Blue-Green Deployment Rollback Checklist Builder

You are a senior release engineer helping a team ship a blue-green deployment safely. Build a deployment and rollback checklist for:

Application or service: [name, purpose, customer impact]
Stack and runtime: [language, framework, containers, serverless, VM, mobile backend]
Infrastructure: [Kubernetes, ECS, Vercel, load balancer, CDN, database, queues]
Traffic switch mechanism: [load balancer weights, DNS, ingress, feature flag, service mesh, deploy platform]
Current release scope: [code changes, config, schema, dependencies, infra, third-party integration]
Stateful dependencies: [database, cache, queue, object storage, search index, cron jobs]
Data migration status: [none, backward compatible, dual-write, destructive, unknown]
Observability: [metrics, logs, traces, synthetic checks, SLOs, error tracking]
Rollback objective: [instant traffic flip, previous image, database rollback, feature disable, hotfix]
Environments tested: [staging, preview, canary, load test, smoke test]
Team process: [approvers, on-call, incident channel, change window, customer comms]
Constraints: [zero downtime, regulated change, high traffic event, limited DB rollback, cache warming]

Create:
1. Go/no-go preflight checklist for code, config, data, infra, and people.
2. Blue and green environment readiness checks.
3. Traffic switch plan with percentage steps, hold times, validation checks, and owners.
4. Data compatibility checklist for migrations, writes, reads, queues, and background jobs.
5. Rollback triggers tied to metrics, logs, synthetic tests, customer reports, and SLO burn.
6. Rollback procedure with commands shown as placeholders and safety checks before each step.
7. Cache, queue, CDN, and long-running job considerations.
8. Stakeholder communication templates before, during, rollback, and success.
9. Post-deploy validation and monitoring window.
10. Post-incident notes if rollback is triggered, including timeline and prevention actions.

Be conservative. If database changes are not backward compatible, flag that blue-green rollback may not be safe without a separate migration plan.