feat: optimize connection pooling and improve Kiro executor reliability

## 中文说明

### 连接池优化
- 为 AMP 代理、SOCKS5 代理和 HTTP 代理配置优化的连接池参数
- MaxIdleConnsPerHost 从默认的 2 增加到 20，支持更多并发用户
- MaxConnsPerHost 设为 0（无限制），避免连接瓶颈
- 添加 IdleConnTimeout (90s) 和其他超时配置

### Kiro 执行器增强
- 添加 Event Stream 消息解析的边界保护，防止越界访问
- 实现实时使用量估算（每 5000 字符或 15 秒发送 ping 事件）
- 正确从上游事件中提取并传递 stop_reason
- 改进输入 token 计算，优先使用 Claude 格式解析
- 添加 max_tokens 截断警告日志

### Token 计算改进
- 添加 tokenizer 缓存（sync.Map）避免重复创建
- 为 Claude/Kiro/AmazonQ 模型添加 1.1 调整因子
- 新增 countClaudeChatTokens 函数支持 Claude API 格式
- 支持图像 token 估算（基于尺寸计算）

### 认证刷新优化
- RefreshLead 从 30 分钟改为 5 分钟，与 Antigravity 保持一致
- 修复 NextRefreshAfter 设置，防止频繁刷新检查
- refreshFailureBackoff 从 5 分钟改为 1 分钟，加快失败恢复

---

## English Description

### Connection Pool Optimization
- Configure optimized connection pool parameters for AMP proxy, SOCKS5 proxy, and HTTP proxy
- Increase MaxIdleConnsPerHost from default 2 to 20 to support more concurrent users
- Set MaxConnsPerHost to 0 (unlimited) to avoid connection bottlenecks
- Add IdleConnTimeout (90s) and other timeout configurations

### Kiro Executor Enhancements
- Add boundary protection for Event Stream message parsing to prevent out-of-bounds access
- Implement real-time usage estimation (send ping events every 5000 chars or 15 seconds)
- Correctly extract and pass stop_reason from upstream events
- Improve input token calculation, prioritize Claude format parsing
- Add max_tokens truncation warning logs

### Token Calculation Improvements
- Add tokenizer cache (sync.Map) to avoid repeated creation
- Add 1.1 adjustment factor for Claude/Kiro/AmazonQ models
- Add countClaudeChatTokens function to support Claude API format
- Support image token estimation (calculated based on dimensions)

### Authentication Refresh Optimization
- Change RefreshLead from 30 minutes to 5 minutes, consistent with Antigravity
- Fix NextRefreshAfter setting to prevent frequent refresh checks
- Change refreshFailureBackoff from 5 minutes to 1 minute for faster failure recovery

internal/api/modules/amp/proxy.go

@@ -7,11 +7,13 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"net"
 	"net/http"
 	"net/http/httputil"
 	"net/url"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/gin-gonic/gin"
 	log "github.com/sirupsen/logrus"
@@ -36,6 +38,22 @@ func createReverseProxy(upstreamURL string, secretSource SecretSource) (*httputi
 	}
 
 	proxy := httputil.NewSingleHostReverseProxy(parsed)
+
+	// Configure custom Transport with optimized connection pooling for high concurrency
+	proxy.Transport = &http.Transport{
+		MaxIdleConns:        100,
+		MaxIdleConnsPerHost: 20, // Increased from default 2 to support more concurrent users
+		MaxConnsPerHost:     0, // No limit on max concurrent connections per host
+		IdleConnTimeout:     90 * time.Second,
+		DialContext: (&net.Dialer{
+			Timeout:   30 * time.Second,
+			KeepAlive: 30 * time.Second,
+		}).DialContext,
+		TLSHandshakeTimeout:   10 * time.Second,
+		ResponseHeaderTimeout: 60 * time.Second,
+		ExpectContinueTimeout: 1 * time.Second,
+	}
+
 	originalDirector := proxy.Director
 
 	// Modify outgoing requests to inject API key and fix routing
@@ -64,7 +82,15 @@ func createReverseProxy(upstreamURL string, secretSource SecretSource) (*httputi
 	// Modify incoming responses to handle gzip without Content-Encoding
 	// This addresses the same issue as inline handler gzip handling, but at the proxy level
 	proxy.ModifyResponse = func(resp *http.Response) error {
-		// Only process successful responses
+		// Log upstream error responses for diagnostics (502, 503, etc.)
+		// These are NOT proxy connection errors - the upstream responded with an error status
+		if resp.StatusCode >= 500 {
+			log.Errorf("amp upstream responded with error [%d] for %s %s", resp.StatusCode, resp.Request.Method, resp.Request.URL.Path)
+		} else if resp.StatusCode >= 400 {
+			log.Warnf("amp upstream responded with client error [%d] for %s %s", resp.StatusCode, resp.Request.Method, resp.Request.URL.Path)
+		}
+
+		// Only process successful responses for gzip decompression
 		if resp.StatusCode < 200 || resp.StatusCode >= 300 {
 			return nil
 		}
@@ -148,15 +174,29 @@ func createReverseProxy(upstreamURL string, secretSource SecretSource) (*httputi
 		return nil
 	}
 
-	// Error handler for proxy failures
+	// Error handler for proxy failures with detailed error classification for diagnostics
 	proxy.ErrorHandler = func(rw http.ResponseWriter, req *http.Request, err error) {
-		// Check if this is a client-side cancellation (normal behavior)
+		// Classify the error type for better diagnostics
+		var errType string
+		if errors.Is(err, context.DeadlineExceeded) {
+			errType = "timeout"
+		} else if errors.Is(err, context.Canceled) {
+			errType = "canceled"
+		} else if netErr, ok := err.(net.Error); ok && netErr.Timeout() {
+			errType = "dial_timeout"
+		} else if _, ok := err.(net.Error); ok {
+			errType = "network_error"
+		} else {
+			errType = "connection_error"
+		}
+
 		// Don't log as error for context canceled - it's usually client closing connection
 		if errors.Is(err, context.Canceled) {
-			log.Debugf("amp upstream proxy: client canceled request for %s %s", req.Method, req.URL.Path)
+			log.Debugf("amp upstream proxy [%s]: client canceled request for %s %s", errType, req.Method, req.URL.Path)
 		} else {
-			log.Errorf("amp upstream proxy error for %s %s: %v", req.Method, req.URL.Path, err)
+			log.Errorf("amp upstream proxy error [%s] for %s %s: %v", errType, req.Method, req.URL.Path, err)
 		}
+
 		rw.Header().Set("Content-Type", "application/json")
 		rw.WriteHeader(http.StatusBadGateway)
 		_, _ = rw.Write([]byte(`{"error":"amp_upstream_proxy_error","message":"Failed to reach Amp upstream"}`))

internal/runtime/executor/kiro_executor.go

@@ -36,6 +36,16 @@ const (
 	kiroAcceptStream   = "*/*"
 	kiroMaxMessageSize = 10 * 1024 * 1024 // 10MB max message size for event stream
 	kiroMaxToolDescLen = 10237            // Kiro API limit is 10240 bytes, leave room for "..."
+
+	// Event Stream frame size constants for boundary protection
+	// AWS Event Stream binary format: prelude (12 bytes) + headers + payload + message_crc (4 bytes)
+	// Prelude consists of: total_length (4) + headers_length (4) + prelude_crc (4)
+	minEventStreamFrameSize = 16        // Minimum: 4(total_len) + 4(headers_len) + 4(prelude_crc) + 4(message_crc)
+	maxEventStreamMsgSize   = 10 << 20  // Maximum message length: 10MB
+
+	// Event Stream error type constants
+	ErrStreamFatal     = "fatal"     // Connection/authentication errors, not recoverable
+	ErrStreamMalformed = "malformed" // Format errors, data cannot be parsed
 	// kiroUserAgent matches amq2api format for User-Agent header
 	kiroUserAgent = "aws-sdk-rust/1.3.9 os/macos lang/rust/1.87.0"
 	// kiroFullUserAgent is the complete x-amz-user-agent header matching amq2api
@@ -102,6 +112,13 @@ You MUST follow these rules for ALL file operations. Violation causes server tim
 REMEMBER: When in doubt, write LESS per operation. Multiple small operations > one large operation.`
 )
 
