Maybe it's more helpful to think of submodules as a convention in .git to manage commit ids of external repos for code your main repo code depends on, with some

Maybe it's more helpful to think of submodules as a convention in .git to manage commit ids of external repos for code your main repo code depends on, with some assumptions (ie. own subdirectory) and porcelain that might or might not match your workflow with respect to how that external code is integrated. It can get tedious if having to deal with submodules of submodules etc., but so would other ways to track ids of transitive deps.