Your AI agent's memory, in an Obsidian vault
agentcairn stores your coding agent's memory as plain Markdown in an Obsidian vault you own — the source of truth, not a one-way export.
The wedge
The memory is readable and editable Markdown with frontmatter and
[[wikilinks]]. Open it in Obsidian, read what your agent
knows, and correct it directly. Hand-edit a fact and the agent honors it
on the next reindex — your edits are not overwritten.
Because the vault is the truth, you are never reverse-engineering a database to find out what your agent remembers. You just read the files.
The Obsidian plugin
The agentcairn-obsidian plugin surfaces your memory inside Obsidian: a filterable list of notes, with provenance (where each memory came from) and currency (how fresh it is). You see what the agent knows, where it learned it, and whether it is still current.
A memory graph wires related memories together — the
related: wikilinks cairn link writes — colored
by project, sized by importance, with superseded memories dimmed. Click a
node to open the note and read its provenance.
Stays in sync
A rebuildable DuckDB index reconciles to the vault and provides fast
hybrid retrieval (BM25 + vector + RRF, with an optional cross-encoder
reranker). The index is a disposable cache; the vault is always the
truth. cairn reindex rebuilds it from the Markdown with zero
data loss.
This works with any host. Plugin hosts like Claude Code and Codex get a
first-class plugin; every other MCP host is wired in with
cairn install <host> (or cairn install --all
for every detected agent). They all share one vault.
FAQ
How do I install the agentcairn Obsidian plugin?
In Obsidian, open Settings → Community plugins → Browse, search for "agentcairn", and install it (turn off Restricted mode first). It is read-only and reads only your vault's Markdown frontmatter.
Does the agentcairn plugin modify or write to my notes?
No. The plugin is read-only and local-only: it reads frontmatter via Obsidian's metadata cache, never your note bodies, never writes to the vault, and makes no network requests.
Can I use my Obsidian vault as memory for Claude Code, Codex, or Cursor?
Yes. agentcairn's CLI and MCP server store and recall memory from the same Markdown vault, and Claude Code and Codex install as plugins. The Obsidian plugin is the layer that lets you see and navigate that shared memory.
Why is the memory graph empty or just dots?
The graph is built from related: wikilinks between memory notes. Run `cairn link` in the vault to write those links from semantic neighbors, then reopen the Graph tab.
Is the agentcairn Obsidian plugin free and open source?
Yes. It is open source under the Apache-2.0 license, and free to install from the Obsidian community plugin store.
Get started
Install agentcairn into your agent in one command:
cairn install --all