Implement MCP API endpoint for prompt exposure to AI clients

[Copilot]

The /api/mcp endpoint referenced in MCPServerDialog was not implemented, breaking Claude Desktop integration and other MCP clients.

Changes

MCP endpoint implementation (api/vite-mcp-plugin.ts)

• Vite middleware serving JSON-RPC 2.0 at /api/mcp
• Methods: initialize, prompts/list, prompts/get
• Dev mode serves 3 demo prompts; production fetches from Spark KV
• CORS headers and proper error handling

Prompt conversion utilities (api/mcp.ts)

• Extracts {{placeholders}} from prompt content as MCP arguments
• Substitutes argument values in prompt content
• Converts Prompt objects to MCP-compliant format

Configuration (vite.config.ts)

• Added MCP plugin to middleware chain

Documentation

• MCP_TESTING.md: curl examples and expected responses
• MCP_SETUP.md: API reference, Claude Desktop setup
• README.md: integration quick start

Usage

# List exposed prompts
curl -X POST http://localhost:5000/api/mcp \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"prompts/list"}'

# Get prompt with placeholder substitution
curl -X POST http://localhost:5000/api/mcp \
  -d '{"jsonrpc":"2.0","id":2,"method":"prompts/get",
       "params":{"name":"prompt-demo-1",
                 "arguments":{"language":"Python","code":"print(123)"}}}'

Claude Desktop config:

{
  "mcpServers": {
    "promptarq-prompts": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-fetch", 
               "http://localhost:5000/api/mcp"]
    }
  }
}

Screenshot

The dialog now displays a working endpoint that successfully responds to MCP clients.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• https://api.github.com/runtime/2bab7d016aa6208e5f2d/kv/categories
  • Triggering command: node /home/REDACTED/work/promptArq/promptArq/node_modules/.bin/vite (http block)
• https://api.github.com/runtime/2bab7d016aa6208e5f2d/kv/model-configs
  • Triggering command: node /home/REDACTED/work/promptArq/promptArq/node_modules/.bin/vite (http block)
• https://api.github.com/runtime/2bab7d016aa6208e5f2d/kv/projects
  • Triggering command: node /home/REDACTED/work/promptArq/promptArq/node_modules/.bin/vite (http block)
• https://api.github.com/runtime/2bab7d016aa6208e5f2d/kv/prompt-comments
  • Triggering command: node /home/REDACTED/work/promptArq/promptArq/node_modules/.bin/vite (http block)
• https://api.github.com/runtime/2bab7d016aa6208e5f2d/kv/prompt-versions
  • Triggering command: node /home/REDACTED/work/promptArq/promptArq/node_modules/.bin/vite (http block)
• https://api.github.com/runtime/2bab7d016aa6208e5f2d/kv/prompts
  • Triggering command: node /home/REDACTED/work/promptArq/promptArq/node_modules/.bin/vite (http block)
• https://api.github.com/runtime/2bab7d016aa6208e5f2d/kv/selected-team-id
  • Triggering command: node /home/REDACTED/work/promptArq/promptArq/node_modules/.bin/vite (http block)
• https://api.github.com/runtime/2bab7d016aa6208e5f2d/kv/shared-prompts
  • Triggering command: node /home/REDACTED/work/promptArq/promptArq/node_modules/.bin/vite (http block)
• https://api.github.com/runtime/2bab7d016aa6208e5f2d/kv/sidebar-collapsed
  • Triggering command: node /home/REDACTED/work/promptArq/promptArq/node_modules/.bin/vite (http block)
• https://api.github.com/runtime/2bab7d016aa6208e5f2d/kv/system-prompts
  • Triggering command: node /home/REDACTED/work/promptArq/promptArq/node_modules/.bin/vite (http block)
• https://api.github.com/runtime/2bab7d016aa6208e5f2d/kv/tags
  • Triggering command: node /home/REDACTED/work/promptArq/promptArq/node_modules/.bin/vite (http block)
• https://api.github.com/runtime/2bab7d016aa6208e5f2d/kv/team-members
  • Triggering command: node /home/REDACTED/work/promptArq/promptArq/node_modules/.bin/vite (http block)
• https://api.github.com/runtime/2bab7d016aa6208e5f2d/kv/teams
  • Triggering command: node /home/REDACTED/work/promptArq/promptArq/node_modules/.bin/vite (http block)
• https://api.github.com/runtime/2bab7d016aa6208e5f2d/kv/users
  • Triggering command: node /home/REDACTED/work/promptArq/promptArq/node_modules/.bin/vite (http block)
• https://api.github.com/runtime/2bab7d016aa6208e5f2d/loaded
  • Triggering command: node /home/REDACTED/work/promptArq/promptArq/node_modules/.bin/vite (http block)
• https://api.github.com/runtime/2bab7d016aa6208e5f2d/user
  • Triggering command: node /home/REDACTED/work/promptArq/promptArq/node_modules/.bin/vite (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

the mcp api doesnt seem to work, fix that, test yourself that prompts are made available throgh mcp and can be used, then update explanations as well

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