NOTE
Interface Segregation Principle
Keeping contracts focused so clients depend only on capabilities they actually use.
This is a historical learning note and may contain outdated or incomplete understanding.
The Interface Segregation Principle favors small, cohesive contracts over large interfaces that force clients to depend on irrelevant operations.
Split interfaces by role/capability when consumers use different subsets. Avoid fragmenting every method into a separate interface; cohesion and real client needs determine the right boundary.