COG is an AI-assisted second brain that stores knowledge in Markdown files and uses agents, skills, and version control to evolve it over time. It helps people manage knowledge and contacts while supporting several coding-agent tools; the catalogue entries are COG’s skills, agents, instructions, rules, and plugin surfaces.
Borrowing it
Nothing to install: this file belongs to huytieu/COG-second-brain. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/huytieu/COG-second-brain/main/.cursorrulesgit clone --depth 1 https://github.com/huytieu/COG-second-brainWrote 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.
[](https://agentmods.dev/rules/huytieu/cog-second-brain/cursorrules)<a href="https://agentmods.dev/rules/huytieu/cog-second-brain/cursorrules"><img src="https://agentmods.dev/badge/rules/huytieu/cog-second-brain/cursorrules/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.
<a href="https://agentmods.dev/rules/huytieu/cog-second-brain/cursorrules"><img src="https://agentmods.dev/badge/rules/huytieu/cog-second-brain/cursorrules.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00802 | $0.00802 |
| Opus 5.5 | $0.00321 | $0.00321 |
| Sonnet 5.5 | $0.00160 | $0.00160 |
| Haiku 4.5 | $0.00080 | $0.00080 |
Grade A, and why
cursorrules 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 15d 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.
How it starts
The opening of the file, as written. The whole thing — 59 lines — stays where its author put it; the contents beside it link to each section on GitHub.
COG Second Brain — Cursor Rules
This is the Cursor-compatible version of CLAUDE.md
COG: Cognition + Obsidian + Git — a self-evolving agentic second brain
Inspired by Garry Tan's gstack and gbrain patterns
Skills
COG exposes 17 skills via .claude/skills/*/SKILL.md. Each skill has a name and description in YAML frontmatter. Use AGENTS.md as the universal command reference.
Worker Agents
10 agents live in .claude/agents/: 6 workers handle data-heavy tasks, 4 read-only verifiers check the result against acceptance criteria by observing the artifact. The lead session handles reasoning and synthesis.
- worker-data-collector: Structured extraction from GitHub, Slack, Jira, Linear
- worker-researcher: Web research with source citations
- worker-file-ops: Vault file operations, metadata, profiles
- worker-executor: Pre-approved mutations (Jira, Linear, APIs)
- worker-publisher: Publishing to Slack, Confluence, Notion
- brief-people-updater: Batch-update people profiles
Brain-First Protocol
Before answering questions about people, projects, strategy, or decisions:
- Read relevant notes from
05-knowledge/first - If project-specific, read
04-projects/<project>/ - Then synthesize an answer
Daily Journal
Ambient, not a command. After finishing a meaningful unit of work (shipped or committed something, produced a deliverable, made a decision, hit a blocker), append one entry to 01-daily/journal/YYYY-MM-DD.md (date +%F). Create the file from the template in .claude/skills/daily-journal/SKILL.md on the first entry of the day; append only. Skip trivia and scratch work, and do not announce the write.
Integration Preferences
Check 00-inbox/MY-INTEGRATIONS.md before using any external integration:
- Active: use normally
- Disabled: skip silently
- Unknown: ask the user
Vault Structure
00-inbox/ — Profiles, interests, integrations
01-daily/ — Briefs and check-ins
02-personal/ — Personal braindumps (private)
03-professional/ — Professional braindumps and strategy
04-projects/ — Per-project tracking
05-knowledge/ — Consolidated insights, people CRM, patterns
06-templates/ — Document templates
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.
- 15d ago Changed · +70 tokens per session 671f4ba49716
- 1mo ago First seen · 59 lines · 732 tokens per session scan A be3118fbb97b
cursorrules is a cursor rule published in the GitHub repository huytieu/COG-second-brain (1,294 stars, last pushed 15d ago), licensed MIT. It adds 802 tokens to every session, about $0.0032 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 2026-08-30.
Other cursor rules, from other repositories
orchestrator
Use when coordinating AI agents through a pipeline — orchestrator role instructions.
workspace
Multi-agent workspace context — loaded on every session.
rules
Agentic Playwright orchestrator -- constitution, workflow, and skills index.
engineering-agent-prompt-engineer
Use when writing, reviewing, or improving prompts for AI agents — agent role design and prompt engineering.
fodda
How to query Fodda Market Intelligence and Knowledge Graphs.
cursor
You are working on the checkout service. Preserve transaction integrity and auditability.