Hello Inkscape team,

I have been working on a server-side vectorization pipeline using Inkscape 1.4.4 in headless mode on Ubuntu 26.04, and I would like to report a behavior that appears to be a limitation of the CLI interface.

When using the object-trace action via --actions in headless mode (with xvfb-run), the 'stack' parameter (position 3 in the argument list) appears to have no effect on the generated SVG output.

The command I am using:

xvfb-run -a inkscape input.png \

--actions="select-all; object-trace:4,0,1,0,0,1.0,0; export-filename:output.svg; export-do"

I tested with both stack=1 and stack=0 and compared the results:

The fills are identical in both outputs
No clip-path elements are generated in either case
The stacking behavior visible in the Desktop UI (Multicolor > Stacked) is not reproduced

In the Desktop version, enabling 'Stacked' produces clip-path elements that allow color layers to overlap correctly. This is important for logos and illustrations where adjacent color regions need to stack rather than be cut out.

My questions:

Is this a known limitation of the current CLI/headless implementation?
Is there a workaround to enable stacking behavior from the command line?
Is full CLI parity for object-trace parameters on the roadmap for a future release?

Thank you for your work on Inkscape. It is a fantastic tool and the CLI capabilities are extremely valuable for server-side automation 🙏🙌

Best regards,

Mathieu Plessis — Lanaworks
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