feat(kiro): enhance request format, stream handling, and usage tracking

## English Description

### Request Format Fixes
- Fix conversationState field order (chatTriggerType must be first)
- Add conditional profileArn inclusion based on auth method
- builder-id auth (AWS SSO) doesn't require profileArn
- social auth (Google OAuth) requires profileArn

### Stream Processing Enhancements
- Add headersLen boundary validation to prevent slice out of bounds
- Handle incomplete tool use at EOF by flushing pending data
- Separate message_delta and message_stop events for proper streaming
- Add error logging for JSON unmarshal failures

### JSON Repair Improvements
- Add escapeNewlinesInStrings() to handle control characters in JSON strings
- Remove incorrect unquotedKeyPattern that broke valid JSON content
- Fix handling of streaming fragments with embedded newlines/tabs

### Debug Info Filtering (Optional)
- Add filterHeliosDebugInfo() to remove [HELIOS_CHK] blocks
- Pattern matches internal state tracking from Kiro/Amazon Q
- Currently disabled pending further testing

### Usage Tracking
- Add usage information extraction in message_delta response
- Include prompt_tokens, completion_tokens, total_tokens in OpenAI format

---

## 中文描述

### 请求格式修复
- 修复 conversationState 字段顺序（chatTriggerType 必须在第一位）
- 根据认证方式条件性包含 profileArn
- builder-id 认证（AWS SSO）不需要 profileArn
- social 认证（Google OAuth）需要 profileArn

### 流处理增强
- 添加 headersLen 边界验证，防止切片越界
- 在 EOF 时处理未完成的工具调用，刷新待处理数据
- 分离 message_delta 和 message_stop 事件以实现正确的流式传输
- 添加 JSON 反序列化失败的错误日志

### JSON 修复改进
- 添加 escapeNewlinesInStrings() 处理 JSON 字符串中的控制字符
- 移除错误的 unquotedKeyPattern，该模式会破坏有效的 JSON 内容
- 修复包含嵌入换行符/制表符的流式片段处理

### 调试信息过滤（可选）
- 添加 filterHeliosDebugInfo() 移除 [HELIOS_CHK] 块
- 模式匹配来自 Kiro/Amazon Q 的内部状态跟踪信息
- 目前已禁用，等待进一步测试

### 使用量跟踪
- 在 message_delta 响应中添加 usage 信息提取
- 以 OpenAI 格式包含 prompt_tokens、completion_tokens、total_tokens

internal/runtime/executor/kiro_executor.go

@@ -121,7 +121,12 @@ func (e *KiroExecutor) Execute(ctx context.Context, auth *cliproxyauth.Auth, req
 		return resp, fmt.Errorf("kiro: access token not found in auth")
 	}
 	if profileArn == "" {
-		log.Warnf("kiro: profile ARN not found in auth, API calls may fail")
+		// Only warn if not using builder-id auth (which doesn't need profileArn)
+		if auth == nil || auth.Metadata == nil {
+			log.Debugf("kiro: profile ARN not found in auth (may be normal for builder-id)")
+		} else if authMethod, ok := auth.Metadata["auth_method"].(string); !ok || authMethod != "builder-id" {
+			log.Warnf("kiro: profile ARN not found in auth, API calls may fail")
+		}
 	}
 
 	reporter := newUsageReporter(ctx, e.Identifier(), req.Model, auth)
@@ -161,10 +166,19 @@ func (e *KiroExecutor) Execute(ctx context.Context, auth *cliproxyauth.Auth, req
 		currentOrigin = "CLI"
 	}
 	
-	kiroPayload := e.buildKiroPayload(body, kiroModelID, profileArn, currentOrigin, isAgentic, isChatOnly)
+	// Determine if profileArn should be included based on auth method
+	// profileArn is only needed for social auth (Google OAuth), not for builder-id (AWS SSO)
+	effectiveProfileArn := profileArn
+	if auth != nil && auth.Metadata != nil {
+		if authMethod, ok := auth.Metadata["auth_method"].(string); ok && authMethod == "builder-id" {
+			effectiveProfileArn = "" // Don't include profileArn for builder-id auth
+		}
+	}
+	
+	kiroPayload := e.buildKiroPayload(body, kiroModelID, effectiveProfileArn, currentOrigin, isAgentic, isChatOnly)
 
