MCP server never loads in Cursor

[bnjns]

Summary

In v0.40.0, the marketplace listing for this plugin shows "MCPs: 1 (Vercel)", but the MCP server never registers in Cursor. Root cause appears to be that the Cursor-specific manifest (.cursor-plugin/plugin.json) only declares:

"skills": "skills",
"agents": "agents",
"commands": "commands"

with no MCP entry. When Cursor materializes the plugin cache (~/.cursor/plugins/cache/cursor-public/vercel/<sha>/), it prunes files not declared in that manifest — including .mcp.json. The cache is a git checkout, and git status inside it shows .mcp.json (and .cursor-plugin/plugin.json, tests/, generated/) as working-tree deletions:

 D .cursor-plugin/plugin.json
 D .mcp.json
 D generated/build-from-skills.manifest.json
 ...

git show HEAD:.mcp.json confirms the repo ships a valid server definition (https://mcp.vercel.com, type http).

Result

• Plugin page in Cursor advertises 1 MCP server (metadata built from the full repo).
• No vercel MCP server ever appears in agent sessions or tool lists (loader reads the pruned on-disk cache).
• Compare: the Linear plugin's cache keeps its mcp.json and its server registers fine.

Expected

The MCP server advertised on the plugin page actually works after install: .mcp.json survives the cache step, the server registers in Cursor, and you get the Vercel OAuth prompt on first use.

Environment

• vercel-plugin 0.40.0 (cache sha 3d9d9cd)
• Cursor 3.12.10, macOS arm64 (darwin 25.5.0)