Cortex

A system for storing and recalling connected knowledge about people, companies, ideas, research, blogs, and books, along with earlier work sessions and conversations. It links related notes so the collection works more like a map than a folder of isolated files.

In plain words
What is it for?
Use it to search, add, develop, import, connect, navigate, and summarize knowledge, and to recall earlier sessions or conversations by topic or date.
Why use it?
It makes old information easier to find and shows connections or contradictions between notes. It also helps recover useful context from previous work.

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/danielmiessler/lifeos/cortex
Any agent
npx skills add danielmiessler/LifeOS --skill cortex
Clone the repo
git clone --depth 1 https://github.com/danielmiessler/LifeOS

Made for: Claude Code, Codex.

Per session 196 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 6,113 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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 $0.00196 $0.06113
Opus 5 $0.00098 $0.03057
Sonnet 5 $0.00039 $0.01223
Haiku 4.5 $0.00020 $0.00611

Measured 2d ago against content hash e01d09b2c2c1, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

Cortex scanned grade A with 1 finding 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 2d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (Tools/ContextSearch.ts), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

- **URL:** Use WebFetch to retrieve and read the content. If WebFetch fails, try `curl -sL` via Bash.
LifeOS/install/skills/Cortex/SKILL.md · 533 lines

How it starts

The opening of the file, as written. The whole thing — 533 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Cortex Skill

What It Does

Operate Cortex, the LifeOS memory system, from one skill. Two halves: the Knowledge Archive — a curated, typed graph of notes across six entity domains (People, Companies, Ideas, Research, Blogs, Books), every note shipping typed related: cross-links so the archive is a connected graph, not a pile of files — and recall — finding prior work (sessions, ISAs, conversations) by topic or date phrase. Operations cover search, add, harvest, develop, ingest, contradiction-finding, graph traversal, compressed retrieval, conversation mining, the weekly distill pass, and session recall.

The Problem

Notes you save in isolation are notes you never find again. A flat folder of facts has no way to tell you that two notes contradict each other, that a new source updates an old claim, or that an idea connects to a person and a company you wrote up months ago. Knowledge dies when it can't be retrieved or related. This archive forces every note into a typed schema with mandatory cross-links and ripples updates through related notes on ingest, so the connections are built in at write time instead of being reconstructed by hand later.

How It Works

Manage the LifeOS Knowledge Archive at ~/.claude/LIFEOS/MEMORY/KNOWLEDGE/. Each operation routes through a subcommand below; notes follow the archive schema and ship with typed cross-links.

Archive schema: ~/.claude/LIFEOS/MEMORY/KNOWLEDGE/_schema.md

Hard rule — never write KNOWLEDGE/ directly. All writes route through this skill (add, harvest, ingest, develop) — never cp, mv, Write, or Edit straight into the directory, even during migration or bulk import. The skill enforces typed frontmatter, mandatory cross-links, and domain classification; raw filesystem writes skip those guarantees and corrupt the graph silently (broken links don't fail loudly — they produce phantom entries retrieval misses). Migration tooling MUST call this skill per chunk, never shell out to cp. The one sanctioned exception is the Algorithm's LEARN phase, which writes to KNOWLEDGE/ directly because it holds the best context and applies the same schemas (see Gotchas).

Read the full file on GitHub · 533 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 2d ago First seen · 533 lines · 196 tokens per session scan A e01d09b2c2c1

Subscribe to this mod's changes

Cortex is a skill published in the GitHub repository danielmiessler/LifeOS (18,798 stars, last pushed 18d ago), licensed MIT. It adds 196 tokens to every session and 6,113 once invoked, about $0.0010 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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