Mine git history for engineering lessons. Auto-load when asked "what went wrong here", "why is this pinned", "find past incidents", "check the git history", "why does this workaround exist", or before touching code whose shape seems inexplicable. Finds reverts, fix-after-fix chains, security hardening arcs, and dependency-pinning incidents; reconstructs incidents from diffs and commit messages; converts history into concrete guardrails (tests, pins, comments, checklists) so the same failure cannot recur silently.
