diff --git a/internal/ai/runtime/internal/engine/service.go b/internal/ai/runtime/internal/engine/service.go
index 1a1d825..ae3e016 100644
--- a/internal/ai/runtime/internal/engine/service.go
+++ b/internal/ai/runtime/internal/engine/service.go
@@ -159,9 +159,9 @@ func (s *Service) Run(ctx context.Context, req Request) (*Summary, error) {
 	messages = append(messages, history.Messages...)
 
 	retriever := retrievers.NewKnowledgeRetriever(req.AIAgent)
-	if retrieveResult, retrieveErr := retriever.RetrieveContextByOptions(ctx, retrievers.KnowledgeRetrieveOptions{
-		QueryPreview: preview(req.UserMessage.Content, 120),
-	}, strings.TrimSpace(req.UserMessage.Content)); retrieveErr == nil && retrieveResult != nil {
+	retrieveOptions := retrievers.DefaultKnowledgeRetrieveOptions()
+	retrieveOptions.QueryPreview = preview(req.UserMessage.Content, 120)
+	if retrieveResult, retrieveErr := retriever.RetrieveContextByOptions(ctx, retrieveOptions, strings.TrimSpace(req.UserMessage.Content)); retrieveErr == nil && retrieveResult != nil {
 		summary.RetrieverCount = len(retrieveResult.Hits)
 		collector.SetRetrieverSummary(retrieveResult.TraceSummary)
 		collector.Data.Retriever.Items = append(collector.Data.Retriever.Items, retrieveResult.TraceItems...)
diff --git a/internal/ai/runtime/internal/impl/callbacks/runlog_callback.go b/internal/ai/runtime/internal/impl/callbacks/runlog_callback.go
index 4e00604..4e39e1f 100644
--- a/internal/ai/runtime/internal/impl/callbacks/runlog_callback.go
+++ b/internal/ai/runtime/internal/impl/callbacks/runlog_callback.go
@@ -74,6 +74,7 @@ func (c *RuntimeTraceCollector) SetRetrieverSummary(summary RetrieverTraceSummar
 	c.Data.Retriever.TopK = summary.TopK
 	c.Data.Retriever.ScoreThreshold = summary.ScoreThreshold
 	c.Data.Retriever.ContextMaxTokens = summary.ContextMaxTokens
+	c.Data.Retriever.MaxContextItems = summary.MaxContextItems
 	c.Data.Retriever.Count = summary.HitCount
 	c.Data.Retriever.ContextCount = summary.ContextCount
 	c.Data.Retriever.EmbeddingMs = summary.EmbeddingMs
diff --git a/internal/ai/runtime/internal/impl/callbacks/trace_callback.go b/internal/ai/runtime/internal/impl/callbacks/trace_callback.go
index 9410072..bb5d686 100644
--- a/internal/ai/runtime/internal/impl/callbacks/trace_callback.go
+++ b/internal/ai/runtime/internal/impl/callbacks/trace_callback.go
@@ -45,6 +45,7 @@ type RetrieverTraceSummary struct {
 	TopK             int
 	ScoreThreshold   float64
 	ContextMaxTokens int
+	MaxContextItems  int
 	HitCount         int
 	ContextCount     int
 	EmbeddingMs      int64
@@ -103,6 +104,7 @@ type RuntimeTraceData struct {
 		TopK             int                        `json:"topK,omitempty"`
 		ScoreThreshold   float64                    `json:"scoreThreshold,omitempty"`
 		ContextMaxTokens int                        `json:"contextMaxTokens,omitempty"`
+		MaxContextItems  int                        `json:"maxContextItems,omitempty"`
 		ContextCount     int                        `json:"contextCount,omitempty"`
 		EmbeddingMs      int64                      `json:"embeddingMs,omitempty"`
 		VectorSearchMs   int64                      `json:"vectorSearchMs,omitempty"`
diff --git a/internal/ai/runtime/internal/impl/retrievers/knowledge_retriever.go b/internal/ai/runtime/internal/impl/retrievers/knowledge_retriever.go
index 6e50e75..eca5317 100644
--- a/internal/ai/runtime/internal/impl/retrievers/knowledge_retriever.go
+++ b/internal/ai/runtime/internal/impl/retrievers/knowledge_retriever.go
@@ -17,6 +17,7 @@ import (
 const defaultRuntimeKnowledgeContextTokens = 4000
 const defaultRuntimeKnowledgeTopK = 8
 const defaultRuntimeKnowledgeScoreThreshold = 0.3
+const defaultRuntimeKnowledgeMaxContextItems = 5
 
 type KnowledgeRetriever struct {
 	AIAgent *models.AIAgent
@@ -24,6 +25,7 @@ type KnowledgeRetriever struct {
 
 type KnowledgeRetrieveOptions struct {
 	ContextMaxTokens int
+	MaxContextItems  int
 	TopK             int
 	ScoreThreshold   float64
 	QueryPreview     string
@@ -52,6 +54,13 @@ func NewKnowledgeRetriever(aiAgent *models.AIAgent) *KnowledgeRetriever {
 	return &KnowledgeRetriever{AIAgent: aiAgent}
 }
 
