diff --git a/README.md b/README.md
index 3d6fd891be..82d0a4d7ae 100644
--- a/README.md
+++ b/README.md
@@ -725,6 +725,7 @@ go generate ./cmd/server
 Simple Mode is designed for individual developers or internal teams who want quick access without full SaaS features.
 
 - Enable: Set environment variable `RUN_MODE=simple`
+- Default groups are seeded on each startup. Set `SIMPLE_MODE_AUTO_CREATE_DEFAULT_GROUPS=false` (or YAML `simple_mode.auto_create_default_groups: false`) to manage groups yourself. The default is `true`; disabling it does not delete existing groups or change runtime auto-binding or admin concurrency setup.
 - Difference: Hides SaaS-related features and skips billing process
 - Security note: In production, you must also set `SIMPLE_MODE_CONFIRM=true` to allow startup
 
diff --git a/README_CN.md b/README_CN.md
index 9a4907c461..6289d0c92b 100644
--- a/README_CN.md
+++ b/README_CN.md
@@ -735,6 +735,7 @@ OAuth / Setup Token 图片请求使用 Responses 主控模型调用 `image_gener
 简易模式适合个人开发者或内部团队快速使用，不依赖完整 SaaS 功能。
 
 - 启用方式：设置环境变量 `RUN_MODE=simple`
+- 默认每次启动会补齐默认分组。设置 `SIMPLE_MODE_AUTO_CREATE_DEFAULT_GROUPS=false`（或 YAML `simple_mode.auto_create_default_groups: false`）可自行管理分组。默认值为 `true`；关闭后不删除已有分组，不改变运行时自动绑定或管理员并发设置。
 - 功能差异：隐藏 SaaS 相关功能，跳过计费流程
 - 安全注意事项：生产环境需同时设置 `SIMPLE_MODE_CONFIRM=true` 才允许启动
 
diff --git a/backend/internal/config/config.go b/backend/internal/config/config.go
index 1d7e41305f..2195c74ae5 100644
--- a/backend/internal/config/config.go
+++ b/backend/internal/config/config.go
@@ -96,6 +96,7 @@ type Config struct {
 	UsageCleanup            UsageCleanupConfig            `mapstructure:"usage_cleanup"`
 	Concurrency             ConcurrencyConfig             `mapstructure:"concurrency"`
 	TokenRefresh            TokenRefreshConfig            `mapstructure:"token_refresh"`
+	SimpleMode              SimpleModeConfig              `mapstructure:"simple_mode" yaml:"simple_mode"`
 	RunMode                 string                        `mapstructure:"run_mode" yaml:"run_mode"`
 	Timezone                string                        `mapstructure:"timezone"` // e.g. "Asia/Shanghai", "UTC"
 	Gemini                  GeminiConfig                  `mapstructure:"gemini"`
@@ -106,6 +107,11 @@ type Config struct {
 	Plugins                 PluginConfig                  `mapstructure:"plugins"`
 }
 
+// SimpleModeConfig controls startup behavior in simple mode.
+type SimpleModeConfig struct {
+	AutoCreateDefaultGroups bool `mapstructure:"auto_create_default_groups" yaml:"auto_create_default_groups"`
+}
+
 // PluginConfig 控制管理员手动上传的本地进程插件。
 // 默认不包含插件，也不允许安装未签名插件；TrustedPublishers 用于追加第三方发布者。
 type PluginConfig struct {
@@ -1992,6 +1998,7 @@ func configureConfigSource(setConfigFile, addConfigPath func(string)) {
 
 func setDefaults() {
 	viper.SetDefault("run_mode", RunModeStandard)
+	viper.SetDefault("simple_mode.auto_create_default_groups", true)
 
