Starting Point

• Core platform had high coupling, limited observability, and risky deployments.
• Previous rewrite proposal was rejected due to business risk.
• Leadership needed modernization with measurable safety controls.

What We Built

• Strangler-pattern service boundaries around volatile subsystems.
• Contract-first integration strategy and service ownership map.
• In-scope: priority domain decomposition and release process hardening. Out-of-scope: full data model rewrite.

How AI Changed the Outcome

• LLM-assisted ADR drafting accelerated architecture option analysis.
• AI-suggested refactor candidates were filtered through team-owned pattern library.
• Automated PR checks surfaced dependency risks before merge.

What We’d Do Differently

We underestimated migration communication overhead with adjacent teams; a formal weekly dependency review should have started in week 1.