@fictjs/mcp

Fict MCP server for docs retrieval, compiler diagnostics, and Playground link generation.

Features

• list-sections: list all documentation section ids.

• search-sections: keyword search for relevant section ids.

• get-documentation: fetch docs content by section id (md or normalized llms format).

  • supports maxCharsPerDocument for bounded per-section output.

• fict-autofixer: run aggregated diagnostics on a virtual file map:

  • Compiler diagnostics (source: "compiler")

  • ESLint diagnostics via @fictjs/eslint-plugin (source: "eslint")

  • TypeScript diagnostics (syntax-focused) (source: "typescript")

• list-playground-templates: discover available template ids before generating links.

• playground-link: generate shareable Fict Playground URLs from template + file overrides.

• fict-task prompt: docs-first + autofixer-before-output workflow template.

• fict://doc/<section-id> resources for each local docs section.

Docs section metadata

list-sections / search-sections can expose per-section metadata from markdown frontmatter:

---
title: Custom Guide Title
tags: [mcp, docs]
use_cases:
  - Explain migration constraints
  - Provide implementation checklist
---

If frontmatter metadata is missing, built-in defaults are still applied for core Fict docs. When available, MCP can load sections from a generated manifest (assets/docs-manifest.json) to avoid full docs scanning at startup.

Build

pnpm build

Test

pnpm test

Run (stdio transport)

pnpm build
pnpm start
# stdio mode also accepts docs/playground overrides:
pnpm start -- --stdio --docs-root ../docs --docs-manifest ./assets/docs-manifest.json --playground-origin http://localhost:4173

Run (Streamable HTTP transport)

pnpm build
pnpm start -- --http --host 127.0.0.1 --port 8788 --path /mcp --health-path /healthz --stats-path /stats --auth-token your-token --enable-cors --cors-origin https://your-client.example --max-sessions 100 --session-ttl-ms 1800000 --docs-root ../docs --docs-manifest ./assets/docs-manifest.json --playground-origin http://localhost:4173

Run (Legacy HTTP+SSE transport, deprecated)

pnpm build
FICT_MCP_ENABLE_SSE=1 pnpm start -- --sse --host 127.0.0.1 --port 8790 --sse-path /sse --messages-path /messages --health-path /healthz --stats-path /stats --max-sessions 100 --session-ttl-ms 1800000

You can also switch transports via env:

FICT_MCP_TRANSPORT=http pnpm start

Environment variables:

• FICT_MCP_DOCS_ROOT: absolute or relative path to a Fict docs checkout. When omitted, the server walks upward from the current working directory looking for docs/.

• FICT_MCP_DOCS_MANIFEST: optional docs manifest path override (if provided but missing/invalid, startup fails fast).

• FICT_PLAYGROUND_ORIGIN: playground base URL (default: http://localhost:4173).

• FICT_MCP_TRANSPORT: stdio, http, or sse (default: stdio, and sse requires FICT_MCP_ENABLE_SSE=1).

• FICT_MCP_ENABLE_SSE: set to 1 to enable deprecated HTTP+SSE transport.

• FICT_MCP_HTTP_HOST: HTTP bind host (default: 127.0.0.1).

• FICT_MCP_HTTP_PORT: HTTP bind port (default: 8788).

• FICT_MCP_HTTP_PATH: HTTP endpoint path (default: /mcp).

• FICT_MCP_AUTH_TOKEN: optional bearer token; when set, all HTTP/SSE requests must include Authorization: Bearer <token>.

• FICT_MCP_HTTP_ENABLE_CORS: set to 1/true to emit CORS headers (default: disabled).

• FICT_MCP_HTTP_CORS_ORIGIN: optional Access-Control-Allow-Origin value when CORS is enabled (default: *).

• FICT_MCP_SSE_PATH: SSE stream endpoint path (default: /sse).

• FICT_MCP_SSE_MESSAGES_PATH: SSE client message POST path (default: /messages).

• FICT_MCP_HTTP_HEALTH_PATH: health endpoint path (default: /healthz).

• FICT_MCP_HTTP_STATS_PATH: stats endpoint path (default: /stats).

• FICT_MCP_HTTP_MAX_SESSIONS: max active HTTP sessions before LRU eviction (default: 100).

• FICT_MCP_HTTP_SESSION_TTL_MS: idle session TTL in milliseconds (default: 1800000).

In HTTP mode, invalid docsRoot config fails fast at startup instead of deferring the error to the first MCP request. When docsManifestPath / FICT_MCP_DOCS_MANIFEST is explicitly provided, missing/invalid manifests also fail fast at startup. If docsRoot is auto-discovered and no override is provided, server startup uses bundled assets/docs-manifest.json when present. For HTTP/SSE transports bound to non-loopback hosts (for example 0.0.0.0), --auth-token / FICT_MCP_AUTH_TOKEN is required.

HTTP observability endpoints

When running with --http, MCP also serves:

• GET /healthz (configurable via --health-path / FICT_MCP_HTTP_HEALTH_PATH)

• GET /stats (configurable via --stats-path / FICT_MCP_HTTP_STATS_PATH)

/stats includes request counters, status counters, error count, active session count, and session lifecycle totals (created/reused/expired/evicted/deleted). --path, --health-path, and --stats-path must be distinct values. For --sse, --sse-path, --messages-path, --health-path, and --stats-path must also be distinct.

fict-autofixer options

fict-autofixer input supports:

• entry: optional entry path; if provided it must exist in files

• profile: app-default | ci-hard-gate | migration

• includeEslint (default: true)

• includeTypescript (default: true)

fict-autofixer issue output includes:

• source: compiler | eslint | typescript

• code: diagnostic/rule code

• suggestion: actionable fix hint

Example MCP client config

{
  "mcpServers": {
    "fict": {
      "command": "fict-mcp",
      "args": ["--stdio"],
      "env": {
        "FICT_MCP_DOCS_ROOT": "/absolute/path/to/fict/docs",
        "FICT_PLAYGROUND_ORIGIN": "http://localhost:4173"
      }
    }
  }
}