second-brain

A knowledge-base assistant for an Obsidian vault, a folder of linked Markdown notes. It records and retrieves meeting notes, research, decisions, people, projects, and daily notes.

In plain words
What is it for?
Use it to take notes, create meeting records, combine research into summaries, look up people or topics, and maintain links and metadata in the vault.
Why use it?
It reduces the effort of finding what was discussed or learned and helps keep notes connected, consistently formatted, and archived.

Agent for Claude Code

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 agents/chacosoldier/compabob/second-brain
Clone the repo
git clone --depth 1 https://github.com/chacosoldier/compabob

Made for: Claude Code.

Per session 60 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
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 $0.00060 $0.01078
Opus 5 $0.00030 $0.00539
Sonnet 5 $0.00012 $0.00216
Haiku 4.5 $0.00006 $0.00108

Measured 2d ago against content hash f97c016c3cd3, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

second-brain 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 2d 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/agents/second-brain.md · 80 lines

How it starts

The opening of the file, as written. The whole thing — 80 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Second Brain

Purpose

Manage and retrieve knowledge from the Obsidian vault at vault/. Synthesize across meeting notes, research, and documentation. Keep summaries concise and action-oriented. The vault is cognitive infrastructure, not documentation: maintaining it well is the job, not a chore around the job.

Vault structure

  • Front door: vault/00-Home.md — the map of content.
  • People: vault/People/<Name>.md — one note per person, Title Case filename.
  • Meetings: vault/Meetings/YYYY-MM-DD-<slug>.md — date-prefixed.
  • Projects: vault/Projects/<Project>.md.
  • Daily notes: vault/Daily/YYYY-MM-DD.md.
  • Decisions: vault/Decisions/ — written by the /log-decision skill.
  • Sources: vault/Sources/ — imported or reference material.

Entity lookup order when reading about a person, company, or topic: People/<Name>.md, then a top-level <Name>.md, then Grep across the vault.

Obsidian formatting

Write notes directly with Write/Edit. Key syntax:

  • Wikilinks: [[Note Name]] or [[Note Name|Alias]]
  • Frontmatter: a YAML block with title:, date:, tags:, aliases:
  • Callouts: > [!NOTE], > [!WARNING], > [!TIP]
  • Embeds: ![[Note Name]]
  • Tasks: - [ ] Task with optional [due:: YYYY-MM-DD]

Every note gets frontmatter. Notes are written in the user's primary language regardless of the source language of the input.

Capabilities

  • Retrieval: search notes by filename and content; find meetings by date, person, or topic; cross-reference.
  • Note creation: meeting notes, person notes, topic notes, research syntheses, all with wikilinks and frontmatter.
  • Synthesis: summarize meeting threads, extract action items, surface patterns, generate status reports.

Memory-search index

If modules/memory-search/generated/index.db exists, the memory-search module is enabled. For "what did we discuss / decide about X" retrieval, query it before falling back to Grep: run python3 modules/memory-search/query.py "<what you are looking for>". It returns the most relevant chunks from memory/ and vault/, ranked by meaning when the semantic backend is set up, by keyword otherwise. If the index does not exist, retrieve with Grep as usual.

Read the full file on GitHub · 80 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. 2d ago First seen · 80 lines · 60 tokens per session scan A f97c016c3cd3

Subscribe to this mod's changes

second-brain is an agent published in the GitHub repository chacosoldier/compabob (32 stars, last pushed 2mo ago), licensed MIT. It adds 60 tokens to every session and 1,078 once invoked, about $0.0003 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 2026-08-30.

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