Course · 8 chapters
Legacy Code with AI: Understand, Modernize, Migrate
Most enterprise engineering is brownfield. Agents finally made it tractable: comprehension, safety nets, strangler slices, and migrations, practiced on a provided legacy codebase, applied to yours.
What you'll be able to do
- Turn a system nobody fully understands into a verified map you can defend in a design review.
- Pin the current behavior of untested code with agent-generated golden-master tests, so refactoring finally has a tripwire.
- Carve one already-tested seam out of the monolith with agent help, then run it safely behind the code it replaces.
- Run the deterministic recipe first, then let an agent clean up only what it leaves behind.
- Translate one already-migrated module into a second language, then ship it with the same proof that showed the original worked.
- Generate the README, the ADRs, and the CI check the codebase never had, then prove they stay honest as the code keeps moving.
What's inside
- 1Legacy Code with AI: Start Here
A 10-minute orientation to the Legacy Code with AI path: why brownfield engineering finally has a safe agent loop, how the seven chapters build on each other, and where to start.
- 2Map an Unknown Codebase
Turn a system nobody fully understands into a verified map you can defend in a design review.
- 3Characterization Tests
Pin the current behavior of untested code with agent-generated golden-master tests, so refactoring finally has a tripwire.
- 4The Strangler Pattern
Carve one already-tested seam out of the monolith with agent help, then run it safely behind the code it replaces.
- 5Migrating to Java 21
Run the deterministic recipe first, then let an agent clean up only what it leaves behind.
- 6Language Ports, Verified
Translate one already-migrated module into a second language, then ship it with the same proof that showed the original worked.
- 7Documentation, Recovered
Generate the README, the ADRs, and the CI check the codebase never had, then prove they stay honest as the code keeps moving.
- 8Rewrite or Refactor
Turn agent-gathered evidence about cost, risk, and reversibility into a decision memo executives can actually hold you to.
Earn a certificate
Complete all chapters to receive your certificate of completion.