From c62ebf6d092243c3b2a09c75d9cf6f803cf3fe2a Mon Sep 17 00:00:00 2001
From: Sidharth Vinod <sidharthv96@gmail.com>
Date: Mon, 4 Aug 2025 13:53:19 +0530
Subject: [PATCH 1/2] fix: #1753 Undo in Monaco

---
 src/lib/components/DesktopEditor.svelte | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/lib/components/DesktopEditor.svelte b/src/lib/components/DesktopEditor.svelte
index 47612015..d73b20d3 100644
--- a/src/lib/components/DesktopEditor.svelte
+++ b/src/lib/components/DesktopEditor.svelte
@@ -170,7 +170,14 @@
       const newText = editorMode === 'code' ? code : mermaid;
       if (newText !== currentText) {
         editor.setScrollTop(0);
-        editor.setValue(newText);
+        editor.pushUndoStop();
+        editor.executeEdits('updateCode', [
+          {
+            range: model.getFullModelRange(),
+            text: newText
+          }
+        ]);
+        editor.pushUndoStop();
         currentText = newText;
         renderAIPromptGutterGlyphIcon();
       }

From 1f0812496eda6fecff3da197e5a871b425c2d28d Mon Sep 17 00:00:00 2001
From: Sidharth Vinod <sidharthv96@gmail.com>
Date: Mon, 8 Jun 2026 18:40:07 +0530
Subject: [PATCH 2/2] fix: prevent state feedback loop when updating Monaco via
 executeEdits

Guard programmatic editor updates so sample diagrams and URL loads do not re-trigger onUpdate, which caused infinite state/URL churn and failing e2e tests.

Co-authored-by: Cursor <cursoragent@cursor.com>
---
 src/lib/components/DesktopEditor.svelte | 28 +++++++++++++++----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/src/lib/components/DesktopEditor.svelte b/src/lib/components/DesktopEditor.svelte
index d73b20d3..e945a1fa 100644
--- a/src/lib/components/DesktopEditor.svelte
+++ b/src/lib/components/DesktopEditor.svelte
@@ -27,6 +27,7 @@
     lineNumbersMinChars: 4
   } satisfies monaco.editor.IStandaloneEditorConstructionOptions;
   let currentText = '';
+  let isUpdatingFromState = false;
   let showPopup = $state(false);
   let popupPosition = $state({ top: 0, lineNumber: 0 });
   let decorationsCollection: monaco.editor.IEditorDecorationsCollection | undefined;
@@ -142,7 +143,7 @@
 
     editor.onDidChangeModelContent(({ isFlush }) => {
       const newText = editor?.getValue();
-      if (!newText || currentText === newText || isFlush) {
+      if (!newText || currentText === newText || isFlush || isUpdatingFromState) {
         return;
       }
       currentText = newText;
@@ -169,16 +170,21 @@
       // Update editor text if it's different
       const newText = editorMode === 'code' ? code : mermaid;
       if (newText !== currentText) {
-        editor.setScrollTop(0);
-        editor.pushUndoStop();
-        editor.executeEdits('updateCode', [
-          {
-            range: model.getFullModelRange(),
-            text: newText
-          }
-        ]);
-        editor.pushUndoStop();
-        currentText = newText;
+        isUpdatingFromState = true;
+        try {
+          editor.setScrollTop(0);
+          editor.pushUndoStop();
+          editor.executeEdits('updateCode', [
+            {
+              range: model.getFullModelRange(),
+              text: newText
+            }
+          ]);
+          editor.pushUndoStop();
+          currentText = newText;
+        } finally {
+          isUpdatingFromState = false;
+        }
         renderAIPromptGutterGlyphIcon();
       }