 	// Server
 	viper.SetDefault("server.host", "0.0.0.0")
diff --git a/backend/internal/config/config_test.go b/backend/internal/config/config_test.go
index d0ed2d6993..8783092b7e 100644
--- a/backend/internal/config/config_test.go
+++ b/backend/internal/config/config_test.go
@@ -2630,3 +2630,42 @@ func TestLoad_DefaultGatewayImageStreamConfig(t *testing.T) {
 		t.Fatalf("image stream timeout = %d, want greater than ordinary stream timeout %d", cfg.Gateway.ImageStreamDataIntervalTimeout, cfg.Gateway.StreamDataIntervalTimeout)
 	}
 }
+
+func TestLoadSimpleModeAutoCreateDefaultGroups(t *testing.T) {
+	for _, loader := range []struct {
+		name string
+		load func() (*Config, error)
+	}{{"Load", Load}, {"LoadForBootstrap", LoadForBootstrap}} {
+		t.Run(loader.name, func(t *testing.T) {
+			for _, tt := range []struct {
+				name  string
+				yaml  string
+				env   string
+				unset bool
+				want  bool
+			}{
+				{name: "unset env uses application default", unset: true, want: true},
+				{name: "empty env uses application default", want: true},
+				{name: "unset env preserves yaml false", unset: true, yaml: "simple_mode:\n  auto_create_default_groups: false\n", want: false},
+				{name: "empty env preserves yaml false", yaml: "simple_mode:\n  auto_create_default_groups: false\n", want: false},
+				{name: "env false overrides yaml true", yaml: "simple_mode:\n  auto_create_default_groups: true\n", env: "false", want: false},
+				{name: "env false without yaml", env: "false", want: false},
+				{name: "env true overrides yaml false", yaml: "simple_mode:\n  auto_create_default_groups: false\n", env: "true", want: true},
+			} {
+				t.Run(tt.name, func(t *testing.T) {
+					resetViperWithJWTSecret(t)
+					t.Setenv("SIMPLE_MODE_AUTO_CREATE_DEFAULT_GROUPS", tt.env)
+					if tt.unset {
+						require.NoError(t, os.Unsetenv("SIMPLE_MODE_AUTO_CREATE_DEFAULT_GROUPS"))
+					}
+					path := filepath.Join(t.TempDir(), "config.yaml")
+					require.NoError(t, os.WriteFile(path, []byte("run_mode: simple\n"+tt.yaml), 0o600))
+					t.Setenv("CONFIG_FILE", path)
+					cfg, err := loader.load()
+					require.NoError(t, err)
+					require.Equal(t, tt.want, cfg.SimpleMode.AutoCreateDefaultGroups)
+				})
+			}
+		})
+	}
+}
diff --git a/backend/internal/repository/ent.go b/backend/internal/repository/ent.go
index 165fea4baf..d8f4ed5639 100644
--- a/backend/internal/repository/ent.go
+++ b/backend/internal/repository/ent.go
@@ -157,21 +157,25 @@ func InitEnt(cfg *config.Config) (*ent.Client, *sql.DB, error) {
 		return nil, nil, fmt.Errorf("validate config after secret bootstrap: %w", err)
 	}
 
-	// SIMPLE 模式：启动时补齐各平台默认分组。
-	// - anthropic/openai/gemini: 确保存在 <platform>-default
-	// - antigravity: 仅要求存在 >=2 个未软删除分组（用于 claude/gemini 混合调度场景）
-	if cfg.RunMode == config.RunModeSimple {
-		seedCtx, seedCancel := context.WithTimeout(context.Background(), 30*time.Second)
-		defer seedCancel()
-		if err := ensureSimpleModeDefaultGroups(seedCtx, client); err != nil {
-			_ = client.Close()
-			return nil, nil, err
-		}
-		if err := ensureSimpleModeAdminConcurrency(seedCtx, client); err != nil {
-			_ = client.Close()
-			return nil, nil, err
-		}
+	seedCtx, seedCancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer seedCancel()
+	if err := ensureSimpleModeStartup(seedCtx, client, cfg); err != nil {
+		_ = client.Close()
+		return nil, nil, err
 	}
 
