signalk-container-helper

signalk-container-helper is a skill for Claude Code from sailingnaturali/claude-skills. It costs 113 tokens per session (4,792 once invoked), scanned A, original, MIT.

A helper workflow for building a SignalK server plugin that runs an application inside a Docker or Podman container. It uses the signalk-container manager to handle starting, readiness checks, updates, and clean shutdowns.

In plain words
What is it for?
Use it when developing a SignalK plugin that needs to start a container, wait for its HTTP service, connect update routes, and stop it safely.
Why use it?
Container-based plugins otherwise repeat the same lifecycle code and can mishandle startup, version checks, updates, or shutdown.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the signalk-container-helper plugin — 1 skill shipped together

Good fit Use it when developing a SignalK plugin that needs to start a container, wait for its HTTP service, connect update routes, and stop it safely.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/sailingnaturali/claude-skills/signalk-container-helper
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 sailingnaturali/claude-skills --skill signalk-container-helper
Clone the repo
git clone --depth 1 https://github.com/sailingnaturali/claude-skills

Made for: Claude Code.

Or install signalk-container-helper, the plugin that ships this one along with the rest of its 1 skill.

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 signalk-container-helper

README.md
[![agentmods](https://agentmods.dev/badge/skills/sailingnaturali/claude-skills/signalk-container-helper/github.svg)](https://agentmods.dev/skills/sailingnaturali/claude-skills/signalk-container-helper)
Your own site
<a href="https://agentmods.dev/skills/sailingnaturali/claude-skills/signalk-container-helper"><img src="https://agentmods.dev/badge/skills/sailingnaturali/claude-skills/signalk-container-helper/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 signalk-container-helper

Your own site · 80×15
<a href="https://agentmods.dev/skills/sailingnaturali/claude-skills/signalk-container-helper"><img src="https://agentmods.dev/badge/skills/sailingnaturali/claude-skills/signalk-container-helper.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 113 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,792 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 $0.00113 $0.04792
Opus 5 $0.00056 $0.02396
Sonnet 5 $0.00023 $0.00958
Haiku 4.5 $0.00011 $0.00479

Measured 5d ago against content hash 5e7511d3838e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

signalk-container-helper 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 5d 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.

signalk-container-helper/skills/signalk-container-helper/SKILL.md · 365 lines

How it starts

The opening of the file, as written. The whole thing — 365 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Build a containerized SignalK plugin with signalk-container-helper

Containerized SignalK plugins all hand-write the same glue: poll for the container manager, validate the image tag, call ensureRunning, wait for the app inside the container to answer HTTP, register for update detection, mount update routes, and stop cleanly. signalk-container-helper packages those patterns — extracted from signalk-backup, mayara-server-signalk-plugin, signalk-doctor, signalk-questdb, and signalk-updater — into one typed, zero-runtime-dependency API. It sits on top of the signalk-container manager plugin, which does the actual podman/docker work.

Verified against signalk-container-helper v0.11.0 (August 2026), manager 1.32.x. Version-sensitive claims — the export list, the error codes in §8, the manager floors — churn while the library is at 0.x. Check them against the installed copy (node_modules/signalk-container-helper/package.json, and src/types.ts for the floors) rather than debugging a mismatch. Numbers below are cited where behaviour depends on them.

0. Wiring & constraints (get these right first)

  • ESM only, Node ≥ 22. The library ships as an ES module (import, not require); your plugin must be ESM too.
  • Runtime-only coupling — never add signalk-container to dependencies. Its prerelease versioning breaks npm semver ranges. Declare the relationship instead; the library reaches the manager through a runtime global:
    { "signalk": { "requires": ["signalk-container"] } }
    
    The types the library ships are a mirror of signalk-container/types, verified at build time — not a dependency.
  • start() must never throw. The SignalK server does not await start(), so an async failure inside it becomes an unhandled rejection. Wrap async startup in startSafely(app, fn).
  • Three entry points. signalk-container-helper (Node, dependency-free), …/schema (plain JSON Schema fragments, also dependency-free), …/ui (browser React — react is an optional peer, bundle-time only).
  • Install: npm install signalk-container-helper.

Read the full file on GitHub · 365 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. 5d ago Changed · +164 lines · +25 tokens per session 5e7511d3838e
  2. 12d ago First seen · 201 lines · 88 tokens per session scan A aa7c04a9a75d

Subscribe to this mod's changes

signalk-container-helper is a skill published in the GitHub repository sailingnaturali/claude-skills (2 stars, last pushed 6d ago), licensed MIT. It adds 113 tokens to every session and 4,792 once invoked, about $0.0006 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 2026-08-31.

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