Merge PR #1529: fix #1458: one reference-app sheet-name quoting rule for formulas, pivot sources and ADDRESS

crates/calc/src/eval.rs

@@ -262,7 +262,7 @@ impl<'h> Evaluator<'h> {
         let wb = self.host.workbook();
         // Sheet-qualified `Sheet1!Name`.
         let (scope_sheet, bare) = match n.split_once('!') {
-            Some((s, b)) => match wb.sheet_index(s.trim_matches('\'')) {
+            Some((s, b)) => match wb.sheet_index(&gridcraft_core::unquote_sheet(s)) {
                 Some(i) => (i, b),
                 None => return err(CellError::Name),
             },

crates/chart/src/resolve.rs

@@ -41,7 +41,7 @@ fn parse_ref(wb: &Workbook, sheet: usize, formula: &str) -> Option<(usize, Range
     let (sh, addr) = match f.rfind('!') {
         Some(i) => {
             let name = f.get(..i)?.trim();
-            let name = name.strip_prefix('\'').and_then(|n| n.strip_suffix('\'')).map(|n| n.replace("''", "'")).unwrap_or_else(|| name.to_string());
+            let name = gridcraft_core::unquote_sheet(name);
             (wb.sheet_index(&name)?, f.get(i + 1..)?)
         }
         None => (sheet, f),

crates/core/src/addr.rs

@@ -237,6 +237,59 @@ impl fmt::Display for RangeRef {
     }
 }
 
+/// Whether `name` reads as an R1C1 reference: `R`, `C`, `RC`, `R1`, `C1`, `R1C`, `RC1`, `R1C1`
+/// in any case.
+fn is_r1c1_token(name: &str) -> bool {
+    let mut chars = name.chars().peekable();
+    let mut letters = 0;
+    for letter in ['r', 'c'] {
+        if chars.peek().is_some_and(|c| c.to_ascii_lowercase() == letter) {
+            chars.next();
+            letters += 1;
+            while chars.peek().is_some_and(|c| c.is_ascii_digit()) {
+                chars.next();
+            }
+        }
+    }
+    letters > 0 && chars.next().is_none()
+}
+
+/// Whether Excel quotes a sheet name in a reference (`'My Sheet'!A1`): it starts with a digit or
+/// `.`, holds anything but letters (any script), digits, `_` and `.`, reads as an A1 cell within
+/// the sheet or as an R1C1 reference, or is a boolean.
+pub fn sheet_needs_quotes(name: &str) -> bool {
+    let Some(first) = name.chars().next() else {
+        return true;
+    };
+    if first.is_ascii_digit() || first == '.' || name.chars().any(|c| !(c.is_alphanumeric() || c == '_' || c == '.')) {
+        return true;
+    }
+    CellRef::parse(name).is_some() || is_r1c1_token(name) || name.eq_ignore_ascii_case("TRUE") || name.eq_ignore_ascii_case("FALSE")
+}
+
+/// A sheet name as it is written in a reference: quoted, with `'` doubled, when Excel quotes it.
+pub fn quote_sheet(name: &str) -> String {
+    if sheet_needs_quotes(name) { format!("'{}'", name.replace('\'', "''")) } else { name.to_string() }
+}
+
+/// The inverse of [`quote_sheet`]: takes the quotes off a sheet name and reads `''` as `'`.
+/// Text that isn't quoted is returned as it is.
+pub fn unquote_sheet(text: &str) -> String {
+    match text.trim().strip_prefix('\'').and_then(|t| t.strip_suffix('\'')) {
+        Some(inner) => inner.replace("''", "'"),
+        None => text.trim().to_string(),
+    }
+}
+
+/// `'My Sheet'!A1` → (`Some("My Sheet")`, `A1`). Splits at the last `!`, so a quoted name may
+/// hold one (`'a!b'!A1`).
+pub fn split_sheet(reference: &str) -> (Option<String>, &str) {
+    match reference.rsplit_once('!') {
+        Some((sheet, body)) => (Some(unquote_sheet(sheet)), body),
+        None => (None, reference),
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -253,6 +306,50 @@ mod tests {
         assert_eq!((r.start.row, r.end.row), (0, 2));
     }
 