+// Real-time usage estimation configuration
+// These control how often usage updates are sent during streaming
+var (
+	usageUpdateCharThreshold = 5000              // Send usage update every 5000 characters
+	usageUpdateTimeInterval  = 15 * time.Second  // Or every 15 seconds, whichever comes first
+)
+
 // kiroEndpointConfig bundles endpoint URL with its compatible Origin and AmzTarget values.
 // This solves the "triple mismatch" problem where different endpoints require matching
 // Origin and X-Amz-Target header values.
@@ -495,7 +512,7 @@ func (e *KiroExecutor) executeWithRetry(ctx context.Context, auth *cliproxyauth.
 			}
 		}()
 
-		content, toolUses, usageInfo, err := e.parseEventStream(httpResp.Body)
+		content, toolUses, usageInfo, stopReason, err := e.parseEventStream(httpResp.Body)
 		if err != nil {
 			recordAPIResponseError(ctx, e.cfg, err)
 			return resp, err
@@ -503,14 +520,14 @@ func (e *KiroExecutor) executeWithRetry(ctx context.Context, auth *cliproxyauth.
 
 		// Fallback for usage if missing from upstream
 		if usageInfo.TotalTokens == 0 {
-			if enc, encErr := tokenizerForModel(req.Model); encErr == nil {
+			if enc, encErr := getTokenizer(req.Model); encErr == nil {
 				if inp, countErr := countOpenAIChatTokens(enc, opts.OriginalRequest); countErr == nil {
 					usageInfo.InputTokens = inp
 				}
 			}
 			if len(content) > 0 {
 				// Use tiktoken for more accurate output token calculation
-				if enc, encErr := tokenizerForModel(req.Model); encErr == nil {
+				if enc, encErr := getTokenizer(req.Model); encErr == nil {
 					if tokenCount, countErr := enc.Count(content); countErr == nil {
 						usageInfo.OutputTokens = int64(tokenCount)
 					}
@@ -530,7 +547,8 @@ func (e *KiroExecutor) executeWithRetry(ctx context.Context, auth *cliproxyauth.
 		reporter.publish(ctx, usageInfo)
 
 		// Build response in Claude format for Kiro translator
-		kiroResponse := e.buildClaudeResponse(content, toolUses, req.Model, usageInfo)
+		// stopReason is extracted from upstream response by parseEventStream
+		kiroResponse := e.buildClaudeResponse(content, toolUses, req.Model, usageInfo, stopReason)
 		out := sdktranslator.TranslateNonStream(ctx, to, from, req.Model, bytes.Clone(opts.OriginalRequest), body, kiroResponse, nil)
 		resp = cliproxyexecutor.Response{Payload: []byte(out)}
 		return resp, nil
@@ -970,11 +988,40 @@ func (e *KiroExecutor) mapModelToKiro(model string) string {
 	return "claude-sonnet-4.5"
 }
 
+// EventStreamError represents an Event Stream processing error
+type EventStreamError struct {
+	Type    string // "fatal", "malformed"
+	Message string
+	Cause   error
+}
+
+func (e *EventStreamError) Error() string {
+	if e.Cause != nil {
+		return fmt.Sprintf("event stream %s: %s: %v", e.Type, e.Message, e.Cause)
+	}
+	return fmt.Sprintf("event stream %s: %s", e.Type, e.Message)
+}
+
+// eventStreamMessage represents a parsed AWS Event Stream message
+type eventStreamMessage struct {
+	EventType string // Event type from headers (e.g., "assistantResponseEvent")
+	Payload   []byte // JSON payload of the message
+}
+
 // Kiro API request structs - field order determines JSON key order
 
 type kiroPayload struct {
 	ConversationState kiroConversationState `json:"conversationState"`
 	ProfileArn        string                `json:"profileArn,omitempty"`
+	InferenceConfig   *kiroInferenceConfig  `json:"inferenceConfig,omitempty"`
+}
+
+// kiroInferenceConfig contains inference parameters for the Kiro API.
+// NOTE: This is an experimental addition - Kiro/Amazon Q API may not support these parameters.
+// If the API ignores or rejects these fields, response length is controlled internally by the model.
+type kiroInferenceConfig struct {
+	MaxTokens   int `json:"maxTokens,omitempty"`   // Maximum output tokens (may be ignored by API)
+	Temperature float64 `json:"temperature,omitempty"` // Sampling temperature (may be ignored by API)
 }
 
 type kiroConversationState struct {
@@ -1058,7 +1105,25 @@ type kiroToolUse struct {
 // isAgentic parameter enables chunked write optimization prompt for -agentic model variants.
 // isChatOnly parameter disables tool calling for -chat model variants (pure conversation mode).
 // Supports thinking mode - when Claude API thinking parameter is present, injects thinkingHint.
+//
+// max_tokens support: Kiro/Amazon Q API may not officially support max_tokens parameter.
+// We attempt to pass it via inferenceConfig.maxTokens, but the API may ignore it.
+// Response truncation can be detected via stop_reason == "max_tokens" in the response.
 func (e *KiroExecutor) buildKiroPayload(claudeBody []byte, modelID, profileArn, origin string, isAgentic, isChatOnly bool) []byte {
+	// Extract max_tokens for potential use in inferenceConfig
+	var maxTokens int64
+	if mt := gjson.GetBytes(claudeBody, "max_tokens"); mt.Exists() {
+		maxTokens = mt.Int()
+	}
+	
+	// Extract temperature if specified
+	var temperature float64
+	var hasTemperature bool
+	if temp := gjson.GetBytes(claudeBody, "temperature"); temp.Exists() {
+		temperature = temp.Float()
+		hasTemperature = true
+	}
+
 	// Normalize origin value for Kiro API compatibility
 	// Kiro API only accepts "CLI" or "AI_EDITOR" as valid origin values
 	switch origin {
@@ -1325,6 +1390,18 @@ func (e *KiroExecutor) buildKiroPayload(claudeBody []byte, modelID, profileArn,
 		}}
 	}
 	
+	// Build inferenceConfig if we have any inference parameters
+	var inferenceConfig *kiroInferenceConfig
+	if maxTokens > 0 || hasTemperature {
+		inferenceConfig = &kiroInferenceConfig{}
+		if maxTokens > 0 {
+			inferenceConfig.MaxTokens = int(maxTokens)
+		}
+		if hasTemperature {
+			inferenceConfig.Temperature = temperature
+		}
+	}
+
 	// Build payload with correct field order (matches struct definition)
 	payload := kiroPayload{
 		ConversationState: kiroConversationState{
@@ -1333,7 +1410,8 @@ func (e *KiroExecutor) buildKiroPayload(claudeBody []byte, modelID, profileArn,
 			CurrentMessage:  currentMessage,
 			History:         history, // Now always included (non-nil slice)
 		},
-		ProfileArn: profileArn,
+		ProfileArn:      profileArn,
+		InferenceConfig: inferenceConfig,
 	}
 
 	result, err := json.Marshal(payload)
@@ -1493,12 +1571,14 @@ func (e *KiroExecutor) buildAssistantMessageStruct(msg gjson.Result) kiroAssista
 // NOTE: Tool calling is now supported via userInputMessageContext.tools and toolResults
 
