schedule_ods already collects every cell style attribute from the spreadsheet — background, font size, weight, style, color, wrap — and uses them. Borders are collected too, and discarded: every cell is drawn as a rectangle carrying one hardcoded class_="border" whose stroke comes from the stylesheet. schedule_xlsx does the same from openpyxl. A thick outline with thin inner rules, the usual look of an architectural schedule, cannot reach the drawing no matter what is set in LibreOffice or Excel.

What changed

The inline rectangle in both branches becomes draw_cell(), which takes a background color and the borders already resolved, so it is independent of the source format. Each branch translates its own:

• get_cell_borders() / parse_border() read .ods style attributes;
• get_xlsx_cell_borders() / parse_xlsx_border() read openpyxl Side objects.

A cell that declares no border keeps the .border class and draws exactly as before. One that declares them gets a line per side, which a single rectangle stroke cannot express.

Width, style and color are read in any order, per the CSS border shorthand grammar (<width> || <style> || <color>), rather than assuming the order LibreOffice happens to emit. dotted and dashed become a dash pattern scaled by the line width; double and the relief styles draw plain.

XLSX_BORDERS converts Excel's fourteen named weights into widths and dash patterns. Excel names a weight instead of measuring one, so that table is a choice rather than a reading of the file, and is commented as such.

One deliberate behaviour change

A cell that declares border: none now draws no line, where before it took the stylesheet's. This is intentional and is half the point of the change: a sheet that says a side has no border should not be given one.

Cells that declare nothing about borders are unaffected — that is the compatibility guarantee, and it covers every schedule IfcCsv writes, since it emits no cell styles at all.

Left as it is

Adjacent cells each stroke the edge they share, so where two neighbours declare it differently the later one wins. The rectangles overlapped the same way before, with the same stroke on both sides. Spreadsheet applications resolve such conflicts by precedence, which this does not attempt.

Testing

src/bonsai/test/bim/module/drawing/test_scheduler.py — 20 tests over both translators and the drawing: the untouched-cell guarantee, the border: none change, per-side overrides of the shorthand, token order, dash patterns, and the openpyxl side. One trap they pin down: asked for the ARGB of a theme color, openpyxl returns its own complaint as a string instead of raising, so the length of the value is what distinguishes a real ARGB from it.

black and ruff clean on both files.

Notes

• Touches the same block of schedule_ods as Bonsai: don't render spreadsheet-hidden columns in schedules (#6729) #8537 (hidden columns), a few lines apart. Whichever lands second wants a trivial rebase; this change keeps the background_color local in place to keep the overlap as small as possible.
• Adjacent but not addressed here: Text wrap doesn't seem to work with schedules that have custom css #4781 (text wrap with custom CSS), When a schedule is built, it has the correct font, but when it's placed on a sheet, it takes on the default font #5221 (font lost when a schedule is placed on a sheet), Place the schedule on the sheet, but later change the column widths, the schedule gets truncated.  #3586 (truncation after column widths change).
• Draft: opened for review of the approach before asking for a merge.

AI disclosure

Per AGENTS.md: this contribution was written with the assistance of an AI coding tool, in whole — both the change to scheduler.py and the new test file, which carries the required header comment.