The second brain your AI agents can actually use.

Tacitus is a plain-Markdown vault that speaks MCP. Your notes stay files on your disk — while Claude Code or any MCP agent searches them under a token budget, remembers what it learned with provenance, and writes with a diff and an undo.

# one native binary — no runtime, no cloud, works offline
curl -LsSf https://github.com/ionasrobert/tacitus-mcp-server/releases/latest/download/tacitus-mcp-installer.sh | sh

windows: same URL, tacitus-mcp-installer.ps1 · via npm: npx -y @dashiro/tacitus-mcp-server ./vault

Connect an agent

Point the server at any folder of Markdown. Claude Code:

claude mcp add tacitus -- tacitus-mcp ~/vault

Any other MCP client:

{ "mcpServers": { "tacitus": { "command": "tacitus-mcp", "args": ["~/vault"] } } }

What agents get

- [x]Search under a token budget. Hybrid lexical + semantic, ranked snippets with scores and token counts — never whole notes.
- [x]Memory with provenance. Every remembered fact carries its source, author, and timestamp. Conflicting memories are flagged, not silently resolved.
- [x]Transactional writes. Propose → diff → commit → revert. Idempotent retries, every change versioned and audited.
- [x]The graph as an API. Links, backlinks, neighbors — plus link suggestions scored by mentions, similarity, and shared tags.
- [x]Structured everything. 25 typed tools; errors return {code, reason, suggestion} so agents can recover instead of guessing.
- [x]Templates, tasks, property queries. Frontmatter as a typed, queryable database; checklists as real entities.
- [ ]CRDT sync. Next up — watch the repo.

The vault stays yours

No database owns your notes. Everything Tacitus adds lives in one sidecar folder:

vault/
├── ideas.md
├── projects/
│   └── launch.md
└── .tacitus/     ← everything Tacitus adds
    ├── memory/   agent memories — markdown + yaml, like everything else
    ├── history/  every write, revertible
    └── audit.log who changed what, and when

Delete .tacitus/ and your vault is untouched. Point any other tool at the same folder. Exit cost: zero.

And a desktop for humans

Agents are first-class here — but you still get an app: a Markdown editor with wikilinks and backlinks, a 2D graph, table views over frontmatter, live task lists, and a chat companion that answers from your notes through local Ollama, citing the [[notes]] it used. In development, built in the open.