Require tile quality evidence for training

docs/BELGIUM_BUILDING_TRAINING_LOOP.md

@@ -131,6 +131,9 @@ the versioned JSON argv command. Invalid state and bounded launch exhaustion
 fail closed.
 The orchestrator refuses to start unless every automated frozen-dataset gate
 passes and the corpus contains zero blank/low-variance positive tiles. The
+separate train tile-quality audit is a required checksummed loop input; missing
+invalid-label, missing-label-file or low-variance evidence fails closed rather
+than being interpreted as zero. The
 audit status may remain `needs_human_review` while training and objective
 evaluation continue: final human sign-off is deliberately the last gate and
 can never be interpreted as model promotion approval in advance.

docs/CODEX_EXECUTION_LOG.md

@@ -11,6 +11,10 @@
   and nine Walloon dense/rural/architecture or difficult-negative samples.
   Added mode-0600 session-token-file support to the official provisioner so
   authenticated Tower acquisition does not expose session material in argv.
+- Closed a fail-open evidence gap between corpus and tile audits. The training
+  loop now requires and hashes the train tile-quality report, and refuses
+  missing counters instead of treating absent invalid/blank-label evidence as
+  zero.
 
 ## 2026-07-27 - Guest demo and product professionalization