Why: both 2026-09-30 incidents produced reusable causal knowledge (nil-slice
JSON null vs .map; shared-checkout conflicts and gitlinks pinning unpushed
commits) that meets the lesson bar of trigger, mechanism, checks, and
verified guards.
Evidence: incident records and fix PRs referenced inline; guards validated
in policy/adoption.md and the tool-adaptation matrices.
Impact: record-only; documents no product code.
Refs: Agent-System-Dev 8f7cf2d; Agent-System-Backend fix/empty-list-json