feat(mcp): per server deferred mode (#1654)

* feat(mcp): per server deferred mode

* fix deferred behavior

pkg/agent/loop_mcp_test.go

@@ -0,0 +1,75 @@
+// PicoClaw - Ultra-lightweight personal AI agent
+// Inspired by and based on nanobot: https://github.com/HKUDS/nanobot
+// License: MIT
+//
+// Copyright (c) 2026 PicoClaw contributors
+
+package agent
+
+import (
+	"testing"
+
+	"github.com/sipeed/picoclaw/pkg/config"
+)
+
+func boolPtr(b bool) *bool { return &b }
+
+func TestServerIsDeferred(t *testing.T) {
+	tests := []struct {
+		name             string
+		discoveryEnabled bool
+		serverDeferred   *bool
+		want             bool
+	}{
+		// --- global false always wins: per-server deferred is ignored ---
+		{
+			name:             "global false: per-server deferred=true is ignored",
+			discoveryEnabled: false,
+			serverDeferred:   boolPtr(true),
+			want:             false,
+		},
+		{
+			name:             "global false: per-server deferred=false stays false",
+			discoveryEnabled: false,
+			serverDeferred:   boolPtr(false),
+			want:             false,
+		},
+		// --- global true: per-server override applies ---
+		{
+			name:             "global true: per-server deferred=false opts out",
+			discoveryEnabled: true,
+			serverDeferred:   boolPtr(false),
+			want:             false,
+		},
+		{
+			name:             "global true: per-server deferred=true stays true",
+			discoveryEnabled: true,
+			serverDeferred:   boolPtr(true),
+			want:             true,
+		},
+		// --- no per-server override: fall back to global ---
+		{
+			name:             "no per-server field, global discovery enabled",
+			discoveryEnabled: true,
+			serverDeferred:   nil,
+			want:             true,
+		},
+		{
+			name:             "no per-server field, global discovery disabled",
+			discoveryEnabled: false,
+			serverDeferred:   nil,
+			want:             false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			serverCfg := config.MCPServerConfig{Deferred: tt.serverDeferred}
+			got := serverIsDeferred(tt.discoveryEnabled, serverCfg)
+			if got != tt.want {
+				t.Errorf("serverIsDeferred(discoveryEnabled=%v, deferred=%v) = %v, want %v",
+					tt.discoveryEnabled, tt.serverDeferred, got, tt.want)
+			}
+		})
+	}
+}