 	return client, drv.DB(), nil
 }
+
+// ensureSimpleModeStartup keeps admin concurrency setup independent of group seeding.
+func ensureSimpleModeStartup(ctx context.Context, client *ent.Client, cfg *config.Config) error {
+	if cfg.RunMode != config.RunModeSimple {
+		return nil
+	}
+	if cfg.SimpleMode.AutoCreateDefaultGroups {
+		if err := ensureSimpleModeDefaultGroups(ctx, client); err != nil {
+			return err
+		}
+	}
+	return ensureSimpleModeAdminConcurrency(ctx, client)
+}
diff --git a/backend/internal/repository/simple_mode_startup_test.go b/backend/internal/repository/simple_mode_startup_test.go
new file mode 100644
index 0000000000..d62a6a2ee3
--- /dev/null
+++ b/backend/internal/repository/simple_mode_startup_test.go
@@ -0,0 +1,69 @@
+package repository
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"entgo.io/ent/dialect"
+	entsql "entgo.io/ent/dialect/sql"
+	"github.com/DATA-DOG/go-sqlmock"
+	"github.com/Wei-Shaw/sub2api/ent"
+	"github.com/Wei-Shaw/sub2api/internal/config"
+	"github.com/stretchr/testify/require"
+)
+
+func TestEnsureSimpleModeStartup(t *testing.T) {
+	for _, tt := range []struct {
+		name string
+		mode string
+		seed bool
+	}{
+		{"simple enabled", config.RunModeSimple, true},
+		{"simple disabled preserves admin setup", config.RunModeSimple, false},
+		{"standard enabled", config.RunModeStandard, true},
+		{"standard disabled", config.RunModeStandard, false},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			db, mock, err := sqlmock.New()
+			require.NoError(t, err)
+			client := ent.NewClient(ent.Driver(entsql.OpenDB(dialect.Postgres, db)))
+			t.Cleanup(func() { _ = client.Close() })
+			if tt.mode == config.RunModeSimple {
+				if tt.seed {
+					// The first seeding operation backfills auto-created Grok groups.
+					mock.ExpectExec(`UPDATE "groups"`).WillReturnResult(sqlmock.NewResult(0, 0))
+					// Existing groups exercise the complete seeding path without inserts.
+					for i := 0; i < 5; i++ {
+						mock.ExpectQuery(`SELECT COUNT\(.*FROM "groups"`).WillReturnRows(sqlmock.NewRows([]string{"count"}).AddRow(2))
+					}
+					// Antigravity only counts; other platforms check the default name.
+					for i := 0; i < 4; i++ {
+						mock.ExpectQuery(`SELECT "groups"\."id" FROM "groups"`).WillReturnRows(sqlmock.NewRows([]string{"id"}).AddRow(1))
+					}
+					// Platform map iteration order is unspecified.
+					mock.MatchExpectationsInOrder(false)
+				}
+				mock.ExpectQuery(`SELECT .*FROM "settings"`).
+					WithArgs(simpleModeAdminConcurrencyUpgradeKey).
+					WillReturnRows(sqlmock.NewRows([]string{"id"}).AddRow(1))
+			}
+			cfg := &config.Config{RunMode: tt.mode, SimpleMode: config.SimpleModeConfig{AutoCreateDefaultGroups: tt.seed}}
+			require.NoError(t, ensureSimpleModeStartup(context.Background(), client, cfg))
+			require.NoError(t, mock.ExpectationsWereMet())
+		})
+	}
+}
+
+func TestEnsureSimpleModeStartupSeedingFailure(t *testing.T) {
+	db, mock, err := sqlmock.New()
+	require.NoError(t, err)
+	client := ent.NewClient(ent.Driver(entsql.OpenDB(dialect.Postgres, db)))
+	t.Cleanup(func() { _ = client.Close() })
+	seedErr := errors.New("group seeding failed")
+	mock.ExpectExec(`UPDATE "groups"`).WillReturnError(seedErr)
+	cfg := &config.Config{RunMode: config.RunModeSimple, SimpleMode: config.SimpleModeConfig{AutoCreateDefaultGroups: true}}
+	// No admin setup query is expected after a seeding failure.
+	require.ErrorIs(t, ensureSimpleModeStartup(context.Background(), client, cfg), seedErr)
+	require.NoError(t, mock.ExpectationsWereMet())
+}
diff --git a/deploy/.env.example b/deploy/.env.example
index 47f249b6aa..31b913e1cd 100644
--- a/deploy/.env.example
+++ b/deploy/.env.example
@@ -119,6 +119,9 @@ SERVER_H2C_MAX_UPLOAD_BUFFER_PER_STREAM=524288
 # 运行模式: standard (默认) 或 simple (内部自用)
 # standard: 完整 SaaS 功能，包含计费/余额校验；simple: 隐藏 SaaS 功能并跳过计费/余额校验
 RUN_MODE=standard
+# 简易模式启动时自动补齐默认分组；留空或未设置时使用 YAML 配置，未配置时应用默认 true
+# 显式 true/false 会覆盖 YAML；false 由用户自行管理，已有分组和运行时行为不变
+SIMPLE_MODE_AUTO_CREATE_DEFAULT_GROUPS=
 
