YANDEX_OAUTH_THEME_COOKIE_HOSTS
+import ru.fromchat.auth.yandex.extractOAuthCode
+import ru.fromchat.auth.yandex.isYandexAuthNavigation
+import ru.fromchat.ui.auth.oauth.OAuthWebView
 
 /**
- * Platform WebView that loads [authorizeUrl] and reports the OAuth redirect.
- * Intercepts `fromchat://oauth/yandex` and returns the authorization code.
- *
- * @param languageTag BCP-47 tag for Accept-Language / WebView locale.
- * @param darkTheme Pins WebView `prefers-color-scheme` via configuration night mode.
- * @param fallbackColor Shown until the page background can be sampled.
- * @param onPageBackgroundColor Reported whenever a non-transparent page background is detected.
- * @param onHistoryBackAvailabilityChanged `true` when the WebView can go back in its own history.
+ * Yandex-specific wrapper around [OAuthWebView].
  */
 @Composable
-expect fun YandexOAuthWebView(
+internal fun YandexOAuthWebView(
     authorizeUrl: String,
     languageTag: String,
     darkTheme: Boolean,
@@ -25,4 +23,23 @@ expect fun YandexOAuthWebView(
     onCode: (String) -> Unit,
     onError: (String) -> Unit,
     onCancel: () -> Unit,
+) {
+    OAuthWebView(
+        authorizeUrl = authorizeUrl,
+        languageTag = languageTag,
+        darkTheme = darkTheme,
+        fallbackColor = fallbackColor,
+        redirectUriPrefix = YANDEX_OAUTH_REDIRECT_URI,
+        isAuthNavigation = ::isYandexAuthNavigation,
+        clearCookies = clearCookies,
+        themeCookieHosts = YANDEX_OAUTH_THEME_COOKIE_HOSTS,
+        onPageBackgroundColor = onPageBackgroundColor,
+        onHistoryBackAvailabilityChanged = onHistoryBackAvailabilityChanged,
+        onRedirectUrl = { url ->
+            val code = extractOAuthCode(url)
+            if (code != null) onCode(code) else onError("")
+        },
+        onError = onError,
+        onCancel = onCancel,
     )
+}

app/shared/src/commonMain/kotlin/ru/fromchat/ui/main/settings/SettingsRoutes.kt

@@ -16,6 +16,9 @@ object SettingsRoutes {
     const val AccountYandexFlow = "settings/account/yandex"
     const val AccountYandexOAuth = "settings/account/yandex/oauth"
     const val AccountYandexDone = "settings/account/yandex/done"
+    const val AccountVkFlow = "settings/account/vk"
+    const val AccountVkOAuth = "settings/account/vk/oauth"
+    const val AccountVkDone = "settings/account/vk/done"
     const val ServerConfig = "serverConfig"
     const val About = "about"
     const val Logs = "settings/logs"

app/shared/src/commonMain/kotlin/ru/fromchat/ui/main/settings/account/AccountScreen.kt

@@ -43,8 +43,11 @@ import ru.fromchat.Res
 import ru.fromchat.api.ApiClient
 import ru.fromchat.back
 import ru.fromchat.cancel
+import ru.fromchat.ic_vk
 import ru.fromchat.ic_yandex
 import ru.fromchat.logout
+import ru.fromchat.settings_account_change_vk
+import ru.fromchat.settings_account_change_vk_d
 import ru.fromchat.settings_account_change_yandex
 import ru.fromchat.settings_account_change_yandex_d
 import ru.fromchat.settings_account_delete
@@ -63,16 +66,20 @@ fun AccountScreen(
     onLogout: () -> Unit,
     onChangePassword: () -> Unit,
     onChangeYandexId: () -> Unit,
+    onChangeVkId: () -> Unit,
     onDeleteAccount: () -> Unit,
 ) {
     val scrollBehavior = TopAppBarDefaults.exitUntilCollapsedScrollBehavior(rememberTopAppBarState())
     val scope = rememberCoroutineScope()
     var showLogoutConfirm by remember { mutableStateOf(false) }
     var yandexAvailable by remember { mutableStateOf(false) }
+    var vkAvailable by remember { mutableStateOf(false) }
     val yandexIcon = vectorResource(Res.drawable.ic_yandex)
+    val vkIcon = vectorResource(Res.drawable.ic_vk)
 
