diff --git a/.claude/settings.local.json b/.claude/settings.local.json
index aab7f875..81c0379b 100644
--- a/.claude/settings.local.json
+++ b/.claude/settings.local.json
@@ -1,7 +1,10 @@
 {
   "permissions": {
     "allow": [
-      "Bash(grep -r \"\\\\.FLATPAK\\\\|Flatpak\\\\|flatpak\" D:/development/Github-Store --include=*.kt)"
+      "Bash(grep -r \"\\\\.FLATPAK\\\\|Flatpak\\\\|flatpak\" . --include=*.kt)",
+      "Bash(./gradlew :composeApp:assembleDebug)",
+      "Bash(./gradlew :composeApp:jvmJar)",
+      "Bash(./gradlew :composeApp:assembleDebug :composeApp:jvmJar)"
     ]
   }
 }
diff --git a/composeApp/release/baselineProfiles/0/composeApp-release.dm b/composeApp/release/baselineProfiles/0/composeApp-release.dm
index 838e163f..ce6abdff 100644
Binary files a/composeApp/release/baselineProfiles/0/composeApp-release.dm and b/composeApp/release/baselineProfiles/0/composeApp-release.dm differ
diff --git a/composeApp/release/baselineProfiles/1/composeApp-release.dm b/composeApp/release/baselineProfiles/1/composeApp-release.dm
index 6ab7c2f2..dd27f85c 100644
Binary files a/composeApp/release/baselineProfiles/1/composeApp-release.dm and b/composeApp/release/baselineProfiles/1/composeApp-release.dm differ
diff --git a/core/data/src/androidMain/kotlin/zed/rainxch/core/data/network/HttpClientFactory.android.kt b/core/data/src/androidMain/kotlin/zed/rainxch/core/data/network/HttpClientFactory.android.kt
index 9afc5b53..89c9e577 100644
--- a/core/data/src/androidMain/kotlin/zed/rainxch/core/data/network/HttpClientFactory.android.kt
+++ b/core/data/src/androidMain/kotlin/zed/rainxch/core/data/network/HttpClientFactory.android.kt
@@ -8,7 +8,6 @@ import java.net.Authenticator
 import java.net.InetSocketAddress
 import java.net.PasswordAuthentication
 import java.net.Proxy
-import java.net.ProxySelector
 
 actual fun createPlatformHttpClient(proxyConfig: ProxyConfig): HttpClient {
     Authenticator.setDefault(null)
@@ -21,9 +20,11 @@ actual fun createPlatformHttpClient(proxyConfig: ProxyConfig): HttpClient {
                 }
 
                 is ProxyConfig.System -> {
-                    config {
-                        proxySelector(ProxySelector.getDefault())
-                    }
+                    // java.net.ProxySelector.getDefault() does not read Android's
+                    // per-network HTTP proxy. Android publishes the active proxy
+                    // through standard system properties instead, which we resolve
+                    // explicitly here so traffic actually flows through it.
+                    proxy = resolveAndroidSystemProxy()
                 }
 
                 is ProxyConfig.Http -> {
@@ -78,3 +79,22 @@ actual fun createPlatformHttpClient(proxyConfig: ProxyConfig): HttpClient {
         }
     }
 }
+
+internal fun resolveAndroidSystemProxy(): Proxy {
+    // System properties are user/OS-supplied, so guard against malformed
+    // values: InetSocketAddress(String, Int) throws IllegalArgumentException
+    // for ports outside 0..65535.
+    val httpsHost = System.getProperty("https.proxyHost")?.takeIf { it.isNotBlank() }
+    val httpsPort = System.getProperty("https.proxyPort")?.toIntOrNull()?.takeIf { it in 1..65535 }
+    if (httpsHost != null && httpsPort != null) {
+        return Proxy(Proxy.Type.HTTP, InetSocketAddress(httpsHost, httpsPort))
+    }
+
+    val httpHost = System.getProperty("http.proxyHost")?.takeIf { it.isNotBlank() }
+    val httpPort = System.getProperty("http.proxyPort")?.toIntOrNull()?.takeIf { it in 1..65535 }
+    if (httpHost != null && httpPort != null) {
+        return Proxy(Proxy.Type.HTTP, InetSocketAddress(httpHost, httpPort))
+    }
+
+    return Proxy.NO_PROXY
+}
diff --git a/core/data/src/androidMain/kotlin/zed/rainxch/core/data/services/AndroidDownloader.kt b/core/data/src/androidMain/kotlin/zed/rainxch/core/data/services/AndroidDownloader.kt
index 56455f98..43d90c7d 100644
--- a/core/data/src/androidMain/kotlin/zed/rainxch/core/data/services/AndroidDownloader.kt
+++ b/core/data/src/androidMain/kotlin/zed/rainxch/core/data/services/AndroidDownloader.kt
@@ -11,6 +11,7 @@ import okhttp3.Credentials
 import okhttp3.OkHttpClient
 import okhttp3.Request
 import zed.rainxch.core.data.network.ProxyManager
+import zed.rainxch.core.data.network.resolveAndroidSystemProxy
 import zed.rainxch.core.domain.model.DownloadProgress
 import zed.rainxch.core.domain.model.ProxyConfig
 import zed.rainxch.core.domain.network.Downloader
@@ -44,7 +45,12 @@ class AndroidDownloader(
                         proxy(Proxy.NO_PROXY)
                     }
 
