fix(cli): resolve CLI-001 — honor SCADALINK_FORMAT and config-file format precedence

src/ScadaLink.CLI/Commands/CommandHelpers.cs

@@ -15,8 +15,8 @@ internal static class CommandHelpers
         Option<string> passwordOption,
         object command)
     {
-        var format = result.GetValue(formatOption) ?? "json";
         var config = CliConfig.Load();
+        var format = ResolveFormat(result, formatOption, config);
 
         // Resolve management URL
         var url = result.GetValue(urlOption);
@@ -53,6 +53,27 @@ internal static class CommandHelpers
         return HandleResponse(response, format);
     }
 
+    /// <summary>
+    /// Resolves the output format using the documented precedence chain:
+    /// an explicitly supplied <c>--format</c> option wins, otherwise the
+    /// config-file / environment-variable default (<see cref="CliConfig.DefaultFormat"/>)
+    /// is used, otherwise <c>json</c>. The <c>--format</c> option must not declare a
+    /// <c>DefaultValueFactory</c> — that would mask whether the flag was supplied.
+    /// </summary>
+    internal static string ResolveFormat(ParseResult result, Option<string> formatOption, CliConfig config)
+    {
+        // GetResult returns non-null only when the option was actually present on the
+        // command line, letting an explicit --format override the config default.
+        if (result.GetResult(formatOption) != null)
+        {
+            var explicitValue = result.GetValue(formatOption);
+            if (!string.IsNullOrWhiteSpace(explicitValue))
+                return explicitValue;
+        }
+
+        return string.IsNullOrWhiteSpace(config.DefaultFormat) ? "json" : config.DefaultFormat;
+    }
+
     internal static int HandleResponse(ManagementResponse response, string format)
     {
         if (response.JsonData != null)

src/ScadaLink.CLI/Commands/DebugCommands.cs

@@ -42,8 +42,8 @@ public static class DebugCommands
         cmd.SetAction(async (ParseResult result) =>
         {
             var instanceId = result.GetValue(idOption);
-            var format = result.GetValue(formatOption) ?? "json";
             var config = CliConfig.Load();
+            var format = CommandHelpers.ResolveFormat(result, formatOption, config);
 
             var url = result.GetValue(urlOption);
             if (string.IsNullOrWhiteSpace(url))