+    #[test]
+    fn sheet_quoting_follows_excel() {
+        for quoted in [
+            "A1",
+            "XFD1",
+            "AB1048576",
+            "R1",
+            "C1",
+            "RC1",
+            "R",
+            "C",
+            "RC",
+            "R1C",
+            "R1C1",
+            "r2c3",
+            "CR1",
+            ".x",
+            "TRUE",
+            "false",
+            "1abc",
+            "My Sheet",
+            "Bob's",
+            "a-b",
+            "",
+        ] {
+            assert!(sheet_needs_quotes(quoted), "{quoted:?} should be quoted");
+        }
+        for bare in ["Sheet1", "XFE1", "AB1048577", "Ärger", "日本", "Σ", "Sheet.1", "_x", "A1A", "Data", "RR", "CRX"] {
+            assert!(!sheet_needs_quotes(bare), "{bare:?} should stay bare");
+        }
+    }
+
+    #[test]
+    fn quote_unquote_and_split_sheet() {
+        assert_eq!(quote_sheet("Bob's"), "'Bob''s'");
+        assert_eq!(quote_sheet("Data"), "Data");
+        assert_eq!(unquote_sheet("'Bob''s'"), "Bob's");
+        assert_eq!(unquote_sheet("Data"), "Data");
+        assert_eq!(unquote_sheet("'"), "'");
+        assert_eq!(split_sheet("'a!b'!A1"), (Some("a!b".to_string()), "A1"));
+        assert_eq!(split_sheet("'Bob''s'!$A$1:$B$2"), (Some("Bob's".to_string()), "$A$1:$B$2"));
+        assert_eq!(split_sheet("A1"), (None, "A1"));
+    }
+
     #[test]
     fn letters_roundtrip() {
         for (c, s) in [(0, "A"), (25, "Z"), (26, "AA"), (51, "AZ"), (52, "BA"), (701, "ZZ"), (702, "AAA"), (16383, "XFD")] {

crates/core/src/lib.rs

@@ -9,6 +9,6 @@ pub mod date;
 pub mod parse;
 pub mod value;
 
-pub use addr::{CellRef, MAX_COLS, MAX_ROWS, RangeRef, col_to_letters, letters_to_col};
+pub use addr::{CellRef, MAX_COLS, MAX_ROWS, RangeRef, col_to_letters, letters_to_col, quote_sheet, sheet_needs_quotes, split_sheet, unquote_sheet};
 pub use date::DateSystem;
 pub use value::{Array, CellError, Value, compare, compare_numbers, compare_text, number_to_text, sort_compare};

crates/engine/src/cmd/edit.rs

@@ -557,7 +557,7 @@ pub(super) fn go_to(s: &mut Session, p: &Json) -> Result<Json> {
         } else if let Some((si, ti)) = d.wb.table(reference) {
             // As in Excel, a table's name stands for its data, without the header and totals rows.
             let t = d.wb.sheet(si).and_then(|sh| sh.tables.get(ti)).map(|t| t.data_range().unwrap_or(t.range).a1()).unwrap_or_default();
-            format!("'{}'!{}", d.wb.sheet(si).map(|s| s.name.clone()).unwrap_or_default(), t)
+            format!("{}!{}", gridcraft_core::quote_sheet(&d.wb.sheet(si).map(|s| s.name.clone()).unwrap_or_default()), t)
         } else {
             return Err(EngineError::Other("Reference isn't valid.".into()));
         }

crates/engine/src/cmd/mod.rs

@@ -269,13 +269,7 @@ pub(crate) fn target_sheet(s: &Session, p: &Json) -> Result<usize> {
     Ok(d.wb.active_sheet)
 }
 
-/// `'My Sheet'!A1` → (`Some("My Sheet")`, `A1`).
-pub(crate) fn split_sheet(r: &str) -> (Option<String>, &str) {
-    match r.rsplit_once('!') {
-        Some((sh, body)) => (Some(sh.trim_matches('\'').replace("''", "'")), body),
-        None => (None, r),
-    }
-}
+pub(crate) use gridcraft_core::split_sheet;
 
