diagnostic: handle mixed indentation diagnostics with severity levels

src/diagnostic.rs

@@ -766,16 +766,25 @@ impl StyleAnalyzer {
 
         // Check for mixed indentation across the file
         if has_tabs && has_spaces {
-            if let Some(preferred) = &config.preferred_indent {
-                let range = Range::single_position(Position::new(0, 0));
-                let diagnostic = Diagnostic::new(
-                    range,
+            let range = Range::single_position(Position::new(0, 0));
+            let (severity, message) = if let Some(preferred) = &config.preferred_indent {
+                (
                     DiagnosticSeverity::Information,
-                    DiagnosticCode::InconsistentIndentation,
                     format!("File uses mixed indentation; prefer {}", preferred),
-                );
-                diagnostics.push(diagnostic);
-            }
+                )
+            } else {
+                (
+                    DiagnosticSeverity::Warning,
+                    "File uses mixed indentation (tabs and spaces)".to_string(),
+                )
+            };
+            let diagnostic = Diagnostic::new(
+                range,
+                severity,
+                DiagnosticCode::InconsistentIndentation,
+                message,
+            );
+            diagnostics.push(diagnostic);
         }
 
         diagnostics

src/main.rs

@@ -352,7 +352,7 @@ fn process_lint_command(
 
     let is_multiple_files = files.len() > 1;
     let mut has_errors = false;
-    
+
     for file_path in files {
         if let Err(e) = process_single_file_lint(
             &file_path,