fix: use execCommand insertText for contenteditable replace - fixes delete-without-paste bug

entrypoints/content.ts

@@ -496,10 +496,23 @@ export default defineContentScript({
             // contenteditable / DOM range path
             console.log('[LexAI Replace] using DOM range');
             try {
+              // Strategy: restore the selection from the cloned range, then use
+              // execCommand('insertText') which works reliably on contenteditable.
+              // insertNode() on stale ranges often fails after async operations.
+              const sel = window.getSelection();
+              if (sel) {
+                sel.removeAllRanges();
+                sel.addRange(snapRange); // restore original selection
+              }
+
+              // Try execCommand first (works on most contenteditable editors)
+              const inserted = document.execCommand('insertText', false, resultText);
+
+              if (!inserted) {
+                // Fallback: direct DOM manipulation
                 snapRange.deleteContents();
                 const textNode = document.createTextNode(resultText);
                 snapRange.insertNode(textNode);
-              const sel = window.getSelection();
                 if (sel) {
                   sel.removeAllRanges();
                   const newRange = document.createRange();
@@ -507,8 +520,11 @@ export default defineContentScript({
                   newRange.collapse(true);
                   sel.addRange(newRange);
                 }
+              }
             } catch (err) {
               console.warn('[LexAI Replace] range replace failed:', err);
+              // Last resort: execCommand
+              try { document.execCommand('insertText', false, resultText); } catch (_) {}
             }
           } else {
             console.warn('[LexAI Replace] NO VALID SNAP STATE — snapStart:', snapStart, 'snapEnd:', snapEnd, 'snapElement:', snapElement, 'snapRange:', snapRange);