-                    is ProxyConfig.System -> {}
+                    is ProxyConfig.System -> {
+                        // ProxySelector.getDefault() does not honor Android's
+                        // per-network HTTP proxy; resolve it explicitly so
+                        // downloads also flow through the device proxy.
+                        proxy(resolveAndroidSystemProxy())
+                    }
 
                     is ProxyConfig.Http -> {
                         proxy(Proxy(Proxy.Type.HTTP, InetSocketAddress(config.host, config.port)))
diff --git a/core/data/src/commonMain/kotlin/zed/rainxch/core/data/di/SharedModule.kt b/core/data/src/commonMain/kotlin/zed/rainxch/core/data/di/SharedModule.kt
index f42f1f10..6283fa61 100644
--- a/core/data/src/commonMain/kotlin/zed/rainxch/core/data/di/SharedModule.kt
+++ b/core/data/src/commonMain/kotlin/zed/rainxch/core/data/di/SharedModule.kt
@@ -22,6 +22,7 @@ import zed.rainxch.core.data.local.db.dao.UpdateHistoryDao
 import zed.rainxch.core.data.logging.KermitLogger
 import zed.rainxch.core.data.network.GitHubClientProvider
 import zed.rainxch.core.data.network.ProxyManager
+import zed.rainxch.core.data.network.ProxyTesterImpl
 import zed.rainxch.core.data.network.createGitHubHttpClient
 import zed.rainxch.core.data.repository.AuthenticationStateImpl
 import zed.rainxch.core.data.repository.FavouritesRepositoryImpl
@@ -36,6 +37,7 @@ import zed.rainxch.core.domain.getPlatform
 import zed.rainxch.core.domain.logging.GitHubStoreLogger
 import zed.rainxch.core.domain.model.Platform
 import zed.rainxch.core.domain.model.ProxyConfig
+import zed.rainxch.core.domain.network.ProxyTester
 import zed.rainxch.core.domain.repository.AuthenticationState
 import zed.rainxch.core.domain.repository.FavouritesRepository
 import zed.rainxch.core.domain.repository.InstalledAppsRepository
@@ -117,6 +119,10 @@ val coreModule =
             )
         }
 
+        single<ProxyTester> {
+            ProxyTesterImpl()
+        }
+
         single<SyncInstalledAppsUseCase> {
             SyncInstalledAppsUseCase(
                 packageMonitor = get(),
diff --git a/core/data/src/commonMain/kotlin/zed/rainxch/core/data/network/ProxyTesterImpl.kt b/core/data/src/commonMain/kotlin/zed/rainxch/core/data/network/ProxyTesterImpl.kt
new file mode 100644
index 00000000..a3b8a115
--- /dev/null
+++ b/core/data/src/commonMain/kotlin/zed/rainxch/core/data/network/ProxyTesterImpl.kt
@@ -0,0 +1,70 @@
+package zed.rainxch.core.data.network
+
+import io.ktor.client.plugins.HttpRequestTimeoutException
+import io.ktor.client.plugins.HttpTimeout
+import io.ktor.client.request.get
+import io.ktor.client.statement.HttpResponse
+import io.ktor.util.network.UnresolvedAddressException
+import zed.rainxch.core.domain.model.ProxyConfig
+import zed.rainxch.core.domain.network.ProxyTestOutcome
+import zed.rainxch.core.domain.network.ProxyTester
+import java.io.IOException
+import java.net.ConnectException
+import java.net.SocketTimeoutException
+import java.net.UnknownHostException
+import kotlin.coroutines.cancellation.CancellationException
+import kotlin.time.TimeSource
+
+class ProxyTesterImpl : ProxyTester {
+    override suspend fun test(config: ProxyConfig): ProxyTestOutcome {
+        val client =
+            createPlatformHttpClient(config).config {
+                install(HttpTimeout) {
+                    requestTimeoutMillis = TEST_TIMEOUT_MS
+                    connectTimeoutMillis = TEST_TIMEOUT_MS
+                    socketTimeoutMillis = TEST_TIMEOUT_MS
+                }
+                expectSuccess = false
+            }
+
+        return try {
+            val started = TimeSource.Monotonic.markNow()
+            val response: HttpResponse = client.get(TEST_URL)
+            val elapsed = started.elapsedNow().inWholeMilliseconds
+
+            when {
+                response.status.value == 407 ->
+                    ProxyTestOutcome.Failure.ProxyAuthRequired
+
+                response.status.value in 200..299 ->
+                    ProxyTestOutcome.Success(latencyMs = elapsed)
+
+                else ->
+                    ProxyTestOutcome.Failure.UnexpectedResponse(response.status.value)
+            }
+        } catch (e: CancellationException) {
+            throw e
+        } catch (e: HttpRequestTimeoutException) {
+            ProxyTestOutcome.Failure.Timeout
+        } catch (e: SocketTimeoutException) {
+            ProxyTestOutcome.Failure.Timeout
+        } catch (e: UnresolvedAddressException) {
+            ProxyTestOutcome.Failure.DnsFailure
+        } catch (e: UnknownHostException) {
+            ProxyTestOutcome.Failure.DnsFailure
+        } catch (e: ConnectException) {
+            ProxyTestOutcome.Failure.ProxyUnreachable
+        } catch (e: IOException) {
+            ProxyTestOutcome.Failure.Unknown(e.message)
+        } catch (e: Exception) {
+            ProxyTestOutcome.Failure.Unknown(e.message)
+        } finally {
+            client.close()
+        }
+    }
+
+    private companion object {
+        const val TEST_URL = "https://api.github.com/zen"
+        const val TEST_TIMEOUT_MS = 8_000L
+    }
+}
diff --git a/core/domain/src/commonMain/kotlin/zed/rainxch/core/domain/network/ProxyTester.kt b/core/domain/src/commonMain/kotlin/zed/rainxch/core/domain/network/ProxyTester.kt
new file mode 100644
index 00000000..076789b0
--- /dev/null
+++ b/core/domain/src/commonMain/kotlin/zed/rainxch/core/domain/network/ProxyTester.kt
@@ -0,0 +1,44 @@
+package zed.rainxch.core.domain.network
+
+import zed.rainxch.core.domain.model.ProxyConfig
+
+/**
+ * Verifies that a [ProxyConfig] can actually reach the GitHub API. Implementations
+ * should issue a single lightweight request through a throwaway HTTP client built
+ * with the supplied config so the test exercises the same engine code path the
+ * real client uses.
+ */
+interface ProxyTester {
+    suspend fun test(config: ProxyConfig): ProxyTestOutcome
+}
+
+sealed interface ProxyTestOutcome {
+    /** Connection succeeded. [latencyMs] is the round-trip time of the test request. */
+    data class Success(
+        val latencyMs: Long,
+    ) : ProxyTestOutcome
+
+    sealed interface Failure : ProxyTestOutcome {
+        /** Could not resolve a hostname (DNS failure or unresolved proxy host). */
+        data object DnsFailure : Failure
+
+        /** Reached the network but could not connect to the proxy itself. */
+        data object ProxyUnreachable : Failure
+
+        /** Connection or socket timed out. */
+        data object Timeout : Failure
+
+        /** Proxy returned 407 / requested authentication. */
+        data object ProxyAuthRequired : Failure
+
+        /** Proxy or upstream returned a non-2xx HTTP status. */
+        data class UnexpectedResponse(
+            val statusCode: Int,
+        ) : Failure
+
+        /** Anything else (TLS errors, malformed config, etc.). */
+        data class Unknown(
+            val message: String?,
+        ) : Failure
+    }
+}
diff --git a/core/presentation/src/commonMain/composeResources/values-ar/strings-ar.xml b/core/presentation/src/commonMain/composeResources/values-ar/strings-ar.xml
index 5f46a32c..843a8446 100644
--- a/core/presentation/src/commonMain/composeResources/values-ar/strings-ar.xml
+++ b/core/presentation/src/commonMain/composeResources/values-ar/strings-ar.xml
@@ -149,6 +149,15 @@
     <string name="invalid_proxy_port">منفذ الوكيل غير صالح</string>
     <string name="proxy_show_password">إظهار كلمة المرور</string>
     <string name="proxy_hide_password">إخفاء كلمة المرور</string>
+    <string name="proxy_test">اختبار</string>
+    <string name="proxy_test_in_progress">جارٍ الاختبار…</string>
+    <string name="proxy_test_success">الاتصال ناجح (%1$d مللي ثانية)</string>
+    <string name="proxy_test_error_dns">تعذر تحليل المضيف. تحقق من عنوان الوكيل.</string>
+    <string name="proxy_test_error_unreachable">تعذر الوصول إلى خادم الوكيل.</string>
+    <string name="proxy_test_error_timeout">انتهت مهلة الاتصال.</string>
+    <string name="proxy_test_error_auth_required">يلزم التحقق من الوكيل.</string>
+    <string name="proxy_test_error_status">استجابة غير متوقعة: HTTP %1$d</string>
+    <string name="proxy_test_error_unknown">فشل اختبار الاتصال</string>
 
