How-to

Fit the topology-cleaned output of step 2 to the previous release's country outline, so every release keeps the same outer edge. The outline is the previous release's admin1 from source.coop/hdx/cod-ab/matched/{iso3}/{vNN}/, dissolved into one admin0 feature:

topo-tools edge-match admin2_topo.parquet previous_admin0.parquet \
  admin2_matched.parquet --issues-file admin2_matched_issues.parquet

edge-match extends each unit outward to fill any gap against the reference boundary, clips any overhang, then cleans the shared edges across the whole layer, keeping every attribute column. The cleaning step can shift interior edges by a hairline, so units away from the border may show small geometry changes too. Load the issues file (if written) as a map layer to check for units that didn't match or clip cleanly. Where the new source's outline differs from the previous one, confirm the difference with the data provider: redigitizing follows the previous outline, and only a real boundary change moves it. For a first release, with no previous outline, agree on one with the data provider before this step.