client ¶

MCP client implementation: HTTP transports, auth retry, reconnection, logging.

What belongs here ¶

• Client struct and options (NewClient, WithSSEClient, WithTransport, etc.)
• HTTP transports: Streamable HTTP (streamableClientTransport), SSE (sseClientTransport)
• Auth retry (DoWithAuthRetry) — 401 token refresh, 403 scope step-up
• Reconnection (WithMaxRetries, WithReconnectBackoff)
• Transport logging (WithClientLogging)
• Server-to-client request handling (HandleServerRequest, WithSamplingHandler, WithElicitationHandler)
• Notification callback (WithNotificationCallback)

Dependencies ¶

• core/ — protocol types (Request, Response, ToolDef, etc.)
• Does NOT import server/

Usage ¶

import (
    "github.com/panyam/mcpkit/client"
    "github.com/panyam/mcpkit/core"
)

c := client.NewClient("http://localhost:8787/mcp",
    core.ClientInfo{Name: "my-client", Version: "1.0"},
    client.WithSamplingHandler(mySamplingHandler),
)
c.Connect()
result, _ := c.ToolCall("greet", map[string]any{"name": "world"})

Extension support ¶

c := client.NewClient(url, info,
    client.WithUIExtension(),  // advertise MCP Apps support
)
c.Connect()

if c.ServerSupportsUI() { /* server can serve app UIs */ }

modelTools, _ := c.ListToolsForModel() // excludes app-only tools

• WithExtension(id, cap) — general extension advertisement
• WithUIExtension() — convenience for MCP Apps
• ServerSupportsExtension(id) / ServerSupportsUI() — detect server support
• ListToolsForModel() — filters out tools with visibility ["app"] only

Transport interface ¶

The client accepts any core.Transport via WithTransport(). This enables:

• server.NewInProcessTransport for testing (no HTTP)
• Custom transports for stdio, WebSocket, etc.