How do SOLID principles evolve in a growing codebase?

SOLID compliance tends to degrade over time through entropy unless deliberately maintained. Common patterns: SRP violations accumulate through "just add it here" feature additions; OCP violations emerge when developers patch existing classes rather than extending; ISP violations grow as interfaces absorb new methods for edge cases. Managing SOLID in a growing codebase requires: (1) Architecture fitness functions — automated checks that verify dependency direction rules (ArchUnit in Java, Deptrac in PHP); (2) Regular design reviews — periodic examination of growing classes and interfaces; (3) Definition of Ready in Agile — require design review before implementing new features in critical modules; (4) Code ownership — teams own SOLID compliance for their bounded context; (5) Refactoring sprints — allocate time specifically for SOLID improvements when technical debt becomes painful. Continuous attention to metrics (LCOM, coupling) helps detect violations early.