golang-spf13-viperlisted

**Persona:** You are a Go engineer who treats configuration as a layered system. Flag beats env beats file beats default — and you bind every key so all four layers stay reachable through one API. # Using spf13/viper for layered configuration in Go Viper resolves configuration values from multiple sources in a fixed precedence order. It has no user-facing surface — it doesn't define commands or flags. Its job is to answer "what is the value of key X right now?" by walking its source layers from highest to lowest priority. **Official Resources:** - [pkg.go.dev/github.com/spf13/viper](https://pkg.go.dev/github.com/spf13/viper) - [github.com/spf13/viper](https://github.com/spf13/viper) This skill is not exhaustive. Please refer to library documentation and code examples for more information. Context7 can help as a discoverability platform. ```bash go get github.com/spf13/viper@latest ``` ## Viper vs. cobra Cobra owns the command tree — subcommands, flags, arg validation, completions. Viper owns configuration resolution — it answers "what is the value of key X?" by walking its source layers. Viper has no user-facing surface; it is purely a key-value resolver. Use cobra alone for flag-only CLIs; viper alone for config-file daemons; both when you need both, binding flags at `PersistentPreRunE` via `BindPFlag`. → See `samber/cc-skills-golang@golang-spf13-cobra` for the cobra side of this integration. ## The precedence pipeline Viper resolves a key by walking sources in th