Service 05
Legacy code modernization
We use coding agents to document, test and migrate legacy systems in small, verified steps, from COBOL and old Java to aging .NET and monoliths.
In one paragraph
AI-assisted modernization uses coding agents to read, document, test and rewrite legacy code. Engineers set the target architecture and verify each step against the old system.
Deliverables
What you get
- 01 An inventory of applications, dependencies and data flows
- 02 Generated documentation of the business rules in the code, reviewed by your experts
- 03 Characterization tests that pin the current behavior before any change
- 04 An incremental migration plan with a rollback path for each step
- 05 Migrated modules with equivalence tests against the old system
- 06 A cutover plan and a runbook for the new system
Where it fits
Typical use cases
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Mainframe and COBOL
Business rules extracted from COBOL and moved to Java, C# or a modern runtime, one batch job or transaction at a time.
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Framework end of life
Upgrades from end-of-life Java, .NET Framework, AngularJS or Python 2 code to supported versions.
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Monolith decomposition
Clear service boundaries found in a monolith and extracted one at a time behind the existing interface.
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Database migration
Stored procedures and schemas moved to a new database, with data checks on every table.
How we work
Read the code first
The hardest part of a legacy system is usually the knowledge, not the code. Rules sit in code paths that nobody has touched in years. Agents read the whole code base and write down what each program does, which data it touches and which rules it applies. Your experts review that document. Most teams have never had one.
Pin the behavior
Before we change anything, we write characterization tests. These tests record what the system does today, including the odd cases. They are the safety net for every later step.
Migrate in slices
We replace the system one piece at a time behind its existing interface. Each slice is small enough to review, test and roll back. The old and the new code run side by side until the outputs match.
Keep the team in charge
Your architects choose the target design. Agents do the volume work: reading, documenting, writing tests and translating code. Engineers review every change.
FAQ
Questions about modernization
Can an agent rewrite the whole system at once?
It can try, but you cannot verify the result. We migrate in small slices that each have tests, a comparison against the old system and a rollback path.
Our original developers are gone. Is that a problem?
It is the common case. Agents read the code and write down the business rules they find. Your domain experts check that list. It is often the first complete description of the system in years.
How do you prove the new code does the same thing?
We run the old and the new code on the same inputs and compare the outputs, field by field, before each slice goes live.
Related
Often combined with
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Service 03
AI software factory
We set up coding agents across your delivery pipeline, from spec to merge. Your engineers own the specs, the review gates and the releases.
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Service 08
AI strategy and operating model
We help leadership pick the AI work that pays off, decide what to build or buy, and set up the operating model that keeps AI systems owned and measured.
Tell us which process you want to hand to an agent
A 30-minute call with an engineer. We will tell you whether an AI system is the right tool for it, and what it would take to run it in production.