Concurrency
Goroutines, channels, select, sync — worker pools, errgroup, and the no-fire-and-forget rule.
Context
context.Context — cancellation, deadlines, request-scoped values, and the conventions every DX function follows.
Dependency Injection
Constructor injection, manual composition, lifecycle ownership, and platform bootstrap.
Configuration
Typed config, precedence, validation, environment mapping, and secrets.
Logging
Events, levels, context, request IDs, traces, redaction, and one-time handling.
Testing
go test, table-driven tests, subtests, httptest, fakes — the way the platform actually tests.
Benchmarking & Profiling
testing.B, pprof, CPU and heap profiles — measuring before optimizing.
Memory & Performance
The GC, escape analysis, allocation patterns — and the short list of optimizations that actually matter.