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LLM Wiki

Build a second brain that maintains itself — an AI reads your sources and keeps a living, cross-referenced wiki of what you know.

Updated 11 d ago

A visual overview: what it is, how it works, and how to start.

In one line. You collect the sources. An AI reads each one and maintains a living, cross-referenced wiki of what you know, so your knowledge compounds instead of scattering.


The big picture

You bring the sources and the judgment. The AI does the reading and the bookkeeping. You read the result.

Color key: gray is your raw sources, blue is the AI, green is the wiki, amber is you.

Think of it as a team of two: you are the editor; the AI is the writer and librarian who has read everything you have.


Why it beats "chat with your docs"

A chat tool answers from your raw files and keeps nothing, so it starts over every time. A second brain does the synthesis once, writes it down, and keeps it.

Chat tool (RAG)Second brain
KnowledgeRetrieved per questionBuilt once, then kept
Repeat questionsRebuilt from scratchRead from the wiki
ConnectionsFound, then discardedSaved and linked
You getAn answerAn answer and a growing wiki

A chat tool retrieves. A second brain remembers and builds.

That's a fair contrast, not a dismissal — RAG is the right architecture when the corpus is the authority and answers must cite it. The RAG transit planning note works through that case in detail: an agency's own reports as institutional memory, where grounding and citations matter more than synthesis.


How it works: the loop

Drop sources in and the AI files and links them; ask a question and a good answer gets filed back as its own page. So the wiki grows on both ends — whether you're feeding it or querying it.


What the wiki looks like

Not a pile of notes. A connected web, where every idea links to related ideas and to the sources it came from.

A single page is small and plain:

# Compound Interest

Returns earn their own returns over time, so growth accelerates.
Starting small and early tends to beat starting big and late.

Related: [[dollar-cost-averaging]], [[time-in-the-market]]
From:    [[author-2023-letter]], [[book-notes]]

Multiply that by a few hundred linked pages and you have a map you can ask questions of.


What you set up

my-second-brain/
├── raw/        # your sources, left untouched
│   ├── article.md
│   └── book-notes.pdf
└── wiki/       # the AI writes everything in here
    ├── overview.md     # the running thesis
    ├── index.md        # catalog of every page
    ├── concepts/       # ideas and frameworks
    ├── sources/        # one summary per source
    └── entities/       # people, places, products

You need an AI agent that can read and write files (Claude Code, Codex) and, ideally, a markdown app like Obsidian to view the result.


Good for

Researching a topic over weeks  ·  reading a dense book  ·  learning a new field  ·  planning a trip or a big purchase  ·  a hobby you love  ·  personal reflection  ·  a team's shared memory.

Anything where knowledge piles up and you wish it were organized.

What it is not

  • Not a thinker. Quality tracks your sources and your questions.
  • Not a dumping ground. Depth beats breadth.
  • Not free. It uses real compute, usually minor for personal use.
  • Not locked in. Just text files you own.

Start in 4 steps

  1. Make a folder with a raw/ subfolder for sources and a wiki/ subfolder for the AI's pages.
  2. Give the AI a short brief: keep a wiki of linked pages, summarize each source, connect ideas, maintain an overview.
  3. Drop in one source and ask the AI to file it. Read what it writes.
  4. Add a few more, ask a question, and watch it take shape.

Lighter on-ramp: with no setup at all, ask any good AI to keep a structured running summary of a topic and paste it back each time so it builds on itself.

The one rule: start tiny and let the structure grow out of your real sources. Do not design an elaborate system for an empty folder.


Wiring it up: AI agent + vault

Everything above describes the idea. This is the implementation layer — how you give an AI reliable, ongoing read/write access to an Obsidian vault so it does the heavy lifting (reading sources, summarizing, linking, maintaining overview.md) while you stay the editor. It's the automation that turns a static pile of Markdown into a living, compounding system.

The specific tools below shift fast — treat them as examples of each pattern, not a fixed list. The architectures are the durable part.

Three architectures

ArchitectureWhat it isStrengthsWeaknessesBest for
In-app pluginsAI inside Obsidian — RAG chat, inline generation, agentsSeamless UX, no external setupLimited autonomy and long-running tasksDaily interaction, light assistance
External agentsCoding agents or scripts with direct file-system access to the vaultHigh autonomy; multi-step and scheduled workflowsNeeds careful prompting and oversightHeavy maintenance, bulk processing, a self-updating wiki
HybridExternal agents do the heavy lifting; in-app plugins keep a human in the loopBest of bothMore to orchestrateSerious second-brain builders

The hybrid model is the most powerful for a self-maintaining wiki: an autonomous agent does the bookkeeping, and you review and steer from inside Obsidian.

The industry has a name for the skill this demands: Context Engineer — architecting the information environment an agent works in, rather than the agent itself. Curating raw/ and writing the librarian brief is that job, at personal scale.

The tools

In-app plugins — for interacting with your knowledge, weak for autonomous upkeep:

  • Smart Connections — RAG chat over the whole vault, grounded in your actual notes.
  • Copilot — multi-model assistant with strong inline editing and generation.
  • Claudian and similar — direct Claude integration.
  • Also: Text Generator, various local-LLM plugins.

