What is first-plan-lens-go?

A Go-project guide for examining how Go code is organised and how it handles errors, contexts, concurrency, generated code, and build options.

Use it to inspect Go layouts such as cmd, internal, and pkg, locate entry points, review error handling, and identify HTTP, GraphQL, messaging, or CLI libraries.

It helps development advice match the project's actual Go version, structure, frameworks, and coding patterns.

first-plan-lens-go — Skill for Claude Code by vynazevedo

Install

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.

Any agent

npx skills add vynazevedo/first-plan --skill lens-go

Clone the repo

git clone --depth 1 https://github.com/vynazevedo/first-plan

Made for: Claude Code.

Or install fp, the plugin that ships this one along with the rest of its 19 skills, 19 commands, 4 agents, 1 hook.

Wrote 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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/vynazevedo/first-plan/lens-go/github.svg)](https://agentmods.dev/skills/vynazevedo/first-plan/lens-go)

Your own site

<a href="https://agentmods.dev/skills/vynazevedo/first-plan/lens-go"><img src="https://agentmods.dev/badge/skills/vynazevedo/first-plan/lens-go/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/vynazevedo/first-plan/lens-go"><img src="https://agentmods.dev/badge/skills/vynazevedo/first-plan/lens-go.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 46 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,132 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

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	$0.00046	$0.01132
Opus 5	$0.00023	$0.00566
Sonnet 5	$0.00009	$0.00226
Haiku 4.5	$0.00005	$0.00113

Measured 9d ago against content hash 376035a771ac, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

first-plan-lens-go 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 9d 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.

skills/lens-go/SKILL.md · 116 lines

How it starts

The opening of the file, as written. The whole thing — 116 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Lens Go

Detecção fina

cmd/<name>/main.go -> binário (CLI ou serviço HTTP)
internal/ -> lib privada do módulo
pkg/ -> lib pública
go.mod em raiz com poucas pastas -> lib pequena
Workspace go.work -> monorepo Go

Frameworks comuns a detectar via imports:

net/http puro = HTTP stdlib
chi, gin, echo, fiber, gorilla/mux = router
gqlgen, graph-gophers/graphql-go = GraphQL
grpc-go = gRPC
cobra, urfave/cli = CLI
kafka-go, segmentio/kafka-go, IBM/sarama = Kafka
streadway/amqp, rabbitmq/amqp091-go = RabbitMQ

Extração de padrões

Layout

Confirmar uso de cmd/, internal/, pkg/
Onde fica o entry point principal (cmd/<name>/main.go?)
Há separação handler/, service/, repository/?

Error handling

errors.New vs fmt.Errorf vs errors.Wrap
Sentinel errors (var ErrNotFound = errors.New(...))
Custom error types (struct com Error() string)
Use de errors.Is / errors.As
Pacote externo (pkg/errors, cockroachdb/errors, hashicorp/go-multierror)

Verificar:

Os handlers retornam erro tipado ou string?
Errors são wrapped com contexto adicional?
Há padrão para mapear erro -> HTTP status?

Context

context.Context é primeiro parametro? (idiomatic)
context.Background() ou context.TODO() em produção? (smell)
Uso de context.WithTimeout / WithCancel

Concurrency

Goroutines + channels?
sync.WaitGroup para coordenar?
errgroup.Group (golang.org/x/sync)?
Pools de worker?

Code generation

go generate directive em arquivos?
mockgen, mockery para mocks?
sqlc, oapi-codegen, protoc-gen-go?
Geradores customizados (sinal: arquivos *.gen.go, *.pb.go, wire_gen.go)

Build tags

//go:build <tag> em arquivos
Tags comuns: integration, e2e, wireinject

Testing

_test.go irmão de cada arquivo?
testify/assert ou stdlib?
Table-driven (presença de t.Run em loop)?
Testes de integração separados (build tag integration)?
Mocks: gerados ou manuais?

Read the full file on GitHub · 116 lines

Changes

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.

9d ago First seen · 116 lines · 46 tokens per session scan A 376035a771ac

Subscribe to this mod's changes

first-plan-lens-go is a skill published in the GitHub repository vynazevedo/first-plan (23 stars, last pushed 15d ago), licensed MIT. It adds 46 tokens to every session and 1,132 once invoked, about $0.0002 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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