Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add alexastrum/skl --skill golang-spf13-vipergit clone --depth 1 https://github.com/alexastrum/sklWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/alexastrum/skl/golang-spf13-viper)<a href="https://agentmods.dev/skills/alexastrum/skl/golang-spf13-viper"><img src="https://agentmods.dev/badge/skills/alexastrum/skl/golang-spf13-viper/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/alexastrum/skl/golang-spf13-viper"><img src="https://agentmods.dev/badge/skills/alexastrum/skl/golang-spf13-viper.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00174 | $0.02426 |
| Opus 5 | $0.00087 | $0.01213 |
| Sonnet 5 | $0.00035 | $0.00485 |
| Haiku 4.5 | $0.00017 | $0.00243 |
Grade A, and why
golang-spf13-viper scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
This is a copy
88% identical to golang-spf13-viper — 22 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 181 lines — stays where its author put it; the contents beside it link to each section on GitHub.
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:
This skill is not exhaustive. Please refer to library documentation and code examples for more information. Context7 can help as a discoverability platform.
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 this order (first set value wins):
1. explicit Set() — viper.Set("key", val) highest priority
2. flag — bound pflag.Flag
3. env var — BindEnv / AutomaticEnv
4. config file — ReadInConfig / MergeInConfig
5. KV remote — etcd / Consul
6. default — viper.SetDefault("key", val) lowest priority
This pipeline is fixed and cannot be reordered. Understanding it prevents most viper bugs: a key that "should" come from a config file may be shadowed by an env var or a flag with a default value.
What ships with it
6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 12d ago First seen · 181 lines · 174 tokens per session scan A ec749de1f917
golang-spf13-viper is a skill published in the GitHub repository alexastrum/skl (11 stars, last pushed 3mo ago), licensed MIT. It adds 174 tokens to every session and 2,426 once invoked, about $0.0009 per session on Opus 5. A static security scan graded it A with 0 findings. It is 88% identical to golang-spf13-viper, differing in 22 lines, and is treated as a copy.
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