feat(mcp): add supabase mcp init command to configure MCP clients

[Rodriguespn]

⚠️ This PR was vibe coded, proceed with caution

What

Implements supabase mcp init command to help users configure Model Context Protocol (MCP) clients to work with Supabase's remote MCP server.

Why

Closes https://linear.app/supabase/issue/AI-81

Users need an easy way to set up MCP integration with their preferred AI coding assistants without manually editing JSON configuration files.

How

Features

• Interactive client detection: Automatically detects installed MCP clients on the system
• 3 supported clients: Claude Code, Cursor, and VS Code (with architecture for easy addition of more)
• --client flag: Target specific client for configuration
• Remote server setup: Configures production server at https://mcp.supabase.com/mcp
• Auto-configuration:
  • Claude Code: Uses claude mcp add CLI command
  • Cursor: Creates/updates .cursor/mcp.json with server URL
  • VS Code: Creates/updates .vscode/mcp.json with server config (type: http)
• Installation validation: Checks for actual binary/app presence before attempting configuration
• Project-local & global configs: Supports both workspace and user-level configurations
• Config merging: Intelligently merges with existing MCP configurations

Architecture

Built with scalability in mind:

• Client interface: Defines contract for all MCP clients
• Base client: Provides common functionality via composition
• Separate files: Each client implementation in its own file
• Easy extensibility: Add new clients by creating a file and registering in clientRegistry

File structure:

internal/mcp/init/
├── client.go       # Interface and base client
├── claude_code.go  # Claude Code implementation
├── cursor.go       # Cursor implementation  
├── vscode.go       # VS Code implementation
├── utils.go        # Helper functions
├── init.go         # Core logic and registry
└── README.md       # Developer documentation

Client-Specific Configurations

Claude Code

claude mcp add --transport http supabase https://mcp.supabase.com/mcp

Cursor (.cursor/mcp.json)

{
  "mcpServers": {
    "supabase": {
      "url": "https://mcp.supabase.com/mcp"
    }
  }
}

VS Code (.vscode/mcp.json)

{
  "mcpServers": {
    "supabase": {
      "type": "http",
      "url": "https://mcp.supabase.com/mcp"
    }
  }
}

Usage Examples

# Interactive mode - detects installed clients and configures automatically
supabase mcp init

# Target specific client
supabase mcp init --client claude-code
supabase mcp init --client cursor
supabase mcp init --client vscode

# See all supported clients
supabase mcp init --help

User Experience Flow

1. No clients installed: Shows list of available clients with installation instructions
2. One client installed: Automatically configures that client
3. Multiple clients installed: Shows menu and prompts user to choose via --client flag
4. Specific client requested: Configures that client or shows installation instructions

Testing

• ✅ Command compiles and installs successfully
• ✅ Interactive mode detects installed clients correctly
• ✅ Installation detection works (no false positives)
• ✅ Config files generated with valid JSON structure
• ✅ Existing configs are preserved and merged correctly
• ✅ Works across all three clients (Claude Code, Cursor, VS Code)

Related

• Linear issue: https://linear.app/supabase/issue/AI-81
• Remote server: https://mcp.supabase.com/mcp

Notes

• Command is in groupQuickStart (no authentication required)
• Uses afero filesystem abstraction for testability
• Scalable architecture makes adding new clients straightforward
• Developer documentation included for adding new clients

[coveralls]

Pull Request Test Coverage Report for Build 19043045070

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 297 (0.0%) changed or added relevant lines in 8 files are covered.
• 26 unchanged lines in 4 files lost coverage.
• Overall coverage decreased (-1.4%) to 53.318%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
cmd/mcp.go	0	3	0.0%
cmd/mcp_init.go	0	8	0.0%
internal/mcp/init/utils.go	0	11	0.0%
internal/mcp/init/client.go	0	18	0.0%
internal/mcp/init/claude_code.go	0	28	0.0%
internal/mcp/init/init.go	0	59	0.0%
internal/mcp/init/cursor.go	0	84	0.0%
internal/mcp/init/vscode.go	0	86	0.0%

Files with Coverage Reduction	New Missed Lines	%
internal/utils/profile.go	2	81.82%
internal/gen/keys/keys.go	5	12.9%
internal/utils/flags/config_path.go	7	56.25%
internal/link/link.go	12	76.26%

Totals
Change from base Build 18900105989:	-1.4%
Covered Lines:	6388
Relevant Lines:	11981

---

💛 - Coveralls