Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

crates/engine/src/cmd/file.rs

@@ -139,8 +139,9 @@ fn save_as(s: &mut Session, p: &Json) -> Result<Json> {
 fn save_bytes(s: &mut Session, p: &Json) -> Result<Json> {
     let fmt = str_param(p, "format").unwrap_or("xlsx");
     let d = s.doc()?;
-    let bytes = crate::io::save_bytes(&d.wb, &format!("x.{fmt}"))?;
     let name = format!("{}.{fmt}", std::path::Path::new(&d.display_title()).file_stem().and_then(|x| x.to_str()).unwrap_or("Book"));
+    // The file name goes into a PivotChart's link to its PivotTable.
+    let bytes = crate::io::save_bytes(&d.wb, &name)?;
     Ok(json!({"name": name, "base64": crate::io::base64_encode(&bytes), "bytes": bytes.len()}))
 }
 

crates/engine/src/io.rs

@@ -207,7 +207,10 @@ pub fn save_bytes_as(wb: &Workbook, path: &str, kind: FileKind) -> Result<Vec<u8
     match kind {
         // The extension picks the package kind; only the macro-enabled kinds (.xlsm, .xltm) carry
         // the VBA project, so any other name saves without it, as Excel does.
-        FileKind::Xlsx => gridcraft_xlsx::write_xlsx_as(wb, gridcraft_xlsx::XlsxKind::from_path(path)).map_err(|e| EngineError::Other(e.to_string())),
+        FileKind::Xlsx => {
+            let book = std::path::Path::new(path).file_name().and_then(|n| n.to_str()).unwrap_or_default();
+            gridcraft_xlsx::write_xlsx_named(wb, gridcraft_xlsx::XlsxKind::from_path(path), book).map_err(|e| EngineError::Other(e.to_string()))
+        }
         FileKind::Xls => {
             Err(EngineError::Other("Excel 97-2003 (.xls) is supported for import only. Save as .xlsx or another supported export format.".into()))
         }

crates/engine/tests/pivotchart_link.rs

@@ -0,0 +1,41 @@
+//! #1447: a PivotChart is bound to its PivotTable behind the workbook's name.
+
+use std::io::Read;
+
+use gridcraft_engine::Session;
+use serde_json::{Value as Json, json};
+
+fn run(s: &mut Session, command: &str, params: Json) -> Json {
+    s.execute(command, params).unwrap()
+}
+
+fn source() -> Session {
+    let mut s = Session::new();
+    s.new_workbook();
+    run(
+        &mut s,
+        "range.setValues",
+        json!({"range": "A1", "values": [["Region ", " Sales ", "Qty"], ["East", 10, 1], ["West", 20, 2], ["East", 5, 3]]}),
+    );
+    s
+}
+
+#[test]
+fn pivot_chart_link_names_the_workbook_in_brackets() {
+    let mut s = source();
+    run(&mut s, "selection.set", json!({"range": "A1"}));
+    run(&mut s, "insert.pivotTable", json!({"rows": ["Region"], "values": ["Sales"]}));
+    run(&mut s, "insert.pivotChart", json!({}));
+    let bytes = gridcraft_engine::io::save_bytes(&s.doc().unwrap().wb, "Q1 Report.xlsx").unwrap();
+    let mut zip = zip::ZipArchive::new(std::io::Cursor::new(bytes)).unwrap();
+    let mut chart = String::new();
+    zip.by_name("xl/charts/chart1.xml").unwrap().read_to_string(&mut chart).unwrap();
+    assert!(chart.contains("<c:name>[Q1 Report.xlsx]Sheet2!PivotTable1</c:name>"), "{chart}");
+
+    // Without a file name, a placeholder workbook is named; reading drops the brackets again.
+    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"]}));
+    let link = reopened.doc().unwrap().wb.sheets.iter().flat_map(|sh| sh.charts.iter()).find_map(|c| c.pivot.clone());
+    assert_eq!(link.as_deref(), Some("Sheet2!PivotTable1"));
+}

crates/xlsx/src/chart.rs

@@ -236,7 +236,7 @@ pub fn read_chart(root: &El) -> Option<Chart> {
         y_title: y_ax.and_then(|a| a.child("title")).and_then(rich_title),
         source: None,
         by_rows: false,
-        pivot: root.path(&["pivotSource", "name"]).map(|n| n.text.trim().to_string()).filter(|n| !n.is_empty()),
+        pivot: root.path(&["pivotSource", "name"]).map(|n| strip_book(n.text.trim()).to_string()).filter(|n| !n.is_empty()),
     })
 }
 
