feat: add answerability runtime trace fields

internal/ai/runtime/internal/impl/callbacks/runlog_callback.go

@@ -106,6 +106,19 @@ func (c *RuntimeTraceCollector) SetRetrieverSummary(summary RetrieverTraceSummar
 	c.Data.Retriever.Policies = append([]RetrieverPolicyTraceItem(nil), summary.Policies...)
 }
 
+func (c *RuntimeTraceCollector) SetAnswerability(data AnswerabilityTraceData) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.Data.Answerability = AnswerabilityTraceData{
+		Status:             data.Status,
+		Reason:             data.Reason,
+		SupportingChunkIDs: append([]string(nil), data.SupportingChunkIDs...),
+		MissingInfo:        append([]string(nil), data.MissingInfo...),
+		LatencyMs:          data.LatencyMs,
+		ErrorMessage:       data.ErrorMessage,
+	}
+}
+
 func (c *RuntimeTraceCollector) AddToolItem(item ToolTraceItem) {
 	c.mu.Lock()
 	defer c.mu.Unlock()

internal/ai/runtime/internal/impl/callbacks/trace_callback.go

@@ -65,6 +65,15 @@ type RetrieverTraceSummary struct {
 	Policies         []RetrieverPolicyTraceItem
 }
 
+type AnswerabilityTraceData struct {
+	Status             string   `json:"status,omitempty"`
+	Reason             string   `json:"reason,omitempty"`
+	SupportingChunkIDs []string `json:"supportingChunkIds,omitempty"`
+	MissingInfo        []string `json:"missingInfo,omitempty"`
+	LatencyMs          int64    `json:"latencyMs,omitempty"`
+	ErrorMessage       string   `json:"errorMessage,omitempty"`
+}
+
 type RetrieverPolicyTraceItem struct {
 	KnowledgeBaseID int64   `json:"knowledgeBaseId,omitempty"`
 	TopK            int     `json:"topK,omitempty"`
@@ -119,7 +128,8 @@ type RuntimeTraceData struct {
 		Policies         []RetrieverPolicyTraceItem `json:"policies,omitempty"`
 		Items            []RetrieverTraceItem       `json:"items,omitempty"`
 	} `json:"retriever"`
-	Tools struct {
+	Answerability AnswerabilityTraceData `json:"answerability,omitempty"`
+	Tools         struct {
 		Count int             `json:"count,omitempty"`
 		Items []ToolTraceItem `json:"items,omitempty"`
 	} `json:"tools"`