check-plain-env

An environment checker for Plain projects, which use .plain files, testscripts, configuration files, and resources. It finds the tools, runtimes, package managers, and external services the project needs, then checks whether they are installed.

In plain words
What is it for?
Use it when opening a project on a new machine, adding dependencies, onboarding, or checking the environment before a render or test run.
Why use it?
It shows whether a machine is ready to render and test the project before work begins.

Skill for Claude CodeCodex

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 skills/plainlang/plain-forge/check-plain-env
Any agent
npx skills add plainlang/plain-forge --skill check-plain-env
Clone the repo
git clone --depth 1 https://github.com/plainlang/plain-forge

Made for: Claude Code, Codex.

Per session 120 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 6,413 The whole file, excluding the scripts and references it only reads on demand.
Security scan F 4 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 $0.00120 $0.06413
Opus 5 $0.00060 $0.03207
Sonnet 5 $0.00024 $0.01283
Haiku 4.5 $0.00012 $0.00641

Measured 2d ago against content hash 06ca6931e16c, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade F, and why

check-plain-env scanned grade F with 4 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 2d 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.

Harvests environment variableshighData exfiltration

Enumerating or grepping the environment for keys collects credentials unrelated to what the mod says it does.

- `CODEPLAIN_API_KEY` env var **set** — `printenv CODEPLAIN_API_KEY >/dev/null && echo set || echo missing` (never echo the value).

Asks for rootmediumPrivilege escalation

A mod that escalates privileges can change anything on the machine, not only the project.

| Java | `brew install openjdk@21` then follow the post-install `sudo ln -sfn ...` step |

Downloads and executes remote codehighSupply chain

curl | sh runs whatever the server returns today, which is not necessarily what it returned when this was reviewed.

When emitting an install command, **match the host OS** detected in Step 1. Prefer the OS's first-party package manager. Don't suggest `curl | sh` style installs unless there is no alternative.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

When emitting an install command, **match the host OS** detected in Step 1. Prefer the OS's first-party package manager. Don't suggest `curl | sh` style installs unless there is no alternative.
forge/skills/check-plain-env/SKILL.md · 289 lines

How it starts

The opening of the file, as written. The whole thing — 289 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Check Plain Env

Always use the skill load-plain-reference to retrieve the ***plain syntax rules — but only if you haven't done so yet.

This skill answers one question: **does the host machine have everything the *plain project needs to render and test? It reads the project, derives the requirement list, probes the machine, and returns a report. It never installs anything itself — that decision belongs to the user.

When to run

  • **First time you open a *plain project on a new machine — before the first codeplain <module>.plain or ./test_scripts/run_unittests*.sh invocation. This is the most common case.
  • At the start of forge-plain Phase 3 environment verificationforge-plain historically did this inline; delegate to this skill instead so the same check runs the same way everywhere.
  • After add-feature — when the new feature brought in a new dependency (a new framework, a new service, a new package manager) the project didn't need before.
  • Before a real render — alongside plain-healthcheck. plain-healthcheck answers "are the specs renderable?"; this skill answers "can this machine render them?". Both should pass.
  • Onboarding — when a teammate (or CI runner, or fresh dev container) is about to start using the project.
  • Debugging a confusing failure — when a test script exits with "command not found", "module not found", "could not connect", or similar before any test runs.
  • On demand — whenever the user asks "what do I need to install for this project?".

This skill is read-only and observational. It does not edit .plain files, scripts, or configs, and it never invokes install commands on the user's behalf.

What this skill does NOT do

  • It does not install anything. It only suggests install commands and lets the user run them.
  • It does not generate scripts, modify config.yaml, or change project files. Use implement-*-testing-script, init-config-file, etc. for that.
  • It does not start services (databases, brokers, Docker daemons). It only checks whether the right binaries and (optionally) running endpoints are reachable.
  • It does not validate the specs themselves (syntax, dry-run, complexity). Use plain-healthcheck for that — the two skills are complementary.
  • It does not print secrets. Check whether an env var is set (e.g. printenv FOO >/dev/null && echo set || echo missing), never echo its value.

Read the full file on GitHub · 289 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. 2d ago First seen · 289 lines · 120 tokens per session scan F 06ca6931e16c

Subscribe to this mod's changes

check-plain-env is a skill published in the GitHub repository plainlang/plain-forge (55 stars, last pushed 5d ago), licensed MIT. It adds 120 tokens to every session and 6,413 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it F with 4 findings (harvests environment variables, asks for root, downloads and executes remote code). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

Other skills, from other repositories

systematic-debugging

Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.

obra/superpowers · 21 tokens

brainstorming

You MUST use this before any creative work - creating features, building components, adding functionality, or modifying behavior. Explores user intent, requirements and design before implementation.

obra/superpowers · 37 tokens

auto-perf-optimize

Run agent-driven VS Code performance or memory investigations. Use when asked to launch Code OSS, automate a VS Code scenario, run the Chat memory smoke runner, capture renderer heap snapshots, take workflow screenshots, compare run summaries, or drive a repeatable scenario before heap-snapshot analysis.

microsoft/vscode · 62 tokens

chat-perf

Run chat perf benchmarks and memory leak checks against the local dev build or any published VS Code version. Use when investigating chat rendering regressions, validating perf-sensitive changes to chat UI, or checking for memory leaks in the chat response pipeline.

microsoft/vscode · 51 tokens

chat-pet-sprite-creation

Use when creating or changing VS Code chat pet sprite art, sprite sheets, state animations, eye treatments, Stable/Insiders variants, or pet transitions under src/vs/workbench/contrib/chat/browser/widget/media/chatPet.

microsoft/vscode · 53 tokens

cpu-profile-analysis

Analyze V8/Chrome CPU profiles (.cpuprofile) and DevTools trace files (Trace-.json). Use when: profiling performance, investigating slow functions, comparing code paths, finding bottlenecks, analyzing timeToRequest, understanding call trees from sampling profiler data, analyzing layout/paint/rendering, investigating…

microsoft/vscode · 71 tokens