From 2506828d3ec9a574fa350328f4f5e50f423c1af5 Mon Sep 17 00:00:00 2001
From: FanOne <294350394@qq.com>
Date: Sat, 27 Dec 2025 17:47:46 +0800
Subject: [PATCH 1/2] feat:remove logger & add Logger in ClientOption

---
 mcp/client.go      | 15 ++++++++++++---
 mcp/client_test.go | 18 ++++++++++++++++++
 2 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/mcp/client.go b/mcp/client.go
index 2dc1a86c..21ab7395 100644
--- a/mcp/client.go
+++ b/mcp/client.go
@@ -18,6 +18,7 @@ import (
 	"time"
 
 	"github.com/google/jsonschema-go/jsonschema"
+
 	"github.com/modelcontextprotocol/go-sdk/internal/jsonrpc2"
 	"github.com/modelcontextprotocol/go-sdk/jsonrpc"
 )
@@ -25,8 +26,9 @@ import (
 // A Client is an MCP client, which may be connected to an MCP server
 // using the [Client.Connect] method.
 type Client struct {
-	impl                    *Implementation
-	opts                    ClientOptions
+	impl *Implementation
+	opts ClientOptions
+	// Deprecated
 	logger                  *slog.Logger // TODO: file proposal to export this
 	mu                      sync.Mutex
 	roots                   *featureSet[*Root]
@@ -56,11 +58,18 @@ func NewClient(impl *Implementation, opts *ClientOptions) *Client {
 	if opts != nil {
 		c.opts = *opts
 	}
+
+	if opts == nil || opts.Logger == nil {
+		c.opts.Logger = ensureLogger(nil)
+	}
+
 	return c
 }
 
 // ClientOptions configures the behavior of the client.
 type ClientOptions struct {
+	// If non-nil, log client activity.
+	Logger *slog.Logger
 	// CreateMessageHandler handles incoming requests for sampling/createMessage.
 	//
 	// Setting CreateMessageHandler to a non-nil value automatically causes the
@@ -407,7 +416,7 @@ func changeAndNotify[P Params](c *Client, notification string, params P, change
 		}
 	}
 	c.mu.Unlock()
-	notifySessions(sessions, notification, params, c.logger)
+	notifySessions(sessions, notification, params, c.opts.Logger)
 }
 
 // shouldSendListChangedNotification checks if the client's capabilities allow
diff --git a/mcp/client_test.go b/mcp/client_test.go
index ad8c0f12..2f7abc0c 100644
--- a/mcp/client_test.go
+++ b/mcp/client_test.go
@@ -7,6 +7,7 @@ package mcp
 import (
 	"context"
 	"fmt"
+	"log/slog"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
@@ -165,6 +166,23 @@ func TestClientPaginateBasic(t *testing.T) {
 	}
 }
 
+func TestClientLogger(t *testing.T) {
+	// Case 1: No logger provided
+	c1 := NewClient(&Implementation{Name: "test", Version: "1.0"}, nil)
+	if c1.opts.Logger == nil {
+		t.Error("expected default logger, got nil")
+	}
+
+	// Case 2: Logger provided
+	logger := slog.Default()
+	c2 := NewClient(&Implementation{Name: "test", Version: "1.0"}, &ClientOptions{
+		Logger: logger,
+	})
+	if c2.opts.Logger != logger {
+		t.Error("expected provided logger, got different one")
+	}
+}
+
 func TestClientPaginateVariousPageSizes(t *testing.T) {
 	ctx := context.Background()
 	for i := 1; i < len(allItems)+1; i++ {

From 44b51eb135071b2248162dd1e0e040702ed055e3 Mon Sep 17 00:00:00 2001
From: FanOne <294350394@qq.com>
Date: Sat, 27 Dec 2025 17:57:07 +0800
Subject: [PATCH 2/2] feat: add Logger option

---
 mcp/client.go | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/mcp/client.go b/mcp/client.go
index 21ab7395..211ca72c 100644
--- a/mcp/client.go
+++ b/mcp/client.go
@@ -44,26 +44,28 @@ type Client struct {
 // The first argument must not be nil.
 //
 // If non-nil, the provided options configure the Client.
-func NewClient(impl *Implementation, opts *ClientOptions) *Client {
+func NewClient(impl *Implementation, options *ClientOptions) *Client {
 	if impl == nil {
 		panic("nil Implementation")
 	}
-	c := &Client{
+	var opts ClientOptions
+	if options != nil {
+		opts = *options
+	}
+	options = nil // prevent reuse
+
+	if opts.Logger == nil { // ensure we have a logger
+		opts.Logger = ensureLogger(nil)
+	}
+
+	return &Client{
 		impl:                    impl,
+		opts:                    opts,
 		logger:                  ensureLogger(nil), // ensure we have a logger
 		roots:                   newFeatureSet(func(r *Root) string { return r.URI }),
 		sendingMethodHandler_:   defaultSendingMethodHandler,
 		receivingMethodHandler_: defaultReceivingMethodHandler[*ClientSession],
 	}
-	if opts != nil {
-		c.opts = *opts
-	}
-
-	if opts == nil || opts.Logger == nil {
-		c.opts.Logger = ensureLogger(nil)
-	}
-
-	return c
 }
 
 // ClientOptions configures the behavior of the client.