XLSX: leading spaces in an xml:space="preserve" cached formula string are trimmed, so ?-placeholder number formats lose their indent

[developer0hye]

Summary

Cached formula string values stored with xml:space="preserve" lose their leading spaces
during parsing, so number formats that use ? placeholders to align digits print flush
left instead of indented. The ? placeholder reserves a digit-width space; Excel writes
the resulting alignment spaces into the cached <v> text and preserves them via
xml:space="preserve".

Measured

NumberFormatTests.xlsx Tests sheet rows 44–46 (Lucida Sans Typewriter 10pt): cached
values ' 1,234,567' / ' 1,234,567' / ' 1,234,567' (1/2/4 leading spaces).

	GT (Excel)	office2pdf
rows 44–46 rendering	indented by ~6.0 / 12.1 / 24.1pt	all flush as 1,234,567

Reproduction

cargo run -p office2pdf-cli -- tests/fixtures/xlsx/poi/NumberFormatTests.xlsx -o out.pdf
pdftotext out.pdf - | grep -n "1,234,567"   # leading spaces gone; GT keeps 1/2/4 spaces

Expected

Leading and trailing spaces in an xml:space="preserve" cached value survive to the text
layer and the rendered indent matches Excel's.

Actual

The spaces are trimmed and the ?-placeholder indent collapses.

Related: #621

Found in: the #621 fix-PR visual audit (NumberFormatTests.xlsx Tests sheet p1, local Excel-for-Mac GT, 150 DPI, 2026-07-30). Visual comparison below.

Visual comparison

Compare

GT left (Letter), office2pdf right (A4), 150 DPI, Tests sheet page 1.