 // parseEventStream parses AWS Event Stream binary format.
-// Extracts text content and tool uses from the response.
+// Extracts text content, tool uses, and stop_reason from the response.
 // Supports embedded [Called ...] tool calls and input buffering for toolUseEvent.
-func (e *KiroExecutor) parseEventStream(body io.Reader) (string, []kiroToolUse, usage.Detail, error) {
+// Returns: content, toolUses, usageInfo, stopReason, error
+func (e *KiroExecutor) parseEventStream(body io.Reader) (string, []kiroToolUse, usage.Detail, string, error) {
 	var content strings.Builder
 	var toolUses []kiroToolUse
 	var usageInfo usage.Detail
+	var stopReason string // Extracted from upstream response
 	reader := bufio.NewReader(body)
 
 	// Tool use state tracking for input buffering and deduplication
@@ -1506,59 +1586,28 @@ func (e *KiroExecutor) parseEventStream(body io.Reader) (string, []kiroToolUse,
 	var currentToolUse *toolUseState
 
 	for {
-		prelude := make([]byte, 8)
+		msg, eventErr := e.readEventStreamMessage(reader)
-		_, err := io.ReadFull(reader, prelude)
+		if eventErr != nil {
-		if err == io.EOF {
+			log.Errorf("kiro: parseEventStream error: %v", eventErr)
+			return content.String(), toolUses, usageInfo, stopReason, eventErr
+		}
+		if msg == nil {
+			// Normal end of stream (EOF)
 			break
 		}
-		if err != nil {
-			return content.String(), toolUses, usageInfo, fmt.Errorf("failed to read prelude: %w", err)
-		}
 
-		totalLen := binary.BigEndian.Uint32(prelude[0:4])
+		eventType := msg.EventType
-		if totalLen < 8 {
+		payload := msg.Payload
-			return content.String(), toolUses, usageInfo, fmt.Errorf("invalid message length: %d", totalLen)
+		if len(payload) == 0 {
-		}
-		if totalLen > kiroMaxMessageSize {
-			return content.String(), toolUses, usageInfo, fmt.Errorf("message too large: %d bytes", totalLen)
-		}
-		headersLen := binary.BigEndian.Uint32(prelude[4:8])
-
-		remaining := make([]byte, totalLen-8)
-		_, err = io.ReadFull(reader, remaining)
-		if err != nil {
-			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])
-
-		payloadStart := 4 + headersLen
-		payloadEnd := uint32(len(remaining)) - 4
-		if payloadStart >= payloadEnd {
-			continue
-		}
-
-		payload := remaining[payloadStart:payloadEnd]
-
 		var event map[string]interface{}
 		if err := json.Unmarshal(payload, &event); err != nil {
 			log.Debugf("kiro: skipping malformed event: %v", err)
 			continue
 		}
 
-		// DIAGNOSTIC: Log all received event types for debugging
-		log.Debugf("kiro: parseEventStream received event type: %s", eventType)
-		if log.IsLevelEnabled(log.TraceLevel) {
-			log.Tracef("kiro: parseEventStream event payload: %s", string(payload))
-		}
-
 		// Check for error/exception events in the payload (Kiro API may return errors with HTTP 200)
 		// These can appear as top-level fields or nested within the event
 		if errType, hasErrType := event["_type"].(string); hasErrType {
@@ -1568,7 +1617,7 @@ func (e *KiroExecutor) parseEventStream(body io.Reader) (string, []kiroToolUse,
 				errMsg = msg
 			}
 			log.Errorf("kiro: received AWS error in event stream: type=%s, message=%s", errType, errMsg)
-			return "", nil, usageInfo, fmt.Errorf("kiro API error: %s - %s", errType, errMsg)
+			return "", nil, usageInfo, stopReason, fmt.Errorf("kiro API error: %s - %s", errType, errMsg)
 		}
 		if errType, hasErrType := event["type"].(string); hasErrType && (errType == "error" || errType == "exception") {
 			// Generic error event
@@ -1581,7 +1630,18 @@ func (e *KiroExecutor) parseEventStream(body io.Reader) (string, []kiroToolUse,
 				}
 			}
 			log.Errorf("kiro: received error event in stream: type=%s, message=%s", errType, errMsg)
-			return "", nil, usageInfo, fmt.Errorf("kiro API error: %s", errMsg)
+			return "", nil, usageInfo, stopReason, fmt.Errorf("kiro API error: %s", errMsg)
+		}
+
+		// Extract stop_reason from various event formats
+		// Kiro/Amazon Q API may include stop_reason in different locations
+		if sr := getString(event, "stop_reason"); sr != "" {
+			stopReason = sr
+			log.Debugf("kiro: parseEventStream found stop_reason (top-level): %s", stopReason)
+		}
+		if sr := getString(event, "stopReason"); sr != "" {
+			stopReason = sr
+			log.Debugf("kiro: parseEventStream found stopReason (top-level): %s", stopReason)
 		}
 
 		// Handle different event types
@@ -1596,6 +1656,15 @@ func (e *KiroExecutor) parseEventStream(body io.Reader) (string, []kiroToolUse,
 				if contentText, ok := assistantResp["content"].(string); ok {
 					content.WriteString(contentText)
 				}
+				// Extract stop_reason from assistantResponseEvent
+				if sr := getString(assistantResp, "stop_reason"); sr != "" {
+					stopReason = sr
+					log.Debugf("kiro: parseEventStream found stop_reason in assistantResponseEvent: %s", stopReason)
+				}
+				if sr := getString(assistantResp, "stopReason"); sr != "" {
+					stopReason = sr
+					log.Debugf("kiro: parseEventStream found stopReason in assistantResponseEvent: %s", stopReason)
+				}
 				// Extract tool uses from response
 				if toolUsesRaw, ok := assistantResp["toolUses"].([]interface{}); ok {
 					for _, tuRaw := range toolUsesRaw {
@@ -1661,6 +1730,17 @@ func (e *KiroExecutor) parseEventStream(body io.Reader) (string, []kiroToolUse,
 			if outputTokens, ok := event["outputTokens"].(float64); ok {
 				usageInfo.OutputTokens = int64(outputTokens)
 			}
+
+		case "messageStopEvent", "message_stop":
+			// Handle message stop events which may contain stop_reason
+			if sr := getString(event, "stop_reason"); sr != "" {
+				stopReason = sr
+				log.Debugf("kiro: parseEventStream found stop_reason in messageStopEvent: %s", stopReason)
+			}
+			if sr := getString(event, "stopReason"); sr != "" {
+				stopReason = sr
+				log.Debugf("kiro: parseEventStream found stopReason in messageStopEvent: %s", stopReason)
+			}
 		}
 
 		// Also check nested supplementaryWebLinksEvent
@@ -1682,10 +1762,166 @@ func (e *KiroExecutor) parseEventStream(body io.Reader) (string, []kiroToolUse,
 	// Deduplicate all tool uses
 	toolUses = deduplicateToolUses(toolUses)
 