     <!-- Snackbar -->
     <string name="logout_success">تم تسجيل الخروج بنجاح، جارٍ إعادة التوجيه...</string>
diff --git a/core/presentation/src/commonMain/composeResources/values-bn/strings-bn.xml b/core/presentation/src/commonMain/composeResources/values-bn/strings-bn.xml
index 83f26e80..9ecb5171 100644
--- a/core/presentation/src/commonMain/composeResources/values-bn/strings-bn.xml
+++ b/core/presentation/src/commonMain/composeResources/values-bn/strings-bn.xml
@@ -410,6 +410,15 @@
     <string name="invalid_proxy_port">অবৈধ প্রক্সি পোর্ট</string>
     <string name="proxy_show_password">পাসওয়ার্ড দেখান</string>
     <string name="proxy_hide_password">পাসওয়ার্ড লুকান</string>
+    <string name="proxy_test">পরীক্ষা</string>
+    <string name="proxy_test_in_progress">পরীক্ষা চলছে…</string>
+    <string name="proxy_test_success">সংযোগ ঠিক আছে (%1$d ms)</string>
+    <string name="proxy_test_error_dns">হোস্ট সমাধান করা যায়নি। প্রক্সি ঠিকানা যাচাই করুন।</string>
+    <string name="proxy_test_error_unreachable">প্রক্সি সার্ভারে পৌঁছানো যায়নি।</string>
+    <string name="proxy_test_error_timeout">সংযোগের সময় শেষ হয়ে গেছে।</string>
+    <string name="proxy_test_error_auth_required">প্রক্সি প্রমাণীকরণ প্রয়োজন।</string>
+    <string name="proxy_test_error_status">অপ্রত্যাশিত প্রতিক্রিয়া: HTTP %1$d</string>
+    <string name="proxy_test_error_unknown">সংযোগ পরীক্ষা ব্যর্থ</string>
 
 
     <!-- Track app feature -->
diff --git a/core/presentation/src/commonMain/composeResources/values-es/strings-es.xml b/core/presentation/src/commonMain/composeResources/values-es/strings-es.xml
index f7ec7bb3..34cf5e9b 100644
--- a/core/presentation/src/commonMain/composeResources/values-es/strings-es.xml
+++ b/core/presentation/src/commonMain/composeResources/values-es/strings-es.xml
@@ -375,6 +375,15 @@
     <string name="invalid_proxy_port">Puerto de proxy no válido</string>
     <string name="proxy_show_password">Mostrar contraseña</string>
     <string name="proxy_hide_password">Ocultar contraseña</string>
+    <string name="proxy_test">Probar</string>
+    <string name="proxy_test_in_progress">Probando…</string>
+    <string name="proxy_test_success">Conexión correcta (%1$d ms)</string>
+    <string name="proxy_test_error_dns">No se pudo resolver el host. Verifica la dirección del proxy.</string>
+    <string name="proxy_test_error_unreachable">No se pudo conectar con el servidor proxy.</string>
+    <string name="proxy_test_error_timeout">Se agotó el tiempo de conexión.</string>
+    <string name="proxy_test_error_auth_required">Se requiere autenticación del proxy.</string>
+    <string name="proxy_test_error_status">Respuesta inesperada: HTTP %1$d</string>
+    <string name="proxy_test_error_unknown">La prueba de conexión falló</string>
 