External agents — the real power layer, because they read and write files directly:

  • Claude Code / Claude Projects — point it at the vault folder, give it skills/prompts for maintenance; in the terminal it can loop over files, edit, and commit.
  • Cursor, Aider, Windsurf — coding agents that excel at large-scale refactoring, consistent linking, and structure across many files.
  • Custom frameworks — LangChain, CrewAI, or a simple script plus a model with file-system tools.
  • Git-backed workflows — wrap any agent in version control so every change is tracked and reversible. revert and reflog are the two that matter most here; the git reference has both, and the reasoning for revert over reset on anything already shared.

The Karpathy "LLM wiki" pattern (the idea introduced above) in practice: sources land in raw/; the agent turns them into summaries in wiki/sources/, maintains overview.md, creates concept pages, adds [[links]], and updates connections; you review through Graph View and give direction. It's exactly what the big picture at the top of this page shows.

A production layout

A fuller version of the earlier What you set up sketch, organized for an agent:

my-second-brain/
├── raw/                  # you drop sources here — AI never edits
│   ├── articles/
│   ├── books/
│   ├── emails/
│   └── notes/
├── wiki/                 # AI writes and maintains everything here
│   ├── overview.md       # the living thesis (updated regularly)
│   ├── index.md          # catalog of every page
│   ├── concepts/         # idea pages, richly linked
│   ├── sources/          # one clean summary per source
│   ├── entities/         # people, companies, models
│   └── projects/         # (optional) project-specific synthesis
├── .obsidian/            # your Obsidian config
└── prompts/              # (optional) stored system prompts / skills

The agent owns wiki/. You own raw/. That one boundary is what keeps the system safe to automate.

Who does what

The agent — librarian and writer:

  • Reads new files in raw/.
  • Creates and updates summaries in wiki/sources/.
  • Extracts concepts into wiki/concepts/, linked with [[wikilinks]].
  • Maintains and evolves overview.md; keeps index.md current.
  • Flags contradictions and proposes updates when new context arrives.

You — editor:

  • Drop high-quality sources into raw/.
  • Review Graph View — Local for recent notes, Global for the whole web — for connection quality.
  • Curate the pages that matter; correct major mistakes.
  • Give high-level direction ("focus on investment frameworks this month").

Setup paths

Claude Code / Claude Projects.

Point Claude at the vault folder, or specific subfolders.

Give it a skill/brief: "You are the librarian for my second brain. When new files appear in raw/, process them by these rules…" — spell out summary style, linking philosophy, and overview maintenance.

For autonomous runs, use Claude Code in the terminal — it loops over files, edits, and commits via Git.

Review in Obsidian via Graph View and Git history.

Cursor or Aider (large-scale maintenance). Open the vault as a project, use agent/composer mode with a strong system prompt, and run targeted passes — "process all new files in raw/ and integrate them with proper linking and overview updates." Git tracks every change.

Hybrid daily loop. Drop sources in the morning → the agent processes them on a schedule or on demand → you open Obsidian, scan the Local Graph on recent notes and the Global Graph for new connections → use Smart Connections or Copilot for quick questions → weekly, run a deeper agent pass for overview and link cleanup.

Best practices

Prompt the agent like an editor. Be specific about output format, linking style, and when not to create a page. Give editorial guidelines (tone, depth, link vs. keep-separate) and a few good-versus-bad page examples.

Keep a human in the loop.

  • Graph View (especially Extended Graph) is your audit tool — weak or hallucinated links show up visually.
  • Git gives full history and one-command rollback.
  • Keep a review queue note where the agent logs uncertain decisions.
  • Run periodic "knowledge health" passes using filtered graphs (orphans, high-degree hubs, recent changes).

Risks and mitigations:

RiskMitigation
Hallucinated or wrong linksHave the agent propose changes; apply via Git + review, not blind auto-commit
Over-linking / structure driftStrong, versioned system prompts + regular Graph review
Privacy and securityA local vault with local models, or a carefully chosen API, beats cloud note apps
Context-window limitsRetrieval (Smart Connections style) or hierarchical processing — summarize, then synthesize

Scale. On large vaults, point the agent at recent changes or specific subfolders rather than the whole vault each run. Pair with Bases for structured dashboards the agent can also update.

Done well, the agent layer hands you back your attention: you stop doing the bookkeeping by hand and spend it on judgment, curation, and direction — with Graph View as your window into the system's health. It's the closest most people get to a self-maintaining second brain without building everything from scratch.


Why it works

The hard part was never the reading. It was the upkeep: linking, updating, and staying consistent across hundreds of pages. People quit because that work scales badly. An AI does not get bored and can revise many pages in a single pass, so the wiki stays alive, and only a living wiki compounds.

The idea is old. Vannevar Bush imagined a personal, linked knowledge machine in 1945; the sociologist Niklas Luhmann wrote dozens of books from a system of linked index cards; the modern note apps turned that into software. The missing piece was always someone willing to do the upkeep forever, and that is the part the AI handles.


Origin: Andrej Karpathy's short "LLM wiki" idea file (search "Karpathy LLM wiki"). The diagrams above render in Obsidian, GitHub, and most markdown viewers. The best way to understand it is to start one.

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