+func DefaultKnowledgeRetrieveOptions() KnowledgeRetrieveOptions {
+	return KnowledgeRetrieveOptions{
+		ContextMaxTokens: defaultRuntimeKnowledgeContextTokens,
+		MaxContextItems:  defaultRuntimeKnowledgeMaxContextItems,
+	}
+}
+
 func (r *KnowledgeRetriever) KnowledgeBaseIDs() []int64 {
 	if r == nil || r.AIAgent == nil {
 		return nil
@@ -60,7 +69,7 @@ func (r *KnowledgeRetriever) KnowledgeBaseIDs() []int64 {
 }
 
 func (r *KnowledgeRetriever) Retrieve(ctx context.Context, query string) ([]rag.RetrieveResult, *rag.RetrieveTrace, error) {
-	return r.RetrieveByOptions(ctx, KnowledgeRetrieveOptions{}, query)
+	return r.RetrieveByOptions(ctx, DefaultKnowledgeRetrieveOptions(), query)
 }
 
 func (r *KnowledgeRetriever) RetrieveByOptions(ctx context.Context, opts KnowledgeRetrieveOptions, query string) ([]rag.RetrieveResult, *rag.RetrieveTrace, error) {
@@ -74,7 +83,7 @@ func (r *KnowledgeRetriever) RetrieveByOptions(ctx context.Context, opts Knowled
 }
 
 func (r *KnowledgeRetriever) RetrieveContext(ctx context.Context, query string) (*KnowledgeRetrieveResult, error) {
-	return r.RetrieveContextByOptions(ctx, KnowledgeRetrieveOptions{}, query)
+	return r.RetrieveContextByOptions(ctx, DefaultKnowledgeRetrieveOptions(), query)
 }
 
 func (r *KnowledgeRetriever) RetrieveContextByOptions(ctx context.Context, opts KnowledgeRetrieveOptions, query string) (*KnowledgeRetrieveResult, error) {
@@ -85,6 +94,10 @@ func (r *KnowledgeRetriever) RetrieveContextByOptions(ctx context.Context, opts
 	if contextMaxTokens <= 0 {
 		contextMaxTokens = defaultRuntimeKnowledgeContextTokens
 	}
+	maxContextItems := opts.MaxContextItems
+	if maxContextItems <= 0 {
+		maxContextItems = defaultRuntimeKnowledgeMaxContextItems
+	}
 	queryPreview := strings.TrimSpace(opts.QueryPreview)
 	if queryPreview == "" {
 		queryPreview = query
@@ -94,6 +107,7 @@ func (r *KnowledgeRetriever) RetrieveContextByOptions(ctx context.Context, opts
 		Query:            query,
 		Options: KnowledgeRetrieveOptions{
 			ContextMaxTokens: contextMaxTokens,
+			MaxContextItems:  maxContextItems,
 			TopK:             opts.TopK,
 			ScoreThreshold:   opts.ScoreThreshold,
 			QueryPreview:     queryPreview,
@@ -110,12 +124,30 @@ func (r *KnowledgeRetriever) RetrieveContextByOptions(ctx context.Context, opts
 	ret.Hits = append([]rag.RetrieveResult(nil), results...)
 	ret.Trace = trace
 	ret.ContextResults = rag.Retrieve.SelectContextResults(results, contextMaxTokens)
-	ret.ContextText = strings.TrimSpace(rag.Retrieve.BuildContext(ctx, results, contextMaxTokens))
+	ret.ContextResults = limitContextResults(ret.ContextResults, maxContextItems)
+	ret.ContextText = strings.TrimSpace(buildContextText(ret.ContextResults))
 	ret.TraceItems = buildRetrieverTraceItems(queryPreview, results, trace)
 	ret.TraceSummary = buildRetrieverTraceSummary(ret.Options, ret.Policies, ret.ContextResults, results, trace)
 	return ret, nil
 }
 
+func limitContextResults(results []rag.RetrieveResult, maxItems int) []rag.RetrieveResult {
+	if len(results) == 0 {
+		return nil
+	}
+	if maxItems <= 0 || len(results) <= maxItems {
+		return append([]rag.RetrieveResult(nil), results...)
+	}
+	return append([]rag.RetrieveResult(nil), results[:maxItems]...)
+}
+
+func buildContextText(results []rag.RetrieveResult) string {
+	if len(results) == 0 {
+		return ""
+	}
+	return strings.TrimSpace(rag.Retrieve.BuildContext(context.Background(), results, 1<<30))
+}
+
 func (r *KnowledgeRetriever) resolvePolicies(knowledgeBaseIDs []int64, opts KnowledgeRetrieveOptions) []KnowledgeBaseRetrievePolicy {
 	if len(knowledgeBaseIDs) == 0 {
 		return nil
@@ -192,6 +224,7 @@ func buildRetrieverTraceSummary(opts KnowledgeRetrieveOptions, policies []Knowle
 		TopK:             opts.TopK,
 		ScoreThreshold:   opts.ScoreThreshold,
 		ContextMaxTokens: opts.ContextMaxTokens,
+		MaxContextItems:  opts.MaxContextItems,
 		HitCount:         len(results),
 		ContextCount:     len(contextResults),
 		Policies:         buildRetrieverPolicyTraceItems(policies),