     LaunchedEffect(Unit) {
         yandexAvailable = runCatching { ApiClient.getAccountYandex() }.isSuccess
+        vkAvailable = runCatching { ApiClient.getAccountVk() }.isSuccess
     }
 
     Scaffold(
@@ -133,6 +140,24 @@ fun AccountScreen(
                     )
                 }
 
+                if (vkAvailable) {
+                    ListItem(
+                        headline = stringResource(Res.string.settings_account_change_vk),
+                        supportingText = stringResource(Res.string.settings_account_change_vk_d),
+                        onClick = onChangeVkId,
+                        leadingContent = { Icon(vkIcon, null) },
+                        divider = true,
+                        trailingContent = {
+                            Icon(
+                                imageVector = Icons.AutoMirrored.Filled.KeyboardArrowRight,
+                                contentDescription = null,
+                                modifier = Modifier.size(24.dp),
+                                tint = MaterialTheme.colorScheme.onSurfaceVariant
+                            )
+                        }
+                    )
+                }
+
                 ListItem(
                     headline = stringResource(Res.string.settings_account_delete),
                     supportingText = stringResource(Res.string.settings_account_delete_d),

app/shared/src/commonMain/kotlin/ru/fromchat/ui/main/settings/account/changevk/ChangeVkConfirmScreen.kt