 /// A single-cell parameter. Absent or null is `Ok(None)` (callers default it); a value that is not
 /// a cell reference, or that names a sheet other than the active one, is an error rather than a

crates/engine/src/cmd/pivot.rs

@@ -1392,7 +1392,7 @@ fn chart_pivot(s: &Session, p: &Json) -> Result<(usize, usize)> {
         let (sheet, addr) = match t.rsplit_once('!') {
             Some((sh, a)) => {
                 let sh = sh.trim();
-                let sh = sh.strip_prefix('\'').and_then(|x| x.strip_suffix('\'')).map(|x| x.replace("''", "'")).unwrap_or_else(|| sh.to_string());
+                let sh = gridcraft_core::unquote_sheet(sh);
                 (d.wb.sheet_index(&sh), a)
             }
             None => (Some(d.wb.active_sheet), t),

crates/engine/src/pivot.rs

@@ -9,7 +9,8 @@ use std::cmp::Ordering;
 use std::collections::{HashMap, HashSet};
 
 use gridcraft_core::date::datetime_from_serial;
-use gridcraft_core::{CellError, CellRef, MAX_COLS, MAX_ROWS, RangeRef, Value};
+pub use gridcraft_core::quote_sheet;
+use gridcraft_core::{CellError, CellRef, MAX_COLS, MAX_ROWS, RangeRef, Value, split_sheet};
 use gridcraft_model::*;
 
 use crate::pivot_calc::CalcSet;
@@ -47,26 +48,6 @@ impl Source {
     }
 }
 
-/// `'My Sheet'!A1` → (`Some("My Sheet")`, `A1`).
-fn split_sheet(r: &str) -> (Option<String>, &str) {
-    match r.rsplit_once('!') {
-        Some((sh, body)) => (Some(sh.trim_matches('\'').replace("''", "'")), body),
-        None => (None, r),
-    }
-}
-
-/// Quotes a sheet name for a reference when needed.
-pub fn quote_sheet(name: &str) -> String {
-    if !name.is_empty()
-        && name.chars().all(|c| c.is_alphanumeric() || c == '_' || c == '.')
-        && !name.chars().next().is_some_and(|c| c.is_ascii_digit())
-    {
-        name.to_string()
-    } else {
-        format!("'{}'", name.replace('\'', "''"))
-    }
-}
-
 /// Absolute reference text for a range on a sheet: `Sheet1!$A$1:$E$20`.
 pub fn range_text(sheet_name: &str, r: RangeRef) -> String {
     let abs = |c: CellRef| format!("${}${}", gridcraft_core::col_to_letters(c.col), c.row as u64 + 1);
@@ -1511,7 +1492,7 @@ pub fn parse_chart_link(link: &str) -> Option<(String, String)> {
     };
     let (sheet, name) = t.rsplit_once('!')?;
     let sheet = sheet.trim();
-    let sheet = sheet.strip_prefix('\'').and_then(|x| x.strip_suffix('\'')).map(|x| x.replace("''", "'")).unwrap_or_else(|| sheet.to_string());
+    let sheet = gridcraft_core::unquote_sheet(sheet);
     let name = name.trim();
     if sheet.is_empty() || name.is_empty() {
         return None;