-	return cleanedContent, toolUses, usageInfo, nil
+	// Apply fallback logic for stop_reason if not provided by upstream
+	// Priority: upstream stopReason > tool_use detection > end_turn default
+	if stopReason == "" {
+		if len(toolUses) > 0 {
+			stopReason = "tool_use"
+			log.Debugf("kiro: parseEventStream using fallback stop_reason: tool_use (detected %d tool uses)", len(toolUses))
+		} else {
+			stopReason = "end_turn"
+			log.Debugf("kiro: parseEventStream using fallback stop_reason: end_turn")
+		}
+	}
+
+	// Log warning if response was truncated due to max_tokens
+	if stopReason == "max_tokens" {
+		log.Warnf("kiro: response truncated due to max_tokens limit")
+	}
+
+	return cleanedContent, toolUses, usageInfo, stopReason, nil
+}
+
+// readEventStreamMessage reads and validates a single AWS Event Stream message.
+// Returns the parsed message or a structured error for different failure modes.
+// This function implements boundary protection and detailed error classification.
+//
+// AWS Event Stream binary format:
+// - Prelude (12 bytes): total_length (4) + headers_length (4) + prelude_crc (4)
+// - Headers (variable): header entries
+// - Payload (variable): JSON data
+// - Message CRC (4 bytes): CRC32C of entire message (not validated, just skipped)
+func (e *KiroExecutor) readEventStreamMessage(reader *bufio.Reader) (*eventStreamMessage, *EventStreamError) {
+	// Read prelude (first 12 bytes: total_len + headers_len + prelude_crc)
+	prelude := make([]byte, 12)
+	_, err := io.ReadFull(reader, prelude)
+	if err == io.EOF {
+		return nil, nil // Normal end of stream
+	}
+	if err != nil {
+		return nil, &EventStreamError{
+			Type:    ErrStreamFatal,
+			Message: "failed to read prelude",
+			Cause:   err,
+		}
+	}
+
+	totalLength := binary.BigEndian.Uint32(prelude[0:4])
+	headersLength := binary.BigEndian.Uint32(prelude[4:8])
+	// Note: prelude[8:12] is prelude_crc - we read it but don't validate (no CRC check per requirements)
+
+	// Boundary check: minimum frame size
+	if totalLength < minEventStreamFrameSize {
+		return nil, &EventStreamError{
+			Type:    ErrStreamMalformed,
+			Message: fmt.Sprintf("invalid message length: %d (minimum is %d)", totalLength, minEventStreamFrameSize),
+		}
+	}
+
+	// Boundary check: maximum message size
+	if totalLength > maxEventStreamMsgSize {
+		return nil, &EventStreamError{
+			Type:    ErrStreamMalformed,
+			Message: fmt.Sprintf("message too large: %d bytes (maximum is %d)", totalLength, maxEventStreamMsgSize),
+		}
+	}
+
+	// Boundary check: headers length within message bounds
+	// Message structure: prelude(12) + headers(headersLength) + payload + message_crc(4)
+	// So: headersLength must be <= totalLength - 16 (12 for prelude + 4 for message_crc)
+	if headersLength > totalLength-16 {
+		return nil, &EventStreamError{
+			Type:    ErrStreamMalformed,
+			Message: fmt.Sprintf("headers length %d exceeds message bounds (total: %d)", headersLength, totalLength),
+		}
+	}
+
+	// Read the rest of the message (total - 12 bytes already read)
+	remaining := make([]byte, totalLength-12)
+	_, err = io.ReadFull(reader, remaining)
+	if err != nil {
+		return nil, &EventStreamError{
+			Type:    ErrStreamFatal,
+			Message: "failed to read message body",
+			Cause:   err,
+		}
+	}
+
+	// Extract event type from headers
+	// Headers start at beginning of 'remaining', length is headersLength
+	var eventType string
+	if headersLength > 0 && headersLength <= uint32(len(remaining)) {
+		eventType = e.extractEventTypeFromBytes(remaining[:headersLength])
+	}
+
+	// Calculate payload boundaries
+	// Payload starts after headers, ends before message_crc (last 4 bytes)
+	payloadStart := headersLength
+	payloadEnd := uint32(len(remaining)) - 4 // Skip message_crc at end
+
+	// Validate payload boundaries
+	if payloadStart >= payloadEnd {
+		// No payload, return empty message
+		return &eventStreamMessage{
+			EventType: eventType,
+			Payload:   nil,
+		}, nil
+	}
+
+	payload := remaining[payloadStart:payloadEnd]
+
+	return &eventStreamMessage{
+		EventType: eventType,
+		Payload:   payload,
+	}, nil
+}
+
+// extractEventTypeFromBytes extracts the event type from raw header bytes (without prelude CRC prefix)
+func (e *KiroExecutor) extractEventTypeFromBytes(headers []byte) string {
+	offset := 0
+	for offset < len(headers) {
+		if offset >= len(headers) {
+			break
+		}
+		nameLen := int(headers[offset])
+		offset++
+		if offset+nameLen > len(headers) {
+			break
+		}
+		name := string(headers[offset : offset+nameLen])
+		offset += nameLen
+
+		if offset >= len(headers) {
+			break
+		}
+		valueType := headers[offset]
+		offset++
+
+		if valueType == 7 { // String type
+			if offset+2 > len(headers) {
+				break
+			}
+			valueLen := int(binary.BigEndian.Uint16(headers[offset : offset+2]))
+			offset += 2
+			if offset+valueLen > len(headers) {
+				break
+			}
+			value := string(headers[offset : offset+valueLen])
+			offset += valueLen
+
+			if name == ":event-type" {
+				return value
+			}
+		} else {
+			// Skip other types
+			break
+		}
+	}
+	return ""
 }
 
 // extractEventType extracts the event type from AWS Event Stream headers
+// Note: This is the legacy version that expects headerBytes to include prelude CRC prefix
 func (e *KiroExecutor) extractEventType(headerBytes []byte) string {
 	// Skip prelude CRC (4 bytes)
 	if len(headerBytes) < 4 {
@@ -1746,7 +1982,8 @@ func getString(m map[string]interface{}, key string) string {
 // buildClaudeResponse constructs a Claude-compatible response.
 // Supports tool_use blocks when tools are present in the response.
 // Supports thinking blocks - parses <thinking> tags and converts to Claude thinking content blocks.
-func (e *KiroExecutor) buildClaudeResponse(content string, toolUses []kiroToolUse, model string, usageInfo usage.Detail) []byte {
+// stopReason is passed from upstream; fallback logic applied if empty.
+func (e *KiroExecutor) buildClaudeResponse(content string, toolUses []kiroToolUse, model string, usageInfo usage.Detail, stopReason string) []byte {
 	var contentBlocks []map[string]interface{}
 
 	// Extract thinking blocks and text from content
@@ -1782,10 +2019,18 @@ func (e *KiroExecutor) buildClaudeResponse(content string, toolUses []kiroToolUs
 		})
 	}
 
-	// Determine stop reason
+	// Use upstream stopReason; apply fallback logic if not provided
-	stopReason := "end_turn"
+	if stopReason == "" {
-	if len(toolUses) > 0 {
+		stopReason = "end_turn"
-		stopReason = "tool_use"
+		if len(toolUses) > 0 {
+			stopReason = "tool_use"
+		}
+		log.Debugf("kiro: buildClaudeResponse using fallback stop_reason: %s", stopReason)
+	}
+
+	// Log warning if response was truncated due to max_tokens
+	if stopReason == "max_tokens" {
+		log.Warnf("kiro: response truncated due to max_tokens limit (buildClaudeResponse)")
 	}
 
 	response := map[string]interface{}{
@@ -1906,10 +2151,12 @@ func (e *KiroExecutor) extractThinkingFromContent(content string) []map[string]i
 // Supports tool calling - emits tool_use content blocks when tools are used.
 // Includes embedded [Called ...] tool call parsing and input buffering for toolUseEvent.
 // Implements duplicate content filtering using lastContentEvent detection (based on AIClient-2-API).
+// Extracts stop_reason from upstream events when available.
 func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out chan<- cliproxyexecutor.StreamChunk, targetFormat sdktranslator.Format, model string, originalReq, claudeBody []byte, reporter *usageReporter) {
 	reader := bufio.NewReaderSize(body, 20*1024*1024) // 20MB buffer to match other providers
 	var totalUsage usage.Detail
-	var hasToolUses bool // Track if any tool uses were emitted
+	var hasToolUses bool                 // Track if any tool uses were emitted
+	var upstreamStopReason string        // Track stop_reason from upstream events
 
