extract

A note-making command that reads a source file and turns its specific, checkable statements into separate claim notes.

In plain words
What is it for?
Use it to process a document in an inbox and create atomic notes for a knowledge base or research archive.
Why use it?
It removes the manual work of finding and splitting useful assertions from a document. It only extracts claims, so linking and quality checks remain separate steps.

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/letrplb/second-brain/extract
Any agent
npx skills add letrplB/second-brain --skill extract
Clone the repo
git clone --depth 1 https://github.com/letrplB/second-brain

Made for: Claude Code, Codex.

Per session 33 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,078 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 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 $0.00033 $0.01078
Opus 5 $0.00016 $0.00539
Sonnet 5 $0.00007 $0.00216
Haiku 4.5 $0.00003 $0.00108

Measured yesterday against content hash d6aafd21ab8e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

extract 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 yesterday.

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.

skills/extract/SKILL.md · 71 lines

How it starts

The opening of the file, as written. The whole thing — 71 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/extract

Intent. Mechanical claim extraction. Read a source, write atomic claim notes. Nothing else.

What this verb does NOT do

  • Does not connect (no inline [[wikilinks]] to other notes added in this step — that's /connect)
  • Does not audit (no quality check — that's /audit)
  • Does not update MOCs (that's /connect)
  • Does not move the source out of inbox/ (that's /learn if invoked, else manual)

It writes claim notes. That is all.

Behaviour

  1. Resolve source. If an argument is given, treat it as the source path. If no argument, list inbox/ files by mtime and process the most recent (or ask).
  2. Read the source. Whole file, in one read, inline.
  3. Identify atomic claims. A claim is:
    • A proposition that is true or false (not a description, not a list of topics)
    • Specific enough that it could in principle be wrong
    • Sourced to this text (don't extract claims the text merely cites)
    • Narrow enough to fit one note (not a multi-claim summary)
  4. Calibrate count to source density. Hard floor: zero. Soft ceiling: model judgement. Reference numbers:
    • Tweet / single short post: 0–3
    • Blog essay (≤2K words): 3–8
    • Long essay / chapter: 8–15
    • Paper: 10–25 (rare to exceed; over-extraction is the known failure mode)
    • When in doubt, fewer is better — duplicates and restatements should collapse to one claim.
  5. Write paper note. If no notes/papers/<source-slug>.md exists, create one. Frontmatter per reference/templates/paper.md. Body: ≤200 words on what the source argues + why you're processing it.
  6. Write claim notes. For each identified claim:
    • Filename: notes/claims/<kebab-case-prose-proposition>.md. Title = filename. Prose proposition, not topic label.
    • Frontmatter per reference/templates/claim.md. Mandatory: description, type: claim, confidence, source: "[[<paper-slug>]]", evidence_type, created: <today>, tags.
    • Body: 150–400 words. Show why the claim holds in this source (mechanism, evidence, scope conditions). Do NOT add [[wikilinks]] to other claims yet — that's connect's job.
  7. Update paper's claims: list. Append the new claim filenames to the paper note's claims: frontmatter array.
  8. Print summary. "Extracted N claims into notes/claims/. Paper note: . Source untouched in ."

Read the full file on GitHub · 71 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. yesterday First seen · 71 lines · 33 tokens per session scan A d6aafd21ab8e

Subscribe to this mod's changes

extract is a skill published in the GitHub repository letrplB/second-brain (1 stars, last pushed 3mo ago), licensed MIT. It adds 33 tokens to every session and 1,078 once invoked, about $0.0002 per session on Opus 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.

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