Calliope MCP Server

Calliope MCP Server

Provides MCP tools to read, write, append, and edit prose sections of nodes, backed by an in-memory or substrate-direct (Urania) backend.

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README

@forge/calliope

Calliope — the node-body prose editor. "clotho for prose": a ProseMirror editor over the urania substrate, the Obsidian replacement.

One urania substrate, two peer facets:

  • Clotho — the work/graph facet (board-mcp replacement). Never touches bodies.
  • Calliope (this repo) — the body/prose facet. Talks to the substrate directly (urania capture via the Hades gate); not through clotho.
  • Tantalus — the render surface for Clotho's graph; imports Calliope's editor for body text.

Body model

A node's body is stored as substrate triples — no blocks, no arrangements:

note    --hasPart-->   section          # node edge
section : hasType "section"             # a placement id (not content-addressed)
section --text-->      "<prose>"        # literal; interned content-addressed
section --order_key--> "<key>"          # fractional key, sorted COLLATE "C"

Reading a body resolves the note's hasPart section targets, resolves each to { text, order_key }, and sorts by order_key. Edits are copy-on-write: changed prose mints a new version node that supersedes the old; hasPart is rewired.

Public API

type Section = { id: string; text: string; orderKey: string };
type SectionInput = { text: string }; // position = array order

interface BodyClient {
  readBody(nodeId: string): Promise<Section[]>;
  saveBody(nodeId: string, sections: SectionInput[]): Promise<void>;
}

function NodeBodyEditor(props: {
  nodeId: string;
  client: BodyClient;
  readOnly?: boolean;
  onSaved?: () => void;
}): JSX.Element;

class FixtureBodyClient implements BodyClient; // in-memory; ships now
class UraniaBodyClient implements BodyClient; // substrate-direct; live wire deferred

Clients

  • FixtureBodyClient — in-memory, fully working. Default for standalone dev and for Tantalus today.
  • UraniaBodyClient — substrate-direct (urania capture via Hades). The body-model mapping (copy-on-write hasPart/text/order_key) is real; the live transport is deferred, guarded behind CALLIOPE_URANIA_WIRED and an injected UraniaCapture, exactly like Tantalus's current clotho swap-seam.

MCP server

The prose facet is also an MCP server exposing four tools (read_body, write_body, append_section, edit_section) over the same backend selection (UraniaBodyClient live by default — URANIA_URL, internal-net http://urania:8202; CALLIOPE_MCP_BACKEND=fixture for a standalone server). Two transports, one shared tool set:

  • stdiocalliope-mcp bin (dist/mcp/main.js); for Tantalus + local use.
  • streamable-HTTPcalliope-mcp-http bin (dist/mcp/http.js, pnpm start:http); serves POST /mcp on $PORT (else $CALLIOPE_MCP_PORT, else 8204). This is the constellation star form: the Hades MCP gateway fronts it east-west at http://calliope-mcp:8204/mcp. Stateless — a fresh server+transport per request over a long-lived backend.

Deploy (nas01 star)

compose.yaml + Dockerfile + .forgejo/workflows/deploy.yml ship the HTTP star to nas01: container/hostname calliope-mcp on the external mnemosyne-net, internal-only (no host port), reaching urania at URANIA_URL=http://urania:8202. Push to main runs the gate (format/lint/typecheck/test/build) then builds, pushes to the Forgejo registry, and recreates the container. Joining the constellation is one line in the gateway's hades.toml [stars] table (calliope = "http://calliope-mcp:8204/mcp") + a Hades restart.

Develop

pnpm install
pnpm lint
pnpm typecheck
pnpm test
pnpm build

The package builds to dist/ (ESM + .d.ts). A consumer links it with file:../calliope.

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