NixDerivationMadness cluster_v1 1: Initial Build & Cache Upload cluster_v2 2: FOD Changed (i.e. garbage added) FOD_V1 FOD drv V1 (k2wjpwq43685j6vlvaarrfml4gl4196n-hello-world-fixed.drv) USES_FOD_V1 Uses-FOD Drv V1 (85d15y7irq7x4fxv4nc7k1cw2rlfp3ag-uses-fod.drv) FOD_V1->USES_FOD_V1 Input OUTPUT Uses-FOD Output (sd12qjak7rlxhdprj10187f9an787lk3-uses-fod) USES_FOD_V1->OUTPUT Produces output path CACHE Nix Cache OUTPUT->CACHE Output cached FOD_V2 FOD drv V2 (yimff0d4zr4krwx6cvdiqlin0y6vkis0-hello-world-fixed.drv) USES_FOD_V2 Uses-FOD Drv V2 (85wkdaaq6q08f71xn420v4irll4a8g8v-uses-fod.drv) FOD_V2->USES_FOD_V2 Input USES_FOD_V2->OUTPUT Produces SAME Output Hash USES_FOD_V2->CACHE Missing Cache Mapping for V2