arc: Skill for Claude Code

.claude/skills/knowledge-extraction/SKILL.md

knowledge-extraction is a skill for Claude Code from teejayen/arc. It costs 36 tokens per session (484 once invoked), scanned A, original, MIT.

A workflow for saving useful knowledge from conversations as organized files. It covers how-to instructions, recurring patterns, insights, references, and lessons from experience.

In plain words
What is it for?
It helps record technical methods, project learnings, life patterns, general references, and notes about tools or products.
Why use it?
It prevents useful information from being lost in old conversations and makes it easier to reuse later.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

This is teejayen/arc's own configuration. It tells Claude Code how to work on arc itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything arc configures →

View source ↗ teejayen/arc
Reuse

Borrowing it

Nothing to install: this file belongs to teejayen/arc. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/teejayen/arc/main/.claude/skills/knowledge-extraction/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/teejayen/arc

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 knowledge-extraction

README.md
[![agentmods](https://agentmods.dev/badge/skills/teejayen/arc/knowledge-extraction/github.svg)](https://agentmods.dev/skills/teejayen/arc/knowledge-extraction)
Your own site
<a href="https://agentmods.dev/skills/teejayen/arc/knowledge-extraction"><img src="https://agentmods.dev/badge/skills/teejayen/arc/knowledge-extraction/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 knowledge-extraction

Your own site · 80×15
<a href="https://agentmods.dev/skills/teejayen/arc/knowledge-extraction"><img src="https://agentmods.dev/badge/skills/teejayen/arc/knowledge-extraction.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 36 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 484 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 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 5.1 $0.00036 $0.00484
Opus 5.5 $0.00014 $0.00194
Sonnet 5.5 $0.00007 $0.00097
Haiku 4.5 $0.00004 $0.00048

Measured 2mo ago against content hash 8f51a5d0aaff, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

knowledge-extraction 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 2mo 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.

.claude/skills/knowledge-extraction/SKILL.md · 84 lines

What it actually says

Knowledge Extraction

Capture learnings, patterns, and reusable knowledge from conversations.

When to Use

  • A useful pattern or approach emerged
  • Something was learned that's worth remembering
  • A solution was found that might apply elsewhere
  • User explicitly wants to save knowledge

Execution Steps

Step 1: Identify the knowledge

Types of extractable knowledge:

  • How-to: Process or technique
  • Pattern: Recurring approach or structure
  • Insight: Understanding about how something works
  • Reference: Facts or information worth keeping
  • Lesson: Learning from experience (including failures)

Step 2: Determine destination

Knowledge Type Destination
Technical how-to areas/learning/[topic].md
Life pattern areas/[relevant-area]/patterns.md or standalone
Project insight areas/[project]/learnings.md
General reference resources/[topic]/
Tool/product knowledge resources/tools/[tool].md

Step 3: Create knowledge file

---
title: "[Clear descriptive title]"
created: YYYY-MM-DD
tags: [knowledge, topic, source-area]
type: [how-to|pattern|insight|reference|lesson]
---

# [Title]

## Summary
[One paragraph - what this knowledge is and why it matters]

## The Knowledge

### Context
[When/where this applies]

### Detail
[The actual knowledge - steps, pattern description, insight explanation]

### Examples
[If applicable - concrete examples of application]

## Caveats
[If applicable - when this doesn't apply, edge cases]

## Source
[Where this came from - session reference, experience, external source]

## Related
- [[related-notes]]

Step 4: Link appropriately

  • Add reference in relevant area/project files
  • Update any index files if they exist
  • Note in session file that knowledge was extracted

Step 5: Confirm

  • Show file location
  • Summarise what was captured
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. 2mo ago First seen · 84 lines · 36 tokens per session scan A 8f51a5d0aaff

Subscribe to this mod's changes

knowledge-extraction is a skill published in the GitHub repository teejayen/arc (5 stars, last pushed 9mo ago), licensed MIT. It adds 36 tokens to every session and 484 once invoked, about $0.0001 per session on Opus 5.5. 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 2026-08-31.

Related

knowledge-extraction compared with skills from other repositories

knowledge-extraction next to 6 skills from other repositories
ModTypeStarsLast pushLicenceScanTokensWorks with
knowledge-extractionteejayen/arcSkill59mo agoMITA36Claude Code
knowledge-ingestopenclaw/openclawSkill394kyesterdayMITA80Claude Code, Codex
mem0-oss-to-platformmem0ai/mem0Skill68k2d agoApache-2.0A217Claude Code, Codex
forgetasgeirtj/system_prompts_leaksSkill71k2d agoCC0-1.0A74Claude Code, Codex
Cortexdanielmiessler/LifeOSSkill20kyesterdayMITA184Claude Code
memoryopensquilla/opensquillaSkill7.1k6d agoApache-2.0A44Claude Code, Codex
ha-data-storesshiwenwen/hope-agentSkill1.9kyesterdayMITA115Claude Code, Codex