WorkSeptember 2, 2026via Forrester Blog
AI Can Rewrite Code, But It Cannot Recover Intent
Why it matters
A practitioner's cautionary tale: AI-assisted code migration tools promise modernization but expose a deeper organizational problem—the loss of institutional knowledge and business intent that no model can recover from bytecode alone. This changes how teams should budget and sequence modernization projects.
Key signals
- Legacy systems accumulate undocumented business rules, integrations, workarounds faster than documentation
- Original developers have moved on; institutional knowledge retiring with specialists
- AI code rewriting tools encounter hidden dependencies and unexpected requirements
- Modernization is framed as a technology problem but is fundamentally a business/knowledge problem
- Cost and risk of AI-assisted refactoring underestimated when intent is lost
- Legacy systems accumulate undocumented business rules faster than they can be formalized
- Original developers and institutional knowledge holders are departing organizations
- AI code-rewriting tools miss hidden dependencies and context-specific requirements
- Modernization success depends on recovering intent, not just rewriting syntax
- Business problem disguised as technology challenge
The hook
AI can modernize legacy code. It cannot decode 30 years of undocumented business logic.
For decades, critical applications have accumulated business rules, integrations, work-arounds, and dependencies faster than organizations could document them. Documentation is incomplete, original developers have moved on, and application specialists are retiring with critical institutional knowled…