 
     <!-- Track app feature -->
diff --git a/core/presentation/src/commonMain/composeResources/values-fr/strings-fr.xml b/core/presentation/src/commonMain/composeResources/values-fr/strings-fr.xml
index 1ba038f7..3af132c1 100644
--- a/core/presentation/src/commonMain/composeResources/values-fr/strings-fr.xml
+++ b/core/presentation/src/commonMain/composeResources/values-fr/strings-fr.xml
@@ -375,6 +375,15 @@
     <string name="invalid_proxy_port">Port proxy invalide</string>
     <string name="proxy_show_password">Afficher le mot de passe</string>
     <string name="proxy_hide_password">Masquer le mot de passe</string>
+    <string name="proxy_test">Tester</string>
+    <string name="proxy_test_in_progress">Test en cours…</string>
+    <string name="proxy_test_success">Connexion OK (%1$d ms)</string>
+    <string name="proxy_test_error_dns">Impossible de résoudre l\'hôte. Vérifiez l\'adresse du proxy.</string>
+    <string name="proxy_test_error_unreachable">Impossible de joindre le serveur proxy.</string>
+    <string name="proxy_test_error_timeout">Délai de connexion dépassé.</string>
+    <string name="proxy_test_error_auth_required">Authentification proxy requise.</string>
+    <string name="proxy_test_error_status">Réponse inattendue : HTTP %1$d</string>
+    <string name="proxy_test_error_unknown">Échec du test de connexion</string>
 
 
     <!-- Track app feature -->
diff --git a/core/presentation/src/commonMain/composeResources/values-hi/strings-hi.xml b/core/presentation/src/commonMain/composeResources/values-hi/strings-hi.xml
index ffdd1973..23ce87ce 100644
--- a/core/presentation/src/commonMain/composeResources/values-hi/strings-hi.xml
+++ b/core/presentation/src/commonMain/composeResources/values-hi/strings-hi.xml
@@ -409,6 +409,15 @@
     <string name="invalid_proxy_port">अमान्य प्रॉक्सी पोर्ट</string>
     <string name="proxy_show_password">पासवर्ड दिखाएँ</string>
     <string name="proxy_hide_password">पासवर्ड छुपाएँ</string>
+    <string name="proxy_test">परीक्षण</string>
+    <string name="proxy_test_in_progress">परीक्षण हो रहा है…</string>
+    <string name="proxy_test_success">कनेक्शन ठीक है (%1$d ms)</string>
+    <string name="proxy_test_error_dns">होस्ट हल नहीं हो सका। प्रॉक्सी पता जाँचें।</string>
+    <string name="proxy_test_error_unreachable">प्रॉक्सी सर्वर तक नहीं पहुँचा जा सका।</string>
+    <string name="proxy_test_error_timeout">कनेक्शन समय समाप्त हो गया।</string>
+    <string name="proxy_test_error_auth_required">प्रॉक्सी प्रमाणीकरण आवश्यक है।</string>
+    <string name="proxy_test_error_status">अप्रत्याशित प्रतिक्रिया: HTTP %1$d</string>
+    <string name="proxy_test_error_unknown">कनेक्शन परीक्षण विफल</string>
 
 
     <!-- Track app feature -->
diff --git a/core/presentation/src/commonMain/composeResources/values-it/strings-it.xml b/core/presentation/src/commonMain/composeResources/values-it/strings-it.xml
index 7a99a8ab..fc49c3a1 100644
--- a/core/presentation/src/commonMain/composeResources/values-it/strings-it.xml
+++ b/core/presentation/src/commonMain/composeResources/values-it/strings-it.xml
@@ -411,6 +411,15 @@
     <string name="invalid_proxy_port">Porta proxy non valida</string>
     <string name="proxy_show_password">Mostra password</string>
     <string name="proxy_hide_password">Nascondi password</string>
+    <string name="proxy_test">Verifica</string>
+    <string name="proxy_test_in_progress">Verifica in corso…</string>
+    <string name="proxy_test_success">Connessione OK (%1$d ms)</string>
+    <string name="proxy_test_error_dns">Impossibile risolvere l\'host. Controlla l\'indirizzo del proxy.</string>
+    <string name="proxy_test_error_unreachable">Impossibile raggiungere il server proxy.</string>
+    <string name="proxy_test_error_timeout">Timeout della connessione.</string>
+    <string name="proxy_test_error_auth_required">Autenticazione proxy richiesta.</string>
+    <string name="proxy_test_error_status">Risposta inattesa: HTTP %1$d</string>
+    <string name="proxy_test_error_unknown">Verifica connessione non riuscita</string>
 
 
     <!-- Track app feature -->
diff --git a/core/presentation/src/commonMain/composeResources/values-ja/strings-ja.xml b/core/presentation/src/commonMain/composeResources/values-ja/strings-ja.xml
index 9f96e4ba..d7615153 100644
--- a/core/presentation/src/commonMain/composeResources/values-ja/strings-ja.xml
+++ b/core/presentation/src/commonMain/composeResources/values-ja/strings-ja.xml
@@ -375,6 +375,15 @@
     <string name="invalid_proxy_port">無効なプロキシポート</string>
     <string name="proxy_show_password">パスワードを表示</string>
     <string name="proxy_hide_password">パスワードを非表示</string>
+    <string name="proxy_test">テスト</string>
+    <string name="proxy_test_in_progress">テスト中…</string>
+    <string name="proxy_test_success">接続OK (%1$d ms)</string>
+    <string name="proxy_test_error_dns">ホストを解決できません。プロキシアドレスを確認してください。</string>
+    <string name="proxy_test_error_unreachable">プロキシサーバーに接続できません。</string>
+    <string name="proxy_test_error_timeout">接続がタイムアウトしました。</string>
+    <string name="proxy_test_error_auth_required">プロキシ認証が必要です。</string>
+    <string name="proxy_test_error_status">予期しない応答：HTTP %1$d</string>
+    <string name="proxy_test_error_unknown">接続テストに失敗しました</string>
 