@@ -0,0 +1,161 @@
+package ru.fromchat.ui.main.settings.account.changevk
+
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.material3.ExperimentalMaterial3ExpressiveApi
+import androidx.compose.material3.MaterialShapes
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.SnackbarDuration
+import androidx.compose.material3.SnackbarHostState
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.intl.Locale
+import kotlinx.coroutines.launch
+import org.jetbrains.compose.resources.stringResource
+import org.jetbrains.compose.resources.vectorResource
+import ru.fromchat.Res
+import ru.fromchat.api.ApiClient
+import ru.fromchat.api.schema.user.auth.VkOAuthParams
+import ru.fromchat.auth.vk.VK_OAUTH_REDIRECT_URI
+import ru.fromchat.auth.vk.buildVkAuthorizeUrl
+import ru.fromchat.auth.vk.generateOAuthState
+import ru.fromchat.auth.vk.generateVkPkcePair
+import ru.fromchat.auth.vk.resolveVkClientId
+import ru.fromchat.auth_vk_client_mismatch
+import ru.fromchat.config.Settings
+import ru.fromchat.error_unexpected
+import ru.fromchat.ic_vk
+import ru.fromchat.settings_next
+import ru.fromchat.settings_vk_step_confirm_body
+import ru.fromchat.settings_vk_step_confirm_cta
+import ru.fromchat.settings_vk_step_confirm_title
+import ru.fromchat.ui.LocalNavController
+import ru.fromchat.ui.components.ActionButton
+import ru.fromchat.ui.components.ExpressiveHeroSpec
+import ru.fromchat.ui.components.ExpressiveStepFlowScaffold
+import ru.fromchat.ui.components.ExpressiveStepPage
+import ru.fromchat.ui.components.ExpressiveStepPageHeader
+import ru.fromchat.ui.components.Text
+import ru.fromchat.ui.components.rememberExpressiveStepFlow
+import ru.fromchat.ui.components.showReplacingSnackbar
+import ru.fromchat.ui.isAppInDarkTheme
+import ru.fromchat.ui.main.settings.SettingsRoutes
+
+@OptIn(ExperimentalMaterial3ExpressiveApi::class)
+@Composable
+fun ChangeVkConfirmScreen(onBack: () -> Unit) {
+    val navController = LocalNavController.current
+    val scope = rememberCoroutineScope()
+    val snackbarHostState = remember { SnackbarHostState() }
+    val flowState = rememberExpressiveStepFlow(1)
+    var vk by remember { mutableStateOf<VkOAuthParams?>(null) }
+    var loadingParams by remember { mutableStateOf(true) }
+    var busy by remember { mutableStateOf(false) }
+    val darkTheme = isAppInDarkTheme()
+    val languageTag = Locale.current.toLanguageTag()
+    val vkIcon = vectorResource(Res.drawable.ic_vk)
+
+    val title = stringResource(Res.string.settings_vk_step_confirm_title)
+    val body = stringResource(Res.string.settings_vk_step_confirm_body)
+    val cta = stringResource(Res.string.settings_vk_step_confirm_cta)
+    val next = stringResource(Res.string.settings_next)
+    val clientMismatch = stringResource(Res.string.auth_vk_client_mismatch)
+    val unexpected = stringResource(Res.string.error_unexpected)
+
+    fun showSnack(text: String) {
+        scope.launch {
+            snackbarHostState.showReplacingSnackbar(
+                message = text,
+                withDismissAction = false,
+                duration = SnackbarDuration.Short,
+            )
+        }
+    }
+
+    LaunchedEffect(Unit) {
+        ChangeVkDraft.clear()
+        loadingParams = true
+        try {
+            vk = ApiClient.getAccountVk().vk
+        } catch (e: Exception) {
+            showSnack(e.message ?: unexpected)
+        } finally {
+            loadingParams = false
+        }
+    }
+
+    val colorScheme = MaterialTheme.colorScheme
+    ExpressiveStepFlowScaffold(
+        flowState = flowState,
+        pages = listOf(
+            ExpressiveStepPage(
+                hero = ExpressiveHeroSpec(
+                    icon = vkIcon,
+                    polygon = MaterialShapes.Cookie9Sided.normalized(),
+                    containerColor = colorScheme.primaryContainer,
+                    contentColor = colorScheme.onPrimaryContainer,
+                ),
+                content = {
+                    ExpressiveStepPageHeader(title = title, body = body)
+                },
+                button = {
+                    ActionButton(
+                        onClick = {
+                            if (busy || loadingParams) return@ActionButton
+                            val params = vk
+                            if (params == null) {
+                                showSnack(unexpected)
+                                return@ActionButton
+                            }
+                            busy = true
+                            scope.launch {
+                                try {
+                                    val serverIp = runCatching { Settings.serverConfig.serverIp }.getOrElse {
+                                        showSnack(it.message ?: unexpected)
+                                        return@launch
+                                    }
+                                    val clientId = resolveVkClientId(params.client_id, serverIp)
+                                    if (clientId == null) {
+                                        showSnack(clientMismatch)
+                                        return@launch
+                                    }
+                                    val pkce = generateVkPkcePair()
+                                    val state = generateOAuthState()
+                                    val redirectUri = params.redirect_uri.ifBlank { VK_OAUTH_REDIRECT_URI }
+                                    ChangeVkDraft.authorizeUrl = buildVkAuthorizeUrl(
+                                        authorizeUrl = params.authorize_url,
+                                        clientId = clientId,
+                                        redirectUri = redirectUri,
+                                        scope = params.scope,
+                                        codeChallenge = pkce.codeChallenge,
+                                        state = state,
+                                        languageTag = languageTag,
+                                        darkTheme = darkTheme,
+                                    )
+                                    ChangeVkDraft.codeVerifier = pkce.codeVerifier
+                                    ChangeVkDraft.state = state
+                                    ChangeVkDraft.redirectUri = redirectUri
+                                    navController.navigate(SettingsRoutes.AccountVkOAuth)
+                                } finally {
+                                    busy = false
+                                }
+                            }
+                        },
+                        enabled = !busy && !loadingParams && vk != null,
+                        loading = busy || loadingParams,
+                        modifier = Modifier.fillMaxWidth(),
+                    ) {
+                        Text(if (busy || loadingParams) next else cta)
+                    }
+                },
+            ),
+        ),
+        snackbarHostState = snackbarHostState,
+        onBackAtFirstPage = onBack,
+    )
+}

app/shared/src/commonMain/kotlin/ru/fromchat/ui/main/settings/account/changevk/ChangeVkDoneScreen.kt

