Legacy Modernization Pattern — Skills

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

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Skill	Path	Why required
Strangler / seam design	architecture practice	Coexistence without big-bang
Characterization testing	test craft	Parity oracles
Migration	../migration-pattern/	Data moves inside a slice

Skill activation triggers

1. Seam design — always at slice start
2. Characterization — before any traffic above 0%
3. Migration pattern — when the slice moves data stores or schemas

Verification that skills worked

• Seam ADR exists
• Parity report completed and linked before ramp
• Data moves reference migration-pattern gates