sentinel-env

A read-only environment check that verifies whether a project has the needed runtimes, command-line tools, ports, environment variables, disk space, and operating-system support.

In plain words
What is it for?
Use it before development, project setup, or onboarding to report clear, warning, or blocking environment conditions.
Why use it?
It identifies setup problems before coding or running the project, helping prevent failures caused by missing tools, incompatible versions, occupied ports, or absent configuration.

Agent

Part of the rune plugin — 57 agents shipped together

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.

agentmods
npx agentmods add agents/rune-kit/rune/sentinel-env
Clone the repo
git clone --depth 1 https://github.com/Rune-kit/rune

Or install rune, the plugin that ships this one along with the rest of its 57 agents.

Per session 44 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 279 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00044 $0.00279
Opus 5 $0.00022 $0.00139
Sonnet 5 $0.00009 $0.00056
Haiku 4.5 $0.00004 $0.00028

Measured 3d ago against content hash 9c25d059864c, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

sentinel-env 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 3d 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.

agents/sentinel-env.md · 27 lines

What it actually says

You are the sentinel-env skill — Rune's environment validation utility.

Quick Reference

Checks:

  1. Runtime versions — Node.js, Python, Bun, Deno, Go, Rust match project requirements
  2. Tools installed — git, npm/pnpm/yarn, docker, required CLIs
  3. Port availability — dev server ports not occupied
  4. Env vars — required .env variables present (not values, just existence)
  5. Disk space — sufficient for node_modules, build artifacts
  6. OS compatibility — path separators, shell availability

Output: PASS (all clear) / WARN (non-blocking issues) / FAIL (blocking — cannot proceed)

Pure L3 utility — read-only, checks and reports, never modifies environment.

Called by: cook (Phase 0.5, first run only), scaffold (post-bootstrap), onboard (developer setup).

Read skills/sentinel-env/SKILL.md for the full specification including check matrix.

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. 3d ago First seen · 27 lines · 44 tokens per session scan A 9c25d059864c

Subscribe to this mod's changes

sentinel-env is an agent published in the GitHub repository Rune-kit/rune (84 stars, last pushed 17d ago), licensed MIT. It adds 44 tokens to every session and 279 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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