DOCX: an auto-layout table splits its columns evenly, flipping a wrap and lifting the rest of the page 11.3pt

[developer0hye]

Summary

A w:tbl whose w:tblGrid is present but which carries no
w:tblLayout w:type="fixed" is auto-fitted by both Word and office2pdf — but by
different rules. When the declared grid has to be redistributed to fit the
content, office2pdf falls back to an equal share; Word grows the column that
carries the widest unbreakable cell and shrinks the rest.

On 01_invoice_en the converter produces column 2 == column 5 == 161.32pt
exactly, which is the equal-share signature. Word instead widens Amount (because
of the w:gridSpan="4" total rows) and narrows Description.

<w:tblGrid>
  <w:gridCol w:w="700"/><w:gridCol w:w="4200"/><w:gridCol w:w="1200"/>
  <w:gridCol w:w="1450"/><w:gridCol w:w="1476"/>
</w:tblGrid>

(= 35.0 / 210.0 / 60.0 / 72.5 / 73.8pt; no w:tblLayout anywhere in the file.)

The one root cause produces three separate symptoms on the page, all recorded
below. 03_meeting_minutes_ko reproduces its declared grid exactly on both
sides, so the divergence appears only when content forces redistribution.

Measured

tests/golden_mocks/business/sources/docx/01_invoice_en.docx, page 1, line-items
table. Column widths from mutool draw -F trace:

column	Word	office2pdf	Δ
#	27.9	26.9	−1.0
Description	156.9	161.4	+4.5
Qty	47.8	46.0	−1.8
Unit Price	65.3	55.7	−9.6
Amount	153.3	161.3	+8.0
table total	451.3	451.4	+0.1

Unit Price is 15% too narrow; the Unit Price / Amount boundary sits at x=360.8
instead of 368.9. The total table width is correct, which is what makes this a
redistribution defect rather than a width defect.

Symptom 2 — the wrap flips and everything below moves up 11.3pt. Word wraps
"Additional render workers (4 vCPU)" onto two lines ("…workers (4" / "vCPU)");
office2pdf fits it on one. Word's Description content box is 147.2pt wide,
office2pdf's 151.3pt, and the string needs 149.4pt — the 4.1pt of extra column
width is exactly what flips the wrap. Row 3's height drops from 31.0 to 19.9pt:

baseline	Δ
row 3	−11.30
Subtotal	−11.29
VAT	−11.29
Total Due	−11.28
"Payment terms" paragraph	−11.50
table bottom rule	−11.30

Symptom 3 — right-aligned totals ride the wrong boundary. The Subtotal / VAT
/ Total Due labels are right-aligned inside the w:gridSpan="4" cell, so they
land on the col-4 / col-5 boundary:

label right edge	Word	office2pdf	Δ
Subtotal	325.98	317.84	−8.14
VAT (19%)	317.52	310.96	−8.15
Total Due	320.70	313.26	−8.16

The Unit Price figures move with it ("$720.00" ends at 355.8 vs Word's 363.9),
while the Amount column's right-aligned figures are correct (511.86 vs 512.03,
−0.17pt) because that column's right edge is the table edge.

Reproduction

cargo run --release -p office2pdf-cli -- \
    tests/golden_mocks/business/sources/docx/01_invoice_en.docx -o out.pdf

Expected

Auto-fit distributes the surplus the way Word does — the column holding the
widest unbreakable content grows, the rest shrink — so the Unit Price column
keeps its 65.3pt, "Additional render workers (4 vCPU)" wraps onto two lines, and
the right-aligned totals land on the col-4 / col-5 boundary.

Actual

The surplus is split equally (columns 2 and 5 come out identical to the
hundredth of a point), the Unit Price column loses 9.6pt, row 2 fails to wrap,
and the whole lower half of the page sits 11.3pt high with the totals 8.1pt left
of where Word puts them.

Related: #355

Found in the 2026-07-29 full-corpus visual audit at c1adfbd (native Office GT, 150 DPI, mutool-trace geometry).

Visual comparison

Compare

GT left, office2pdf right, 150 DPI, same page.

[developer0hye]

Fixed by #726. Auto-layout tables now redistribute conflicting tcW preferences by Word's rule — each grid column floors at its min-content width (widest unbreakable token, real font advances, CJK characters as singleton tokens, NBSP non-breaking) and the deficit is absorbed in proportion to compressible slack: width = min + (pref − min)·k.

Fresh GT comparison on the invoice: every column within 0.10pt of Word's 27.9/156.9/47.8/65.3/153.3 (the equal-share 161.32/161.32 signature is gone), the row-2 wrap flips to Word's two lines, the totals ride the col-4/5 boundary within 0.28pt, and the table bottom sits within 0.30pt (was 11.3pt high). All nine other business docx mocks and the 39-page technical brief are byte-identical to main.

Remaining deviations on the audited page each have their own open issue: #724 (border edge alignment, filed from this audit), #725 (footer PAGE-field width, filed from this audit), #649, #647, #646, #638, #628.