basecoat-ui-mcp

<p align="center"> <img src="assets/logo.svg" alt="Basecoat UI MCP" width="64" height="64" /> </p> <h1 align="center">Basecoat UI MCP</h1> <p align="center"> <strong>Offline Model Context Protocol server for Basecoat UI (shadcn/ui look without React).</strong><br> Curated templates, macro layouts, rhythm tokens, and static validation for Astro, Next.js, HTML, and Tailwind CSS 4. </p> <p align="center"> <a href="https://www.npmjs.com/package/@intellmedia/basecoat-ui-mcp"><img src="https://img.shields.io/npm/v/@intellmedia/basecoat-ui-mcp?style=flat&color=3b82f6&logo=npm&label=npm" alt="npm version" /></a> <a href="https://www.npmjs.com/package/@intellmedia/basecoat-ui-mcp"><img src="https://img.shields.io/npm/dm/@intellmedia/basecoat-ui-mcp?style=flat&color=10b981" alt="npm downloads" /></a> <a href="LICENSE"><img src="https://img.shields.io/badge/license-MIT-amber?style=flat" alt="MIT License" /></a> <img src="https://img.shields.io/badge/node-%3E%3D22.14-emerald?style=flat&logo=node.js&logoColor=white" alt="Node.js version" /> <img src="https://img.shields.io/badge/TypeScript-5.9-3178c6?style=flat&logo=typescript&logoColor=white" alt="TypeScript" /> <img src="https://img.shields.io/badge/Network-0KB_Offline-09090b?style=flat&logo=shield&logoColor=emerald" alt="Offline Safe" /> </p>

The server exposes a deterministic, offline registry for AI coding agents instead of requiring clients to scrape documentation. It runs over local stdio with zero runtime network requests, bounded < 2 KB responses, and static AST validation. The host application remains responsible for rendering, data access, authentication, sessions, credentials, OAuth, captcha, and other runtime behavior.

Install

Requires Node.js 22.14.0 or newer.

Quick Start by Client

Cursor (.cursor/mcp.json)

{
  "mcpServers": {
    "basecoat-ui": {
      "command": "npx",
      "args": ["-y", "@intellmedia/basecoat-ui-mcp", "--project-root", "${workspaceFolder}"]
    }
  }
}

Claude Desktop (claude_desktop_config.json)

{
  "mcpServers": {
    "basecoat-ui": {
      "command": "npx",
      "args": ["-y", "@intellmedia/basecoat-ui-mcp", "--project-root", "/absolute/path/to/your/application"]
    }
  }
}

Claude Code (CLI)

claude mcp add basecoat-ui -- npx -y @intellmedia/basecoat-ui-mcp --project-root $(pwd)

Generic npx (no install)

{
  "mcpServers": {
    "basecoat-ui": {
      "command": "npx",
      "args": ["-y", "@intellmedia/basecoat-ui-mcp", "--project-root", "/absolute/path/to/your/application"]
    }
  }
}

npm

npm install --global @intellmedia/basecoat-ui-mcp

Add the server to an MCP client. Use an absolute path for the host application so design context and persistent sessions belong to the intended project:

{
  "mcpServers": {
    "basecoat-ui": {
      "command": "basecoat-ui-mcp",
      "args": ["--project-root", "/absolute/path/to/your/application"]
    }
  }
}

The compiled entry can also be invoked directly:

{
  "mcpServers": {
    "basecoat-ui": {
      "command": "node",
      "args": [
        "/absolute/path/to/node_modules/@intellmedia/basecoat-ui-mcp/dist/server/stdio.js",
        "--project-root",
        "/absolute/path/to/your/application"
      ]
    }
  }
}

Published packages include prebuilt dist/ and the immutable semantic snapshot under src/semantics/. Server startup reads that snapshot and does not write inside the installed package. The package contract test builds first, creates and extracts an actual npm tarball, marks the extracted package tree read-only, starts its dist/server/stdio.js under a network tripwire, completes MCP initialize and tool-list requests, and closes the connection. A source checkout does not include dist/.

From source

git clone https://github.com/zygiu-zygis/basecoat-ui-mcp.git
cd basecoat-ui-mcp
npm ci
npm run build
npm start -- --project-root /absolute/path/to/your/application

--project-root takes precedence over BASECOAT_PROJECT_ROOT, which takes precedence over the launch directory. The selected directory is the host project, not the MCP installation directory. The server exposes stdio only.

Project-root configuration

The configured root controls two things:

• DESIGN.md is read from that directory by basecoat://project/context.
• Persistent macro sessions are stored under <project-root>/.basecoat/designer/.
• .basecoat/rhythm.json is an optional strict override. It must live under a real .basecoat directory inside the project root, be a regular non-symlink file no larger than 65,536 UTF-8 bytes, and resolve inside that root; missing or rejected files leave the packaged profile unchanged. Matching mapping IDs replace in place and keep packaged order.

Only that exact directory is used. The server does not walk parent directories. Keep .basecoat/ in the host project and back it up if design sessions are part of your workflow. The MCP server never writes host application source files.

Basecoat MCP tools

The server exposes three component tools, six macro tools, and two semantic tools. Every macro and semantic result is a bounded MCP packet of at most 1,999 UTF-8 bytes. Larger result sets use cursors; responses are not sliced mid-JSON.

