Minimize Reader Load
Maintainability is the work a reader must do to understand code. Track two axes:
- Layers to trace. How many indirections sit between the question and the answer.
- State to hold. How much hidden or mutable context the reader must keep in their head.
Why: Code is read far more than it is written. LOC, cyclomatic complexity, and "clean architecture" are proxies. Reader load is the thing that matters. The two axes are independent. A flat file with 50 globals can be as hard to reason about as a 6-layer adapter stack. Guard both. This is the human analog of Guard the Context Window. Working memory is finite for readers too.
The pattern:
- Collapse layers that cost more than they save: wrappers with one caller, adapters with no second implementation, speculative indirection that was never needed. Inline them.
- Make adjacent layers change the abstraction. A layer that repeats the same methods and arguments adds reader load without compression. Collapse pass-through layers.
- Demand interface compression. A broad interface that hides little complexity makes readers learn both the surface and the implementation. Prefer boundaries that hide meaningful decisions.
- Shrink state scope: prefer pure functions (returns over mutations), locals over fields, fields over module state, and module state over globals. Derive instead of sync.
- Name the invariant at the boundary, not in every consumer, so the reader learns it once.
- Before adding a layer or a piece of state, ask: does this reduce reader load somewhere else by at least as much?
The test: Can a new reader answer "where does X come from?" and "what can change X?" in under 30 seconds? If not, cut layers or cut state.