 
     <!-- Track app feature -->
diff --git a/core/presentation/src/commonMain/composeResources/values-ko/strings-ko.xml b/core/presentation/src/commonMain/composeResources/values-ko/strings-ko.xml
index 039cab47..2d99333c 100644
--- a/core/presentation/src/commonMain/composeResources/values-ko/strings-ko.xml
+++ b/core/presentation/src/commonMain/composeResources/values-ko/strings-ko.xml
@@ -408,6 +408,15 @@
     <string name="invalid_proxy_port">잘못된 프록시 포트</string>
     <string name="proxy_show_password">비밀번호 표시</string>
     <string name="proxy_hide_password">비밀번호 숨기기</string>
+    <string name="proxy_test">테스트</string>
+    <string name="proxy_test_in_progress">테스트 중…</string>
+    <string name="proxy_test_success">연결 성공 (%1$d ms)</string>
+    <string name="proxy_test_error_dns">호스트를 확인할 수 없습니다. 프록시 주소를 확인하세요.</string>
+    <string name="proxy_test_error_unreachable">프록시 서버에 연결할 수 없습니다.</string>
+    <string name="proxy_test_error_timeout">연결 시간이 초과되었습니다.</string>
+    <string name="proxy_test_error_auth_required">프록시 인증이 필요합니다.</string>
+    <string name="proxy_test_error_status">예기치 않은 응답: HTTP %1$d</string>
+    <string name="proxy_test_error_unknown">연결 테스트 실패</string>
 
 
     <!-- Track app feature -->
diff --git a/core/presentation/src/commonMain/composeResources/values-pl/strings-pl.xml b/core/presentation/src/commonMain/composeResources/values-pl/strings-pl.xml
index 5c76bd83..756f3572 100644
--- a/core/presentation/src/commonMain/composeResources/values-pl/strings-pl.xml
+++ b/core/presentation/src/commonMain/composeResources/values-pl/strings-pl.xml
@@ -373,6 +373,15 @@
     <string name="invalid_proxy_port">Nieprawidłowy port proxy</string>
     <string name="proxy_show_password">Pokaż hasło</string>
     <string name="proxy_hide_password">Ukryj hasło</string>
+    <string name="proxy_test">Testuj</string>
+    <string name="proxy_test_in_progress">Testowanie…</string>
+    <string name="proxy_test_success">Połączenie OK (%1$d ms)</string>
+    <string name="proxy_test_error_dns">Nie można rozwiązać hosta. Sprawdź adres proxy.</string>
+    <string name="proxy_test_error_unreachable">Nie można połączyć się z serwerem proxy.</string>
+    <string name="proxy_test_error_timeout">Upłynął limit czasu połączenia.</string>
+    <string name="proxy_test_error_auth_required">Wymagane uwierzytelnienie proxy.</string>
+    <string name="proxy_test_error_status">Nieoczekiwana odpowiedź: HTTP %1$d</string>
+    <string name="proxy_test_error_unknown">Test połączenia nie powiódł się</string>
 
 
     <!-- Track app feature -->
diff --git a/core/presentation/src/commonMain/composeResources/values-ru/strings-ru.xml b/core/presentation/src/commonMain/composeResources/values-ru/strings-ru.xml
index 6eeb2e75..33683cd1 100644
--- a/core/presentation/src/commonMain/composeResources/values-ru/strings-ru.xml
+++ b/core/presentation/src/commonMain/composeResources/values-ru/strings-ru.xml
@@ -375,6 +375,15 @@
     <string name="invalid_proxy_port">Недопустимый порт прокси</string>
     <string name="proxy_show_password">Показать пароль</string>
     <string name="proxy_hide_password">Скрыть пароль</string>
+    <string name="proxy_test">Проверить</string>
+    <string name="proxy_test_in_progress">Проверка…</string>
+    <string name="proxy_test_success">Соединение в порядке (%1$d мс)</string>
+    <string name="proxy_test_error_dns">Не удалось разрешить хост. Проверьте адрес прокси.</string>
+    <string name="proxy_test_error_unreachable">Не удалось подключиться к прокси-серверу.</string>
+    <string name="proxy_test_error_timeout">Время ожидания истекло.</string>
+    <string name="proxy_test_error_auth_required">Требуется аутентификация прокси.</string>
+    <string name="proxy_test_error_status">Неожиданный ответ: HTTP %1$d</string>
+    <string name="proxy_test_error_unknown">Не удалось проверить соединение</string>
 
 
     <!-- Track app feature -->
diff --git a/core/presentation/src/commonMain/composeResources/values-tr/strings-tr.xml b/core/presentation/src/commonMain/composeResources/values-tr/strings-tr.xml
index a8301596..f43b397d 100644
--- a/core/presentation/src/commonMain/composeResources/values-tr/strings-tr.xml
+++ b/core/presentation/src/commonMain/composeResources/values-tr/strings-tr.xml
@@ -407,6 +407,15 @@
     <string name="invalid_proxy_port">Geçersiz proxy portu</string>
     <string name="proxy_show_password">Şifreyi göster</string>
     <string name="proxy_hide_password">Şifreyi gizle</string>
+    <string name="proxy_test">Test</string>
+    <string name="proxy_test_in_progress">Test ediliyor…</string>
+    <string name="proxy_test_success">Bağlantı tamam (%1$d ms)</string>
+    <string name="proxy_test_error_dns">Sunucu adresi çözümlenemedi. Proxy adresini kontrol edin.</string>
+    <string name="proxy_test_error_unreachable">Proxy sunucusuna ulaşılamadı.</string>
+    <string name="proxy_test_error_timeout">Bağlantı zaman aşımına uğradı.</string>
+    <string name="proxy_test_error_auth_required">Proxy kimlik doğrulaması gerekiyor.</string>
+    <string name="proxy_test_error_status">Beklenmeyen yanıt: HTTP %1$d</string>
+    <string name="proxy_test_error_unknown">Bağlantı testi başarısız</string>
 
