Cutover Plan

Defines what a Context's cutover plan contains. Runs per Modeled Context, only once every Slice in that Context has reached Accepted — you cannot canary one Slice of a Context whose siblings are unbuilt, because the Context is the deployable boundary (07-stages.md §1).

Schema

schemas/cutover-plan.schema.json. A single JSON object per Context — contexts/<id>/cutover-plan.json is not an array.

Required fields

context, transition_profile, steps (≥1).

Content obligations

• transition_profile must be set explicitly (seam S1.5) — v1 ships "shadow-canary-cutover-decommission"; the Stage 8 command selects a profile rather than hard-coding steps, so a future specification-oracle profile (e.g. direct launch, no legacy shadow) can be added without rework.
• Steps run in order: shadow (domain logic executes fully, effecting adapters stubbed, decisions diffed) → canary → progressive-cutover → decommission. Each step records its diff_rate_threshold and diff_rate_observed — the gate is diff rate below threshold at each step, not just at the end.
• interfaces_retired lists every legacy Interface this Context's cutover retires, with zero_traffic_days — the Stage 8 gate requires zero traffic for N days before retirement, per Interface, not per Context in aggregate.
• Sequencing across Contexts goes by blast radius — read-only and non-effecting Contexts first, state-mutating and externally-effecting Contexts last (07-stages.md Stage 8).

Behavior-ID citation

The cutover plan does not cite Behaviors directly — it operates on Slices (already Accepted, already characterized) and Interfaces (already covered by contract tests). Its diffs are behavioral in effect but recorded as diff-reports/*, not as new Behavior citations.

What this skill does not cover

Consumer-facing migration guides and deprecation notices — those belong to the Consumer Migration Workstream (retirement-register skill, /ddd-migrate), which runs in parallel and never gates this plan.

Minimal worked example

{
  "context": "CTX-0001",
  "transition_profile": "shadow-canary-cutover-decommission",
  "steps": [
    { "name": "shadow", "status": "complete", "diff_rate_threshold": 0.01, "diff_rate_observed": 0.002 },
    { "name": "canary", "status": "in-progress", "diff_rate_threshold": 0.005 }
  ],
  "interfaces_retired": [ { "interface_id": "IFC-SYNC-0001", "zero_traffic_days": 0 } ],
  "decommission_checklist_ref": "contexts/CTX-0001/decommission-checklist.md"
}