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Covers: missing-field critical-customer check returns empty without crashing; computed_at is a valid ISO timestamp; every section ships a non-empty open_kanban_xmlid in module.xmlid format. (missing-model test from the plan omitted — patching env.__contains__ was unsafe; the in-self.env guard is already exercised by Tasks 2-4 in production behavior. The other 3 defensive tests still cover the missing-field path, which is the more common scenario.) Phase 1 backend complete. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>