Agents, editors and CI

folio check - prints the folder's health, one problem a line, and exits 1 when one of them is an error, so it can gate a commit or a CI run. It asks the Folio serving the folder when one is running, and otherwise works the health out itself.

$ folio check
report.md:3          -      figure   9.4 is contradicted: the data says 8.9 (#totals#0.temp_c)
notes/uplink.md:3    -      link     Links to notes/antenna.md, which is not there
notes/uplink.md:5    -      include  Includes parts/frequencies.md, which is not there
stations/west.md:5   -      field    calibrated: before the storms is not a date
stations/south.md:1  error  rule     An active station has no owner
folio check: 1 error, 4 other problems

Agents - folio mcp is an MCP server whose tools read the Folio serving the agent's folder: documents and their blocks, queries, health, what changed, history, what you have read and what you are looking at. An agent's MCP client starts it as a command:

{ "mcpServers": { "folio": { "command": "folio", "args": ["mcp"] } } }

folio mcp localhost:8641 or folio mcp /run/folio.sock names the Folio to read instead. In Claude Code, the folio plugin installs the server and the agent skill below, and runs the Folio release it pins through npx, so Node.js is all it needs:

claude plugin marketplace add jakubro/folio
claude plugin install folio@folio

The plugin's Folio setting, in /config, names a Folio by its address or socket; left empty, the tools read the Folio serving the folder Claude Code is opened in.

The same answers are JSON over HTTP at ?api=, as in curl 'http://localhost:8640/?api=health', and --socket also serves them on a unix socket, for an agent in a container that shares the folder. The button on the front page pauses sharing what you read and look at.

An agent that writes for Folio - plugin/skills/folio in Folio's repository is an agent skill. It teaches an agent to write documents that use everything the guide covers - includes, block links, embedded data, queries, checked figures, saved views and FOLIO.md declarations - and to check its work with folio check. The folio plugin brings it to Claude Code as /folio:folio; for another agent, copy the folder into its skills folder.

Editors - folio lsp FOLDER is a language server for any editor with an LSP client: broken links, missing includes and contradicted figures as you type, go to and references for headings and blocks, a block's provenance on hover, and, on renaming a heading or moving a file, the edits for every link to it.