 
     <!-- Track app feature -->
diff --git a/core/presentation/src/commonMain/composeResources/values-zh-rCN/strings-zh-rCN.xml b/core/presentation/src/commonMain/composeResources/values-zh-rCN/strings-zh-rCN.xml
index 9c9c085e..2c008681 100644
--- a/core/presentation/src/commonMain/composeResources/values-zh-rCN/strings-zh-rCN.xml
+++ b/core/presentation/src/commonMain/composeResources/values-zh-rCN/strings-zh-rCN.xml
@@ -376,6 +376,15 @@
     <string name="invalid_proxy_port">无效的代理端口</string>
     <string name="proxy_show_password">显示密码</string>
     <string name="proxy_hide_password">隐藏密码</string>
+    <string name="proxy_test">测试</string>
+    <string name="proxy_test_in_progress">测试中…</string>
+    <string name="proxy_test_success">连接正常 (%1$d ms)</string>
+    <string name="proxy_test_error_dns">无法解析主机。请检查代理地址。</string>
+    <string name="proxy_test_error_unreachable">无法连接到代理服务器。</string>
+    <string name="proxy_test_error_timeout">连接超时。</string>
+    <string name="proxy_test_error_auth_required">需要代理身份验证。</string>
+    <string name="proxy_test_error_status">意外响应：HTTP %1$d</string>
+    <string name="proxy_test_error_unknown">连接测试失败</string>
 
 
     <!-- Track app feature -->
diff --git a/core/presentation/src/commonMain/composeResources/values/strings.xml b/core/presentation/src/commonMain/composeResources/values/strings.xml
index fed21943..9ad81f84 100644
--- a/core/presentation/src/commonMain/composeResources/values/strings.xml
+++ b/core/presentation/src/commonMain/composeResources/values/strings.xml
@@ -152,6 +152,15 @@
     <string name="invalid_proxy_port">Invalid proxy port</string>
     <string name="proxy_show_password">Show password</string>
     <string name="proxy_hide_password">Hide password</string>
+    <string name="proxy_test">Test</string>
+    <string name="proxy_test_in_progress">Testing…</string>
+    <string name="proxy_test_success">Connection OK (%1$d ms)</string>
+    <string name="proxy_test_error_dns">Could not resolve host. Check the proxy address.</string>
+    <string name="proxy_test_error_unreachable">Could not reach the proxy server.</string>
+    <string name="proxy_test_error_timeout">Connection timed out.</string>
+    <string name="proxy_test_error_auth_required">Proxy authentication required.</string>
+    <string name="proxy_test_error_status">Unexpected response: HTTP %1$d</string>
+    <string name="proxy_test_error_unknown">Connection test failed</string>
 
     <!-- Snackbar -->
     <string name="logout_success">Logged out successfully, redirecting...</string>
diff --git a/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/TweaksAction.kt b/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/TweaksAction.kt
index 4d5e7c76..41511304 100644
--- a/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/TweaksAction.kt
+++ b/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/TweaksAction.kt
@@ -56,6 +56,8 @@ sealed interface TweaksAction {
 
     data object OnProxySave : TweaksAction
 
+    data object OnProxyTest : TweaksAction
+
     data class OnInstallerTypeSelected(
         val type: InstallerType,
     ) : TweaksAction
diff --git a/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/TweaksEvent.kt b/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/TweaksEvent.kt
index f711b5d4..73ae34ca 100644
--- a/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/TweaksEvent.kt
+++ b/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/TweaksEvent.kt
@@ -7,6 +7,14 @@ sealed interface TweaksEvent {
         val message: String,
     ) : TweaksEvent
 
+    data class OnProxyTestSuccess(
+        val latencyMs: Long,
+    ) : TweaksEvent
+
+    data class OnProxyTestError(
+        val message: String,
+    ) : TweaksEvent
+
     data object OnCacheCleared : TweaksEvent
 
     data class OnCacheClearError(
diff --git a/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/TweaksRoot.kt b/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/TweaksRoot.kt
index 4ec18e88..d89d6594 100644
--- a/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/TweaksRoot.kt
+++ b/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/TweaksRoot.kt
@@ -36,6 +36,7 @@ import zed.rainxch.core.presentation.utils.ObserveAsEvents
 import zed.rainxch.githubstore.core.presentation.res.Res
 import zed.rainxch.githubstore.core.presentation.res.downloads_cleared
 import zed.rainxch.githubstore.core.presentation.res.proxy_saved
+import zed.rainxch.githubstore.core.presentation.res.proxy_test_success
 import zed.rainxch.githubstore.core.presentation.res.seen_history_cleared
 import zed.rainxch.githubstore.core.presentation.res.tweaks_title
 import zed.rainxch.tweaks.presentation.components.ClearDownloadsDialog
@@ -77,6 +78,20 @@ fun TweaksRoot(viewModel: TweaksViewModel = koinViewModel()) {
                 }
             }
 
+            is TweaksEvent.OnProxyTestSuccess -> {
+                coroutineScope.launch {
+                    snackbarState.showSnackbar(
+                        getString(Res.string.proxy_test_success, event.latencyMs),
+                    )
+                }
+            }
+
+            is TweaksEvent.OnProxyTestError -> {
+                coroutineScope.launch {
+                    snackbarState.showSnackbar(event.message)
+                }
+            }
+
             TweaksEvent.OnCacheCleared -> {
                 coroutineScope.launch {
                     snackbarState.showSnackbar(getString(Res.string.downloads_cleared))
diff --git a/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/TweaksState.kt b/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/TweaksState.kt
index 2eb1ab00..a2d78052 100644
--- a/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/TweaksState.kt
+++ b/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/TweaksState.kt
@@ -18,6 +18,7 @@ data class TweaksState(
     val proxyUsername: String = "",
     val proxyPassword: String = "",
     val isProxyPasswordVisible: Boolean = false,
+    val isProxyTestInProgress: Boolean = false,
     val autoDetectClipboardLinks: Boolean = true,
     val cacheSize: String = "",
     val isClearDownloadsDialogVisible: Boolean = false,
diff --git a/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/TweaksViewModel.kt b/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/TweaksViewModel.kt
index de26ebf7..7b7153d0 100644
--- a/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/TweaksViewModel.kt
+++ b/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/TweaksViewModel.kt
@@ -2,6 +2,7 @@ package zed.rainxch.tweaks.presentation
 