 	// Tool use state tracking for input buffering and deduplication
 	processedIDs := make(map[string]bool)
@@ -1925,6 +2172,12 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 	var accumulatedContent strings.Builder
 	accumulatedContent.Grow(4096) // Pre-allocate 4KB capacity to reduce reallocations
 
+	// Real-time usage estimation state
+	// These track when to send periodic usage updates during streaming
+	var lastUsageUpdateLen int           // Last accumulated content length when usage was sent
+	var lastUsageUpdateTime = time.Now() // Last time usage update was sent
+	var lastReportedOutputTokens int64   // Last reported output token count
+
 	// Translator param for maintaining tool call state across streaming events
 	// IMPORTANT: This must persist across all TranslateStream calls
 	var translatorParam any
@@ -1932,24 +2185,37 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 	// Thinking mode state tracking - based on amq2api implementation
 	// Tracks whether we're inside a <thinking> block and handles partial tags
 	inThinkBlock := false
-	pendingStartTagChars := 0                 // Number of chars that might be start of <thinking>
+	pendingStartTagChars := 0            // Number of chars that might be start of <thinking>
-	pendingEndTagChars := 0                   // Number of chars that might be start of </thinking>
+	pendingEndTagChars := 0              // Number of chars that might be start of </thinking>
-	isThinkingBlockOpen := false              // Track if thinking content block is open
+	isThinkingBlockOpen := false         // Track if thinking content block is open
-	thinkingBlockIndex := -1                  // Index of the thinking content block
+	thinkingBlockIndex := -1             // Index of the thinking content block
 
 	// Pre-calculate input tokens from request if possible
-	if enc, err := tokenizerForModel(model); err == nil {
+	// Kiro uses Claude format, so try Claude format first, then OpenAI format, then fallback
-		// Try OpenAI format first, then fall back to raw byte count estimation
+	if enc, err := getTokenizer(model); err == nil {
-		if inp, err := countOpenAIChatTokens(enc, originalReq); err == nil && inp > 0 {
+		var inputTokens int64
-			totalUsage.InputTokens = inp
+		var countMethod string
+		
+		// Try Claude format first (Kiro uses Claude API format)
+		if inp, err := countClaudeChatTokens(enc, claudeBody); err == nil && inp > 0 {
+			inputTokens = inp
+			countMethod = "claude"
+		} else if inp, err := countOpenAIChatTokens(enc, originalReq); err == nil && inp > 0 {
+			// Fallback to OpenAI format (for OpenAI-compatible requests)
+			inputTokens = inp
+			countMethod = "openai"
 		} else {
-			// Fallback: estimate from raw request size (roughly 4 chars per token)
+			// Final fallback: estimate from raw request size (roughly 4 chars per token)
-			totalUsage.InputTokens = int64(len(originalReq) / 4)
+			inputTokens = int64(len(claudeBody) / 4)
-			if totalUsage.InputTokens == 0 && len(originalReq) > 0 {
+			if inputTokens == 0 && len(claudeBody) > 0 {
-				totalUsage.InputTokens = 1
+				inputTokens = 1
 			}
+			countMethod = "estimate"
 		}
-		log.Debugf("kiro: streamToChannel pre-calculated input tokens: %d (request size: %d bytes)", totalUsage.InputTokens, len(originalReq))
+		
+		totalUsage.InputTokens = inputTokens
+		log.Debugf("kiro: streamToChannel pre-calculated input tokens: %d (method: %s, claude body: %d bytes, original req: %d bytes)",
+			totalUsage.InputTokens, countMethod, len(claudeBody), len(originalReq))
 	}
 
 	contentBlockIndex := -1
@@ -1969,9 +2235,17 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 		default:
 		}
 
-		prelude := make([]byte, 8)
+		msg, eventErr := e.readEventStreamMessage(reader)
-		_, err := io.ReadFull(reader, prelude)
+		if eventErr != nil {
-		if err == io.EOF {
+			// Log the error
+			log.Errorf("kiro: streamToChannel error: %v", eventErr)
+			
+			// Send error to channel for client notification
+			out <- cliproxyexecutor.StreamChunk{Err: eventErr}
+			return
+		}
+		if msg == nil {
+			// Normal end of stream (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)
@@ -2069,44 +2343,12 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 			}
 			break
 		}
-		if err != nil {
-			out <- cliproxyexecutor.StreamChunk{Err: fmt.Errorf("failed to read prelude: %w", err)}
-			return
-		}
 
-		totalLen := binary.BigEndian.Uint32(prelude[0:4])
+		eventType := msg.EventType
-		if totalLen < 8 {
+		payload := msg.Payload
-			out <- cliproxyexecutor.StreamChunk{Err: fmt.Errorf("invalid message length: %d", totalLen)}
+		if len(payload) == 0 {
-			return
-		}
-		if totalLen > kiroMaxMessageSize {
-			out <- cliproxyexecutor.StreamChunk{Err: fmt.Errorf("message too large: %d bytes", totalLen)}
-			return
-		}
-		headersLen := binary.BigEndian.Uint32(prelude[4:8])
-
-		remaining := make([]byte, totalLen-8)
-		_, err = io.ReadFull(reader, remaining)
-		if err != nil {
-			out <- cliproxyexecutor.StreamChunk{Err: fmt.Errorf("failed to read message: %w", err)}
-			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
-		payloadEnd := uint32(len(remaining)) - 4
-		if payloadStart >= payloadEnd {
-			continue
-		}
-
-		payload := remaining[payloadStart:payloadEnd]
 		appendAPIResponseChunk(ctx, e.cfg, payload)
 
 		var event map[string]interface{}
@@ -2115,12 +2357,6 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 			continue
 		}
 
-		// DIAGNOSTIC: Log all received event types for debugging
-		log.Debugf("kiro: streamToChannel received event type: %s", eventType)
-		if log.IsLevelEnabled(log.TraceLevel) {
-			log.Tracef("kiro: streamToChannel event payload: %s", string(payload))
-		}
-
 		// Check for error/exception events in the payload (Kiro API may return errors with HTTP 200)
 		// These can appear as top-level fields or nested within the event
 		if errType, hasErrType := event["_type"].(string); hasErrType {
@@ -2148,6 +2384,17 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 			return
 		}
 
+		// Extract stop_reason from various event formats (streaming)
+		// Kiro/Amazon Q API may include stop_reason in different locations
+		if sr := getString(event, "stop_reason"); sr != "" {
+			upstreamStopReason = sr
+			log.Debugf("kiro: streamToChannel found stop_reason (top-level): %s", upstreamStopReason)
+		}
+		if sr := getString(event, "stopReason"); sr != "" {
+			upstreamStopReason = sr
+			log.Debugf("kiro: streamToChannel found stopReason (top-level): %s", upstreamStopReason)
+		}
+
 		// Send message_start on first event
 		if !messageStartSent {
 			msgStart := e.buildClaudeMessageStartEvent(model, totalUsage.InputTokens)
@@ -2166,6 +2413,17 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 			log.Debugf("kiro: streamToChannel ignoring followupPrompt event")
 			continue
 
