fix(xlsx): honor the 1904 date system on read#3
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readXlsx and readXlsxRows now parse <workbookPr date1904="1"/> and convert date serials from the 1904 epoch — previously the flag was ignored and dates in legacy Mac workbooks read back ~4 years off (the conversion utility existed in utils/date.ts but was unwired). Writes still emit the 1900 system: the model stores real Dates, so a 1904 round-trip preserves instants while normalizing the file. Verified against the 1904.xlsx fixture with exceljs as oracle (B4 = serial 0 = 1904-01-01). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01JrxsnGbCRtq7VPskBRoSPr
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Summary
readXlsxandreadXlsxRowsnow parse<workbookPr date1904="1"/>and convert date serials from the 1904 epoch. Previously the flag was ignored — the conversion support existed insrc/utils/date.ts(oracle-validated in SP-1) but was never wired into the xlsx codecs, so dates in legacy Mac workbooks read back ~4 years off. This was documented as a known gap in the migration guide and README roadmap; this PR closes it.Write behavior is unchanged by design: the model stores real
Dateobjects, so writes keep emitting the standard 1900 system. Round-tripping a 1904 workbook preserves every instant while normalizing the file to 1900.Changes
workbook-reader: parseworkbookPr→ newdate1904field onWorkbookPartsworksheet-reader/read: thread the flag intoserialToDateviaReadContextstream-reader: same threading throughparseRowTest plan
TDD: both tests were written first and failed on the 1900 epoch (read
1900-01-01), then passed after the fix:read-conformance:1904.xlsxfixture B4 (serial 0) must read as1904-01-01— expected value confirmed against the exceljs oraclestream-reader: same assertion throughreadXlsxRowsFull suite: 255 tests green, typecheck/lint/format clean.
🤖 Generated with Claude Code
https://claude.ai/code/session_01JrxsnGbCRtq7VPskBRoSPr