crates/engine/tests/sheet_name_quoting.rs

@@ -0,0 +1,51 @@
+//! #1458: sheet names are quoted in references the way Excel quotes them, in formulas, saved
+//! files, PivotTable sources and ADDRESS.
+
+use gridcraft_engine::Session;
+use gridcraft_engine::core::{CellRef, Value};
+use serde_json::{Value as Json, json};
+
+fn run(s: &mut Session, command: &str, params: Json) -> Json {
+    s.execute(command, params).unwrap()
+}
+
+fn formula(s: &Session, cell: &str) -> String {
+    s.doc().unwrap().wb.active().unwrap().cell(CellRef::parse(cell).unwrap()).unwrap().formula.as_ref().unwrap().text.clone()
+}
+
+#[test]
+fn formulas_keep_the_quotes_excel_needs_through_a_save() {
+    let mut s = Session::new();
+    s.new_workbook();
+    for name in [".x", "R1C1", "A1", "Bob's"] {
+        run(&mut s, "home.insertSheet", json!({"name": name}));
+    }
+    run(&mut s, "sheet.activate", json!({"sheet": "Sheet1"}));
+    let input = "='.x'!A1+'R1C1'!A1+'A1'!B1+'Bob''s'!A1";
+    run(&mut s, "cell.set", json!({"cell": "A1", "input": input}));
+    assert_eq!(formula(&s, "A1"), input.trim_start_matches('='));
+
+    let saved = run(&mut s, "file.saveBytes", json!({"format": "xlsx"}));
+    let mut reopened = Session::new();
+    run(&mut reopened, "file.open", json!({"name": "q.xlsx", "base64": saved["base64"]}));
+    run(&mut reopened, "sheet.activate", json!({"sheet": "Sheet1"}));
+    assert_eq!(formula(&reopened, "A1"), input.trim_start_matches('='));
+}
+
+#[test]
+fn address_and_pivot_source_quote_a_sheet_named_like_a_cell() {
+    let mut s = Session::new();
+    s.new_workbook();
+    run(&mut s, "home.insertSheet", json!({"name": "A1"}));
+    run(&mut s, "sheet.activate", json!({"sheet": "A1"}));
+    for (cell, input) in [("A1", "K"), ("B1", "V"), ("A2", "a"), ("B2", "1"), ("A3", "b"), ("B3", "2")] {
+        run(&mut s, "cell.set", json!({"cell": cell, "input": input}));
+    }
+    run(&mut s, "cell.set", json!({"cell": "D1", "input": "=ADDRESS(1,1,1,TRUE,\"A1\")"}));
+    let d1 = s.doc().unwrap().wb.active().unwrap().value(CellRef::parse("D1").unwrap());
+    assert_eq!(d1, Value::from("'A1'!$A$1"));
+
+    run(&mut s, "selection.set", json!({"range": "A2"}));
+    let pivot = run(&mut s, "insert.pivotTable", json!({"rows": ["K"], "values": ["V"]}));
+    assert_eq!(pivot["source"], json!("'A1'!$A$1:$B$3"));
+}

crates/formula/src/printer.rs

@@ -6,22 +6,7 @@ use gridcraft_core::{CellRef, col_to_letters, number_to_text};
 
 use crate::ast::*;
 
-/// Whether a sheet name needs quotes in a reference.
-pub fn needs_quotes(name: &str) -> bool {
-    if name.is_empty() {
-        return true;
-    }
-    let first = name.chars().next().unwrap_or('_');
-    if first.is_ascii_digit() || name.chars().any(|c| !(c.is_alphanumeric() || c == '_' || c == '.')) {
-        return true;
-    }
-    // Looks like a cell ref (`A1`, `R1C1`) or a boolean.
-    gridcraft_core::CellRef::parse(name).is_some() || name.eq_ignore_ascii_case("TRUE") || name.eq_ignore_ascii_case("FALSE")
-}
-
-pub fn quote_sheet(name: &str) -> String {
-    if needs_quotes(name) { format!("'{}'", name.replace('\'', "''")) } else { name.to_string() }
-}
+pub use gridcraft_core::{quote_sheet, sheet_needs_quotes as needs_quotes};
 
 fn sheet_prefix(s: &SheetSel) -> String {
     match s {

crates/formula/src/tests.rs

@@ -401,3 +401,15 @@ fn formulas_longer_than_excel_allows_are_refused() {
     assert!(text.len() > crate::MAX_FORMULA_LEN);
     assert!(parse(&text).is_ok());
 }
+
+#[test]
+fn sheet_names_excel_quotes_stay_quoted() {
+    // Excel quotes R1C1-looking names, a leading `.`, cells within the sheet and booleans (#1458).
+    for name in ["R", "C", "RC", "R1C", "RC1", "R1C1", "r2c3", "R1", "C1", "A1", "XFD1", "AB1048576", ".x", "TRUE", "false"] {
+        assert_eq!(rt(&format!("'{name}'!A1")), format!("'{name}'!A1"), "{name}");
+    }
+    // Names Excel leaves bare.
+    for name in ["XFE1", "AB1048577", "Sheet.1", "_x", "A1A", "\u{3a3}"] {
+        assert_eq!(rt(&format!("'{name}'!A1")), format!("{name}!A1"), "{name}");
+    }
+}

crates/functions/src/lookup.rs

@@ -413,15 +413,15 @@ fn transpose(args: &[Arg], _c: &mut dyn Ctx) -> R<Value> {
     }
 }
 
