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 eduardo-sl/go-agent-skills --skill go-design-patternsgit clone --depth 1 https://github.com/eduardo-sl/go-agent-skillsWrote 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/eduardo-sl/go-agent-skills/go-design-patterns)<a href="https://agentmods.dev/skills/eduardo-sl/go-agent-skills/go-design-patterns"><img src="https://agentmods.dev/badge/skills/eduardo-sl/go-agent-skills/go-design-patterns/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/eduardo-sl/go-agent-skills/go-design-patterns"><img src="https://agentmods.dev/badge/skills/eduardo-sl/go-agent-skills/go-design-patterns.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00099 | $0.01376 |
| Opus 5 | $0.00049 | $0.00688 |
| Sonnet 5 | $0.00020 | $0.00275 |
| Haiku 4.5 | $0.00010 | $0.00138 |
Grade A, and why
go-design-patterns 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 11d 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.
How it starts
The opening of the file, as written. The whole thing — 178 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Go Design Patterns
Go favors composition over inheritance and simplicity over abstraction. These patterns are idiomatic Go — not Java patterns ported to Go.
Detailed reference material, loaded on demand:
references/creation-patterns.md— functional options (full example), options vs config struct, constructors, factory.references/behavioral-patterns.md— strategy, middleware/decorator, result type, defer cleanup, sentinel vs zero values.
Read a reference file only when the summary below is not enough.
Pattern Selection
| Need | Pattern | Reference |
|---|---|---|
| Constructor with many optional settings | Functional options | creation-patterns.md |
| Config loaded from file/env, mostly required fields | Config struct | creation-patterns.md |
| Enforce invariants at creation | Constructor returning error | creation-patterns.md |
| Pick implementation from runtime config | Factory returning interface | creation-patterns.md |
| Swap simple behavior at runtime | Strategy via function type | behavioral-patterns.md |
| Swap complex behavior at runtime | Strategy via interface | behavioral-patterns.md |
| Wrap cross-cutting concerns (log, cache, metrics) | Middleware / decorator | behavioral-patterns.md |
| Value-or-error in concurrent pipelines | Result[T] struct |
behavioral-patterns.md |
1. Functional Options (essentials)
type Option func(*Server)
func WithAddr(addr string) Option {
return func(s *Server) { s.addr = addr }
}
func NewServer(opts ...Option) *Server {
s := &Server{
addr: ":8080", // sensible defaults first
readTimeout: 5 * time.Second,
logger: slog.Default(),
}
for _, opt := range opts {
opt(s)
}
return s
}
srv := NewServer(WithAddr(":9090"))
Use when: many optional parameters with sensible defaults, API evolves over time (new options don't break callers), options need validation. Use a plain config struct instead when most fields are required or the configuration is deserialized from file/env.
What ships with it
2 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.
- 11d ago First seen · 178 lines · 99 tokens per session scan A fa809cc76487
go-design-patterns is a skill published in the GitHub repository eduardo-sl/go-agent-skills (71 stars, last pushed 24d ago), licensed MIT. It adds 99 tokens to every session and 1,376 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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