diff --git a/agent/assistant/history_test.go b/agent/assistant/history_test.go
index f02fc767..33fdf928 100644
--- a/agent/assistant/history_test.go
+++ b/agent/assistant/history_test.go
@@ -414,7 +414,8 @@ func TestHistoryLoading(t *testing.T) {
 			chatStore.DeleteChat(chatID)
 		}()
 
-		// Add various message types
+		// Add various message types (only user/assistant roles allowed by DB constraint)
+		// loadHistory filters by role (user/assistant only) and converts based on type
 		err = chatStore.SaveMessages(chatID, []*storetypes.Message{
 			{
 				MessageID:   fmt.Sprintf("filter_1_%s", reqID),
@@ -425,7 +426,7 @@ func TestHistoryLoading(t *testing.T) {
 				Props:       map[string]interface{}{"content": "User message"},
 				Sequence:    1,
 				AssistantID: ast.ID,
-				CreatedAt:   time.Now().Add(-4 * time.Minute),
+				CreatedAt:   time.Now().Add(-3 * time.Minute),
 			},
 			{
 				MessageID:   fmt.Sprintf("filter_2_%s", reqID),
@@ -436,7 +437,7 @@ func TestHistoryLoading(t *testing.T) {
 				Props:       map[string]interface{}{"text": "Loading..."},
 				Sequence:    2,
 				AssistantID: ast.ID,
-				CreatedAt:   time.Now().Add(-3 * time.Minute),
+				CreatedAt:   time.Now().Add(-2 * time.Minute),
 			},
 			{
 				MessageID:   fmt.Sprintf("filter_3_%s", reqID),
@@ -447,17 +448,6 @@ func TestHistoryLoading(t *testing.T) {
 				Props:       map[string]interface{}{"text": "Assistant response"},
 				Sequence:    3,
 				AssistantID: ast.ID,
-				CreatedAt:   time.Now().Add(-2 * time.Minute),
-			},
-			{
-				MessageID:   fmt.Sprintf("filter_4_%s", reqID),
-				ChatID:      chatID,
-				RequestID:   fmt.Sprintf("req_filter_%s", reqID),
-				Role:        "system",
-				Type:        "event",
-				Props:       map[string]interface{}{"event": "stream_end"},
-				Sequence:    4,
-				AssistantID: ast.ID,
 				CreatedAt:   time.Now().Add(-1 * time.Minute),
 			},
 		})
@@ -471,17 +461,19 @@ func TestHistoryLoading(t *testing.T) {
 		require.NoError(t, err)
 		require.NotNil(t, result)
 
-		// User and assistant roles are included, system is filtered out
-		// Note: loading type messages with role=assistant are included (role-based filtering)
-		// Only system role messages are filtered out
+		// User and assistant roles are included
+		// loading type messages with role=assistant are included (role-based filtering)
+		// History contains: 1 user + 2 assistant (loading + text) = 3 messages
+		// Plus 1 new input = 4 total
 		assert.GreaterOrEqual(t, len(result.FullMessages), 3) // At least 1 user + 1 assistant from history + 1 new
 
-		// Verify no system role messages
+		// Verify only user and assistant roles
 		for _, msg := range result.FullMessages {
-			assert.NotEqual(t, "system", string(msg.Role))
+			assert.True(t, msg.Role == agentcontext.RoleUser || msg.Role == agentcontext.RoleAssistant,
+				"Expected user or assistant role, got: %s", msg.Role)
 		}
 
-		t.Log("✓ System role messages filtered out")
+		t.Log("✓ Only user and assistant roles included in history")
 	})
 
 	t.Run("ContentExtraction", func(t *testing.T) {
diff --git a/agent/context/context.go b/agent/context/context.go
index fa2b91b4..20f77033 100644
--- a/agent/context/context.go
+++ b/agent/context/context.go
@@ -6,9 +6,7 @@ import (
 	"sync"
 	"time"
 
-	jsoniter "github.com/json-iterator/go"
 	"github.com/yaoapp/gou/plan"
-	"github.com/yaoapp/kun/log"
 	"github.com/yaoapp/yao/agent/output/message"
 	"github.com/yaoapp/yao/config"
 	"github.com/yaoapp/yao/openapi/oauth/types"
@@ -43,46 +41,6 @@ func New(parent context.Context, authorized *types.AuthorizedInfo, chatID string
 	return ctx
 }
 
-// NewWithPayload create a new context and unmarshal from payload
-func NewWithPayload(parent context.Context, authorized *types.AuthorizedInfo, chatID, payload string) *Context {
-	ctx := New(parent, authorized, chatID)
-
-	if payload != "" {
-		err := jsoniter.Unmarshal([]byte(payload), ctx)
-		if err != nil {
-			log.Error("%s", err.Error())
-		}
-	}
-
-	return ctx
-}
-
-// NewWithCancel create a new context with cancel
-func NewWithCancel(parent context.Context, authorized *types.AuthorizedInfo, chatID string) (*Context, context.CancelFunc) {
-	ctx := New(parent, authorized, chatID)
-	return WithCancel(ctx)
-}
-
-// NewWithTimeout create a new context with timeout
-func NewWithTimeout(parent context.Context, authorized *types.AuthorizedInfo, chatID string, timeout time.Duration) (*Context, context.CancelFunc) {
-	ctx := New(parent, authorized, chatID)
-	return WithTimeout(ctx, timeout)
-}
-
-// WithCancel create a new context
-func WithCancel(parent *Context) (*Context, context.CancelFunc) {
-	new, cancel := context.WithCancel(parent.Context)
-	parent.Context = new
-	return parent, cancel
-}
-
-// WithTimeout create a new context
-func WithTimeout(parent *Context, timeout time.Duration) (*Context, context.CancelFunc) {
-	new, cancel := context.WithTimeout(parent.Context, timeout)
-	parent.Context = new
-	return parent, cancel
-}
-
 // Release the context and clean up all resources including stacks and trace
 func (ctx *Context) Release() {
 	if ctx.Logger != nil {
@@ -355,21 +313,6 @@ func (ctx *Context) TraceID() string {
 	return ""
 }
 
-// recordMessageMetadata records metadata for a sent message
-// Used to inherit BlockID and ThreadID in subsequent delta operations
-func (ctx *Context) recordMessageMetadata(msg *message.Message) {
-	if msg.MessageID == "" || ctx.messageMetadata == nil {
-		return
-	}
-
-	ctx.messageMetadata.setMessage(msg.MessageID, &MessageMetadata{
-		MessageID: msg.MessageID,
-		BlockID:   msg.BlockID,
-		ThreadID:  msg.ThreadID,
-		Type:      msg.Type,
-	})
-}
-
 // getMessageMetadata retrieves metadata for a message by ID
 // Returns nil if message metadata is not found
 func (ctx *Context) getMessageMetadata(messageID string) *MessageMetadata {
diff --git a/agent/context/log.go b/agent/context/log.go
index d6cb7128..1f555bc6 100644
--- a/agent/context/log.go
+++ b/agent/context/log.go
@@ -41,10 +41,15 @@ const (
 type LogLevel int
 
 const (
+	// LogLevelTrace represents the most verbose logging level for detailed tracing
 	LogLevelTrace LogLevel = iota
+	// LogLevelDebug represents debug level logging for development diagnostics
 	LogLevelDebug
+	// LogLevelInfo represents informational messages for normal operation
 	LogLevelInfo
+	// LogLevelWarn represents warning messages for potentially harmful situations
 	LogLevelWarn
+	// LogLevelError represents error messages for serious problems
 	LogLevelError
 )