-/// Sheet text for ADDRESS, quoted when it needs to be. A `[Book]Sheet` prefix is judged by its
+/// Sheet text for ADDRESS, quoted when Excel quotes it. A `[Book]Sheet` prefix is judged by its
 /// parts (Microsoft's ADDRESS examples: `"[Book1]Sheet1"` stays bare, `"EXCEL SHEET"` becomes
-/// `'EXCEL SHEET'`).
+/// `'EXCEL SHEET'`). Unlike in a formula, `TRUE` and `FALSE` stay bare.
 fn quote_sheet(s: &str) -> String {
-    let word = |p: &str| p.chars().all(|c| c.is_alphanumeric() || c == '_' || c == '.');
-    let bare_sheet = |p: &str| !p.is_empty() && word(p) && !p.chars().next().is_some_and(|c| c.is_ascii_digit());
+    let bare = |p: &str| p.eq_ignore_ascii_case("TRUE") || p.eq_ignore_ascii_case("FALSE") || !gridcraft_core::sheet_needs_quotes(p);
+    let word = |p: &str| !p.is_empty() && p.chars().all(|c| c.is_alphanumeric() || c == '_' || c == '.');
     let plain = match s.strip_prefix('[').and_then(|r| r.split_once(']')) {
-        Some((book, sheet)) => !book.is_empty() && word(book) && bare_sheet(sheet),
-        None => bare_sheet(s),
+        Some((book, sheet)) => word(book) && bare(sheet),
+        None => bare(s),
     };
     if plain { s.to_string() } else { format!("'{}'", s.replace('\'', "''")) }
 }
@@ -791,6 +791,13 @@ mod tests {
         for (r, c, abs, a1, sheet, want) in cases {
             is_text(ev("ADDRESS", vec![n(r), n(c), n(abs), b(a1), t(sheet)]), want);
         }
+        // Sheet names that read as a cell or an R1C1 reference, or start with a dot, are quoted;
+        // off-sheet cells and booleans are not (#1458).
+        for (sheet, want) in
+            [("A1", "'A1'!$A$1"), ("R1C1", "'R1C1'!$A$1"), ("RC", "'RC'!$A$1"), (".x", "'.x'!$A$1"), ("XFE1", "XFE1!$A$1"), ("TRUE", "TRUE!$A$1")]
+        {
+            is_text(ev("ADDRESS", vec![n(1.0), n(1.0), n(1.0), b(true), t(sheet)]), want);
+        }
         is_text(ev("ADDRESS", vec![n(1048576.0), n(16384.0)]), "$XFD$1048576");
         is_err(ev("ADDRESS", vec![n(0.0), n(1.0)]), CellError::Value);
         is_err(ev("ADDRESS", vec![n(1.0), n(16385.0)]), CellError::Value);

crates/ui-egui/src/lib.rs

@@ -1295,7 +1295,7 @@ impl SheetApp {
             for n in &d.wb.names {
                 let target = n.formula.replace('$', "");
                 let (sheet, body) = match target.rsplit_once('!') {
-                    Some((s, b)) => (Some(s.trim_matches('\'').to_string()), b.to_string()),
+                    Some((s, b)) => (Some(gridcraft_engine::core::unquote_sheet(s)), b.to_string()),
                     None => (None, target.clone()),
                 };
                 if sheet.as_deref().is_none_or(|s| s.eq_ignore_ascii_case(&sh.name)) && RangeRef::parse(&body) == Some(cur) {

crates/ui-egui/tests/interaction.rs

@@ -227,6 +227,19 @@ fn name_box_enter_goes_to_the_typed_cell_not_the_one_below() {
     assert_eq!(h.state().session.active().unwrap().selection.active, CellRef::new(1, 0));
 }
 