@@ -0,0 +1,62 @@
+package ru.fromchat.ui.main.settings.account.changevk
+
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.CheckCircle
+import androidx.compose.material3.ExperimentalMaterial3ExpressiveApi
+import androidx.compose.material3.MaterialShapes
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.SnackbarHostState
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+import androidx.compose.ui.Modifier
+import org.jetbrains.compose.resources.stringResource
+import ru.fromchat.Res
+import ru.fromchat.settings_done
+import ru.fromchat.settings_vk_step_done_body
+import ru.fromchat.settings_vk_step_done_title
+import ru.fromchat.ui.components.ActionButton
+import ru.fromchat.ui.components.ExpressiveHeroSpec
+import ru.fromchat.ui.components.ExpressiveStepFlowScaffold
+import ru.fromchat.ui.components.ExpressiveStepPage
+import ru.fromchat.ui.components.ExpressiveStepPageHeader
+import ru.fromchat.ui.components.Text
+import ru.fromchat.ui.components.rememberExpressiveStepFlow
+
+@OptIn(ExperimentalMaterial3ExpressiveApi::class)
+@Composable
+fun ChangeVkDoneScreen(onDone: () -> Unit) {
+    val flowState = rememberExpressiveStepFlow(1)
+    val snackbarHostState = remember { SnackbarHostState() }
+    val title = stringResource(Res.string.settings_vk_step_done_title)
+    val body = stringResource(Res.string.settings_vk_step_done_body)
+    val done = stringResource(Res.string.settings_done)
+    val colorScheme = MaterialTheme.colorScheme
+
+    ExpressiveStepFlowScaffold(
+        flowState = flowState,
+        pages = listOf(
+            ExpressiveStepPage(
+                hero = ExpressiveHeroSpec(
+                    icon = Icons.Filled.CheckCircle,
+                    polygon = MaterialShapes.Cookie9Sided.normalized(),
+                    containerColor = colorScheme.tertiaryContainer,
+                    contentColor = colorScheme.onTertiaryContainer,
+                ),
+                content = {
+                    ExpressiveStepPageHeader(title = title, body = body)
+                },
+                button = {
+                    ActionButton(
+                        onClick = onDone,
+                        modifier = Modifier.fillMaxWidth(),
+                    ) {
+                        Text(done)
+                    }
+                },
+            ),
+        ),
+        snackbarHostState = snackbarHostState,
+        onBackAtFirstPage = onDone,
+    )
+}

app/shared/src/commonMain/kotlin/ru/fromchat/ui/main/settings/account/changevk/ChangeVkDraft.kt

@@ -0,0 +1,19 @@
+package ru.fromchat.ui.main.settings.account.changevk
+
+/**
+ * Stages PKCE + authorize URL + OAuth state while the change-VK OAuth WebView is open
+ * (settings composition can leave the confirm screen).
+ */
+internal object ChangeVkDraft {
+    var authorizeUrl: String? = null
+    var codeVerifier: String? = null
+    var state: String? = null
+    var redirectUri: String? = null
+
+    fun clear() {
+        authorizeUrl = null
+        codeVerifier = null
+        state = null
+        redirectUri = null
+    }
+}

app/shared/src/commonMain/kotlin/ru/fromchat/ui/main/settings/account/changevk/ChangeVkOAuthScreen.kt

