[Bug] Graphical Modeler: multiple variables used in single option are not substituted properly

[landam]

Describe the bug

Let's have a model which uses multiple variables in a single tool option:

When the model is converted into Python code (using GRASS 8.4.2), only one of variables is substituted:

    run_command("r.in.pdal",
                flags="eo",
                overwrite=True,
                input=f"%path/dmr5g/{options['tile']}.laz",
                output=f"{options['tile']}_dmr",

Current dev version (main) is even worse - no variables are substituted!

                input="%path/dmr5g/%tile.laz",
                output="%tile_dmr",

To reproduce

1. Open attached model 06_grass_chm_v3.zip in Graphical Modeler
2. Go to Script editor tab

Expected behavior

All variables substituted properly:

    run_command("r.in.pdal",
                flags="eo",
                overwrite=True,
                input=f"{options['path']}/dmr5g/{options['tile']}.laz",

System description

• Operating System: Linux
• GRASS version: 8.4.2 and 8.6 (main)

[SyedAhad01]

Hi, I would like to work on this issue.

From my understanding, the problem occurs when a model with multiple variables is converted to Python code, where not all variables are properly substituted in the generated script.

I plan to investigate the variable substitution logic in the Graphical Modeler and ensure that all variables are correctly replaced during code generation. I will also try to reproduce the issue using the provided example and verify the fix with multiple input variables.

Please let me know if this approach sounds good or if there are any pointers on where to start.