fix(BufferReflow): clear stale isWrapped after larger reflow

When widening the terminal unwraps a multi-row soft wrap and removes
trailing buffer lines, the last retained row could still have
isWrapped set, and the following line could still think it continued
a removed row. That broke wrapped range translation.

Clear isWrapped on the last retained row in the group and on the
first line after the group when rows are removed during reflow.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/common/buffer/BufferReflow.test.ts

@@ -10,6 +10,7 @@ import { CellData } from './CellData';
 import { NULL_CELL_CHAR, NULL_CELL_WIDTH, NULL_CELL_CODE } from './Constants';
 import { reflowLargerGetLinesToRemove, reflowSmallerGetNewLineLengths } from './BufferReflow';
 import { IBufferLine } from './Types';
+import { createCellData, NULL_CELL_DATA } from '../TestUtils.test';
 
 const TEST_STRING_CACHE = new BufferLineStringCache();
 
@@ -122,5 +123,27 @@ describe('BufferReflow', () => {
       const lines = createWrappedLines('abcde');
       assert.notDeepEqual(reflowLargerGetLinesToRemove(lines, 1, 5, 10, nullCell, false), []);
     });
+
+    it('should clear isWrapped on the last retained row after unwrap', () => {
+      const lines = new CircularList<BufferLine>(10);
+      const set2 = (line: BufferLine, s: string) => {
+        for (let i = 0; i < s.length; i++) {
+          line.setCell(i, createCellData(0, s[i], 1));
+        }
+      };
+      const l0 = new BufferLine(TEST_STRING_CACHE, 2);
+      set2(l0, 'ab');
+      const l1 = new BufferLine(TEST_STRING_CACHE, 2, undefined, true);
+      set2(l1, 'cd');
+      const l2 = new BufferLine(TEST_STRING_CACHE, 2, undefined, true);
+      set2(l2, 'ef');
+      lines.push(l0);
+      lines.push(l1);
+      lines.push(l2);
+
+      reflowLargerGetLinesToRemove(lines, 2, 6, 99, NULL_CELL_DATA, false);
+
+      assert.equal(l1.isWrapped, false);
+    });
   });
 });

src/common/buffer/BufferReflow.ts

@@ -99,6 +99,11 @@ export function reflowLargerGetLinesToRemove(lines: CircularList<IBufferLine>, o
     }
 
     if (countToRemove > 0) {
+      wrappedLines[destLineIndex].isWrapped = false;
+      const lineAfterGroup = lines.get(y + wrappedLines.length);
+      if (lineAfterGroup) {
+        lineAfterGroup.isWrapped = false;
+      }
       toRemove.push(y + wrappedLines.length - countToRemove); // index
       toRemove.push(countToRemove);
     }