From 669e6d662c62c3e0b69def3f4485aaa9ddd87b05 Mon Sep 17 00:00:00 2001
From: ahfoysal <ahfoysal30@gmail.com>
Date: Tue, 7 Jul 2026 14:38:15 +0600
Subject: [PATCH] fix(formatting): realign scanner for mis-spanned child tokens

Handle recovery cases where a token ends after the current child while formatting invalid syntax, to avoid entering invalid scanner state.

Fixes #63598.
---
 src/services/formatting/formatting.ts              | 14 +++++++-------
 .../cases/fourslash/formattingTokenEndChildEnd.ts  |  7 +++++++
 2 files changed, 14 insertions(+), 7 deletions(-)
 create mode 100644 tests/cases/fourslash/formattingTokenEndChildEnd.ts

diff --git a/src/services/formatting/formatting.ts b/src/services/formatting/formatting.ts
index e641b0f2b0434..6570e4174654f 100644
--- a/src/services/formatting/formatting.ts
+++ b/src/services/formatting/formatting.ts
@@ -857,13 +857,13 @@ function formatSpanWorker(
                 if (tokenInfo.token.end > originalRange.end) {
                     return inheritedIndentation;
                 }
-                if (tokenInfo.token.end > childStartPos) {
-                    if (tokenInfo.token.pos > childStartPos) {
-                        formattingScanner.skipToStartOf(child);
-                    }
-                    // stop when formatting scanner advances past the beginning of the child
-                    break;
-                }
+                if (tokenInfo.token.end > childStartPos) {
+                    if (tokenInfo.token.pos > childStartPos || tokenInfo.token.end > child.end) {
+                        formattingScanner.skipToStartOf(child);
+                    }
+                    // stop when formatting scanner advances past the beginning of the child
+                    break;
+                }
 
                 consumeTokenAndAdvanceScanner(tokenInfo, node, parentDynamicIndentation, node);
             }
diff --git a/tests/cases/fourslash/formattingTokenEndChildEnd.ts b/tests/cases/fourslash/formattingTokenEndChildEnd.ts
new file mode 100644
index 0000000000000..30b52c42956c8
--- /dev/null
+++ b/tests/cases/fourslash/formattingTokenEndChildEnd.ts
@@ -0,0 +1,7 @@
+/// <reference path='fourslash.ts' />
+
+/////*start*/type X = { prop: = `${abc}`xyz };
+format.document();
+
+goTo.marker("start");
+verify.currentLineContentIs("type X = { prop: = `${abc}`xyz };");