Expand failed regional building contexts

docs/BELGIUM_BUILDING_TRAINING_LOOP.md

@@ -67,6 +67,15 @@ contexts. Its remaining known gaps are:
 
 The active production model remains unchanged while any gate fails.
 
+The v31 expansion adds eighteen independent train-only AOIs after the v30
+rotated-holdout calibration isolated the remaining domain gaps. Nine Flemish
+AOIs cover industrial roofs, ribbon development and coastal urban fabric. Nine
+Walloon AOIs add dense urban, rural-town, regional-architecture and difficult
+industrial/rail/quarry negatives. Existing validation, calibration, test and
+background-test AOIs remain frozen. The provisioner can load a short-lived
+operator session from a mode-0600 token file, allowing governed acquisition on
+an authenticated runtime without exposing credentials in process arguments.
+
 ## Reproducible evidence
 
 - corpus assembler: `scripts/assemble_belgium_building_corpus.py`;