 	// Execute with retry on 401/403 and 429 (quota exhausted)
-	resp, err = e.executeWithRetry(ctx, auth, req, opts, accessToken, profileArn, kiroPayload, body, from, to, reporter, currentOrigin, kiroModelID, isAgentic, isChatOnly)
+	resp, err = e.executeWithRetry(ctx, auth, req, opts, accessToken, effectiveProfileArn, kiroPayload, body, from, to, reporter, currentOrigin, kiroModelID, isAgentic, isChatOnly)
 	return resp, err
 }
 
@@ -330,7 +344,12 @@ func (e *KiroExecutor) ExecuteStream(ctx context.Context, auth *cliproxyauth.Aut
 		return nil, fmt.Errorf("kiro: access token not found in auth")
 	}
 	if profileArn == "" {
-		log.Warnf("kiro: profile ARN not found in auth, API calls may fail")
+		// Only warn if not using builder-id auth (which doesn't need profileArn)
+		if auth == nil || auth.Metadata == nil {
+			log.Debugf("kiro: profile ARN not found in auth (may be normal for builder-id)")
+		} else if authMethod, ok := auth.Metadata["auth_method"].(string); !ok || authMethod != "builder-id" {
+			log.Warnf("kiro: profile ARN not found in auth, API calls may fail")
+		}
 	}
 
 	reporter := newUsageReporter(ctx, e.Identifier(), req.Model, auth)
@@ -370,10 +389,19 @@ func (e *KiroExecutor) ExecuteStream(ctx context.Context, auth *cliproxyauth.Aut
 		currentOrigin = "CLI"
 	}
 	
-	kiroPayload := e.buildKiroPayload(body, kiroModelID, profileArn, currentOrigin, isAgentic, isChatOnly)
+	// Determine if profileArn should be included based on auth method
+	// profileArn is only needed for social auth (Google OAuth), not for builder-id (AWS SSO)
+	effectiveProfileArn := profileArn
+	if auth != nil && auth.Metadata != nil {
+		if authMethod, ok := auth.Metadata["auth_method"].(string); ok && authMethod == "builder-id" {
+			effectiveProfileArn = "" // Don't include profileArn for builder-id auth
+		}
+	}
+	
+	kiroPayload := e.buildKiroPayload(body, kiroModelID, effectiveProfileArn, currentOrigin, isAgentic, isChatOnly)
 
 	// Execute stream with retry on 401/403 and 429 (quota exhausted)
-	return e.executeStreamWithRetry(ctx, auth, req, opts, accessToken, profileArn, kiroPayload, body, from, reporter, currentOrigin, kiroModelID, isAgentic, isChatOnly)
+	return e.executeStreamWithRetry(ctx, auth, req, opts, accessToken, effectiveProfileArn, kiroPayload, body, from, reporter, currentOrigin, kiroModelID, isAgentic, isChatOnly)
 }
 
 // executeStreamWithRetry performs the streaming HTTP request with automatic retry on auth errors.
@@ -587,10 +615,10 @@ type kiroPayload struct {
 }
 
 type kiroConversationState struct {
+	ChatTriggerType string               `json:"chatTriggerType"` // Required: "MANUAL" - must be first field
 	ConversationID  string               `json:"conversationId"`
-	History         []kiroHistoryMessage `json:"history"`
 	CurrentMessage  kiroCurrentMessage   `json:"currentMessage"`
-	ChatTriggerType string               `json:"chatTriggerType"` // Required: "MANUAL"
+	History         []kiroHistoryMessage `json:"history,omitempty"` // Only include when non-empty
 }
 
 type kiroCurrentMessage struct {
@@ -805,21 +833,18 @@ func (e *KiroExecutor) buildKiroPayload(claudeBody []byte, modelID, profileArn,
 		}}
 	}
 	