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
+import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -13,6 +14,8 @@ import kotlinx.coroutines.flow.update
 import kotlinx.coroutines.launch
 import org.jetbrains.compose.resources.getString
 import zed.rainxch.core.domain.model.ProxyConfig
+import zed.rainxch.core.domain.network.ProxyTestOutcome
+import zed.rainxch.core.domain.network.ProxyTester
 import zed.rainxch.core.domain.repository.ProxyRepository
 import zed.rainxch.core.domain.repository.SeenReposRepository
 import zed.rainxch.core.domain.repository.TweaksRepository
@@ -23,6 +26,12 @@ import zed.rainxch.githubstore.core.presentation.res.Res
 import zed.rainxch.githubstore.core.presentation.res.failed_to_save_proxy_settings
 import zed.rainxch.githubstore.core.presentation.res.invalid_proxy_port
 import zed.rainxch.githubstore.core.presentation.res.proxy_host_required
+import zed.rainxch.githubstore.core.presentation.res.proxy_test_error_auth_required
+import zed.rainxch.githubstore.core.presentation.res.proxy_test_error_dns
+import zed.rainxch.githubstore.core.presentation.res.proxy_test_error_status
+import zed.rainxch.githubstore.core.presentation.res.proxy_test_error_timeout
+import zed.rainxch.githubstore.core.presentation.res.proxy_test_error_unknown
+import zed.rainxch.githubstore.core.presentation.res.proxy_test_error_unreachable
 import zed.rainxch.profile.domain.repository.ProfileRepository
 import zed.rainxch.tweaks.presentation.model.ProxyType
 
@@ -32,6 +41,7 @@ class TweaksViewModel(
     private val profileRepository: ProfileRepository,
     private val installerStatusProvider: InstallerStatusProvider,
     private val proxyRepository: ProxyRepository,
+    private val proxyTester: ProxyTester,
     private val updateScheduleManager: UpdateScheduleManager,
     private val seenReposRepository: SeenReposRepository,
 ) : ViewModel() {
@@ -396,6 +406,26 @@ class TweaksViewModel(
                 }
             }
 
