From 2717712bd311a984c666554549ddcd72f2eeadac Mon Sep 17 00:00:00 2001
From: cyphercodes <cyphercodes@users.noreply.github.com>
Date: Sat, 23 May 2026 18:38:03 +0300
Subject: [PATCH] fix: correct validation diagnostic highlight range

---
 .changeset/loud-fields-dance.md                 |  5 +++++
 .../interface/__tests__/getDiagnostics.test.ts  | 17 +++++++++++++++--
 .../src/interface/getDiagnostics.ts             | 11 ++++++-----
 3 files changed, 26 insertions(+), 7 deletions(-)
 create mode 100644 .changeset/loud-fields-dance.md

diff --git a/.changeset/loud-fields-dance.md b/.changeset/loud-fields-dance.md
new file mode 100644
index 00000000000..5148b143ea7
--- /dev/null
+++ b/.changeset/loud-fields-dance.md
@@ -0,0 +1,5 @@
+---
+'graphql-language-service': patch
+---
+
+Fix validation diagnostic ranges so highlights stop at the invalid token instead of including the following character.
diff --git a/packages/graphql-language-service/src/interface/__tests__/getDiagnostics.test.ts b/packages/graphql-language-service/src/interface/__tests__/getDiagnostics.test.ts
index 8016bb6e170..d5c73622a51 100644
--- a/packages/graphql-language-service/src/interface/__tests__/getDiagnostics.test.ts
+++ b/packages/graphql-language-service/src/interface/__tests__/getDiagnostics.test.ts
@@ -44,6 +44,19 @@ describe('getDiagnostics', () => {
     );
     expect(error.severity).toEqual(DIAGNOSTIC_SEVERITY.Error);
     expect(error.source).toEqual('GraphQL: Validation');
+    expect(error.range).toMatchObject({
+      start: { line: 0, character: 18 },
+      end: { line: 0, character: 23 },
+    });
+  });
+
+  it('does not include trailing whitespace in validation highlights', () => {
+    const error = validateQuery(parse('query {\n  title \n}'), schema)[0];
+
+    expect(error.range).toMatchObject({
+      start: { line: 1, character: 2 },
+      end: { line: 1, character: 7 },
+    });
   });
 
   it('catches with multiple highlighted nodes', () => {
@@ -55,7 +68,7 @@ describe('getDiagnostics', () => {
       {
         range: {
           end: {
-            character: 20,
+            character: 19,
             line: 0,
           },
           start: {
@@ -67,7 +80,7 @@ describe('getDiagnostics', () => {
       {
         range: {
           end: {
-            character: 32,
+            character: 31,
             line: 0,
           },
           start: {
diff --git a/packages/graphql-language-service/src/interface/getDiagnostics.ts b/packages/graphql-language-service/src/interface/getDiagnostics.ts
index d41c3ff80fc..0ee5996f46e 100644
--- a/packages/graphql-language-service/src/interface/getDiagnostics.ts
+++ b/packages/graphql-language-service/src/interface/getDiagnostics.ts
@@ -154,15 +154,16 @@ function annotations(
       // https://github.com/microsoft/TypeScript/pull/32695
       const loc = error.locations[i];
       const highlightLoc = getLocation(highlightNode);
-      const end = loc.column + (highlightLoc.end - highlightLoc.start);
+      const start = new Position(loc.line - 1, loc.column - 1);
+      const end = new Position(
+        start.line,
+        start.character + highlightLoc.end - highlightLoc.start,
+      );
       highlightedNodes.push({
         source: `GraphQL: ${type}`,
         message: error.message,
         severity,
-        range: new Range(
-          new Position(loc.line - 1, loc.column - 1),
-          new Position(loc.line - 1, end),
-        ),
+        range: new Range(start, end),
       });
     }
   }