+	// Build payload with correct field order (matches struct definition)
+	// Note: history is omitempty, so nil/empty slice won't be serialized
 	payload := kiroPayload{
 		ConversationState: kiroConversationState{
+			ChatTriggerType: "MANUAL", // Required by Kiro API - must be first
 			ConversationID:  uuid.New().String(),
-			History:         history,
 			CurrentMessage:  currentMessage,
-			ChatTriggerType: "MANUAL", // Required by Kiro API
+			History:         history, // Will be omitted if empty due to omitempty tag
 		},
 		ProfileArn: profileArn,
 	}
 
-	// Ensure history is not nil (empty array)
-	if payload.ConversationState.History == nil {
-		payload.ConversationState.History = []kiroHistoryMessage{}
-	}
-
 	result, err := json.Marshal(payload)
 	if err != nil {
 		log.Debugf("kiro: failed to marshal payload: %v", err)
@@ -1001,6 +1026,12 @@ func (e *KiroExecutor) parseEventStream(body io.Reader) (string, []kiroToolUse,
 			return content.String(), toolUses, usageInfo, fmt.Errorf("failed to read message: %w", err)
 		}
 
+		// Validate headersLen to prevent slice out of bounds
+		if headersLen+4 > uint32(len(remaining)) {
+			log.Warnf("kiro: invalid headersLen %d exceeds remaining buffer %d", headersLen, len(remaining))
+			continue
+		}
+
 		// Extract event type from headers
 		eventType := e.extractEventType(remaining[:headersLen+4])
 
@@ -1111,6 +1142,11 @@ func (e *KiroExecutor) parseEventStream(body io.Reader) (string, []kiroToolUse,
 	// Deduplicate all tool uses
 	toolUses = deduplicateToolUses(toolUses)
 
+	// OPTIONAL: Filter out [HELIOS_CHK] debug blocks from Kiro/Amazon Q internal systems
+	// These blocks contain internal state tracking information that should not be exposed to users.
+	// To enable filtering, uncomment the following line:
+	// cleanedContent = filterHeliosDebugInfo(cleanedContent)
+
 	return cleanedContent, toolUses, usageInfo, nil
 }
 
@@ -1279,6 +1315,51 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 		prelude := make([]byte, 8)
 		_, err := io.ReadFull(reader, prelude)
 		if err == io.EOF {
+			// Flush any incomplete tool use before ending stream
+			if currentToolUse != nil && !processedIDs[currentToolUse.toolUseID] {
+				log.Warnf("kiro: flushing incomplete tool use at EOF: %s (ID: %s)", currentToolUse.name, currentToolUse.toolUseID)
+				fullInput := currentToolUse.inputBuffer.String()
+				repairedJSON := repairJSON(fullInput)
+				var finalInput map[string]interface{}
+				if err := json.Unmarshal([]byte(repairedJSON), &finalInput); err != nil {
+					log.Warnf("kiro: failed to parse incomplete tool input at EOF: %v", err)
+					finalInput = make(map[string]interface{})
+				}
+				
+				processedIDs[currentToolUse.toolUseID] = true
+				contentBlockIndex++
+				
+				// Send tool_use content block
+				blockStart := e.buildClaudeContentBlockStartEvent(contentBlockIndex, "tool_use", currentToolUse.toolUseID, currentToolUse.name)
+				sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, blockStart, &translatorParam)
+				for _, chunk := range sseData {
+					if chunk != "" {
+						out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunk + "\n\n")}
+					}
+				}
+				
+				// Send tool input as delta
+				inputBytes, _ := json.Marshal(finalInput)
+				inputDelta := e.buildClaudeInputJsonDeltaEvent(string(inputBytes), contentBlockIndex)
+				sseData = sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, inputDelta, &translatorParam)
+				for _, chunk := range sseData {
+					if chunk != "" {
+						out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunk + "\n\n")}
+					}
+				}
+				
+				// Close block
+				blockStop := e.buildClaudeContentBlockStopEvent(contentBlockIndex)
+				sseData = sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, blockStop, &translatorParam)
+				for _, chunk := range sseData {
+					if chunk != "" {
+						out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunk + "\n\n")}
+					}
+				}
+				
+				hasToolUses = true
+				currentToolUse = nil
+			}
 			break
 		}
 		if err != nil {
@@ -1304,6 +1385,12 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 			return
 		}
 
