vigiles: Skill for Claude Code

.claude/skills/add-a-linter/SKILL.md

add-a-linter is a skill for Claude Code from zernie/vigiles. It costs 53 tokens per session (1,722 once invoked), scanned A, original, MIT.

A contributor workflow for adding a built-in linter to Vigiles, a tool that checks and cross-references linter support across its code, documentation, and website.

In plain words
What is it for?
Use it when adding a linter to Vigiles's closed built-in registry, including its existence checks, configuration handling, suggestions, type generation, documentation, and site listing.
Why use it?
Previously, linter support was spread across several files, so contributors could update one place and silently forget another. Type checks and a conformance test help reveal incomplete additions.

Skill for Claude Code

Written for Claude Code: disable-model-invocation in frontmatter.

This is zernie/vigiles's own configuration. It tells Claude Code how to work on vigiles itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything vigiles configures →

Part of the vigiles plugin — 26 skills, 4 hooks, 2 plugins shipped together

Reuse

Borrowing it

Nothing to install: this file belongs to zernie/vigiles. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/zernie/vigiles/main/.claude/skills/add-a-linter/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/zernie/vigiles

Made for: Claude Code.

Or install vigiles, the plugin that ships this one along with the rest of its 26 skills, 4 hooks, 2 plugins.

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.

agentmods badge for add-a-linter

README.md
[![agentmods](https://agentmods.dev/badge/skills/zernie/vigiles/add-a-linter/github.svg)](https://agentmods.dev/skills/zernie/vigiles/add-a-linter)
Your own site
<a href="https://agentmods.dev/skills/zernie/vigiles/add-a-linter"><img src="https://agentmods.dev/badge/skills/zernie/vigiles/add-a-linter/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.

agentmods 80×15 button for add-a-linter

Your own site · 80×15
<a href="https://agentmods.dev/skills/zernie/vigiles/add-a-linter"><img src="https://agentmods.dev/badge/skills/zernie/vigiles/add-a-linter.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 53 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,722 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00053 $0.01722
Opus 5 $0.00026 $0.00861
Sonnet 5 $0.00011 $0.00344
Haiku 4.5 $0.00005 $0.00172

Measured 12d ago against content hash 08aba024300e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

add-a-linter 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.

.claude/skills/add-a-linter/SKILL.md · 110 lines

How it starts

The opening of the file, as written. The whole thing — 110 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Add a linter to vigiles's cross-referencing engine (the enforce("eslint/...") moat). This is a contributor task, not a third-party extension point: the LINTERS registry is a Record<BuiltinLinter, LinterAdapter> — a closed set baked into core — so a linter is added by editing vigiles itself, and the type system + the conformance test make the parity un-forgettable.

The whole reason this skill exists: a linter used to be smeared across ~7 scattered sites (existence check, config checker, CLI-tool map, suggestion enumerator, generate-types discoverer, docs, site) with nothing enforcing that you touched all of them — miss one and it failed silently. Now tsc fails if the registry entry is missing, and src/core/linter-contract.test.ts fails if the docs table or the marketing site drifts. Follow the steps; let the gates catch what you forget. See research/linter-adapter-architecture.md.

The one invariant

A linter is one LinterAdapter in one registry. Everything else — existence, config-enabled, suggestions, type-gen, docs, site — is a field or a method on that adapter, cross-checked by the conformance test. You never again hunt for "the other place this linter is registered."

Steps

Work in this order — each step's gate tells you the next is needed.

  1. Name it (the single source). Add the lowercase name to BUILTIN_LINTERS in src/core/spec.ts. BuiltinLinter derives from this array, so the moment you save, tsc fails on LINTERS in linters.ts with "property <name> is missing" — that error is your to-do list.

  2. Pick the existence-check kind (LinterCapabilities.existenceCheck in src/core/linter-adapter.ts) — this decides which helper builds the adapter:

    • node-api — the rule set is resolved from an installed npm package (eslint, stylelint). Use nodeApiAdapter(name, resolver, configEnabled, discover).
    • cli — a real command asks the tool whether a rule exists (ruff, clippy, pylint, rubocop, detekt, ktlint, checkstyle, golangci-lint). Use cliAdapter(name, cliTool, checkExists, configEnabled, discover, enumerate?).
    • filesystem — presence in a project file counts, no tool (cedar). Write a literal adapter (see cedar in linters.ts).
    • format-only — only the reference shape is validated, no tool exists to list rules (ktlint's catalog is unlistable). Still a cli adapter, just omit the enumerate arg; the existence check is the qualified-shape rule.

Read the full file on GitHub · 110 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.

  1. 12d ago First seen · 110 lines · 53 tokens per session scan A 08aba024300e

Subscribe to this mod's changes

add-a-linter is a skill published in the GitHub repository zernie/vigiles (15 stars, last pushed yesterday), licensed MIT. It adds 53 tokens to every session and 1,722 once invoked, about $0.0003 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.