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Vladimir Pavlunin

Legacy Modernization with AI

Modernizing legacy systems — recovering knowledge, tests, step-by-step migration with AI.

01 · The problem

The legacy system works and makes money — and slows everything else down. There is no documentation, the authors have left, and every change is a risk.

AI is good at reading large unfamiliar codebases, explaining them and helping cover them with tests. But “rewrite everything with AI” leads to the same system nobody understands — only newer. You need an engineering strategy.

02 · When you need it

  • Changes to the system have become too slow and risky
  • Knowledge of the system rests with one or two people or has been lost
  • An outdated stack gets in the way of hiring, security and growth
  • A “rewrite from scratch” has already been tried and failed

03 · What we analyze

  • The system's architecture and boundaries — what can be separated
  • Business-critical scenarios and their test coverage
  • Data and integrations — the hardest part of any migration
  • Risks — what will break first and what it will cost
  • Readiness of the team and the delivery pipeline

04 · How we work

  1. step 01

    Knowledge recovery

    With AI we build a description of the system — structure, scenarios, dependencies — and verify it with the people who know it.

  2. step 02

    Safety net

    Characterization tests capture the current behavior — before any changes.

  3. step 03

    Strategy

    We choose the approach — gradual replacement, module extraction, stack migration — and the sequence of steps.

  4. step 04

    Step-by-step migration

    Small, verifiable steps. AI speeds up routine work; tests and reviews keep the result under control.

05 · What you get

The exact set of deliverables is agreed after the diagnostic. I don't promise effect figures in advance — they depend on the starting point and are written into the plan as criteria.

  • 01A description of the system — architecture, scenarios, dependencies
  • 02A set of characterization tests for critical scenarios
  • 03A modernization strategy with stages and risks
  • 04An AI-assisted migration process with quality control

Next step

Let's discuss your project

Tell me what is happening with your development and what you expect from AI. I reply personally and suggest a format — a diagnostic, an audit or a consultation.