+            TweaksAction.OnProxyTest -> {
+                if (_state.value.isProxyTestInProgress) return
+                val config = buildProxyConfigForTest() ?: return
+                _state.update { it.copy(isProxyTestInProgress = true) }
+                viewModelScope.launch {
+                    val outcome: ProxyTestOutcome =
+                        try {
+                            proxyTester.test(config)
+                        } catch (e: CancellationException) {
+                            // Preserve structured concurrency — never swallow.
+                            throw e
+                        } catch (e: Exception) {
+                            ProxyTestOutcome.Failure.Unknown(e.message)
+                        } finally {
+                            _state.update { it.copy(isProxyTestInProgress = false) }
+                        }
+                    _events.send(outcome.toEvent())
+                }
+            }
+
             is TweaksAction.OnInstallerTypeSelected -> {
                 viewModelScope.launch {
                     tweaksRepository.setInstallerType(action.type)
@@ -483,4 +513,83 @@ class TweaksViewModel(
             }
         }
     }
+
+    /**
+     * Builds the [ProxyConfig] to test from the current form state. For
+     * [ProxyType.HTTP] / [ProxyType.SOCKS] this requires a valid host and port —
+     * if either is missing the user is told via an error event and `null` is
+     * returned, mirroring the validation in [TweaksAction.OnProxySave].
+     */
+    private fun buildProxyConfigForTest(): ProxyConfig? {
+        val current = _state.value
+        return when (current.proxyType) {
+            ProxyType.NONE -> ProxyConfig.None
+            ProxyType.SYSTEM -> ProxyConfig.System
+            ProxyType.HTTP, ProxyType.SOCKS -> {
+                val port =
+                    current.proxyPort
+                        .toIntOrNull()
+                        ?.takeIf { it in 1..65535 }
+                        ?: run {
+                            viewModelScope.launch {
+                                _events.send(
+                                    TweaksEvent.OnProxyTestError(
+                                        getString(Res.string.invalid_proxy_port),
+                                    ),
+                                )
+                            }
+                            return null
+                        }
+                val host =
+                    current.proxyHost.trim().takeIf { it.isNotBlank() }
+                        ?: run {
+                            viewModelScope.launch {
+                                _events.send(
+                                    TweaksEvent.OnProxyTestError(
+                                        getString(Res.string.proxy_host_required),
+                                    ),
+                                )
+                            }
+                            return null
+                        }
+                val username = current.proxyUsername.takeIf { it.isNotBlank() }
+                val password = current.proxyPassword.takeIf { it.isNotBlank() }
+                if (current.proxyType == ProxyType.HTTP) {
+                    ProxyConfig.Http(host, port, username, password)
+                } else {
+                    ProxyConfig.Socks(host, port, username, password)
+                }
+            }
+        }
+    }
+
+    private suspend fun ProxyTestOutcome.toEvent(): TweaksEvent =
+        when (this) {
+            is ProxyTestOutcome.Success ->
+                TweaksEvent.OnProxyTestSuccess(latencyMs = latencyMs)
+
+            ProxyTestOutcome.Failure.DnsFailure ->
+                TweaksEvent.OnProxyTestError(getString(Res.string.proxy_test_error_dns))
+
+            ProxyTestOutcome.Failure.ProxyUnreachable ->
+                TweaksEvent.OnProxyTestError(getString(Res.string.proxy_test_error_unreachable))
+
+            ProxyTestOutcome.Failure.Timeout ->
+                TweaksEvent.OnProxyTestError(getString(Res.string.proxy_test_error_timeout))
+
+            ProxyTestOutcome.Failure.ProxyAuthRequired ->
+                TweaksEvent.OnProxyTestError(getString(Res.string.proxy_test_error_auth_required))
+
+            is ProxyTestOutcome.Failure.UnexpectedResponse ->
+                TweaksEvent.OnProxyTestError(
+                    getString(Res.string.proxy_test_error_status, statusCode),
+                )
+
+            is ProxyTestOutcome.Failure.Unknown ->
+                // Raw exception messages are platform-specific, untranslated,
+                // and may leak internal detail — always show the localized
+                // fallback to the user. The original `message` is intentionally
+                // dropped here; surface it via logging if diagnostics are needed.
+                TweaksEvent.OnProxyTestError(getString(Res.string.proxy_test_error_unknown))
+        }
 }
diff --git a/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/components/sections/Network.kt b/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/components/sections/Network.kt
index 56959619..c77b3004 100644
--- a/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/components/sections/Network.kt
+++ b/feature/tweaks/presentation/src/commonMain/kotlin/zed/rainxch/tweaks/presentation/components/sections/Network.kt
@@ -19,10 +19,12 @@ import androidx.compose.foundation.lazy.items
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.foundation.text.KeyboardOptions
 import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.NetworkCheck
 import androidx.compose.material.icons.filled.Save
 import androidx.compose.material.icons.filled.Visibility
 import androidx.compose.material.icons.filled.VisibilityOff
 import androidx.compose.material3.CardDefaults
+import androidx.compose.material3.CircularProgressIndicator
 import androidx.compose.material3.ElevatedCard
 import androidx.compose.material3.ExperimentalMaterial3ExpressiveApi
 import androidx.compose.material3.FilledTonalButton
@@ -30,6 +32,7 @@ import androidx.compose.material3.FilterChip
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
 import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.OutlinedButton
 import androidx.compose.material3.OutlinedTextField
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
@@ -72,16 +75,27 @@ fun LazyListScope.networkSection(
             enter = expandVertically() + fadeIn(),
             exit = shrinkVertically() + fadeOut(),
         ) {
-            Text(
-                text =
-                    when (state.proxyType) {
-                        ProxyType.SYSTEM -> stringResource(Res.string.proxy_system_description)
-                        else -> stringResource(Res.string.proxy_none_description)
-                    },
-                style = MaterialTheme.typography.bodyMedium,
-                color = MaterialTheme.colorScheme.onSurfaceVariant,
-                modifier = Modifier.padding(start = 8.dp, top = 12.dp),
-            )
+            Column {
+                Text(
+                    text =
+                        when (state.proxyType) {
+                            ProxyType.SYSTEM -> stringResource(Res.string.proxy_system_description)
+                            else -> stringResource(Res.string.proxy_none_description)
+                        },
+                    style = MaterialTheme.typography.bodyMedium,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                    modifier = Modifier.padding(start = 8.dp, top = 12.dp),
+                )
+
+                Spacer(Modifier.height(12.dp))
+
+                ProxyTestButton(
+                    isInProgress = state.isProxyTestInProgress,
+                    enabled = !state.isProxyTestInProgress,
+                    onClick = { onAction(TweaksAction.OnProxyTest) },
+                    modifier = Modifier.padding(start = 8.dp),
+                )
+            }
         }
 
         AnimatedVisibility(
@@ -266,20 +280,64 @@ private fun ProxyDetailsCard(
                 shape = RoundedCornerShape(12.dp),
             )
 
-            // Save button
-            FilledTonalButton(
-                onClick = { onAction(TweaksAction.OnProxySave) },
-                enabled = isFormValid,
+            // Test + Save buttons
+            Row(
                 modifier = Modifier.align(Alignment.End),
+                horizontalArrangement = Arrangement.spacedBy(8.dp),
+                verticalAlignment = Alignment.CenterVertically,
             ) {
-                Icon(
-                    imageVector = Icons.Default.Save,
-                    contentDescription = null,
-                    modifier = Modifier.size(18.dp),
+                ProxyTestButton(
+                    isInProgress = state.isProxyTestInProgress,
+                    enabled = isFormValid && !state.isProxyTestInProgress,
+                    onClick = { onAction(TweaksAction.OnProxyTest) },
                 )
-                Spacer(Modifier.size(8.dp))
-                Text(stringResource(Res.string.proxy_save))
+
+                FilledTonalButton(
+                    onClick = { onAction(TweaksAction.OnProxySave) },
+                    enabled = isFormValid && !state.isProxyTestInProgress,
+                ) {
+                    Icon(
+                        imageVector = Icons.Default.Save,
+                        contentDescription = null,
+                        modifier = Modifier.size(18.dp),
+                    )
+                    Spacer(Modifier.size(8.dp))
+                    Text(stringResource(Res.string.proxy_save))
+                }
             }
         }
     }
 }
+
+@OptIn(ExperimentalMaterial3ExpressiveApi::class)
+@Composable
+private fun ProxyTestButton(
+    isInProgress: Boolean,
+    enabled: Boolean,
+    onClick: () -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    OutlinedButton(
+        onClick = onClick,
+        enabled = enabled,
+        modifier = modifier,
+    ) {
+        if (isInProgress) {
+            CircularProgressIndicator(
+                modifier = Modifier.size(16.dp),
+                strokeWidth = 2.dp,
+                color = MaterialTheme.colorScheme.primary,
+            )
+            Spacer(Modifier.size(8.dp))
+            Text(stringResource(Res.string.proxy_test_in_progress))
+        } else {
+            Icon(
+                imageVector = Icons.Default.NetworkCheck,
+                contentDescription = null,
+                modifier = Modifier.size(18.dp),
+            )
+            Spacer(Modifier.size(8.dp))
+            Text(stringResource(Res.string.proxy_test))
+        }
+    }
+}