@@ -610,17 +610,24 @@ fn axis_xml(a: &Ax<'_>) -> String {
     s
 }
 
+/// A PivotChart link without the workbook in brackets: `[Book.xlsx]Sheet2!PT` → `Sheet2!PT`.
+fn strip_book(link: &str) -> &str {
+    link.strip_prefix('[').and_then(|r| r.split_once(']')).map_or(link, |(_, rest)| rest)
+}
+
 /// Chart part XML for a model chart on sheet `si`.
-pub fn write_chart(wb: &Workbook, si: usize, ch: &Chart) -> String {
+pub fn write_chart(wb: &Workbook, si: usize, ch: &Chart, book_name: &str) -> String {
     let mut s = String::from(
         "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>\n<c:chartSpace xmlns:c=\"http://schemas.openxmlformats.org/drawingml/2006/chart\" xmlns:a=\"http://schemas.openxmlformats.org/drawingml/2006/main\" xmlns:r=\"http://schemas.openxmlformats.org/officeDocument/2006/relationships\"><c:roundedCorners val=\"0\"/>",
     );
     if (1..=48).contains(&ch.style) {
         let _ = write!(s, "<c:style val=\"{}\"/>", ch.style);
     }
-    // A PivotChart names its PivotTable (`Sheet2!PivotTable1`).
+    // A PivotChart names its PivotTable behind the workbook in brackets (`[Book.xlsx]Sheet2!PivotTable1`);
+    // without the brackets Excel shows an ordinary chart.
     if let Some(link) = ch.pivot.as_deref().map(str::trim).filter(|l| !l.is_empty()) {
-        let _ = write!(s, "<c:pivotSource><c:name>{}</c:name><c:fmtId val=\"0\"/></c:pivotSource>", esc(link));
+        let link = strip_book(link);
+        let _ = write!(s, "<c:pivotSource><c:name>[{}]{}</c:name><c:fmtId val=\"0\"/></c:pivotSource>", esc(book_name), esc(link));
     }
     s.push_str("<c:chart>");
     match &ch.title {

crates/xlsx/src/lib.rs

@@ -138,6 +138,12 @@ pub fn write_xlsx_as(wb: &Workbook, kind: XlsxKind) -> Result<Vec<u8>, IoError>
     write::write_xlsx(wb, kind)
 }
 
+/// Writes a workbook as the given member of the `.xlsx` family for the file `book_name` (a bare
+/// file name, used for the workbook in a PivotChart's link to its PivotTable).
+pub fn write_xlsx_named(wb: &Workbook, kind: XlsxKind, book_name: &str) -> Result<Vec<u8>, IoError> {
+    write::write_xlsx_named(wb, kind, Some(book_name))
+}
+
 /// CSV import options.
 #[derive(Clone, Debug, PartialEq)]
 pub struct CsvOptions {

crates/xlsx/src/sheet_write.rs

@@ -522,7 +522,7 @@ pub fn write_sheet(wb: &Workbook, si: usize, selected: bool, out: &mut Out) -> (
                 drels.add_uri(crate::chartex::REL_CHARTEX, &format!("../charts/chartEx{n}.xml"))
             } else {
                 let name = format!("xl/charts/chart{}.xml", out.charts);
-                out.part(&name, Some(CT_CHART), crate::chart::write_chart(wb, si, ch).into_bytes());
+                out.part(&name, Some(CT_CHART), crate::chart::write_chart(wb, si, ch, &out.book_name).into_bytes());
                 drels.add("chart", &format!("../charts/chart{}.xml", out.charts))
             };
             objs.push(Obj::Chart(ch, rid));

crates/xlsx/src/write.rs

@@ -113,6 +113,8 @@ pub struct Out {
     pub sst: Sst,
     pub images: u32,
     pub charts: u32,
+    /// The workbook's file name, which a PivotChart's link to its PivotTable names in brackets.
+    pub book_name: String,
     /// References of chartex parts, defined as hidden `_xlchart.v1.N` names.
     pub chart_names: Vec<String>,
     pub drawings: u32,
@@ -185,7 +187,16 @@ fn check_sheet_names(wb: &Workbook) -> Result<(), IoError> {
     Ok(())
 }
 
+/// Workbook name written in a PivotChart's link when the file name isn't known.
+const DEFAULT_BOOK_NAME: &str = "Workbook.xlsx";
+
 pub fn write_xlsx(wb: &Workbook, kind: XlsxKind) -> Result<Vec<u8>, IoError> {
+    write_xlsx_named(wb, kind, None)
+}
+
+/// Writes the workbook for the file `book_name` (a bare file name). A PivotChart is bound to its
+/// PivotTable in Excel only when its link starts with the workbook in brackets.
+pub fn write_xlsx_named(wb: &Workbook, kind: XlsxKind, book_name: Option<&str>) -> Result<Vec<u8>, IoError> {
     if wb.sheets.is_empty() {
         return Err(IoError::Format("a workbook needs at least one sheet".into()));
     }
@@ -201,6 +212,7 @@ pub fn write_xlsx(wb: &Workbook, kind: XlsxKind) -> Result<Vec<u8>, IoError> {
         sst: Sst::default(),
         images: 0,
         charts: 0,
+        book_name: book_name.filter(|n| !n.is_empty() && !n.contains(['[', ']'])).unwrap_or(DEFAULT_BOOK_NAME).to_string(),
         chart_names: vec![],
         drawings: 0,
         tables: 0,

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 PivotCharts stay bound to their PivotTable in Excel (#1447); .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` |
+| 2026-10-16 | minor | XLSX PivotTables: a PivotChart's link to its PivotTable is written behind the workbook in brackets (`[Q1 Report.xlsx]Sheet2!PivotTable1`; `Workbook.xlsx` when the file name is unknown), so Excel binds the chart to the PivotTable instead of showing an ordinary chart; the reader drops the prefix (#1447, item 7) |
 | 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) |