Tool system: Dynamic MCP server discovery from ~/.config/mcp/ and project config

[Delqhi]

Problem

mcpclient.DefaultServers() is hard-coded. Users cannot add MCP servers without editing code. SOTA agents scan ~/.config/mcp/ or claude_desktop_config.json for servers.

What to do

1. mcpclient.DiscoverConfigs() scans:
   • ~/.config/mcp/servers/*.json
   • ~/.config/claude/claude_desktop_config.json
   • ./.sin-code/mcp.json
   • ~/.opencode/opencode.json (mcpServers)
   • ~/.codex/config.json (mcpServers)
2. Normalize each config to ServerConfig
3. Add discovered servers to DefaultServers()
4. sin-code mcp discover — list discovered servers
5. sin-code mcp add <name> --command "..." --env KEY=VALUE — add to ~/.config/mcp/servers/<name>.json
6. Deduplicate by name

Acceptance criteria

• Scan standard MCP config locations
• Add discovered servers at startup
• sin-code mcp discover works
• sin-code mcp add works
• Deduplication works