Legacy Modernization Pattern — Checklist

Pattern: Legacy Modernization
Component: checklist.md
Version: 1.1 | Updated: 2026-07-16

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Gate: No production traffic ramp without parity green; no legacy delete without 100% evidence.

Slice design

• Capability in/out of scope written
• Legacy entry points mapped
• Seam chosen and recorded
• SME / business owner named

Parity and shift

• Parity fixtures include edge cases
• Shadow/parity report green
• Traffic steps + abort KPIs written
• Rollback to legacy path tested

Retirement

• 100% traffic evidence file
• Idle period observed
• Legacy path disabled/removed for slice only
• Next slice selected