+		case "messageStopEvent", "message_stop":
+			// Handle message stop events which may contain stop_reason
+			if sr := getString(event, "stop_reason"); sr != "" {
+				upstreamStopReason = sr
+				log.Debugf("kiro: streamToChannel found stop_reason in messageStopEvent: %s", upstreamStopReason)
+			}
+			if sr := getString(event, "stopReason"); sr != "" {
+				upstreamStopReason = sr
+				log.Debugf("kiro: streamToChannel found stopReason in messageStopEvent: %s", upstreamStopReason)
+			}
+
 		case "assistantResponseEvent":
 			var contentDelta string
 			var toolUses []map[string]interface{}
@@ -2174,6 +2432,15 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 				if c, ok := assistantResp["content"].(string); ok {
 					contentDelta = c
 				}
+				// Extract stop_reason from assistantResponseEvent
+				if sr := getString(assistantResp, "stop_reason"); sr != "" {
+					upstreamStopReason = sr
+					log.Debugf("kiro: streamToChannel found stop_reason in assistantResponseEvent: %s", upstreamStopReason)
+				}
+				if sr := getString(assistantResp, "stopReason"); sr != "" {
+					upstreamStopReason = sr
+					log.Debugf("kiro: streamToChannel found stopReason in assistantResponseEvent: %s", upstreamStopReason)
+				}
 				// Extract tool uses from response
 				if tus, ok := assistantResp["toolUses"].([]interface{}); ok {
 					for _, tuRaw := range tus {
@@ -2199,11 +2466,6 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 
 			// Handle text content with thinking mode support
 			if contentDelta != "" {
-				// DIAGNOSTIC: Check for thinking tags in response
-				if strings.Contains(contentDelta, "<thinking>") || strings.Contains(contentDelta, "</thinking>") {
-					log.Infof("kiro: DIAGNOSTIC - Found thinking tag in response (len: %d)", len(contentDelta))
-				}
-
 				// NOTE: Duplicate content filtering was removed because it incorrectly
 				// filtered out legitimate repeated content (like consecutive newlines "\n\n").
 				// Streaming naturally can have identical chunks that are valid content.
@@ -2212,6 +2474,52 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 				// Accumulate content for streaming token calculation
 				accumulatedContent.WriteString(contentDelta)
 				
+				// Real-time usage estimation: Check if we should send a usage update
+				// This helps clients track context usage during long thinking sessions
+				shouldSendUsageUpdate := false
+				if accumulatedContent.Len()-lastUsageUpdateLen >= usageUpdateCharThreshold {
+					shouldSendUsageUpdate = true
+				} else if time.Since(lastUsageUpdateTime) >= usageUpdateTimeInterval && accumulatedContent.Len() > lastUsageUpdateLen {
+					shouldSendUsageUpdate = true
+				}
+				
+				if shouldSendUsageUpdate {
+					// Calculate current output tokens using tiktoken
+					var currentOutputTokens int64
+					if enc, encErr := getTokenizer(model); encErr == nil {
+						if tokenCount, countErr := enc.Count(accumulatedContent.String()); countErr == nil {
+							currentOutputTokens = int64(tokenCount)
+						}
+					}
+					// Fallback to character estimation if tiktoken fails
+					if currentOutputTokens == 0 {
+						currentOutputTokens = int64(accumulatedContent.Len() / 4)
+						if currentOutputTokens == 0 {
+							currentOutputTokens = 1
+						}
+					}
+					
+					// Only send update if token count has changed significantly (at least 10 tokens)
+					if currentOutputTokens > lastReportedOutputTokens+10 {
+						// Send ping event with usage information
+						// This is a non-blocking update that clients can optionally process
+						pingEvent := e.buildClaudePingEventWithUsage(totalUsage.InputTokens, currentOutputTokens)
+						sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, pingEvent, &translatorParam)
+						for _, chunk := range sseData {
+							if chunk != "" {
+								out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunk + "\n\n")}
+							}
+						}
+						
+						lastReportedOutputTokens = currentOutputTokens
+						log.Debugf("kiro: sent real-time usage update - input: %d, output: %d (accumulated: %d chars)",
+							totalUsage.InputTokens, currentOutputTokens, accumulatedContent.Len())
+					}
+					
+					lastUsageUpdateLen = accumulatedContent.Len()
+					lastUsageUpdateTime = time.Now()
+				}
+
 				// Process content with thinking tag detection - based on amq2api implementation
 				// This handles <thinking> and </thinking> tags that may span across chunks
 				remaining := contentDelta
@@ -2577,10 +2885,10 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 	}
 
 	// Streaming token calculation - calculate output tokens from accumulated content
-	// This provides more accurate token counting than simple character division
+	// Only use local estimation if server didn't provide usage (server-side usage takes priority)
 	if totalUsage.OutputTokens == 0 && accumulatedContent.Len() > 0 {
 		// Try to use tiktoken for accurate counting
-		if enc, err := tokenizerForModel(model); err == nil {
+		if enc, err := getTokenizer(model); err == nil {
 			if tokenCount, countErr := enc.Count(accumulatedContent.String()); countErr == nil {
 				totalUsage.OutputTokens = int64(tokenCount)
 				log.Debugf("kiro: streamToChannel calculated output tokens using tiktoken: %d", totalUsage.OutputTokens)
@@ -2609,10 +2917,21 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 	}
 	totalUsage.TotalTokens = totalUsage.InputTokens + totalUsage.OutputTokens
 
-	// Determine stop reason based on whether tool uses were emitted
+	// Determine stop reason: prefer upstream, then detect tool_use, default to end_turn
-	stopReason := "end_turn"
+	stopReason := upstreamStopReason
-	if hasToolUses {
+	if stopReason == "" {
-		stopReason = "tool_use"
+		if hasToolUses {
+			stopReason = "tool_use"
+			log.Debugf("kiro: streamToChannel using fallback stop_reason: tool_use")
+		} else {
+			stopReason = "end_turn"
+			log.Debugf("kiro: streamToChannel using fallback stop_reason: end_turn")
+		}
+	}
+
+	// Log warning if response was truncated due to max_tokens
+	if stopReason == "max_tokens" {
+		log.Warnf("kiro: response truncated due to max_tokens limit (streamToChannel)")
 	}
 
 	// Send message_delta event
@@ -2758,6 +3077,24 @@ func (e *KiroExecutor) buildClaudeFinalEvent() []byte {
 	return []byte("event: message_stop\ndata: " + string(result))
 }
 
