data-tier-cutoverlisted

# data-tier-cutover — the stateful-tier decision model, inventory, gate, runbooks, and review hook Migrating the stateful tier is the hardest step of a platform migration and is categorically different from the stateless `id-*` flow. This skill encodes the decision model and the four evidence-backed traps so they are driven, not re-derived. **Read-only / never-apply:** this skill authors the plan artifact + runbook; every mutating step in the emitted runbook is operator-run (the `id-apply` posture discipline). The merge floor — the adopter's branch protection + CI checks (see docs/merge-floor.md) — stays the merge authority. ## Stage A — the cutover-mechanism decision tree (fail-closed) - **Inputs (all three required):** `downtime_tolerance` (`window_ok` | `near_zero`), `source_shared_with_prod` (bool), `source_is_replicable` (bool). A missing input is a STOP — never assume tolerance. - **`window_ok` AND not shared ⇒ snapshot-restore** (the simple path): a snapshot restore PRESERVES the source DB users and passwords — the app keeps its credentials and only the host string changes. - **`near_zero` OR shared-with-prod ⇒ CDC-replicate + fast-promote**, and the plan artifact MUST carry the three required CDC caveat items: **sequences are NOT replicated by logical CDC — resync them at promote**; **the cache cannot be slaved cross-environment — provision it FRESH and warm it**; **define a replication-lag SLA before promote** (stale reads until promote). - **Record