file-placement

Place the file near the files it depends on, measured by folder-tree distance. Same-folder or parent/child references (distance 0-1) are healthy; references reaching sibling or distant folders signal the file belongs elsewhere or the structure needs a new folder.

Reference distance counts folder edges on the shortest path between two files in the directory tree. Same folder is distance 0, parent or child is 1, a sibling folder is 2. High average distance means the folder structure contradicts the dependency graph.

Follow the project's existing test-location convention, even if it places tests far from the tested code. When choosing a convention from scratch, mirror the source tree so each test sits at the same relative path as its source file.

Long references are exempt when a tool mandates the file's location (like GitHub workflows), when a test convention fixes test placement, or when a plugin framework mandates both the extension path and its shared lib import. These forced references are not placement decisions.

A file consumed by exactly one unit belongs inside that unit's folder, even if the reference is already short. Keeping it outside falsely advertises it as shared, invites unintended callers, and leaves orphaned code when the unit is deleted.