 # Timezone
 TZ=Asia/Shanghai
diff --git a/deploy/config.example.yaml b/deploy/config.example.yaml
index e93f6c96f1..3507cbc03d 100644
--- a/deploy/config.example.yaml
+++ b/deploy/config.example.yaml
@@ -100,6 +100,11 @@ webauthn:
 # - simple: 隐藏 SaaS 功能，跳过计费和余额校验
 run_mode: "standard"
 
+simple_mode:
+  # 仅控制简易模式启动时补齐默认分组；false 不删除已有分组，不改变运行时自动绑定或管理员并发设置。
+  # 环境变量：SIMPLE_MODE_AUTO_CREATE_DEFAULT_GROUPS
+  auto_create_default_groups: true
+
 # =============================================================================
 # CORS Configuration
 # 跨域资源共享 (CORS) 配置
diff --git a/deploy/docker-compose.dev.yml b/deploy/docker-compose.dev.yml
index c2a2ac9246..92a075ceb7 100644
--- a/deploy/docker-compose.dev.yml
+++ b/deploy/docker-compose.dev.yml
@@ -30,6 +30,7 @@ services:
       - SERVER_MODE=debug
       - ENABLE_SERVER_TIMING=${ENABLE_SERVER_TIMING:-false}
       - RUN_MODE=${RUN_MODE:-standard}
+      - SIMPLE_MODE_AUTO_CREATE_DEFAULT_GROUPS=${SIMPLE_MODE_AUTO_CREATE_DEFAULT_GROUPS:-}
       - DATABASE_HOST=postgres
       - DATABASE_PORT=5432
       - DATABASE_USER=${POSTGRES_USER:-sub2api}
diff --git a/deploy/docker-compose.local.yml b/deploy/docker-compose.local.yml
index 8a14f4d7aa..8e8956cd69 100644
--- a/deploy/docker-compose.local.yml
+++ b/deploy/docker-compose.local.yml
@@ -55,6 +55,7 @@ services:
       - SERVER_MODE=${SERVER_MODE:-release}
       - ENABLE_SERVER_TIMING=${ENABLE_SERVER_TIMING:-false}
       - RUN_MODE=${RUN_MODE:-standard}
+      - SIMPLE_MODE_AUTO_CREATE_DEFAULT_GROUPS=${SIMPLE_MODE_AUTO_CREATE_DEFAULT_GROUPS:-}
       - UPDATE_GITHUB_TOKEN=${UPDATE_GITHUB_TOKEN:-}
 
