diff --git a/agent.go b/agent.go
index 568babb..8423435 100644
--- a/agent.go
+++ b/agent.go
@@ -3,6 +3,7 @@ package goba
 
 import (
 	"bytes"
+	"encoding/base64"
 	"encoding/json"
 	"fmt"
 	"image"
@@ -39,16 +40,14 @@ var (
 // Agent is a OneBot event context, it is recommended to create one agent
 // per group or per user.
 type Agent struct {
-	log           chat.Log[fmt.Stringer]
-	id            int64
-	nickname, sex string
-	chars         string
-	perm          *Perm
-	imgpcache     *ttl.Cache[uint64, string]
-	mem           MemoryStorage
-	manualaddreq  bool
-	manualaddmem  bool
-	hasimageapi   bool
+	log          chat.Log[fmt.Stringer]
+	cfg          *Config
+	perm         *Perm
+	imgpcache    *ttl.Cache[uint64, string]
+	mem          MemoryStorage
+	manualaddreq bool
+	manualaddmem bool
+	hasimageapi  bool
 }
 
 // NewAgent 创建一个 Agent 实例。
@@ -58,15 +57,16 @@ type Agent struct {
 //   - manualaddreq 表示是否由用户手动添加请求。
 //   - manualaddmem 表示是否由用户手动添加记忆。
 func NewAgent(
-	id int64, batchcap, itemscap int, imgpcachettl time.Duration,
-	nickname, sex, characteristics, defaultprompt string, mem MemoryStorage,
+	cfg *Config, batchcap, itemscap int, imgpcachettl time.Duration,
+	defaultprompt string, mem MemoryStorage,
 	manualaddreq, manualaddmem bool,
 ) (ag Agent) {
 	ag = Agent{
-		id: id, nickname: nickname, sex: sex, chars: characteristics,
-		imgpcache: ttl.NewCache[uint64, string](imgpcachettl),
-		log:       chat.NewLog[fmt.Stringer](batchcap, itemscap, "\n", defaultprompt),
-		mem:       mem, manualaddreq: manualaddreq, manualaddmem: manualaddmem,
+		log:          chat.NewLog[fmt.Stringer](batchcap, itemscap, "\n", defaultprompt),
+		cfg:          cfg,
+		imgpcache:    ttl.NewCache[uint64, string](imgpcachettl),
+		mem:          mem,
+		manualaddreq: manualaddreq, manualaddmem: manualaddmem,
 	}
 	_ = ag.LoadPermTable()
 	return
@@ -117,20 +117,37 @@ func (ag *Agent) SetViewImageAPI(api deepinfra.API, p model.Protocol) {
 					continue
 				}
 				u := msg.Data["url"]
-				if !strings.HasPrefix(u, "http") {
-					continue
-				}
-				resp, err := http.Get(u)
-				if err != nil {
-					logrus.Debugln("[goba] SetViewImageAPI get http err:", err)
-					continue
-				}
-				data, err := io.ReadAll(resp.Body)
-				_ = resp.Body.Close()
-				if err != nil {
-					logrus.Debugln("[goba] SetViewImageAPI read body err:", err)
+				if u == "" {
+					u = msg.Data["file"]
+				}
+				var (
+					data []byte
+					err  error
+				)
+				switch {
+				case strings.HasPrefix(u, "http"):
+					resp, err := http.Get(u)
+					if err != nil {
+						logrus.Debugln("[goba] SetViewImageAPI get http err:", err)
+						continue
+					}
+					data, err = io.ReadAll(resp.Body)
+					_ = resp.Body.Close()
+					if err != nil {
+						logrus.Debugln("[goba] SetViewImageAPI read body err:", err)
+						continue
+					}
+				case strings.HasPrefix(u, "base64://"):
+					data, err = base64.StdEncoding.DecodeString(u[9:])
+					if err != nil {
+						logrus.Debugln("[goba] SetViewImageAPI decode base64 err:", err)
+						continue
+					}
+				default:
+					// we can support local files but skip due to security concerns.
 					continue
 				}
+
 				img, _, err := image.Decode(bytes.NewReader(data))
 				if err != nil {
 					logrus.Debugln("[goba] SetViewImageAPI decode img err:", err)
diff --git a/prompt.go b/prompt.go
index 78dd362..e1e6077 100644
--- a/prompt.go
+++ b/prompt.go
@@ -9,6 +9,14 @@ import (
 //go:embed README.md
 var sysp string
 
+// Config stores mutable characteristics of the agent.
+type Config struct {
+	ID       int64  // ID QQ
+	Nickname string // Nickname 昵称
+	Sex      string // Sex 性别
+	Chars    string // Chars 个性
+}
+
 func (ag *Agent) system(role PermRole, iter int, grp int64) (string, error) {
 	tab, err := ag.perm.mdtable(role)
 	if err != nil {
@@ -20,8 +28,8 @@ func (ag *Agent) system(role PermRole, iter int, grp int64) (string, error) {
 		typ = "私聊"
 	}
 	return fmt.Sprintf(
-		sysp, ag.id, ag.nickname, ag.sex,
-		ag.chars, tab, ag.memoryof(grp),
+		sysp, ag.cfg.ID, ag.cfg.Nickname, ag.cfg.Sex,
+		ag.cfg.Chars, tab, ag.memoryof(grp),
 		t.Format(time.RFC3339), t.Unix(), typ, iter,
 	), nil
 }
diff --git a/prompt_test.go b/prompt_test.go
index 42ee652..37802a5 100644
--- a/prompt_test.go
+++ b/prompt_test.go
@@ -462,10 +462,9 @@ func (fakemem) Load(grp int64) []string {
 }
 
 func TestAgent_system(t *testing.T) {
-	ag := NewAgent(
-		12345, 10, 10, time.Minute, "testname", "testsex", "testchar",
-		"testd", &fakemem{}, false, false,
-	)
+	ag := NewAgent(&Config{
+		12345, "testname", "testsex", "testchar",
+	}, 10, 10, time.Minute, "testd", &fakemem{}, false, false)
 	p, err := ag.system(PermRoleAdmin, 1, 123)
 	if err != nil {
 		t.Fatal(err)