fix: allow non-ASCII characters in SSH host aliases

pkg/remote/connutil.go

@@ -26,7 +26,7 @@ import (
 	"golang.org/x/crypto/ssh"
 )
 
-var userHostRe = regexp.MustCompile(`^([a-zA-Z0-9][a-zA-Z0-9._@\\-]*@)?([a-zA-Z0-9][a-zA-Z0-9.-]*)(?::([0-9]+))?$`)
+var userHostRe = regexp.MustCompile(`^([a-zA-Z0-9\p{L}\p{N}][a-zA-Z0-9._@\p{L}\p{N}\\-]*@)?([a-zA-Z0-9\p{L}\p{N}][a-zA-Z0-9.\p{L}\p{N}-]*)(?::([0-9]+))?$`)
 
 func ParseOpts(input string) (*SSHOpts, error) {
 	m := userHostRe.FindStringSubmatch(input)

pkg/remote/connutil_test.go

@@ -0,0 +1,52 @@
+// Copyright 2025, Command Line Inc.
+// SPDX-License-Identifier: Apache-2.0
+
+package remote
+
+import (
+	"testing"
+)
+
+func TestParseOpts(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		wantUser string
+		wantHost string
+		wantPort string
+		wantErr  bool
+	}{
+		{"user@host:port", "user@myserver:22", "user", "myserver", "22", false},
+		{"host only", "myserver", "", "myserver", "", false},
+		{"chinese host alias", "PROD-服务器", "", "PROD-服务器", "", false},
+		{"mixed ascii and chinese with user and port", "user@PROD-阿里云:22", "user", "PROD-阿里云", "22", false},
+		{"unicode only host", "服务器", "", "服务器", "", false},
+		{"japanese host", "サーバー", "", "サーバー", "", false},
+		{"empty string", "", "", "", "", true},
+		{"just colon", ":", "", "", "", true},
+		{"just at", "@", "", "", "", true},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			opts, err := ParseOpts(tt.input)
+			if tt.wantErr {
+				if err == nil {
+					t.Fatalf("expected error, got nil")
+				}
+				return
+			}
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+			if opts.SSHUser != tt.wantUser {
+				t.Errorf("user: got %q, want %q", opts.SSHUser, tt.wantUser)
+			}
+			if opts.SSHHost != tt.wantHost {
+				t.Errorf("host: got %q, want %q", opts.SSHHost, tt.wantHost)
+			}
+			if opts.SSHPort != tt.wantPort {
+				t.Errorf("port: got %q, want %q", opts.SSHPort, tt.wantPort)
+			}
+		})
+	}
+}