#833: opened files grow non-custom rows to their tallest font

crates/engine/src/io.rs

@@ -56,7 +56,9 @@ pub fn open_bytes(name: &str, bytes: &[u8]) -> Result<(Workbook, Vec<String>)> {
 /// quote the password.
 pub fn open_bytes_with_password(name: &str, bytes: &[u8], password: Option<&str>) -> Result<(Workbook, Vec<String>)> {
     if gridcraft_xlsx::sniff(bytes) != gridcraft_xlsx::Format::Encrypted {
-        return open_plain(name, bytes);
+        let (mut wb, warnings) = open_plain(name, bytes)?;
+        fit_imported_rows(&mut wb);
+        return Ok((wb, warnings));
     }
     // A scheme no password opens is said straight away, rather than after asking for one.
     let decrypt_error = |e: gridcraft_xlsx::DecryptError| EngineError::Other(decrypt_message(name, e));
@@ -68,11 +70,36 @@ pub fn open_bytes_with_password(name: &str, bytes: &[u8], password: Option<&str>
     if gridcraft_xlsx::sniff(&plain) == gridcraft_xlsx::Format::Encrypted {
         return Err(EngineError::Other(format!("We can't open '{name}': the encrypted file is damaged (it holds another encrypted file).")));
     }
-    let (wb, mut warnings) = open_plain(name, &plain)?;
+    let (mut wb, mut warnings) = open_plain(name, &plain)?;
+    fit_imported_rows(&mut wb);
     warnings.insert(0, DECRYPTED_NOTICE.into());
     Ok((wb, warnings))
 }
 
+/// Excel auto-fits rows to their tallest font when opening a file: rows without a user-set
+/// height grow to fit their content. Rows the file made taller keep their height — our
+/// line-height estimate can differ from Excel's, and shrinking files that already look
+/// right would be a visible regression. Custom-height rows are left alone entirely.
+fn fit_imported_rows(wb: &mut Workbook) {
+    for si in 0..wb.sheets.len() {
+        let Some(sh) = wb.sheet(si) else { continue };
+        let mut rows: Vec<u32> = sh.cells.iter().map(|(c, _)| c.row).collect();
+        rows.sort_unstable();
+        rows.dedup();
+        for row in rows {
+            let before = wb.sheet(si).and_then(|sh| sh.rows.get(&row)).and_then(|i| i.size);
+            crate::cmd::auto_row_height(wb, si, row);
+            let Some(before) = before else { continue };
+            let after = wb.sheet(si).and_then(|sh| sh.rows.get(&row)).and_then(|i| i.size);
+            if after.is_none_or(|a| before > a + 0.5)
+                && let Some(sh) = wb.sheet_mut(si)
+            {
+                sh.rows.entry(row).or_default().size = Some(before);
+            }
+        }
+    }
+}
+
 /// What to tell the user when an encrypted workbook can't be decrypted. Never quotes the password.
 fn decrypt_message(name: &str, e: gridcraft_xlsx::DecryptError) -> String {
     match e {

crates/engine/src/tests.rs

@@ -1007,6 +1007,71 @@ fn spill_references_roundtrip_through_xlsx() {
     assert_eq!((v(&s, "C1"), v(&s, "C2")), (Value::Number(10.0), Value::Number(4.0)));
 }
 
+/// Fixture for the open-time row fit (issue #833): `row_info` = (size, custom, hidden) for
+/// row 5 (index 4), `None` = no row entry at all. Cell A5 = "plain big bold", whole-cell
+/// font 20pt. 11pt cell in A1 for contrast rows. Built with the model API, never through
+/// commands — commands would auto-fit the rows — and exported with `write_xlsx`, which
+/// omits `ht` for rows without a size: exactly the bug's input.
+fn big_font_workbook(row_info: Option<(f32, bool, bool)>) -> Vec<u8> {
+    let mut wb = gridcraft_model::Workbook::new();
+    let big = wb.styles.derive(gridcraft_model::StyleId::DEFAULT, |s| s.font.size = 20.0);
+    let sh = wb.sheet_mut(0).unwrap();
+    sh.set_value(CellRef::new(0, 0), Value::text("small"));
+    sh.set_value(CellRef::new(4, 0), Value::text("plain big bold"));
+    sh.set_style(CellRef::new(4, 0), big);
+    if let Some((size, custom, hidden)) = row_info {
+        let e = sh.rows.entry(4).or_default();
+        e.size = Some(size);
+        e.custom = custom;
+        e.hidden = hidden;
+    }
+    gridcraft_xlsx::write_xlsx(&wb).unwrap()
+}
+
+#[test] // A — the issue's repro
+fn open_grows_default_height_rows_to_their_font() {
+    let default_h = gridcraft_model::Workbook::new().active().unwrap().row_height(0);
+    let mut s = Session::new();
+    s.execute("file.open", json!({"name": "bigfont.xlsx", "base64": crate::io::base64_encode(&big_font_workbook(None))})).unwrap();
+    let h = s.doc().unwrap().wb.active().unwrap().row_height(4);
+    assert!(h >= 30.0, "20pt cell must grow its default-height row on open, got {h}");
+    assert_eq!(s.doc().unwrap().wb.active().unwrap().row_height(0), default_h, "11pt row stays default");
+}
+
+#[test] // B — Review Focus 1
+fn open_keeps_custom_height_rows() {
+    let mut s = Session::new();
+    s.execute("file.open", json!({"name": "custom.xlsx", "base64": crate::io::base64_encode(&big_font_workbook(Some((25.0, true, false))))}))
+        .unwrap();
+    assert_eq!(s.doc().unwrap().wb.active().unwrap().row_height(4), 25.0, "custom-height rows are left alone on open");
+}
+
+#[test] // C — Review Focus 2
+fn open_never_shrinks_taller_auto_rows() {
+    let mut s = Session::new();
+    s.execute("file.open", json!({"name": "tall.xlsx", "base64": crate::io::base64_encode(&big_font_workbook(Some((60.0, false, false))))})).unwrap();
+    assert_eq!(s.doc().unwrap().wb.active().unwrap().row_height(4), 60.0, "open is grow-only: a 60px auto-height row keeps its height");
+}
+
+#[test] // D — Review Focus 5
+fn open_fitting_keeps_hidden_rows_hidden() {
+    let mut s = Session::new();
+    s.execute("file.open", json!({"name": "hidden.xlsx", "base64": crate::io::base64_encode(&big_font_workbook(Some((20.0, false, true))))}))
+        .unwrap();
+    let sh = s.doc().unwrap().wb.active().unwrap();
+    let info = sh.rows.get(&4).unwrap();
+    assert!(info.size.is_none_or(|h| h >= 20.0), "hidden row grows or keeps its height, got {:?}", info.size);
+    assert!(info.hidden, "fitting a hidden row must not unhide it");
+}
+
+#[test] // E — Review Focus 4
+fn open_leaves_plain_workbooks_untouched() {
+    let mut s = Session::new();
+    s.execute("file.open", json!({"name": "plain.xlsx", "base64": crate::io::base64_encode(&big_font_workbook(None))})).unwrap();
+    let sh = s.doc().unwrap().wb.active().unwrap();
+    assert!(sh.rows.get(&0).is_none_or(|i| i.size.is_none()), "11pt default rows get no height entry");
+}
+
 #[test]
 fn tables_and_structured_refs() {
     let mut s = s();