feat(frpc): improve boot service error handling and response

- Add bootServiceError field to system config modify response when boot service operations fail
- Include instanceID in list instances response
- Update error message for unknown modify type
- Document bootServiceError behavior in README

.vscode/launch.json

@@ -0,0 +1,15 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": "Launch Package",
+            "type": "go",
+            "request": "launch",
+            "mode": "auto",
+            "program": "${fileDirname}"
+        }
+    ]
+}

README.md

@@ -355,6 +355,33 @@ Modify system-level settings such as instance name, boot-at-start configuration,
 }
 ```
 
+**Response with bootServiceError (when boot service operations fail):**
+```json
+{
+  "success": true,
+  "message": "System config modified successfully",
+  "data": {
+    "instanceName": "new_frpc_name",
+    "instanceID": 1,
+    "configPath": "./configs/superfrpc_user_new_frpc_name.toml",
+    "bootAtStart": true,
+    "runUser": "www-data",
+    "bootServiceError": "Failed to create boot service: unsupported init system"
+  }
+}
+```
+
+> **Note about bootServiceError:**
+> - The `bootServiceError` field appears in the response when boot service operations (create/remove) fail
+> - This field is only present when there is an error; it will not be included in the response if operations succeed
+> - The overall request still returns `success: true` because the system config modification (database update, config file rename, etc.) succeeded
+> - Common scenarios where `bootServiceError` may appear:
+>   - Enabling `bootAtStart` when the init system is not supported (e.g., on Windows or systems without systemd/init.d)
+>   - Disabling `bootAtStart` when the service file cannot be removed due to permission issues
+>   - Changing instance name or run user when `bootAtStart` is enabled (requires removing old service and creating new one)
+> - The error message provides detailed information about what went wrong, which should be displayed to the user
+> - Frontend applications should check for this field and display the error message to the user, even though the request was technically successful
+
 ---
 
 ### 6. List frpc Instances

frpc.go

@@ -350,7 +350,7 @@ func ModifyInstanceHandler(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if modifyType != "configFile" && modifyType != "systemConfig" { // Detect valid modify type
-		SendErrorResponse(w, http.StatusBadRequest, "type must be 'configFile' or 'systemConfig'")
+		SendErrorResponse(w, http.StatusBadRequest, fmt.Sprintf("Unknown modify type %s", modifyType))
 		return
 	}
 
@@ -501,6 +501,7 @@ func handleSystemConfigModify(w http.ResponseWriter, r *http.Request, instance F
 	newRunUser := instance.RunUser
 	newBootAtStart := instance.BootAtStart
 	oldBootAtStart := instance.BootAtStart
+	var bootServiceError string
 
 	if v, ok := modifiedData["name"].(string); ok && v != "" {
 		newName = v
@@ -556,27 +557,38 @@ func handleSystemConfigModify(w http.ResponseWriter, r *http.Request, instance F
 	if oldBootAtStart && !newBootAtStart {
 		if err := removeBootService(user.Username, instance.Name); err != nil {
 			postLog.Error(fmt.Sprintf("[handleSystemConfigModify] Failed to remove boot service: %v", err))
+			bootServiceError = fmt.Sprintf("Failed to remove boot service: %v", err)
 		}
 	} else if !oldBootAtStart && newBootAtStart {
 		if err := createBootService(user.Username, newName, newConfigPath, newRunUser); err != nil {
 			postLog.Error(fmt.Sprintf("[handleSystemConfigModify] Failed to create boot service: %v", err))
+			bootServiceError = fmt.Sprintf("Failed to create boot service: %v", err)
 		}
 	} else if oldBootAtStart && newBootAtStart && (instance.Name != newName || instance.RunUser != newRunUser) {
 		if err := removeBootService(user.Username, instance.Name); err != nil {
 			postLog.Error(fmt.Sprintf("[handleSystemConfigModify] Failed to remove old boot service: %v", err))
+			bootServiceError = fmt.Sprintf("Failed to remove old boot service: %v", err)
 		}
 		if err := createBootService(user.Username, newName, newConfigPath, newRunUser); err != nil {
 			postLog.Error(fmt.Sprintf("[handleSystemConfigModify] Failed to create new boot service: %v", err))
+			if bootServiceError != "" {
+				bootServiceError += "; "
+			}
+			bootServiceError += fmt.Sprintf("Failed to create new boot service: %v", err)
 		}
 	}
 
-	SendSuccessResponse(w, "System config modified successfully", map[string]interface{}{
+	data := map[string]interface{}{
 		"instanceName": newName,
 		"instanceID":   instance.ID,
 		"configPath":   newConfigPath,
 		"bootAtStart":  newBootAtStart,
 		"runUser":      newRunUser,
-	})
+	}
+	if bootServiceError != "" {
+		data["bootServiceError"] = bootServiceError
+	}
+	SendSuccessResponse(w, "System config modified successfully", data)
 	postLog.Info(fmt.Sprintf("[handleSystemConfigModify] System config for instance %s modified successfully: bootAtStart=%v, runUser=%s", newName, newBootAtStart, newRunUser))
 }
 
@@ -614,6 +626,7 @@ func ListInstancesHandler(w http.ResponseWriter, r *http.Request) {
 	var responseInstances []map[string]interface{}
 	for _, instance := range instanceList {
 		instanceData := map[string]interface{}{
+			"instanceID":  instance.ID,
 			"name":        instance.Name,
 			"serverAddr":  instance.ServerAddr,
 			"serverPort":  instance.ServerPort,