The index is the snapshot prepared for the next commit. Adding one file does not automatically stage its neighbors, and editing it afterward can leave the working copy different from the staged copy. Select the requested path rather than using a broad add when a scratch file is present. Inspect staged content before committing. These tasks separate a delivery change from temporary notes so you can practice choosing what belongs in one snapshot. If a route file changes from east to west after you stage it, the index still contains east. Running add again updates that prepared snapshot. Use this distinction to avoid committing a stale version.