+		// Validate headersLen to prevent slice out of bounds
+		if headersLen+4 > uint32(len(remaining)) {
+			log.Warnf("kiro: invalid headersLen %d exceeds remaining buffer %d", headersLen, len(remaining))
+			continue
+		}
+
 		eventType := e.extractEventType(remaining[:headersLen+4])
 
 		payloadStart := 4 + headersLen
@@ -1317,6 +1404,7 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 
 		var event map[string]interface{}
 		if err := json.Unmarshal(payload, &event); err != nil {
+			log.Warnf("kiro: failed to unmarshal event payload: %v, raw: %s", err, string(payload))
 			continue
 		}
 
@@ -1553,9 +1641,18 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 		stopReason = "tool_use"
 	}
 
-	// Send message_delta and message_stop
+	// Send message_delta event
-	msgStop := e.buildClaudeMessageStopEvent(stopReason, totalUsage)
+	msgDelta := e.buildClaudeMessageDeltaEvent(stopReason, totalUsage)
-	sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, msgStop, &translatorParam)
+	sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, msgDelta, &translatorParam)
+	for _, chunk := range sseData {
+		if chunk != "" {
+			out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunk + "\n\n")}
+		}
+	}
+
+	// Send message_stop event separately
+	msgStop := e.buildClaudeMessageStopOnlyEvent()
+	sseData = sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, msgStop, &translatorParam)
 	for _, chunk := range sseData {
 		if chunk != "" {
 			out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunk + "\n\n")}
@@ -1646,8 +1743,8 @@ func (e *KiroExecutor) buildClaudeContentBlockStopEvent(index int) []byte {
 	return []byte("event: content_block_stop\ndata: " + string(result))
 }
 
-func (e *KiroExecutor) buildClaudeMessageStopEvent(stopReason string, usageInfo usage.Detail) []byte {
+// buildClaudeMessageDeltaEvent creates the message_delta event with stop_reason and usage.
-	// First message_delta
+func (e *KiroExecutor) buildClaudeMessageDeltaEvent(stopReason string, usageInfo usage.Detail) []byte {
 	deltaEvent := map[string]interface{}{
 		"type": "message_delta",
 		"delta": map[string]interface{}{
@@ -1660,14 +1757,16 @@ func (e *KiroExecutor) buildClaudeMessageStopEvent(stopReason string, usageInfo
 		},
 	}
 	deltaResult, _ := json.Marshal(deltaEvent)
+	return []byte("event: message_delta\ndata: " + string(deltaResult))
+}
 
-	// Then message_stop
+// buildClaudeMessageStopOnlyEvent creates only the message_stop event.
+func (e *KiroExecutor) buildClaudeMessageStopOnlyEvent() []byte {
 	stopEvent := map[string]interface{}{
 		"type": "message_stop",
 	}
 	stopResult, _ := json.Marshal(stopEvent)
-
+	return []byte("event: message_stop\ndata: " + string(stopResult))
-	return []byte("event: message_delta\ndata: " + string(deltaResult) + "\n\nevent: message_stop\ndata: " + string(stopResult))
 }
 
 // buildClaudeFinalEvent constructs the final Claude-style event.
@@ -1873,6 +1972,12 @@ func (e *KiroExecutor) streamEventStream(ctx context.Context, body io.Reader, c
 			return fmt.Errorf("failed to read message: %w", err)
 		}
 
+		// Validate headersLen to prevent slice out of bounds
+		if headersLen+4 > uint32(len(remaining)) {
+			log.Warnf("kiro: invalid headersLen %d exceeds remaining buffer %d", headersLen, len(remaining))
+			continue
+		}
+
 		eventType := e.extractEventType(remaining[:headersLen+4])
 
 		payloadStart := 4 + headersLen
@@ -1886,6 +1991,7 @@ func (e *KiroExecutor) streamEventStream(ctx context.Context, body io.Reader, c
 
 		var event map[string]interface{}
 		if err := json.Unmarshal(payload, &event); err != nil {
+			log.Warnf("kiro: failed to unmarshal event payload: %v, raw: %s", err, string(payload))
 			continue
 		}
 