Component tools

• search_components returns up to 8 compact {id, name, intent} summaries and never returns markup. intent and query are optional; an empty search returns an empty list.
• get_component_details returns one Astro or HTML template with dependencies and composition guidance. Oversized entries fail closed. theme-toggle resolves to theme-switcher.
• validate_composition statically checks up to 256 KiB (262,144 UTF-8 bytes) of HTML or Astro source and returns at most 24 issues. Pass code or html, and optional semanticProfile or densityProfile (comfortable|compact). It does not render, execute, resolve application modules, or certify accessibility.

Macro tools

The macro layer is this project's curated, project-specific composition system for shells, auth flows, data workspaces, slots, ports, rules, and recipes. It is compiled into a pinned registry snapshot. These layout contracts are not supplied automatically by shadcn or by MCP.

1. search_macro_blocks - find compatible blueprint blocks by query, role, family, or tag.
2. get_macro_block - read a block section such as manifest, structure, slots, ports, rules, dependencies, or provenance.
3. begin_design - create a persistent design session and pin its profile and registry revision. Pinned registries are hash-verified on load.
4. get_design_context - read session lists or focused views such as overview, graph, rules, focus, and next.
5. apply_design_patch - apply atomic graph changes with expectedRevision and an idempotent operationId. A committed mutation always returns a success acknowledgement; oversized optional payload may be omitted with truncated: true.
6. validate_design - validate a draft or complete design graph and page its diagnostics.

Design sessions persist under <project-root>/.basecoat/designer/. Registry revisions are content-addressed; a session keeps using its pinned revision even after the package snapshot changes. Design snapshots use the form d:<designId>@<revision>.

Curated block blueprints:

• Shells & Navigation: app-shell, sidebar-dashboard-shell, sidebar-inset-shell, sidebar-collapsible-icon, sidebar-mobile-flyout, page-header.
• Authentication: auth-sign-in, auth-sign-up, auth-split-screen.
• Application & Workspace: dashboard-workspace, dashboard-main, dashboard-activity, settings-workspace, data-table-detail-layout, detail-drawer-panel.
• Forms & Data: form-section, data-filters, data-records, data-pagination.
• Marketing, Content & Utility: pricing-tiers, newsletter-waitlist, empty-state, error-boundary, svg-area-chart, segmented-toggle.

Multi-block recipes:

• workspace-dashboard - full analytics dashboard (KPI cards, activity chart, records table).
• workspace-settings - application shell with navigation, header, and settings workspace tabs.
• workspace-detail - data table workspace with slide-over detail inspection drawer.
• auth-flow - bidirectional authentication flow between sign-in and sign-up cards.
• auth-split-flow - split-screen auth frame pairing sign-in and sign-up with hero media.
• marketing-pricing - 3-tier pricing table paired with newsletter/waitlist banner.

Semantic tools

The semantic layer provides compiled rhythm profiles and finite state machine recipes:

7. get_rhythm_rules - access approved spacing, typography, surfaces, borders, and layout patterns by profile and family filters.
8. get_fsm_recipe - read interaction states, events, transitions, guards, and actions for dialog, navigation (collapsible-navigation), auth-flow, and tabs.

Semantic tools use the same bounded pagination as macro tools. Each rhythm record keeps the semantic token ID separate from its approved Tailwind utility. Put the utility in class; keep the semantic ID in design metadata and agent reasoning. Project overrides from <project-root>/.basecoat/rhythm.json are reflected in an effective content ref and revision. FSM recipes are structural metadata, not runtime implementations.

End-to-end example

A dashboard page can follow this sequence:

get_design_context(view="sessions")
begin_design(designId="admin", profile="app-default", operationId="begin-admin")
get_rhythm_rules(profile="default", family="density")
search_macro_blocks(q="shell", limit=8)
apply_design_patch(
  designId="admin",
  expectedRevision=0,
  operationId="add-dashboard",
  operations=[{ op: "instantiate_recipe",
               recipe: "workspace-dashboard",
               pagePrefix: "admin" }]
)
get_design_context(view="overview", designId="admin")
get_macro_block(idOrRef="app-shell", section="structure", designId="admin")
get_fsm_recipe(recipe="dialog", section="transitions")

Implement the selected component leaves in the host project, then record completed regions with apply_design_patch(record_written). Finish with validate_design(mode="complete") and validate_composition on the generated Astro or HTML source. After a conflict or restart, reread the session and use the returned revision and cursors.

Copy templates/cursor/basecoat-designer.mdc into a host project's .cursor/rules for agent guidance. The MCP server does not write consumer application source files.

Auditing or restyling an existing UI

No design session is needed. Read basecoat://design/theming and basecoat://design/rhythm, call get_component_details for each control you change, then run validate_composition on the rendered layout source including <head> scripts and <style>. Theme rules:

• theme-strategy-mixed - @media (prefers-color-scheme: dark) combined with the .dark class strategy (dark tokens leak into light mode).
• theme-storage-key - a theme script persists under a key other than Basecoat's themeMode, creating a second resolver that drifts from window.basecoat.theme.

Check light and dark screenshots with an OS dark preference and empty localStorage before deploying.

Source adaptation and offline import

The macro importer is intentionally local-first. It accepts a checked-out or otherwise locally saved shadcn-style registry-item.json, a reviewed mapping, and a local dependency lock:

npm run import:blocks -- \
  --item=/path/to/registry-item.json \
  --mapping=/path/to/mapping.json \
  --lock=/path/to/dependency-lock.json \
  --dry-run

This command does not fetch live shadcn registry items, install packages, execute upstream code, or make runtime network requests. Unknown, unlocked, or explicitly unsupported depe