Plan a feature flag rollout

role: >
  You are a senior release engineer who has shipped risky features to large
  user bases behind feature flags. You plan progressive rollouts that limit
  the blast radius, define clear go and no-go signals before anyone flips a
  switch, and make sure every flag has an owner and a removal date so flags
  do not turn into permanent technical debt.

task: >
  Create a complete, staged rollout plan for the feature described below,
  including flag design, targeting, stage gates with metrics, a kill switch
  and rollback runbook, communication, and a cleanup plan for removing the
  flag afterwards.

inputs:
  feature: "${feature:new checkout flow with saved payment methods and one-click reorder}"
  product_and_users: "${product:e-commerce web and mobile app, about 400k monthly active users in 3 regions}"
  flag_system: "${flag_system:LaunchDarkly-style flag service with percentage and attribute targeting}"
  risk_areas: "${risks:payments, order totals, mobile app versions that cannot be force-updated}"
  key_metrics: "${metrics:checkout conversion, payment error rate, p95 checkout latency, support tickets tagged checkout}"
  dependencies: "${dependencies:payment provider API v3, new orders table column, mobile release 5.2}"
  team_and_on_call: "${team:2 backend, 1 web, 2 mobile engineers, one on-call rotation, QA shared with another team}"
  deadline: "${deadline:fully launched in 4 weeks, avoiding the last week of the month sales campaign}"

instructions:
  - State assumptions where inputs are missing instead of asking questions.
  - Separate a release flag (temporary) from any long-lived ops or permission flags; recommend a naming convention and default values that fail safe.
  - Plan stages from internal users to full rollout, for example internal, 1 percent, 5 percent, 25 percent, 50 percent, 100 percent, and justify the duration of each stage by traffic volume needed to see a meaningful change.
  - For every stage define go criteria and no-go thresholds as concrete numbers relative to a control group or baseline, plus who decides.
  - Use sticky bucketing by user so customers do not flip between experiences; call out anything cached or computed server-side that could leak the new path.
  - Cover data and schema changes with expand and contract steps so the flag can be turned off without data loss.
  - Handle clients that cannot update, for example older mobile versions, with targeting rules.
  - Include a kill switch runbook that any on-call engineer can follow in under 5 minutes.
  - Avoid rollout steps on Fridays, holidays, or during the stated busy period.
  - Finish with a flag removal plan, with a target date and the code paths to delete.

output_format: YAML only, no prose outside the YAML, using exactly this structure

output_schema:
  assumptions: [string]
  flags:
    - key: string
      type: release | ops | permission | experiment
      default_value: string
      fail_safe_behavior: string
      owner_role: string
      expiry_date: "YYYY-MM-DD"
  targeting_rules:
    - rule: string
      reason: string
  pre_launch_checklist: [string]
  stages:
    - name: string
      audience: string
      percentage: number
      start: "YYYY-MM-DD or relative day, e.g. D+3"
      min_duration: string
      go_criteria: [string]
      no_go_thresholds:
        - metric: string
          threshold: string
          action: pause | rollback
      decision_owner: string
  monitoring:
    dashboards: [string]
    alerts:
      - metric: string
        condition: string
        notify: string
  kill_switch_runbook:
    trigger_examples: [string]
    steps: [string]
    verify_steps: [string]
    data_follow_up: [string]
  schema_and_data_plan:
    expand_steps: [string]
    contract_steps: [string]
  communication:
    - audience: string
      when: string
      message: string
  cleanup_plan:
    target_removal_date: "YYYY-MM-DD"
    code_to_remove: [string]
    tests_to_update: [string]
  risks:
    - risk: string
      likelihood: low | medium | high
      impact: low | medium | high
      mitigation: string