principle-prove-it-works

principle-prove-it-works is a skill for Claude Code from ericlitman/open-pstack. It costs 50 tokens per session (292 once invoked), scanned A, a copy of principle-prove-it-works, MIT.

A verification practice for checking the real result of completed work, such as running the feature and inspecting its output or code changes.

In plain words
What is it for?
Use it after coding, testing integrations, or reviewing delegated work to confirm that data and behavior work through the full path.
Why use it?
It prevents false confidence from indirect signs like a successful build, cached output, or a task summary.

Skill for Claude Code

Written for Claude Code: user-invocable in frontmatter.

Part of the pstack plugin — 63 skills, 27 agents, 1 hook shipped together

Good fit Use it after coding, testing integrations, or reviewing delegated work to confirm that data and behavior work through the full path.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/ericlitman/open-pstack/principle-prove-it-works
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 ericlitman/open-pstack --skill principle-prove-it-works
Clone the repo
git clone --depth 1 https://github.com/ericlitman/open-pstack

Made for: Claude Code.

Or install pstack, the plugin that ships this one along with the rest of its 63 skills, 27 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.

agentmods badge for principle-prove-it-works

README.md
[![agentmods](https://agentmods.dev/badge/skills/ericlitman/open-pstack/principle-prove-it-works/github.svg)](https://agentmods.dev/skills/ericlitman/open-pstack/principle-prove-it-works)
Your own site
<a href="https://agentmods.dev/skills/ericlitman/open-pstack/principle-prove-it-works"><img src="https://agentmods.dev/badge/skills/ericlitman/open-pstack/principle-prove-it-works/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 principle-prove-it-works

Your own site · 80×15
<a href="https://agentmods.dev/skills/ericlitman/open-pstack/principle-prove-it-works"><img src="https://agentmods.dev/badge/skills/ericlitman/open-pstack/principle-prove-it-works.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 50 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 292 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 100% copy Near-identical to another mod 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 $0.00050 $0.00292
Opus 5.5 $0.00020 $0.00117
Sonnet 5.5 $0.00010 $0.00058
Haiku 4.5 $0.00005 $0.00029

Measured 23d ago against content hash 80ee4a50fe1d, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

principle-prove-it-works 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 23d 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.

Origin

This is a copy

100% identical to principle-prove-it-works — 5 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

plugins/pstack/skills/principle-prove-it-works/SKILL.md · 23 lines

What it actually says

Prove It Works

Verify every task output by checking the real thing directly. Do not infer from proxies, self-reports, or "it compiles."

Why: Unverified work has unknown correctness. Indirect verification (file mtimes, output freshness, agent self-reports, cached screenshots) feels cheaper than direct observation. Acting on a wrong inference costs far more than checking the source.

Check the real thing, not a proxy:

  • Check process liveness directly, not indirectly through derived state
  • Read the actual value, not a cached or derived representation
  • When verification fails, suspect the observation method before suspecting the system

Script the check when you can

The strongest proof is a deterministic script that re-runs the same comparison, not a one-time eyeball. Write the script, run it, and keep its output as an artifact a reviewer can re-run instead of trusting your word.

Keep the artifact visible for the human. Commit it only for large or complex work where the trail has to be auditable later, like a big port or migration (the show-me-your-work skill).

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. 23d ago Changed · -11 lines 80ee4a50fe1d
  2. 1mo ago Changed 646959d52751
  3. 1mo ago First seen · 34 lines · 50 tokens per session scan A 34dc051f170f

Subscribe to this mod's changes

principle-prove-it-works is a skill published in the GitHub repository ericlitman/open-pstack (522 stars, last pushed 2d ago), licensed MIT. It adds 50 tokens to every session and 292 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to principle-prove-it-works, differing in 5 lines, and is treated as a copy.

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