@@ -1983,9 +2089,19 @@ func (e *KiroExecutor) streamEventStream(ctx context.Context, body io.Reader, c
 	}
 	totalUsage.TotalTokens = totalUsage.InputTokens + totalUsage.OutputTokens
 
-	// Always use end_turn (no tool_use support)
+	// Send message_delta event
-	msgStop := e.buildClaudeMessageStopEvent("end_turn", totalUsage)
+	msgDelta := e.buildClaudeMessageDeltaEvent("end_turn", totalUsage)
-	sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, msgStop, &translatorParam)
+	sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, msgDelta, &translatorParam)
+	for _, chunk := range sseData {
+		if chunk != "" {
+			c.Writer.Write([]byte(chunk + "\n\n"))
+		}
+	}
+	c.Writer.Flush()
+
+	// Send message_stop event separately
+	msgStop := e.buildClaudeMessageStopOnlyEvent()
+	sseData = sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, msgStop, &translatorParam)
 	for _, chunk := range sseData {
 		if chunk != "" {
 			c.Writer.Write([]byte(chunk + "\n\n"))
@@ -2079,8 +2195,12 @@ var (
 	whitespaceCollapsePattern = regexp.MustCompile(`\s+`)
 	// trailingCommaPattern matches trailing commas before closing braces/brackets
 	trailingCommaPattern = regexp.MustCompile(`,\s*([}\]])`)
-	// unquotedKeyPattern matches unquoted JSON keys that need quoting
+	
-	unquotedKeyPattern = regexp.MustCompile(`([{,]\s*)([a-zA-Z_][a-zA-Z0-9_]*)\s*:`)
+	// heliosDebugPattern matches [HELIOS_CHK] debug blocks from Kiro/Amazon Q internal systems
+	// These blocks contain internal state tracking information that should not be exposed to users
+	// Format: [HELIOS_CHK]\nPhase: ...\nHelios: ...\nAction: ...\nTask: ...\nContext-Map: ...\nNext: ...
+	// The pattern matches from [HELIOS_CHK] to the end of the "Next:" line (which may span multiple lines until double newline)
+	heliosDebugPattern = regexp.MustCompile(`(?s)\[HELIOS_CHK\].*?(?:Next:.*?)(?:\n\n|\z)`)
 )
 
 // parseEmbeddedToolCalls extracts [Called tool_name with args: {...}] format from text.
@@ -2249,13 +2369,70 @@ func findMatchingBracket(text string, startPos int) int {
 // Based on AIClient-2-API's JSON repair implementation.
 // Uses pre-compiled regex patterns for performance.
 func repairJSON(raw string) string {
+	// First, escape unescaped newlines/tabs within JSON string values
+	repaired := escapeNewlinesInStrings(raw)
 	// Remove trailing commas before closing braces/brackets
-	repaired := trailingCommaPattern.ReplaceAllString(raw, "$1")
+	repaired = trailingCommaPattern.ReplaceAllString(repaired, "$1")
-	// Fix unquoted keys (basic attempt - handles simple cases)
+	// Note: unquotedKeyPattern removed - it incorrectly matches content inside
-	repaired = unquotedKeyPattern.ReplaceAllString(repaired, `$1"$2":`)
+	// JSON string values (e.g., "classDef fill:#1a1a2e,stroke:#00d4ff" would have
+	// ",stroke:" incorrectly treated as an unquoted key)
 	return repaired
 }
 
