Scenario:

You have two separate Git repositories at /home/interview/repo-a (5 commits) and /home/interview/repo-b (4 commits) developed independently. Create a new monorepo at /home/interview/monorepo that combines both repositories into separate subdirectories using subtree (project-a/ and project-b/) while preserving the full commit history from both repositories.

Example:

# Before (two separate repositories)
$ cd /home/interview/repo-a && git log --oneline | wc -l
5

$ cd /home/interview/repo-b && git log --oneline | wc -l
4

# After (combined monorepo with both histories)
$ cd /home/interview/monorepo && ls -la
project-a/  project-b/  .git/

$ git log --all --oneline | wc -l
12

$ find project-a/ -type f | wc -l
2

$ find project-b/ -type f | wc -l
2

Step 1: Check repository histories

cd /home/interview/repo-a && git log --oneline && cd ..
cd /home/interview/repo-b && git log --oneline && cd ..

See how many commits exist in each repository.

Step 2: Create and initialize monorepo

mkdir monorepo && cd monorepo
git init
git config user.name "Test User"
git config user.email "[email protected]"
git commit --allow-empty -m "Initial monorepo commit"

Create directory, initialize Git repository, and create initial empty commit.

Step 3: Import both repositories into subdirectories

git subtree add --prefix=project-a ../repo-a main
git subtree add --prefix=project-b ../repo-b main

The git subtree add imports the entire history of each repository into separate subdirectories while preserving all commits.

Step 4: Verify the monorepo

ls -la
git log --all --oneline | wc -l

Confirm both project directories exist and all commits from both repositories are preserved.