Impact-category interchange (agent notes)

Canonical user docs: docs/advanced-topics/impact-category-interchange.md.

Glossary in root CONTEXT.md: AB impact-category file, bw2io impact-category file. Prefer “impact category” / “LCIA method”; avoid “Indicators” for AB metadata and avoid “one-shot” / “bw2io native”.

Implementation seam: activity_browser.bwutils.impact_categories — ab_lcia_file / bw2io_lcia_file / ecoinvent_lcia / common; ABLCIAImporter links and writes prepared datasets (fed by AB or bw2io loaders).

UI: one ABAction per file under app.actions.method (method_import_*, method_export_*, method_get_template). Action-specific dialogs and worker threads live in those same modules (repo convention). Shared sticky-cancel progress starter is app.dialogs.run_thread_with_progress (ABProgressDialog remains in ui.dialogs). Menu export selection is live_impact_category_selection() / resolve_methods_for_export() on the Impact categories pane.

AB CSV pair suffixes: .cfs.csv + .metadata.csv (Excel sheet name remains Impact categories). Do not use “Indicators” for AB metadata.

Templates: activity_browser/templates/impact-categories/.