diff --git a/src/schema.ts b/src/schema.ts
index 4368c26..885d398 100644
--- a/src/schema.ts
+++ b/src/schema.ts
@@ -1,14 +1,31 @@
 import * as vscode from 'vscode';
-import { parseDocument, Document } from 'yaml';
+import { parseDocument, isMap, isSeq, Pair, Node, Scalar, YAMLMap, YAMLSeq, Document } from 'yaml';
 import { getPackagePath } from './npm';
 import Ajv from 'ajv';
 
-const findNodeByPath = (doc: Document.Parsed, path: string): any => {
+const buildPathMap = (node: Node | null, path = '', map = new Map<string, Node>()): Map<string, Node> => {
+  if (!node) return map;
+  map.set(path, node);
 
+  if (isMap(node)) {
+    for (const item of (node as YAMLMap).items) {
+      const key = item.key instanceof Scalar ? String(item.key.value) : String(item.key);
+      const newPath = `${path}/${key}`;
+      if (item.value && typeof item.value === 'object') {
+        buildPathMap(item.value as Node, newPath, map);
+      }
+    }
+  } else if (isSeq(node)) {
+    (node as YAMLSeq).items.forEach((item, index) => {
+      const newPath = `${path}/${index}`;
+      if (item && typeof item === 'object') {
+        map.set(newPath, item as Node);
+        buildPathMap(item as Node, newPath, map);
+      }
+    });
+  }
 
-  const parts = path.split('/').slice(1); // Remove leading slash
-  const node = doc.getIn(parts, true);   // Get original YAML node, not JSON-converted
-  return node?.cstNode || node?.key?.cstNode || null;
+  return map;
 };
 
 export function validate(context: vscode.ExtensionContext) {
@@ -26,30 +43,34 @@ export function validate(context: vscode.ExtensionContext) {
     const diagnostics: vscode.Diagnostic[] = [];
 
     try {
-      const doc = parseDocument(text, { keepCstNodes: true });
-
-      const jsonData = doc.toJSON(); // Just for AJV
+      const doc = parseDocument(text, { keepSourceTokens: true });
+      const pathMap = buildPathMap(doc.contents);
+      const jsonData = doc.toJSON();
       const valid = ajv.validate(schema, jsonData);
 
       if (!valid && ajv.errors) {
         for (const error of ajv.errors) {
-          const cstNode = findNodeByPath(doc, error.instancePath || '');
-          const range = cstNode?.rangeAsLinePos;
+          let node = pathMap.get(error.instancePath || '');
+          if (!node && error.instancePath) {
+            const parentPath = error.instancePath.split('/').slice(0, -1).join('/');
+            node = pathMap.get(parentPath || '');
+          }
+          const cstNode = (node as any)?.cstNode;
 
-          if (range) {
-            const startPos = new vscode.Position(range.start.line, range.start.col);
-            const endPos = new vscode.Position(range.end.line, range.end.col);
+          if (cstNode?.range) {
+            const [startOffset, endOffset] = cstNode.range;
+            const startPos = document.positionAt(startOffset);
+            const endPos = document.positionAt(endOffset);
 
-            const diagnostic = new vscode.Diagnostic(
+            diagnostics.push(new vscode.Diagnostic(
               new vscode.Range(startPos, endPos),
-              error.instancePath + ' ' + error.message || 'Validation error',
+              `${error.instancePath || '/'} ${error.message ?? 'Validation error'}`,
               vscode.DiagnosticSeverity.Error
-            );
-            diagnostics.push(diagnostic);
+            ));
           } else {
             diagnostics.push(new vscode.Diagnostic(
-              new vscode.Range(0, 0, 0, 999),
-              error.instancePath + ' ' + error.message || 'Validation error (no position info)',
+              new vscode.Range(0, 0, 0, 1),
+              `${error.instancePath || '/'} ${error.message ?? 'Validation error (no position info)'}`,
               vscode.DiagnosticSeverity.Error
             ));
           }
@@ -57,7 +78,7 @@ export function validate(context: vscode.ExtensionContext) {
       }
     } catch (err: any) {
       diagnostics.push(new vscode.Diagnostic(
-        new vscode.Range(0, 0, 0, 999),
+        new vscode.Range(0, 0, 0, 1),
         `YAML Parse error: ${err.message}`,
         vscode.DiagnosticSeverity.Error
       ));
diff --git a/test.js b/test.js
new file mode 100644
index 0000000..e69de29