  Let $V$ and $W$ be quiver representations over $\mathbb{F}_1$ and let $K$ be
a field. The scalar extensions $V^K$ and $W^K$ are quiver representations over
$K$ with a distinguished, very well-behaved basis. We construct a basis of
$\mathrm{Hom}_{KQ}(V^K,W^K)$ generalising the well-known basis of the morphism
spaces between string and tree modules. We use this basis to give a
combinatorial characterisation of absolutely indecomposable representations.
Furthermore, we show that indecomposable representations with finite nice
length are absolutely indecomposable. This answers a question of Jun and
Sistko.
