principle-build-the-lever

principle-build-the-lever is a skill for Claude Code from backnotprop/pstack. It costs 71 tokens per session (614 once invoked), scanned A, a copy of principle-build-the-lever, MIT.

A working method for building a reusable script, code-modification tool, generator, or checking tool for non-trivial work.

In plain words
What is it for?
Automated code edits, generating repetitive files, processing many items consistently, analyzing data, and rerunning verification checks.
Why use it?
It replaces repeated manual changes with a repeatable process that reviewers can run again to check the result.

Skill for Claude Code

Written for Claude Code: disable-model-invocation in frontmatter. Also seen: mentions subagents.

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/backnotprop/pstack/principle-build-the-lever
Any agent
npx skills add backnotprop/pstack --skill principle-build-the-lever
Clone the repo
git clone --depth 1 https://github.com/backnotprop/pstack

Made for: Claude Code.

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-build-the-lever

README.md
[![agentmods](https://agentmods.dev/badge/skills/backnotprop/pstack/principle-build-the-lever.svg)](https://agentmods.dev/skills/backnotprop/pstack/principle-build-the-lever)
Your own site
<a href="https://agentmods.dev/skills/backnotprop/pstack/principle-build-the-lever"><img src="https://agentmods.dev/badge/skills/backnotprop/pstack/principle-build-the-lever.svg" alt="Measured on agentmods" height="20"></a>
Per session 71 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 614 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 98% 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 $0.00071 $0.00614
Opus 5 $0.00036 $0.00307
Sonnet 5 $0.00014 $0.00123
Haiku 4.5 $0.00007 $0.00061

Measured 6d ago against content hash 3a0b02b1b890, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

principle-build-the-lever 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 6d 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

98% identical to principle-build-the-lever — 4 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.

skills/principle-build-the-lever/SKILL.md · 24 lines

What it actually says

Build the Lever

When the work isn't trivial, build the tool that does it instead of doing it by hand.

Why: Two payoffs. Throughput: a codemod, generator, or script does the work the same way every time and reruns for free. Confidence: the tool is one artifact a reviewer can read and rerun to check the work. Hand-done changes can only be re-verified by redoing them. A deterministic script turns "trust me" into "run this".

Pattern: Default to building the lever. Skip it only when the task is genuinely trivial, a couple of obvious edits you can see at a glance.

  • Do the first unit by hand to learn the recipe, then build the tool. Prove it by rerunning it on that unit and diffing against your hand-done version. Make the lever safe to rerun. A reviewer will.
  • Codemod or script for edits, generator for repetitive files, a dump-to-sqlite query for analysis, a rerunnable check for verification.
  • A deterministic lever beats fan-out. If the tool can process every unit in one pass, run it yourself; don't fan out delegates to hand-apply what a script can do.
  • When you fan work out to subagents, write the lever as a skill they all read: the recipe, the verification contract, and the do-not-touch fences in one artifact, so every delegate inherits the same hardened version instead of re-explaining it per prompt and watching each one drift. Keep it outside the delegates' write scope so they can't quietly edit the contract.
  • Applying this principle produces a file. If you cited it and there is no codemod, script, generator, or delegate skill in the diff, you didn't apply it.
  • Commit the lever when the work outlives the session, so the next run reruns it instead of redoing it.

Balance: The bar is triviality, not repetition. A one-off still earns a lever when the lever is what makes the work checkable. Per the Laziness Protocol, build the smallest script that does or proves the job, never a framework.

Distinct from Encode Lessons in Structure, which makes a recurring instruction a durable guardrail. This is throughput and reviewability on the work in front of you. For scripting the verification itself, see Prove It Works.

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. 6d ago First seen · 24 lines · 71 tokens per session scan A 3a0b02b1b890

Subscribe to this mod's changes

principle-build-the-lever is a skill published in the GitHub repository backnotprop/pstack (198 stars, last pushed 17d ago), licensed MIT. It adds 71 tokens to every session and 614 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. It is 98% identical to principle-build-the-lever, differing in 4 lines, and is treated as a copy.