diff --git a/apps/vscode/src/providers/format.ts b/apps/vscode/src/providers/format.ts
index 92c078e5..c6a5eb84 100644
--- a/apps/vscode/src/providers/format.ts
+++ b/apps/vscode/src/providers/format.ts
@@ -138,9 +138,13 @@ class FormatCellCommand implements Command {
       const edits = await formatActiveCell(editor, this.engine_);
       if (edits) {
         editor.edit((editBuilder) => {
-          edits.forEach((edit) => {
-            editBuilder.replace(edit.range, edit.newText);
-          });
+          // Sort edits by descending start position to avoid range shifting issues
+          edits
+            .slice()
+            .sort((a, b) => b.range.start.compareTo(a.range.start))
+            .forEach((edit) => {
+              editBuilder.replace(edit.range, edit.newText);
+            });
         });
       } else {
         window.showInformationMessage(
@@ -204,15 +208,20 @@ async function formatActiveCell(editor: TextEditor, engine: MarkdownEngine) {
 }
 
 async function formatBlock(doc: TextDocument, block: TokenMath | TokenCodeBlock, language: EmbeddedLanguage) {
-  const blockLines = lines(codeForExecutableLanguageBlock(block));
-  blockLines.push("");
+  // Create virtual document containing the block
+  const blockLines = lines(codeForExecutableLanguageBlock(block, false));
   const vdoc = virtualDocForCode(blockLines, language);
+
   const edits = await executeFormatDocumentProvider(
     vdoc,
     doc,
     formattingOptions(doc.uri, vdoc.language)
   );
+
   if (edits) {
+    // Because we format with the block code copied in an empty virtual
+    // document, we need to adjust the ranges to match the edits to the block
+    // cell in the original file.
     const blockRange = new Range(
       new Position(block.range.start.line, block.range.start.character),
       new Position(block.range.end.line, block.range.end.character)
@@ -224,8 +233,17 @@ async function formatBlock(doc: TextDocument, block: TokenMath | TokenCodeBlock,
           new Position(edit.range.end.line + block.range.start.line + 1, edit.range.end.character)
         );
         return new TextEdit(range, edit.newText);
-      })
-      .filter(edit => blockRange.contains(edit.range));
+      });
+
+    // Bail if any edit is out of range. We used to filter these edits out but
+    // this could bork the cell.
+    if (edits.some(edit => !blockRange.contains(edit.range))) {
+      window.showInformationMessage(
+        "Formatting edits were out of range and could not be applied to the code cell."
+      );
+      return [];
+    }
+
     return adjustedEdits;
   }
 }
diff --git a/apps/vscode/src/test/examples/cell-format.qmd b/apps/vscode/src/test/examples/cell-format.qmd
new file mode 100644
index 00000000..c3fbd011
--- /dev/null
+++ b/apps/vscode/src/test/examples/cell-format.qmd
@@ -0,0 +1,5 @@
+See https://github.com/quarto-dev/quarto/issues/745 "Reformating R cell in VSCODE with air does not correctly close chunk."
+
+```{r}
+list(foobar, foobar, foobar, foobar, foobar, foobar, foobar, foobar, foobar, foobar, foobar, foobar)
+```
\ No newline at end of file
diff --git a/apps/vscode/src/test/quartoDoc.test.ts b/apps/vscode/src/test/quartoDoc.test.ts
index d4ca47aa..f456dae0 100644
--- a/apps/vscode/src/test/quartoDoc.test.ts
+++ b/apps/vscode/src/test/quartoDoc.test.ts
@@ -41,8 +41,72 @@ suite("Quarto basics", function () {
   roundtripSnapshotTest('capsule-leak.qmd');
 
   roundtripSnapshotTest('attr-equals.qmd');
+
+  test("quarto.formatCell deals with formatters that do or don't add trailing newline consistently", async function () {
+
+    async function testFormatter(filename: string, [line, character]: [number, number], format: (sourceText: string) => string) {
+      const { doc } = await openAndShowTextDocument(filename);
+
+      const formattingEditProvider = vscode.languages.registerDocumentFormattingEditProvider(
+        { scheme: 'file', language: 'r' },
+        createFormatterFromStringFunc(format)
+      )
+
+      setCursorPosition(line, character);
+      await wait(450);
+      await vscode.commands.executeCommand("quarto.formatCell");
+      await wait(450)
+
+      const result = doc.getText()
+      formattingEditProvider.dispose()
+      await vscode.commands.executeCommand("workbench.action.closeActiveEditor");
+
+      return result
+    }
+
+    const newlineFormatterResult = await testFormatter(
+      "cell-format.qmd",
+      [3, 1],
+      (sourceText) => sourceText + 'FORMAT SUCCESS\n'
+    )
+    const noopFormatterResult = await testFormatter(
+      "cell-format.qmd",
+      [3, 1],
+      (sourceText) => sourceText + 'FORMAT SUCCESS'
+    )
+
+    assert.ok(newlineFormatterResult.includes('FORMAT SUCCESS'), 'newlineFormatter failed')
+    assert.ok(noopFormatterResult.includes('FORMAT SUCCESS'), 'noopFormatter failed')
+
+    assert.equal(newlineFormatterResult, noopFormatterResult)
+  });
+
+  suiteTeardown(() => {
+    vscode.window.showInformationMessage('All tests done!');
+  });
 });
 
+function createFormatterFromStringFunc(format: (sourceText: string) => string) {
+  return {
+    provideDocumentFormattingEdits(document: vscode.TextDocument): vscode.ProviderResult<vscode.TextEdit[]> {
+      const fileStart = new vscode.Position(0, 0);
+      const fileEnd = document.lineAt(document.lineCount - 1).range.end;
+
+      return [new vscode.TextEdit(new vscode.Range(fileStart, fileEnd), format(document.getText()))];
+    }
+  }
+}
+
+function setCursorPosition(line: number, character: number) {
+  const editor = vscode.window.activeTextEditor;
+  if (editor) {
+    const position = new vscode.Position(line, character);
+    const newSelection = new vscode.Selection(position, position);
+    editor.selection = newSelection;
+    editor.revealRange(newSelection, vscode.TextEditorRevealType.InCenter); // Optional: scroll to the new position
+  }
+}
+
 /**
  *
  * When the test is run on the dev's machine for the first time, saves the roundtripped file as a snapshot.
diff --git a/packages/quarto-core/src/markdown/language.ts b/packages/quarto-core/src/markdown/language.ts
index ea3f88fe..201fc259 100644
--- a/packages/quarto-core/src/markdown/language.ts
+++ b/packages/quarto-core/src/markdown/language.ts
@@ -38,11 +38,14 @@ export function isExecutableLanguageBlock(token: Token) : token is TokenMath | T
   }
 }
 
-export function codeForExecutableLanguageBlock(token: TokenMath | TokenCodeBlock) {
+export function codeForExecutableLanguageBlock(
+  token: TokenMath | TokenCodeBlock,
+  appendNewline = true,
+) {
   if (isMath(token)) {
     return token.data.text;
   } else if (isCodeBlock(token)) {
-    return token.data + "\n";
+    return token.data + (appendNewline ? "\n" : "");
   } else {
     return "";
   }