+// escapeNewlinesInStrings escapes literal newlines, tabs, and other control characters
+// that appear inside JSON string values. This handles cases where streaming fragments
+// contain unescaped control characters within string content.
+func escapeNewlinesInStrings(raw string) string {
+	var result strings.Builder
+	result.Grow(len(raw) + 100) // Pre-allocate with some extra space
+
+	inString := false
+	escaped := false
+
+	for i := 0; i < len(raw); i++ {
+		c := raw[i]
+
+		if escaped {
+			// Previous character was backslash, this is an escape sequence
+			result.WriteByte(c)
+			escaped = false
+			continue
+		}
+
+		if c == '\\' && inString {
+			// Start of escape sequence
+			result.WriteByte(c)
+			escaped = true
+			continue
+		}
+
+		if c == '"' {
+			// Toggle string state
+			inString = !inString
+			result.WriteByte(c)
+			continue
+		}
+
+		if inString {
+			// Inside a string, escape control characters
+			switch c {
+			case '\n':
+				result.WriteString("\\n")
+			case '\r':
+				result.WriteString("\\r")
+			case '\t':
+				result.WriteString("\\t")
+			default:
+				result.WriteByte(c)
+			}
+		} else {
+			result.WriteByte(c)
+		}
+	}
+
+	return result.String()
+}
+
 // processToolUseEvent handles a toolUseEvent from the Kiro stream.
 // It accumulates input fragments and emits tool_use blocks when complete.
 // Returns events to emit and updated state.
@@ -2330,6 +2507,8 @@ func (e *KiroExecutor) processToolUseEvent(event map[string]interface{}, current
 
 	// Accumulate input fragments
 	if currentToolUse != nil && inputFragment != "" {
+		// Accumulate fragments directly - they form valid JSON when combined
+		// The fragments are already decoded from JSON, so we just concatenate them
 		currentToolUse.inputBuffer.WriteString(inputFragment)
 		log.Debugf("kiro: accumulated input fragment, total length: %d", currentToolUse.inputBuffer.Len())
 	}
@@ -2389,3 +2568,39 @@ func deduplicateToolUses(toolUses []kiroToolUse) []kiroToolUse {
 
 	return unique
 }
+
+// filterHeliosDebugInfo removes [HELIOS_CHK] debug blocks from Kiro/Amazon Q responses.
+// These blocks contain internal state tracking information from the Helios system
+// that should not be exposed to end users.
+//
+// The [HELIOS_CHK] block format typically looks like:
+//
+//	[HELIOS_CHK]
+//	Phase: E (Evaluate & Evolve)
+//	Helios: [P1_Intent: OK] [P2_Research: OK] [P3_Strategy: OK]
+//	Action: [TEXT_RESPONSE]
+//	Task: #T001 - Some task description
+//	Context-Map: [SYNCED]
+//	Next: Some next action description...
+//
+// This function is currently DISABLED (commented out in callers) pending further testing.
+// To enable, uncomment the filterHeliosDebugInfo calls in parseEventStream() and streamToChannel().
+func filterHeliosDebugInfo(content string) string {
+	if !strings.Contains(content, "[HELIOS_CHK]") {
+		return content
+	}
+	
+	// Remove [HELIOS_CHK] blocks
+	filtered := heliosDebugPattern.ReplaceAllString(content, "")
+	
+	// Clean up any resulting double newlines or leading/trailing whitespace
+	filtered = strings.TrimSpace(filtered)
+	
+	// Log when filtering occurs for debugging purposes
+	if filtered != content {
+		log.Debugf("kiro: filtered HELIOS debug info from response (original len: %d, filtered len: %d)",
+			len(content), len(filtered))
+	}
+	
+	return filtered
+}

internal/translator/kiro/openai/chat-completions/kiro_openai_response.go

@@ -171,7 +171,7 @@ func convertClaudeEventToOpenAI(jsonStr string, model string) []string {
 		return results
 
 	case "message_delta":
-		// Final message delta with stop_reason
+		// Final message delta with stop_reason and usage
 		stopReason := root.Get("delta.stop_reason").String()
 		if stopReason != "" {
 			finishReason := "stop"
@@ -196,6 +196,19 @@ func convertClaudeEventToOpenAI(jsonStr string, model string) []string {
 					},
 				},
 			}
+
+			// Extract and include usage information from message_delta event
+			usage := root.Get("usage")
+			if usage.Exists() {
+				inputTokens := usage.Get("input_tokens").Int()
+				outputTokens := usage.Get("output_tokens").Int()
+				response["usage"] = map[string]interface{}{
+					"prompt_tokens":     inputTokens,
+					"completion_tokens": outputTokens,
+					"total_tokens":      inputTokens + outputTokens,
+				}
+			}
+
 			result, _ := json.Marshal(response)
 			results = append(results, string(result))
 		}