From 1d07b6a592558b80cf23f3bea1d6103e6f45a0b5 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Wed, 28 Jan 2026 17:08:42 +0000
Subject: [PATCH 1/2] Initial plan


From 9305e6b6ff48af3c8180d174a10c1f88f2d05706 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Wed, 28 Jan 2026 17:17:55 +0000
Subject: [PATCH 2/2] Fix UTF-32 surrogate handling bug

Co-authored-by: ChALkeR <291301+ChALkeR@users.noreply.github.com>
---
 fallback/utf32.js | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/fallback/utf32.js b/fallback/utf32.js
index 7edf18ca..85045334 100644
--- a/fallback/utf32.js
+++ b/fallback/utf32.js
@@ -51,18 +51,10 @@ export function toWellFormed(u32) {
   for (let i = 0; i < length; i++) {
     const x = u32[i]
     if (x >= 0xd8_00) {
+      // In UTF-32, all surrogate codepoints (0xD800-0xDFFF) are invalid
+      // Unlike UTF-16, there are no surrogate pairs in UTF-32
       if (x < 0xe0_00) {
-        // An unexpected trail or a lead at the very end of input
-        if (x > 0xdb_ff || i + 1 >= length) {
-          u32[i] = replacementCodepoint
-        } else {
-          const next = u32[i + 1] // Process valid pairs immediately
-          if (next < 0xdc_00 || next >= 0xe0_00) {
-            u32[i] = replacementCodepoint
-          } else {
-            i++ // consume next
-          }
-        }
+        u32[i] = replacementCodepoint
       } else if (x >= 0x11_00_00) {
         // also fix out-of-range in the same pass, both are unlikely
         u32[i] = replacementCodepoint