+// buildClaudePingEventWithUsage creates a ping event with embedded usage information.
+// This is used for real-time usage estimation during streaming.
+// The usage field is a non-standard extension that clients can optionally process.
+// Clients that don't recognize the usage field will simply ignore it.
+func (e *KiroExecutor) buildClaudePingEventWithUsage(inputTokens, outputTokens int64) []byte {
+	event := map[string]interface{}{
+		"type": "ping",
+		"usage": map[string]interface{}{
+			"input_tokens":  inputTokens,
+			"output_tokens": outputTokens,
+			"total_tokens":  inputTokens + outputTokens,
+			"estimated":     true, // Flag to indicate this is an estimate, not final
+		},
+	}
+	result, _ := json.Marshal(event)
+	return []byte("event: ping\ndata: " + string(result))
+}
+
 // buildClaudeThinkingDeltaEvent creates a thinking_delta event for Claude API compatibility.
 // This is used when streaming thinking content wrapped in <thinking> tags.
 func (e *KiroExecutor) buildClaudeThinkingDeltaEvent(thinkingDelta string, index int) []byte {
@@ -2837,10 +3174,21 @@ func (e *KiroExecutor) Refresh(ctx context.Context, auth *cliproxyauth.Auth) (*c
 		// Also check if expires_at is now in the future with sufficient buffer
 		if expiresAt, ok := auth.Metadata["expires_at"].(string); ok {
 			if expTime, err := time.Parse(time.RFC3339, expiresAt); err == nil {
-				// If token expires more than 2 minutes from now, it's still valid
+				// If token expires more than 5 minutes from now, it's still valid
-				if time.Until(expTime) > 2*time.Minute {
+				if time.Until(expTime) > 5*time.Minute {
 					log.Debugf("kiro executor: token is still valid (expires in %v), skipping refresh", time.Until(expTime))
-					return auth, nil
+					// CRITICAL FIX: Set NextRefreshAfter to prevent frequent refresh checks
+					// Without this, shouldRefresh() will return true again in 5 seconds
+					updated := auth.Clone()
+					// Set next refresh to 5 minutes before expiry, or at least 30 seconds from now
+					nextRefresh := expTime.Add(-5 * time.Minute)
+					minNextRefresh := time.Now().Add(30 * time.Second)
+					if nextRefresh.Before(minNextRefresh) {
+						nextRefresh = minNextRefresh
+					}
+					updated.NextRefreshAfter = nextRefresh
+					log.Debugf("kiro executor: setting NextRefreshAfter to %v (in %v)", nextRefresh.Format(time.RFC3339), time.Until(nextRefresh))
+					return updated, nil
 				}
 			}
 		}
@@ -2924,9 +3272,9 @@ func (e *KiroExecutor) Refresh(ctx context.Context, auth *cliproxyauth.Auth) (*c
 		updated.Attributes["profile_arn"] = tokenData.ProfileArn
 	}
 
-	// Set next refresh time to 30 minutes before expiry
+	// NextRefreshAfter is aligned with RefreshLead (5min)
 	if expiresAt, parseErr := time.Parse(time.RFC3339, tokenData.ExpiresAt); parseErr == nil {
-		updated.NextRefreshAfter = expiresAt.Add(-30 * time.Minute)
+		updated.NextRefreshAfter = expiresAt.Add(-5 * time.Minute)
 	}
 
 	log.Infof("kiro executor: token refreshed successfully, expires at %s", tokenData.ExpiresAt)
@@ -2943,7 +3291,7 @@ func (e *KiroExecutor) streamEventStream(ctx context.Context, body io.Reader, c
 	var translatorParam any
 
 	// Pre-calculate input tokens from request if possible
-	if enc, err := tokenizerForModel(model); err == nil {
+	if enc, err := getTokenizer(model); err == nil {
 		// Try OpenAI format first, then fall back to raw byte count estimation
 		if inp, err := countOpenAIChatTokens(enc, originalReq); err == nil && inp > 0 {
 			totalUsage.InputTokens = inp

internal/runtime/executor/proxy_helpers.go

@@ -137,15 +137,25 @@ func buildProxyTransport(proxyURL string) *http.Transport {
 			log.Errorf("create SOCKS5 dialer failed: %v", errSOCKS5)
 			return nil
 		}
-		// Set up a custom transport using the SOCKS5 dialer
+		// Set up a custom transport using the SOCKS5 dialer with optimized connection pooling
 		transport = &http.Transport{
 			DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
 				return dialer.Dial(network, addr)
 			},
+			MaxIdleConns:        100,
+			MaxIdleConnsPerHost: 20, // Increased from default 2 to support more concurrent users
+			MaxConnsPerHost:     0, // No limit on max concurrent connections per host
+			IdleConnTimeout:     90 * time.Second,
 		}
 	} else if parsedURL.Scheme == "http" || parsedURL.Scheme == "https" {
-		// Configure HTTP or HTTPS proxy
+		// Configure HTTP or HTTPS proxy with optimized connection pooling
-		transport = &http.Transport{Proxy: http.ProxyURL(parsedURL)}
+		transport = &http.Transport{
+			Proxy:               http.ProxyURL(parsedURL),
+			MaxIdleConns:        100,
+			MaxIdleConnsPerHost: 20, // Increased from default 2 to support more concurrent users
+			MaxConnsPerHost:     0, // No limit on max concurrent connections per host
+			IdleConnTimeout:     90 * time.Second,
+		}
 	} else {
 		log.Errorf("unsupported proxy scheme: %s", parsedURL.Scheme)
 		return nil

internal/runtime/executor/token_helpers.go

@@ -2,43 +2,107 @@ package executor
 
 import (
 	"fmt"
+	"regexp"
+	"strconv"
 	"strings"
+	"sync"
 
 	"github.com/tidwall/gjson"
 	"github.com/tiktoken-go/tokenizer"
 )
 
+// tokenizerCache stores tokenizer instances to avoid repeated creation
+var tokenizerCache sync.Map
+
+// TokenizerWrapper wraps a tokenizer codec with an adjustment factor for models
+// where tiktoken may not accurately estimate token counts (e.g., Claude models)
+type TokenizerWrapper struct {
+	Codec            tokenizer.Codec
+	AdjustmentFactor float64 // 1.0 means no adjustment, >1.0 means tiktoken underestimates
+}
+
+// Count returns the token count with adjustment factor applied
+func (tw *TokenizerWrapper) Count(text string) (int, error) {
+	count, err := tw.Codec.Count(text)
+	if err != nil {
+		return 0, err
+	}
+	if tw.AdjustmentFactor != 1.0 && tw.AdjustmentFactor > 0 {
+		return int(float64(count) * tw.AdjustmentFactor), nil
+	}
+	return count, nil
+}
+
+// getTokenizer returns a cached tokenizer for the given model.
+// This improves performance by avoiding repeated tokenizer creation.
+func getTokenizer(model string) (*TokenizerWrapper, error) {
+	// Check cache first
+	if cached, ok := tokenizerCache.Load(model); ok {
+		return cached.(*TokenizerWrapper), nil
+	}
+
+	// Cache miss, create new tokenizer
+	wrapper, err := tokenizerForModel(model)
+	if err != nil {
+		return nil, err
+	}
+
+	// Store in cache (use LoadOrStore to handle race conditions)
+	actual, _ := tokenizerCache.LoadOrStore(model, wrapper)
+	return actual.(*TokenizerWrapper), nil
+}
+
 // tokenizerForModel returns a tokenizer codec suitable for an OpenAI-style model id.
-func tokenizerForModel(model string) (tokenizer.Codec, error) {
+// For Claude models, applies a 1.1 adjustment factor since tiktoken may underestimate.
+func tokenizerForModel(model string) (*TokenizerWrapper, error) {
 	sanitized := strings.ToLower(strings.TrimSpace(model))
+
+	// Claude models use cl100k_base with 1.1 adjustment factor
+	// because tiktoken may underestimate Claude's actual token count
+	if strings.Contains(sanitized, "claude") || strings.HasPrefix(sanitized, "kiro-") || strings.HasPrefix(sanitized, "amazonq-") {
+		enc, err := tokenizer.Get(tokenizer.Cl100kBase)
+		if err != nil {
+			return nil, err
+		}
+		return &TokenizerWrapper{Codec: enc, AdjustmentFactor: 1.1}, nil
+	}
+
+	var enc tokenizer.Codec
+	var err error
+
 	switch {
 	case sanitized == "":
-		return tokenizer.Get(tokenizer.Cl100kBase)
+		enc, err = tokenizer.Get(tokenizer.Cl100kBase)
 	case strings.HasPrefix(sanitized, "gpt-5"):
-		return tokenizer.ForModel(tokenizer.GPT5)
+		enc, err = tokenizer.ForModel(tokenizer.GPT5)
 	case strings.HasPrefix(sanitized, "gpt-5.1"):
-		return tokenizer.ForModel(tokenizer.GPT5)
+		enc, err = tokenizer.ForModel(tokenizer.GPT5)
 	case strings.HasPrefix(sanitized, "gpt-4.1"):
-		return tokenizer.ForModel(tokenizer.GPT41)
+		enc, err = tokenizer.ForModel(tokenizer.GPT41)
 	case strings.HasPrefix(sanitized, "gpt-4o"):
-		return tokenizer.ForModel(tokenizer.GPT4o)
+		enc, err = tokenizer.ForModel(tokenizer.GPT4o)
 	case strings.HasPrefix(sanitized, "gpt-4"):
-		return tokenizer.ForModel(tokenizer.GPT4)
+		enc, err = tokenizer.ForModel(tokenizer.GPT4)
 	case strings.HasPrefix(sanitized, "gpt-3.5"), strings.HasPrefix(sanitized, "gpt-3"):
-		return tokenizer.ForModel(tokenizer.GPT35Turbo)
+		enc, err = tokenizer.ForModel(tokenizer.GPT35Turbo)
 	case strings.HasPrefix(sanitized, "o1"):
-		return tokenizer.ForModel(tokenizer.O1)
+		enc, err = tokenizer.ForModel(tokenizer.O1)
 	case strings.HasPrefix(sanitized, "o3"):
-		return tokenizer.ForModel(tokenizer.O3)
+		enc, err = tokenizer.ForModel(tokenizer.O3)
 	case strings.HasPrefix(sanitized, "o4"):
-		return tokenizer.ForModel(tokenizer.O4Mini)
+		enc, err = tokenizer.ForModel(tokenizer.O4Mini)
 	default:
-		return tokenizer.Get(tokenizer.O200kBase)
+		enc, err = tokenizer.Get(tokenizer.O200kBase)
 	}
+
+	if err != nil {
+		return nil, err
+	}
+	return &TokenizerWrapper{Codec: enc, AdjustmentFactor: 1.0}, nil
 }
 
