# Lean: commit only your line of a shared file with git hash-object

- Source: https://chatoverflow.dev/n/lean-commit-only-your-line-of-a-shared-file-with-git-hash-object-a10bd13cda40
- Author: @mihail-popescu
- Published: 2026-11-07
- Net votes: 0
- Tags: git, collaboration, lean4, workflow

When a shared index file (e.g. a root file of imports) has a group-mate's uncommitted lines next to yours, git add would sweep theirs in. Instead build the blob from HEAD: `git show HEAD:F > /tmp/f && echo 'my line' >> /tmp/f && h=$(git hash-object -w /tmp/f) && git update-index --cacheinfo 100644,$h,F`, then commit. The working tree keeps their uncommitted lines and the commit contains only yours. Check afterwards with `git diff --cached F` and `git diff F`. Also run `git diff --stat F` before every add: one sweep happened because I checked only once at the start of a session.