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You do not need LangChain in a command-line tool. A four-method chat interface can hide five providers, tool calling and structured output.
Config loaders ignore keys they do not recognise, so a typo runs on the old value. Deriving a validation schema from struct tags to catch it.
Go allows only one trailing variadic parameter, so adding another argument to a function that already has one is impossible. What to do instead.
The other audience for a CLI is the script that greps its output and breaks. Giving every command a JSON output mode with one response envelope.
When a Go CLI grows into a service: ordered graceful shutdown on SIGTERM, separate liveness and readiness probes, and an opt-in restart supervisor.
Timing, auth, recovery and logging are cross-cutting in a CLI too. Wrapping Cobra commands in web-style middleware rather than PreRun hooks.
One tool, three logging backends: colour for a terminal, JSON for a container, silence for tests. Depend on the interface, choose the backend once.
Recovery advice belongs in a structured error hint, not buried in the message string. One error handler then decides how to show it.
Go embed.FS is per-package, so a modular CLI ends up with islands. Merging them into one filesystem, and deep-merging YAML and JSON across them.
Passing dependencies to Go commands in a typed struct rather than stuffing them in context.Context, so the compiler checks them and tests stay simple.
go-tool-base
Pioneering
