fix(config): align Kael registration naming with Koko

config_example.yml

@@ -3,7 +3,8 @@
 CODEX_BINARY: codex
 # CHAT_AI_BASE_URL in Core must support Responses API. Chat Completions is not supported.
 # 与 Koko 一致，Kael 只使用平铺配置。
-# 默认名称为 [Kael]-主机名-7位随机串；手动指定时需保证名称唯一。
+# 默认名称为 [Kael]-主机名-7位随机大小写字母；设置 SERVER_HOSTNAME 环境变量时会拼在主机名前。
+# 超过 128 个字符时保留前 64 和后 64 个字符；手动指定 NAME 时需保证名称唯一。
 # NAME: "[Kael]-custom-name"
 
 CORE_HOST: http://127.0.0.1:8080

internal/config/config.go

@@ -3,6 +3,7 @@ package config
 import (
 	"crypto/rand"
 	"fmt"
+	"math/big"
 	"net/url"
 	"os"
 	"path/filepath"
@@ -141,16 +142,22 @@ func setDefaults(v *viper.Viper) {
 }
 
 func defaultName() string {
-	hostname, err := os.Hostname()
-	if err != nil || strings.TrimSpace(hostname) == "" {
-		hostname = "localhost"
+	const letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	suffix := make([]byte, 7)
+	for i := range suffix {
+		index, _ := rand.Int(rand.Reader, big.NewInt(int64(len(letters))))
+		suffix[i] = letters[index.Int64()]
+	}
+	hostname, _ := os.Hostname()
+	hostname = fmt.Sprintf("%s-%s", hostname, suffix)
+	if serverHostname, ok := os.LookupEnv("SERVER_HOSTNAME"); ok {
+		hostname = fmt.Sprintf("%s-%s", serverHostname, hostname)
 	}
 	value := []rune("[Kael]-" + hostname)
-	suffix := "-" + rand.Text()[:7]
-	if len(value) > 128-len(suffix) {
-		value = value[:128-len(suffix)]
+	if len(value) > 128 {
+		value = append(value[:64], value[len(value)-64:]...)
 	}
-	return string(value) + suffix
+	return string(value)
 }
 
 func (c Config) Validate() error {

internal/config/config_test.go

@@ -3,10 +3,56 @@ package config
 import (
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 	"time"
+	"unicode/utf8"
 )
 
+func TestDefaultName(t *testing.T) {
+	hostname, _ := os.Hostname()
+	for _, tc := range []struct {
+		name       string
+		serverHost string
+		wantPrefix string
+	}{
+		{name: "unset", wantPrefix: "[Kael]-" + hostname + "-"},
+		{name: "empty", wantPrefix: "[Kael]--" + hostname + "-"},
+		{name: "set", serverHost: "server", wantPrefix: "[Kael]-server-" + hostname + "-"},
+		{name: "long unicode", serverHost: strings.Repeat("界", 128), wantPrefix: "[Kael]-" + strings.Repeat("界", 57)},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Setenv("SERVER_HOSTNAME", tc.serverHost)
+			if tc.name == "unset" {
+				if err := os.Unsetenv("SERVER_HOSTNAME"); err != nil {
+					t.Fatal(err)
+				}
+			}
+			name := defaultName()
+			wantLength := utf8.RuneCountInString(tc.wantPrefix) + 7
+			if wantLength > 128 {
+				wantLength = 128
+				tc.wantPrefix = string([]rune(tc.wantPrefix)[:64])
+			}
+			if tc.name == "long unicode" {
+				wantLength = 128
+				tail := []rune(tc.serverHost + "-" + hostname + "-")
+				if !strings.HasSuffix(name[:len(name)-7], string(tail[len(tail)-57:])) {
+					t.Fatalf("truncated name lost its tail: %q", name)
+				}
+			}
+			if !utf8.ValidString(name) || utf8.RuneCountInString(name) != wantLength || !strings.HasPrefix(name, tc.wantPrefix) {
+				t.Fatalf("unexpected default name: %q", name)
+			}
+			for _, char := range name[len(name)-7:] {
+				if !(char >= 'a' && char <= 'z' || char >= 'A' && char <= 'Z') {
+					t.Fatalf("random suffix contains a non-letter: %q", name)
+				}
+			}
+		})
+	}
+}
+
 func TestLoadFlatKokoStyleEnvironment(t *testing.T) {
 	t.Setenv("CORE_HOST", "https://core.example.test")
 	t.Setenv("BOOTSTRAP_TOKEN", "bootstrap-secret")