feat: classify stream check errors with color-coded toasts

Distinguish between "provider rejects probe" (yellow warning) and
"genuinely broken" (red error) in health check results.

Backend: add AppError::HttpStatus variant to carry structured HTTP
status codes, populate http_status on error results, classify codes
into short labels (e.g. "Auth rejected (401)"), and truncate overly
long response bodies.

Frontend: route 401/403/400/429/5xx to toast.warning with localized
hints explaining the error may not indicate actual unusability; route
404/402/connection errors to toast.error. Add i18n keys for all three
locales (zh/en/ja).

Also deduplicate check_once by reusing build_stream_check_result.

src-tauri/src/commands/stream_check.rs

@@ -116,15 +116,24 @@ pub async fn stream_check_all_providers(
             claude_api_format_override,
         )
         .await
-        .unwrap_or_else(|e| StreamCheckResult {
-            status: HealthStatus::Failed,
-            success: false,
-            message: e.to_string(),
-            response_time_ms: None,
-            http_status: None,
-            model_used: String::new(),
-            tested_at: chrono::Utc::now().timestamp(),
-            retry_count: 0,
+        .unwrap_or_else(|e| {
+            let (http_status, message) = match &e {
+                crate::error::AppError::HttpStatus { status, .. } => (
+                    Some(*status),
+                    StreamCheckService::classify_http_status(*status).to_string(),
+                ),
+                _ => (None, e.to_string()),
+            };
+            StreamCheckResult {
+                status: HealthStatus::Failed,
+                success: false,
+                message,
+                response_time_ms: None,
+                http_status,
+                model_used: String::new(),
+                tested_at: chrono::Utc::now().timestamp(),
+                retry_count: 0,
+            }
         });
 
         let _ = state

src-tauri/src/error.rs

@@ -44,6 +44,8 @@ pub enum AppError {
     McpValidation(String),
     #[error("{0}")]
     Message(String),
+    #[error("HTTP {status}: {body}")]
+    HttpStatus { status: u16, body: String },
     #[error("{zh} ({en})")]
     Localized {
         key: &'static str,

src-tauri/src/services/stream_check.rs

@@ -271,34 +271,11 @@ impl StreamCheckService {
         };
 
         let response_time = start.elapsed().as_millis() as u64;
-        let tested_at = chrono::Utc::now().timestamp();
-
-        match result {
-            Ok((status_code, model)) => {
-                let health_status =
-                    Self::determine_status(response_time, config.degraded_threshold_ms);
-                Ok(StreamCheckResult {
-                    status: health_status,
-                    success: true,
-                    message: "Check succeeded".to_string(),
-                    response_time_ms: Some(response_time),
-                    http_status: Some(status_code),
-                    model_used: model,
-                    tested_at,
-                    retry_count: 0,
-                })
-            }
-            Err(e) => Ok(StreamCheckResult {
-                status: HealthStatus::Failed,
-                success: false,
-                message: e.to_string(),
-                response_time_ms: Some(response_time),
-                http_status: None,
-                model_used: String::new(),
-                tested_at,
-                retry_count: 0,
-            }),
-        }
+        Ok(Self::build_stream_check_result(
+            result,
+            response_time,
+            config.degraded_threshold_ms,
+        ))
     }
 
     /// Claude 流式检查
@@ -475,7 +452,7 @@ impl StreamCheckService {
 
         if !response.status().is_success() {
             let error_text = response.text().await.unwrap_or_default();
-            return Err(AppError::Message(format!("HTTP {status}: {error_text}")));
+            return Err(Self::http_status_error(status, error_text));
         }
 
         // 流式读取：只需首个 chunk
@@ -555,7 +532,7 @@ impl StreamCheckService {
                 if i == 0 && status == 404 && urls.len() > 1 {
                     continue;
                 }
-                return Err(AppError::Message(format!("HTTP {status}: {error_text}")));
+                return Err(Self::http_status_error(status, error_text));
             }
 
             let mut stream = response.bytes_stream();
@@ -630,7 +607,7 @@ impl StreamCheckService {
 
         if !response.status().is_success() {
             let error_text = response.text().await.unwrap_or_default();
-            return Err(AppError::Message(format!("HTTP {status}: {error_text}")));
+            return Err(Self::http_status_error(status, error_text));
         }
 
         let mut stream = response.bytes_stream();
@@ -717,16 +694,25 @@ impl StreamCheckService {
                 tested_at,
                 retry_count: 0,
             },
-            Err(e) => StreamCheckResult {
-                status: HealthStatus::Failed,
-                success: false,
-                message: e.to_string(),
-                response_time_ms: Some(response_time),
-                http_status: None,
-                model_used: String::new(),
-                tested_at,
-                retry_count: 0,
-            },
+            Err(e) => {
+                let (http_status, message) = match &e {
+                    AppError::HttpStatus { status, .. } => (
+                        Some(*status),
+                        Self::classify_http_status(*status).to_string(),
+                    ),
+                    _ => (None, e.to_string()),
+                };
+                StreamCheckResult {
+                    status: HealthStatus::Failed,
+                    success: false,
+                    message,
+                    response_time_ms: Some(response_time),
+                    http_status,
+                    model_used: String::new(),
+                    tested_at,
+                    retry_count: 0,
+                }
+            }
         }
     }
 
@@ -1124,6 +1110,39 @@ impl StreamCheckService {
         }
     }
 
+    /// 构造 HTTP 状态码错误，截断过长的响应体
+    fn http_status_error(status: u16, body: String) -> AppError {
+        let body = if body.len() > 200 {
+            // 安全截断：找到 200 字节内最近的 char 边界
+            let mut end = 200;
+            while end > 0 && !body.is_char_boundary(end) {
+                end -= 1;
+            }
+            format!("{}…", &body[..end])
+        } else {
+            body
+        };
+        AppError::HttpStatus { status, body }
+    }
+
+    /// 将 HTTP 状态码映射为简短的分类标签
+    pub(crate) fn classify_http_status(status: u16) -> &'static str {
+        match status {
+            400 => "Bad request (400)",
+            401 => "Auth rejected (401)",
+            402 => "Payment required (402)",
+            403 => "Access denied (403)",
+            404 => "Not found (404)",
+            429 => "Rate limited (429)",
+            500 => "Internal server error (500)",
+            502 => "Bad gateway (502)",
+            503 => "Service unavailable (503)",
+            504 => "Gateway timeout (504)",
+            s if (500..600).contains(&s) => "Server error",
+            _ => "HTTP error",
+        }
+    }
+
     fn resolve_test_model(
         app_type: &AppType,
         provider: &Provider,