Universal Foundations
Needed regardless of specialisation. The highest density of Layer 0–1 on the map, and therefore the best return per hour spent anywhere here.
Clusters
Section titled “Clusters”Version control
The object model — blob, tree, commit, ref — transfers to every host, workflow and recovery. PR mechanics and CI syntax are per-host and do not.
Command line & OS
Process model, file descriptors, signals, permissions and exit codes transfer to every Unix, container and CI runner. Distro packaging and…
Networking basics
Connection lifecycle, caching semantics, name resolution and the TLS handshake transfer to every client, proxy, CDN and debugging session. Header…
Data languages & formats
Relational algebra under SQL and the automaton model under regex transfer to every dialect and engine. Vendor functions, YAML coercion rules and…
One language done well
What transfers to the next language is the set of questions — concurrency model, type system, memory behaviour, dependency resolution — not the…
Containers
Union filesystem, namespaces, cgroups and the build cache transfer to Podman, containerd, Kubernetes and every runner. CLI flags and Compose keys are…
One cloud’s core services
The primitive set — object store, VM, managed SQL, queue, function, identity — maps near 1:1 across providers, which is what makes the second cloud…
Testing & debugging
Hypothesis-driven debugging is the most transferable skill on this map — it survives every language, tool and decade. Debugger keybindings and…
Security hygiene
Threat modelling and least privilege transfer to every system ever built. The scanners and vaults that implement them are Layer 3.
DSA & problem solving
Fully covered in domain 13; listed here because it is a foundation, not a specialisation.