[minutechreview]

Summary

A workbook saved with the 1904 date system now gets the same date labels in the web engine as in pandas, instead of dates four years and a day early.

Type

• Audit
• Explainer
• Bug fix
• Other

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Details

• parseXLSX reads workbook.Workbook.WBProps.date1904 after XLSX.read and passes it through stringifyXlsxDateCells to formatXlsxDateCell, which calls XLSX.SSF.parse_date_code(serial, { date1904 }).
• test_xlsx_date_cells_get_the_same_labels_in_both_engines is now parametrized over both date systems (with the existing three time zones), using openpyxl's CALENDAR_MAC_1904 epoch for the 1904 workbook.

Checks: tests/test_xlsx_edge_cases.py 14 passed; the three new 1904 cases fail without the JS change. ruff check, check_em_dash.py and check_generated_files_current.py pass. The full suite (without tests/browser) has the same 10 failures before and after this change, all in test_cli.py and two JS parity tests, which look like a local environment issue rather than this change.

Linked issue

Fixes #1076

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[github-actions]

@yakew7 @ahmdkaml - new PR touching a path you own, please review.