+#[test]
+fn name_box_shows_a_name_defined_on_a_sheet_with_an_apostrophe() {
+    // #1458: the quotes of `'Bob''s'!$A$1:$B$2` were taken off without reading `''` as `'`.
+    let mut h = harness(blank());
+    let session = &mut h.state_mut().session;
+    session.run("home.insertSheet", json!({"name": "Bob's"})).unwrap();
+    session.run("sheet.activate", json!({"sheet": "Bob's"})).unwrap();
+    session.run("formulas.defineName", json!({"name": "Box", "refersTo": "='Bob''s'!$A$1:$B$2"})).unwrap();
+    session.run("selection.set", json!({"range": "A1:B2"})).unwrap();
+    h.run_steps(2);
+    assert_eq!(h.state().name_box_text(), "Box");
+}
+
 #[test]
 fn typing_enters_values_and_moves_down() {
     let mut h = harness(blank());

crates/xlsx/src/array_formula.rs

@@ -53,7 +53,7 @@ impl Scan<'_> {
                     return *shape;
                 }
                 let (scope, bare) = match n.rsplit_once('!') {
-                    Some((s, name)) => (self.wb.sheet_index(&s.trim_matches('\'').replace("''", "'")).unwrap_or(sheet), name),
+                    Some((s, name)) => (self.wb.sheet_index(&gridcraft_core::unquote_sheet(s)).unwrap_or(sheet), name),
                     None => (sheet, n.as_str()),
                 };
                 if let Some(def) = self.wb.name(bare, scope) {

crates/xlsx/src/pivot.rs

@@ -378,10 +378,7 @@ fn resolve_source(wb: &Workbook, text: &str, default_sheet: usize, depth: u32) -
         let xml = if valid { format!("<worksheetSource name=\"{}\"/>", esc_attr(&tb.name)) } else { range_source_xml(&sh.name, r) };
         return Some((si, r, xml));
     }
-    let (sheet, body) = match t.rsplit_once('!') {
-        Some((sh, body)) => (Some(sh.trim_matches('\'').replace("''", "'")), body),
-        None => (None, t),
-    };
+    let (sheet, body) = gridcraft_core::split_sheet(t);
     if let Some(r) = RangeRef::parse(body) {
         let si = match &sheet {
             Some(n) => wb.sheet_index(n)?,

docs/file-format-parity.md

@@ -1,6 +1,6 @@
 # File-format parity
 
-> **Last reviewed:** 2026-10-11 · **Last updated:** 2026-10-19 · **Change:** minor (.xls dialog sheets are skipped instead of read as worksheets; `.xls` import reads each sheet's display options from WINDOW2: right-to-left, gridlines, headings, zeros, formulas; XLSX text boxes and shapes keep their paragraphs' right-to-left direction on save; CSV/TSV/TXT can open with every field kept as text via `file.open {csvAsText}`; formulas over Excel's 8,192 characters, and `%` or call chains past the nesting limit, are parse errors instead of stack overflows when a file is opened; XLSX PivotTables read and write `rowGrandTotals`/`colGrandTotals` the way Excel does, so a table saved with only one grand total opens with the right one; HTML export keeps right-to-left) · **Target:** Microsoft Excel (Microsoft 365), Excel for Mac 16.113.4
+> **Last reviewed:** 2026-10-11 · **Last updated:** 2026-10-19 · **Change:** minor (XLSX formulas and PivotTable sources quote sheet names like Excel, so `'.x'!A1` no longer saves as `.x!A1` (#1458); .xls dialog sheets are skipped instead of read as worksheets; `.xls` import reads each sheet's display options from WINDOW2: right-to-left, gridlines, headings, zeros, formulas; XLSX text boxes and shapes keep their paragraphs' right-to-left direction on save; CSV/TSV/TXT can open with every field kept as text via `file.open {csvAsText}`; formulas over Excel's 8,192 characters, and `%` or call chains past the nesting limit, are parse errors instead of stack overflows when a file is opened; XLSX PivotTables read and write `rowGrandTotals`/`colGrandTotals` the way Excel does, so a table saved with only one grand total opens with the right one; HTML export keeps right-to-left) · **Target:** Microsoft Excel (Microsoft 365), Excel for Mac 16.113.4
 
