# BIM IFC preference recovery

Batch: `dbb80dc113c531df7634151f`

The supplied first error is IFC export failing with `list indices must be
integers or slices, not NoneType`. The desktop exporter indexes its export
models with `params.get_param_arch("ifcExportModel")`. That accessor returns
None when the preference is absent from its dictionary. The existing headless
UI fallback searched only Draft/Resources/ui, while preferences-ifc-export.ui
belongs to BIM/Resources/ui.

The fallback now locates Arch's source with PathFinder without importing its
GUI dependencies, and reads BIM's actual preference forms with the existing
XML parser. Defaults and saved parameter values retain desktop semantics;
no export result or geometry is substituted.

Remaining boundary: outer pipeline must build/package the affected Draft
source and BIM UI resources, sync, and run the isolated IFC export/import
business cases. This edit is not business acceptance. Both selected IFC IDs
remain pending, including changed-geometry roundtrip and rejection/recovery.
Other selected business cases and their existing evidence are unchanged.