Composition root

One file that wires everything.

Where: src/composition.ts.

The rule: all new Service(...) calls happen here. Every other file receives dependencies.

Why: grepability. "Where does this service come from?" has one answer. Swapping implementations is a one-file change.

Reading: Mark Seemann, Dependency Injection Principles, Practices, and Patterns (ch. 4).

See Composition root concept for more.