feat(proxy): 网关随机 API Key + 启动失败提示

- SettingsViewModel 每次进程生成随机本机 Key，start 失败时暴露错误信息
- Settings 页显示 API Key 与错误提示

app/src/main/java/com/rainy/token/ui/settings/SettingsScreen.kt

@@ -91,6 +91,8 @@ fun SettingsScreen(
 
     val uiState by viewModel.uiState.collectAsStateWithLifecycle()
     val proxyRunning by viewModel.proxyRunning.collectAsStateWithLifecycle()
+    val proxyApiKey by viewModel.proxyApiKey.collectAsStateWithLifecycle()
+    val proxyError by viewModel.proxyError.collectAsStateWithLifecycle()
     var showLanguageDialog by remember { mutableStateOf(false) }
 
     Scaffold(
@@ -164,6 +166,8 @@ fun SettingsScreen(
                 item {
                     ProxyGatewayCard(
                         running = proxyRunning,
+                        apiKey = proxyApiKey,
+                        error = proxyError,
                         onToggle = viewModel::setProxyEnabled
                     )
                 }
@@ -192,6 +196,8 @@ fun SettingsScreen(
 @Composable
 private fun ProxyGatewayCard(
     running: Boolean,
+    apiKey: String,
+    error: String?,
     onToggle: (Boolean) -> Unit
 ) {
     Card(
@@ -221,6 +227,20 @@ private fun ProxyGatewayCard(
                     color = InkMuted,
                     modifier = Modifier.padding(top = 2.dp)
                 )
+                Text(
+                    text = "API Key：$apiKey",
+                    style = MaterialTheme.typography.bodySmall,
+                    color = InkMuted,
+                    modifier = Modifier.padding(top = 2.dp)
+                )
+                if (error != null) {
+                    Text(
+                        text = error,
+                        style = MaterialTheme.typography.bodySmall,
+                        color = MaterialTheme.colorScheme.error,
+                        modifier = Modifier.padding(top = 2.dp)
+                    )
+                }
             }
             Switch(
                 checked = running,

app/src/main/java/com/rainy/token/ui/settings/SettingsViewModel.kt

@@ -8,6 +8,7 @@ import com.rainy.token.data.repository.CredentialRepository
 import com.rainy.token.domain.model.CredentialStatus
 import com.rainy.token.domain.service.ServiceType
 import dagger.hilt.android.lifecycle.HiltViewModel
+import java.util.UUID
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
@@ -31,15 +32,28 @@ class SettingsViewModel @Inject constructor(
     /** 本地反代服务运行状态。 */
     val proxyRunning: StateFlow<Boolean> = localProxyServer.isRunning
 
-    /** 启动/停止本地反代服务。M1b 使用固定本地 Key，后续改为可配置。 */
+    /** 当前本机 API Key（每次进程随机生成，仅提示用）。 */
+    val proxyApiKey: StateFlow<String> = MutableStateFlow(generateProxyKey())
+
+    /** 启动失败时的错误信息。 */
+    private val _proxyError = MutableStateFlow<String?>(null)
+    val proxyError: StateFlow<String?> = _proxyError.asStateFlow()
+
+    /** 启动/停止本地反代服务。 */
     fun setProxyEnabled(enabled: Boolean) {
         if (enabled) {
-            localProxyServer.start(ProxyServerConfig(apiKey = "rainytoken"))
+            localProxyServer.start(ProxyServerConfig(apiKey = proxyApiKey.value))
+                .onSuccess { _proxyError.value = null }
+                .onFailure { e -> _proxyError.value = e.message ?: "代理网关启动失败" }
         } else {
             localProxyServer.stop()
+            _proxyError.value = null
         }
     }
 
+    private fun generateProxyKey(): String =
+        "rainy-" + UUID.randomUUID().toString().replace("-", "").take(16)
+
     init {
         refresh()
     }

docs/PROXY-ROADMAP.md

@@ -72,7 +72,7 @@ WBAdpt TraeAdpt  QoderAdpt  RaccoonAdpt  OfficialPassthrough
 - WorkBuddy INTL / Trae SOLO/Work 实际协议归一化
 - M3 agent2api 全家桶（Qoder / 小浣熊 / CatPaw / AutoClaw / Cline / Accio / ZCode / CodeArts / Loomy）
   - Qoder 需 COSY 请求签名/编码（ed25519 类原语），已列为攻坚项
-- M4 长尾 + 官方透传 + 网关配置 UI 完善
+- M4 长尾 + 官方透传 + 网关配置 UI 完善（已做：随机 API Key / 启动失败提示；待做：端口配置 / 状态持久化）
 
 ## 4. 里程碑