@@ -0,0 +1,142 @@
+package ru.fromchat.ui.main.settings.account.changevk
+
+import androidx.compose.animation.AnimatedVisibility
+import androidx.compose.animation.fadeIn
+import androidx.compose.animation.fadeOut
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.safeDrawingPadding
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.automirrored.filled.ArrowBack
+import androidx.compose.material3.FilledIconButton
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButtonDefaults
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.intl.Locale
+import androidx.compose.ui.unit.dp
+import kotlinx.coroutines.launch
+import org.jetbrains.compose.resources.stringResource
+import ru.fromchat.Res
+import ru.fromchat.api.ApiClient
+import ru.fromchat.back
+import ru.fromchat.ui.LocalNavController
+import ru.fromchat.ui.auth.vk.VkOAuthWebView
+import ru.fromchat.ui.isAppInDarkTheme
+import ru.fromchat.ui.main.settings.SettingsRoutes
+
+@Composable
+fun ChangeVkOAuthScreen(onBack: () -> Unit) {
+    val navController = LocalNavController.current
+    val scope = rememberCoroutineScope()
+    val authorizeUrl = remember { ChangeVkDraft.authorizeUrl }
+    val codeVerifier = remember { ChangeVkDraft.codeVerifier }
+    val expectedState = remember { ChangeVkDraft.state }
+    val redirectUri = remember { ChangeVkDraft.redirectUri }
+    val fallbackColor = MaterialTheme.colorScheme.background
+    var chromeColor by remember { mutableStateOf(fallbackColor) }
+    var busy by remember { mutableStateOf(false) }
+    var webViewCanGoBack by remember { mutableStateOf(false) }
+    val backLabel = stringResource(Res.string.back)
+
+    LaunchedEffect(authorizeUrl, codeVerifier, expectedState, redirectUri) {
+        if (authorizeUrl.isNullOrBlank() ||
+            codeVerifier.isNullOrBlank() ||
+            expectedState.isNullOrBlank() ||
+            redirectUri.isNullOrBlank()
+        ) {
+            onBack()
+        }
+    }
+
+    val url = authorizeUrl ?: return
+    val verifier = codeVerifier ?: return
+    val state = expectedState ?: return
+    val callbackUri = redirectUri ?: return
+
+    fun finishSuccess() {
+        ChangeVkDraft.clear()
+        navController.navigate(SettingsRoutes.AccountVkDone) {
+            popUpTo(SettingsRoutes.AccountVkFlow) { inclusive = true }
+        }
+    }
+
+    fun cancel() {
+        if (busy) return
+        ChangeVkDraft.clear()
+        onBack()
+    }
+
+    Box(
+        modifier = Modifier
+            .fillMaxSize()
+            .background(chromeColor),
+    ) {
+        VkOAuthWebView(
+            authorizeUrl = url,
+            redirectUri = callbackUri,
+            languageTag = Locale.current.toLanguageTag(),
+            darkTheme = isAppInDarkTheme(),
+            fallbackColor = fallbackColor,
+            clearCookies = true,
+            onPageBackgroundColor = { chromeColor = it },
+            onHistoryBackAvailabilityChanged = { webViewCanGoBack = it },
+            onRedirect = { redirect ->
+                if (busy) return@VkOAuthWebView
+                if (redirect.state != state) {
+                    cancel()
+                    return@VkOAuthWebView
+                }
+                scope.launch {
+                    busy = true
+                    try {
+                        val proof = ApiClient.authVkExchange(
+                            code = redirect.code,
+                            codeVerifier = verifier,
+                            deviceId = redirect.deviceId,
+                            state = redirect.state,
+                        ).registration_proof
+                        ApiClient.changeAccountVk(proof)
+                        finishSuccess()
+                    } catch (_: Exception) {
+                        cancel()
+                    } finally {
+                        busy = false
+                    }
+                }
+            },
+            onError = { cancel() },
+            onCancel = { cancel() },
+        )
+
+        AnimatedVisibility(
+            visible = !webViewCanGoBack && !busy,
+            enter = fadeIn(),
+            exit = fadeOut(),
+            modifier = Modifier
+                .align(Alignment.TopStart)
+                .safeDrawingPadding()
+                .padding(start = 12.dp, top = 12.dp),
+        ) {
+            FilledIconButton(
+                onClick = { cancel() },
+                colors = IconButtonDefaults.filledIconButtonColors(
+                    containerColor = MaterialTheme.colorScheme.surfaceContainerHigh.copy(alpha = 0.92f),
+                    contentColor = MaterialTheme.colorScheme.onSurface,
+                ),
+            ) {
+                Icon(Icons.AutoMirrored.Filled.ArrowBack, contentDescription = backLabel)
+            }
+        }
+    }
+}

app/shared/src/iosMain/kotlin/ru/fromchat/ui/auth/oauth/OAuthWebView.ios.kt

@@ -1,23 +1,26 @@
-package ru.fromchat.ui.auth.yandex
+package ru.fromchat.ui.auth.oauth
 
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.ui.graphics.Color
 
 @Composable
-actual fun YandexOAuthWebView(
+actual fun OAuthWebView(
     authorizeUrl: String,
     languageTag: String,
     darkTheme: Boolean,
     fallbackColor: Color,
+    redirectUriPrefix: String,
+    isAuthNavigation: (url: String) -> Boolean,
     clearCookies: Boolean,
+    themeCookieHosts: List<String>,
     onPageBackgroundColor: (Color) -> Unit,
     onHistoryBackAvailabilityChanged: (Boolean) -> Unit,
-    onCode: (String) -> Unit,
+    onRedirectUrl: (String) -> Unit,
     onError: (String) -> Unit,
     onCancel: () -> Unit,
 ) {
     LaunchedEffect(authorizeUrl) {
-        onError("Yandex sign-in is not available on this platform yet.")
+        onError("OAuth sign-in is not available on this platform yet.")
     }
 }