napkin

napkin is a skill for Claude Code, Codex from SZoloth/skill-pack. It costs 75 tokens per session (742 once invoked), scanned A, a copy of napkin, MIT.

A per-repository Markdown runbook stored at `.claude/napkin.md`. It records recurring, high-value instructions for future coding-agent sessions and is curated whenever a session starts.

In plain words
What is it for?
Use it to maintain repeatable project rules, command advice, and validation guidance that the agent should remember across sessions.
Why use it?
It prevents useful project guidance from being lost between sessions while removing stale or low-value notes.

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/szoloth/skill-pack/napkin
Any agent
npx skills add SZoloth/skill-pack --skill napkin
Clone the repo
git clone --depth 1 https://github.com/SZoloth/skill-pack

Made for: Claude Code, Codex.

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 napkin

README.md
[![agentmods](https://agentmods.dev/badge/skills/szoloth/skill-pack/napkin.svg)](https://agentmods.dev/skills/szoloth/skill-pack/napkin)
Your own site
<a href="https://agentmods.dev/skills/szoloth/skill-pack/napkin"><img src="https://agentmods.dev/badge/skills/szoloth/skill-pack/napkin.svg" alt="Measured on agentmods" height="20"></a>
Per session 75 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 742 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00075 $0.00742
Opus 5 $0.00037 $0.00371
Sonnet 5 $0.00015 $0.00148
Haiku 4.5 $0.00007 $0.00074

Measured 5d ago against content hash 3a4cae73a78a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

napkin 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.

Origin

This is a copy

100% identical to napkin — 0 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/napkin/SKILL.md · 107 lines

How it starts

The opening of the file, as written. The whole thing — 107 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Napkin

You maintain a per-repo markdown runbook, not a chronological log. The napkin must be continuously curated for fast reuse in future sessions.

This skill is always active. Every session. No trigger required.

Session Start: Read And Curate

First thing, every session — read .claude/napkin.md before doing anything else. Internalize what's there and apply it silently. Don't announce that you read it. Just apply what you know.

Every time you read it, curate it immediately:

  • Re-prioritize items by importance (highest first).
  • Merge duplicates and remove stale/low-signal notes.
  • Keep only recurring, high-frequency guidance.
  • Ensure each item contains an explicit "Do instead" action.
  • Enforce category caps (top 10 per category).

If no napkin exists yet, create one at .claude/napkin.md:

# Napkin Runbook

## Curation Rules
- Re-prioritize on every read.
- Keep recurring, high-value notes only.
- Max 10 items per category.
- Each item includes date + "Do instead".

## Execution & Validation (Highest Priority)
1. **[YYYY-MM-DD] Short rule**
   Do instead: concrete repeatable action.

## Shell & Command Reliability
1. **[YYYY-MM-DD] Short rule**
   Do instead: concrete repeatable action.

## Domain Behavior Guardrails
1. **[YYYY-MM-DD] Short rule**
   Do instead: concrete repeatable action.

## User Directives
1. **[YYYY-MM-DD] Directive**
   Do instead: exactly follow this preference.

Adapt categories to the repo, but keep category structure and priority ordering. Do not use raw journal-style entries.

Continuous Runbook Updates

Update during work whenever you learn something reusable.

What qualifies for inclusion:

  • Frequent gotchas or surprising behavior in this repo/toolchain.
  • User directives that affect repeated behavior.
  • Non-obvious tactics that repeatedly work.

What does not qualify:

  • One-off timeline notes.
  • Verbose postmortems without reusable action.
  • Pure mistake logs without "Do instead" guidance.

Entry format requirements:

Read the full file on GitHub · 107 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 First seen · 107 lines · 75 tokens per session scan A 3a4cae73a78a

Subscribe to this mod's changes

napkin is a skill published in the GitHub repository SZoloth/skill-pack (14 stars, last pushed 5mo ago), licensed MIT. It adds 75 tokens to every session and 742 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to napkin, differing in 0 lines, and is treated as a copy.

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