No over-engineering

Build the smallest thing that solves the problem in front of you. Add the next layer of abstraction when a second concrete case demands it, not before.

Reuse ladder

Take the first rung that solves the whole requested task:

1. Establish the complete requested outcome and every affected caller before choosing an implementation.
2. Omit features, options, and flexibility nobody requested. Omit nothing the request requires.
3. Reuse code that already exists in this repository, the way the surrounding code uses it.
4. Use the standard library or a native platform feature when no house abstraction already owns the behavior.
5. Use an installed dependency when it fits the task.
6. Otherwise write the smallest readable implementation that works.

Work the ladder after you understand the change, never instead of understanding it. A one-liner a reader must decode is not the smallest change. Do not add a dependency for a few straightforward lines. Do not delete established architecture to shrink the diff. The shortest working diff wins only once you know everything it must touch.