 Every format Excel opens or saves, with GridCraft's read and write support, fidelity and tests.
 Part of [target-app-parity.md](target-app-parity.md). **File formats: ~50% ready, 80–120 h**
@@ -91,6 +91,7 @@ refresh. Counted under features (Get & Transform, ~10% ready), not here.
 | 2026-10-18 | trivial | `file.open {csvAsText: true}` keeps every CSV/TSV/TXT field as the text the file holds, so identifiers (GTINs, SKUs, ZIP codes) keep their digits and leading zeros (#1808; a preference and a CLI flag are separate work) |
 | 2026-10-18 | trivial | XLSX PivotTables: `rowGrandTotals` is the Grand Total row and `colGrandTotals` the Grand Total column. Both were read and written the other way round, which a GridCraft round trip hid, so an Excel file with only one grand total opened showing the other |
 | 2026-10-19 | minor | HTML (Save as Web Page and clipboard) marks right-to-left sheets and right-to-left cell text with `dir` |
+| 2026-10-15 | minor | XLSX: formulas and PivotTable sources quote sheet names like Excel (a leading `.`, R1C1-like and cell-like names), so `'.x'!A1` no longer saves as `.x!A1`, which Excel could not open (#1458) |
 | 2026-10-14 | trivial | Formula parser: text longer than Excel's 8,192 characters, and postfix chains (`1%%%…`, `f(1)(1)…`) past the 256-level nesting limit, are parse errors (the cell keeps its formula text and cached value) instead of trees deep enough to overflow the stack when a hostile file is opened, saved or dropped |
 | 2026-10-12 | trivial | XLSX chart sheets are kept on save (#727) |
 | 2026-10-12 | trivial | CSV and TSV export is capped at 512 MiB and refuses a larger used range with an error (#528) |

docs/function-parity.md

@@ -1,6 +1,6 @@
 # Function parity: worksheet functions and formulas
 
-> **Last reviewed:** 2026-10-15 · **Last updated:** 2026-10-15 · **Change:** minor (MEDIAN and AGGREGATE median avoid intermediate overflow) · **Target:** Microsoft Excel (Microsoft 365), Excel for Mac 16.113.4
+> **Last reviewed:** 2026-10-15 · **Last updated:** 2026-10-19 · **Change:** minor (ADDRESS quotes sheet names like Excel (#1458); MEDIAN and AGGREGATE median avoid intermediate overflow) · **Target:** Microsoft Excel (Microsoft 365), Excel for Mac 16.113.4
 
 Excel's worksheet functions, category by category, against GridCraft's function library. Part of
 [target-app-parity.md](target-app-parity.md); gaps feed [gaps.md](gaps.md).
@@ -115,6 +115,7 @@ workbooks; results checked in as data, not Excel files) and fixing what it finds
 | Date | Change | Summary |
 |---|---|---|
 | 2026-10-15 | minor | MEDIAN and AGGREGATE median use an overflow-safe midpoint (#1579); regressions cover finite extremes, tiny values and dependent recalculation |
+| 2026-10-15 | minor | ADDRESS quotes a sheet name the way Excel does: names that read as an A1 cell (`A1`) or an R1C1 reference (`R1C1`, `RC`) and names starting with `.` get quotes; `TRUE` / `FALSE` stay bare (#1458) |
 | 2026-10-13 | minor | Clear reports changed stored cells sparsely, including those beyond the first million coordinates; dependent formulas and removed spills update, while clearing empty merges still unblocks spills (#1032) |
 | 2026-10-12 | minor | USDOLLAR added as a Compatibility function (not on Microsoft's list, so the counts don't change); MIRR with no positive flow is -1, COUNTIF's bare `"<="` / `">="` skip empty strings, INDIRECT with `a1` = FALSE gives `#REF!` for A1-style text (#738) |
 | 2026-10-11 | minor | TEXT / number formats fixed against Excel-cached results: fraction literals and zero fractions, `0` denominators zero padded, `?` pads the thousands separator, booleans use the text section (226 mismatches → 0 in 352 TEXT cells) |