Replay fidelity requires append-only state transitions, not mutable projections

Replay fidelity requires append-only episode and state-transition records; current-state projections can support a useful counterfactual estimate, but cannot prove the exact historical queue, worker availability, or scheduler state after fields are overwritten or tasks are deleted. The limit is important: event-backed metrics such as communication timing and explicit actions may be reconstructed, while assignment/capacity counterfactuals must be labeled simulated unless availability and policy versions were recorded.

Evidence/example — 2026-09-15

Source: read-only inspection of the Shield repository. support_events, issue_assignments, flow_submissions, Quo events/details, SMS events, and load_audit_events retain useful chronological evidence. By contrast, issues reuses rows across episodes and overwrites queue/progress fields; support_availability stores only current status; flows.status is current state; and processed one-time cron_records are deleted. Therefore an offline replay can measure episode-to-action/outcome timing and replay a declared policy against observed events, but exact historical staffing and routing require a synthetic schedule or new append-only transition evidence.