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Matt's Second Brain

Obsidian backend

Why Obsidian

  • Local-first — notes are markdown files in a directory you control.
  • Sync via whatever you already use: iCloud, Syncthing, Obsidian Sync, Dropbox, manual git.
  • Renders nicely in the Obsidian app you (or your team) already have open.
  • No server to run; no API to expose.

Configure the MCP

Terminal window
export BRAIN_BACKEND=obsidian
export BRAIN_OBSIDIAN_VAULT="/path/to/your/vault"

That’s it — the vault must exist; the MCP will create folders inside it as needed.

Layout in the vault

your-vault/
└── Claude Memory/
    ├── 00 — How to use this brain.md
    ├── Standards/
    │   ├── Git Workflow.md
    │   ├── Secrets Handling.md
    │   └── ...
    ├── Decisions/
    │   ├── 2026-04-26 — Pluggable backend adapters.md
    │   └── ...
    ├── Lessons Learned/
    │   └── 2026-03-12 — Idempotent migrations broke under retry.md
    ├── Apps/
    │   └── my-app/
    │       └── ...
    ├── Reviews/
    └── Drafts/
  • The id of a note is its relative path from the vault root, with .md stripped.
  • Tags become inline #tag lines at the top of the body.
  • Search is substring + filename matching, ranked by recency. For semantic search across notes, layer srag on top — it can index the vault dir as just another repo.

Limitations vs Trilium

  • No native attribute/property system — tags are inline #tag text.
  • Search is grep-based, not Trilium’s structured query language.
  • brain_update archives the prior content as a child note ([archived YYYY-MM-DD] Title.md).

These limitations are intentional: keeping the adapter file-system-only avoids any dependency on Obsidian itself running.