       # =======================================================================
diff --git a/deploy/docker-compose.standalone.yml b/deploy/docker-compose.standalone.yml
index 7273dd0fed..af98c34a60 100644
--- a/deploy/docker-compose.standalone.yml
+++ b/deploy/docker-compose.standalone.yml
@@ -41,6 +41,7 @@ services:
       - SERVER_MODE=${SERVER_MODE:-release}
       - ENABLE_SERVER_TIMING=${ENABLE_SERVER_TIMING:-false}
       - RUN_MODE=${RUN_MODE:-standard}
+      - SIMPLE_MODE_AUTO_CREATE_DEFAULT_GROUPS=${SIMPLE_MODE_AUTO_CREATE_DEFAULT_GROUPS:-}
       - UPDATE_GITHUB_TOKEN=${UPDATE_GITHUB_TOKEN:-}
 
       # =======================================================================
diff --git a/deploy/docker-compose.yml b/deploy/docker-compose.yml
index e6b84a54d3..f9086dda4a 100644
--- a/deploy/docker-compose.yml
+++ b/deploy/docker-compose.yml
@@ -51,6 +51,7 @@ services:
       - SERVER_MODE=${SERVER_MODE:-release}
       - ENABLE_SERVER_TIMING=${ENABLE_SERVER_TIMING:-false}
       - RUN_MODE=${RUN_MODE:-standard}
+      - SIMPLE_MODE_AUTO_CREATE_DEFAULT_GROUPS=${SIMPLE_MODE_AUTO_CREATE_DEFAULT_GROUPS:-}
       - UPDATE_GITHUB_TOKEN=${UPDATE_GITHUB_TOKEN:-}
       - ALIPAY_MOBILE_PRECREATE_DEEP_LINK=${ALIPAY_MOBILE_PRECREATE_DEEP_LINK:-}
 
diff --git a/deploy/tests/docker-compose-simple-mode-env-test.sh b/deploy/tests/docker-compose-simple-mode-env-test.sh
new file mode 100644
index 0000000000..28f4eec14a
--- /dev/null
+++ b/deploy/tests/docker-compose-simple-mode-env-test.sh
@@ -0,0 +1,46 @@
+#!/bin/sh
+set -eu
+
+repo_root=$(CDPATH= cd -- "$(dirname -- "$0")/../.." && pwd)
+cd "$repo_root"
+
+python3 - <<'PY'
+import json
+import os
+from pathlib import Path
+import subprocess
+
+key = "SIMPLE_MODE_AUTO_CREATE_DEFAULT_GROUPS"
+sample = Path("deploy/.env.example").read_text().splitlines()
+assert [line for line in sample if line.startswith(key + "=")] == [key + "="], \
+    ".env.example must preserve YAML configuration by leaving the override empty"
+
+for filename in (
+    "docker-compose.yml",
+    "docker-compose.local.yml",
+    "docker-compose.standalone.yml",
+    "docker-compose.dev.yml",
+):
+    path = Path("deploy") / filename
+    expected = "      - " + key + "=${" + key + ":-}"
+    assert path.read_text().splitlines().count(expected) == 1, \
+        f"{path} must pass the override with an empty fallback exactly once"
+    for value in (None, "", "true", "false"):
+        env = dict(
+            os.environ, POSTGRES_PASSWORD="compose-test-password",
+            DATABASE_HOST="postgres", DATABASE_PASSWORD="compose-test-password",
+            REDIS_HOST="redis",
+        )
+        env.pop(key, None)
+        if value is not None:
+            env[key] = value
+        result = subprocess.run(
+            ["docker", "compose", "--env-file", "/dev/null", "-f", str(path),
+             "config", "--format", "json"],
+            env=env, check=True, capture_output=True, text=True,
+        )
+        actual = json.loads(result.stdout)["services"]["sub2api"]["environment"][key]
+        assert actual == (value or ""), f"{path}: override {value!r} rendered as {actual!r}"
+
+print("docker compose simple mode environment test passed")
+PY