Legacy System Modernization
Problem
Core merchant-facing services ran on Scala/Lift — a framework with a shrinking community and increasing maintenance cost. Some React codebases had years of tech debt. Both needed modernization, but the system was live and revenue-critical.
Ownership
Led the migration strategy, defined the phased rollout plan, and implemented the frontend bridge layer allowing old and new systems to coexist.
Architecture
Incremental migration: new features built in the modern stack, existing Lift-rendered pages progressively replaced. A bridge layer maintained shared state between legacy and modern components. Backend APIs versioned to support both consumers.
Highlights
- •Phased migration — not a rewrite. Features shipped continuously during transition
- •Bridge layer maintained shared auth and state between Lift and modern React
- •API versioning let both systems coexist without breaking changes
- •Rollback plan at every phase — no merchant ever saw a broken state
Deployment
Phased rollout with validation gates, monitoring windows, and rollback triggers. Feature flags controlled which merchants saw the new system.
Impact
Zero production incidents during migration. Established migration patterns and rollout playbooks reused across the org for subsequent modernization efforts.
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