From e8c6fcb8b0fc65deedf245000bef859657bd4d77 Mon Sep 17 00:00:00 2001
From: Marco Arnulfo <marcoarnulfo1@gmail.com>
Date: Fri, 16 Oct 2026 05:11:07 +0200
Subject: [PATCH] XLSX: keep custom column widths that round to the default
 width (fixes #1607)

---
 crates/xlsx/src/sheet_read.rs     |  4 ++--
 crates/xlsx/src/tests/fixtures.rs | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/crates/xlsx/src/sheet_read.rs b/crates/xlsx/src/sheet_read.rs
index 0194d2268..83f8d0d91 100644
--- a/crates/xlsx/src/sheet_read.rs
+++ b/crates/xlsx/src/sheet_read.rs
@@ -324,8 +324,8 @@ fn read_cols(cx: &Ctx<'_>, e: &El, sheet: &mut Sheet) {
                 info.style = Some(id);
             }
         }
-        // A width equal to the default with nothing else set is noise.
-        if info == LineInfo::default() || (info.size == Some(sheet.default_col_width) && LineInfo { size: None, ..info } == LineInfo::default()) {
+        // A custom width equal to the default still pins the column (Standard Width leaves it alone).
+        if info == LineInfo::default() {
             continue;
         }
         for col in (min - 1)..max {
diff --git a/crates/xlsx/src/tests/fixtures.rs b/crates/xlsx/src/tests/fixtures.rs
index 39ea30951..4ca580a5b 100644
--- a/crates/xlsx/src/tests/fixtures.rs
+++ b/crates/xlsx/src/tests/fixtures.rs
@@ -577,3 +577,25 @@ fn user_defined_function_prefix_round_trips() {
         assert_eq!(cell.child("f").unwrap().text, f, "written {a}");
     }
 }
+
+/// `customWidth="1"` pins a column even when its width rounds to the default: Standard Width does not
+/// move it, and a save must keep its `<col>` (openpyxl writes 9.08 for Excel's 8.43, #1607).
+#[test]
+fn custom_widths_equal_to_the_default_round_trip() {
+    let body = r#"<sheetFormatPr baseColWidth="8" defaultRowHeight="15"/>
+      <cols><col min="4" max="5" width="9.08" customWidth="1"/><col min="6" max="6" width="9.140625" customWidth="1"/><col min="7" max="7" width="9.2" customWidth="1"/><col min="8" max="8" width="9.140625"/></cols>
+      <sheetData/>"#;
+    let (wb, _) = read_xlsx(&minimal(body, &[], "", "")).unwrap();
+    let s = wb.sheet(0).unwrap();
+    assert_eq!(s.default_col_width, 64.0);
+    for c in 3..=6 {
+        assert_eq!(s.cols.get(&c).and_then(|i| i.size), Some(64.0), "read col {c}");
+    }
+    assert_eq!(s.cols.get(&7), None, "a width without customWidth equal to the default stays the default");
+    let bytes = crate::write_xlsx(&wb).unwrap();
+    let mut pkg = crate::package::Package::open(&bytes).unwrap();
+    let sheet = pkg.read_xml("xl/worksheets/sheet1.xml").unwrap().unwrap();
+    let cols: Vec<_> =
+        sheet.child("cols").unwrap().kids("col").map(|c| (c.attr_u32("min"), c.attr_u32("max"), c.flag("customWidth", false))).collect();
+    assert_eq!(cols, [(Some(4), Some(7), true)]);
+}