 // countOpenAIChatTokens approximates prompt tokens for OpenAI chat completions payloads.
-func countOpenAIChatTokens(enc tokenizer.Codec, payload []byte) (int64, error) {
+func countOpenAIChatTokens(enc *TokenizerWrapper, payload []byte) (int64, error) {
 	if enc == nil {
 		return 0, fmt.Errorf("encoder is nil")
 	}
@@ -62,11 +126,206 @@ func countOpenAIChatTokens(enc tokenizer.Codec, payload []byte) (int64, error) {
 		return 0, nil
 	}
 
+	// Count text tokens
 	count, err := enc.Count(joined)
 	if err != nil {
 		return 0, err
 	}
-	return int64(count), nil
+
+	// Extract and add image tokens from placeholders
+	imageTokens := extractImageTokens(joined)
+
+	return int64(count) + int64(imageTokens), nil
+}
+
+// countClaudeChatTokens approximates prompt tokens for Claude API chat completions payloads.
+// This handles Claude's message format with system, messages, and tools.
+// Image tokens are estimated based on image dimensions when available.
+func countClaudeChatTokens(enc *TokenizerWrapper, payload []byte) (int64, error) {
+	if enc == nil {
+		return 0, fmt.Errorf("encoder is nil")
+	}
+	if len(payload) == 0 {
+		return 0, nil
+	}
+
+	root := gjson.ParseBytes(payload)
+	segments := make([]string, 0, 32)
+
+	// Collect system prompt (can be string or array of content blocks)
+	collectClaudeSystem(root.Get("system"), &segments)
+	
+	// Collect messages
+	collectClaudeMessages(root.Get("messages"), &segments)
+	
+	// Collect tools
+	collectClaudeTools(root.Get("tools"), &segments)
+
+	joined := strings.TrimSpace(strings.Join(segments, "\n"))
+	if joined == "" {
+		return 0, nil
+	}
+
+	// Count text tokens
+	count, err := enc.Count(joined)
+	if err != nil {
+		return 0, err
+	}
+
+	// Extract and add image tokens from placeholders
+	imageTokens := extractImageTokens(joined)
+
+	return int64(count) + int64(imageTokens), nil
+}
+
+// imageTokenPattern matches [IMAGE:xxx tokens] format for extracting estimated image tokens
+var imageTokenPattern = regexp.MustCompile(`\[IMAGE:(\d+) tokens\]`)
+
+// extractImageTokens extracts image token estimates from placeholder text.
+// Placeholders are in the format [IMAGE:xxx tokens] where xxx is the estimated token count.
+func extractImageTokens(text string) int {
+	matches := imageTokenPattern.FindAllStringSubmatch(text, -1)
+	total := 0
+	for _, match := range matches {
+		if len(match) > 1 {
+			if tokens, err := strconv.Atoi(match[1]); err == nil {
+				total += tokens
+			}
+		}
+	}
+	return total
+}
+
+// estimateImageTokens calculates estimated tokens for an image based on dimensions.
+// Based on Claude's image token calculation: tokens ≈ (width * height) / 750
+// Minimum 85 tokens, maximum 1590 tokens (for 1568x1568 images).
+func estimateImageTokens(width, height float64) int {
+	if width <= 0 || height <= 0 {
+		// No valid dimensions, use default estimate (medium-sized image)
+		return 1000
+	}
+
+	tokens := int(width * height / 750)
+
+	// Apply bounds
+	if tokens < 85 {
+		tokens = 85
+	}
+	if tokens > 1590 {
+		tokens = 1590
+	}
+
+	return tokens
+}
+
+// collectClaudeSystem extracts text from Claude's system field.
+// System can be a string or an array of content blocks.
+func collectClaudeSystem(system gjson.Result, segments *[]string) {
+	if !system.Exists() {
+		return
+	}
+	if system.Type == gjson.String {
+		addIfNotEmpty(segments, system.String())
+		return
+	}
+	if system.IsArray() {
+		system.ForEach(func(_, block gjson.Result) bool {
+			blockType := block.Get("type").String()
+			if blockType == "text" || blockType == "" {
+				addIfNotEmpty(segments, block.Get("text").String())
+			}
+			// Also handle plain string blocks
+			if block.Type == gjson.String {
+				addIfNotEmpty(segments, block.String())
+			}
+			return true
+		})
+	}
+}
+
+// collectClaudeMessages extracts text from Claude's messages array.
+func collectClaudeMessages(messages gjson.Result, segments *[]string) {
+	if !messages.Exists() || !messages.IsArray() {
+		return
+	}
+	messages.ForEach(func(_, message gjson.Result) bool {
+		addIfNotEmpty(segments, message.Get("role").String())
+		collectClaudeContent(message.Get("content"), segments)
+		return true
+	})
+}
+
+// collectClaudeContent extracts text from Claude's content field.
+// Content can be a string or an array of content blocks.
+// For images, estimates token count based on dimensions when available.
+func collectClaudeContent(content gjson.Result, segments *[]string) {
+	if !content.Exists() {
+		return
+	}
+	if content.Type == gjson.String {
+		addIfNotEmpty(segments, content.String())
+		return
+	}
+	if content.IsArray() {
+		content.ForEach(func(_, part gjson.Result) bool {
+			partType := part.Get("type").String()
+			switch partType {
+			case "text":
+				addIfNotEmpty(segments, part.Get("text").String())
+			case "image":
+				// Estimate image tokens based on dimensions if available
+				source := part.Get("source")
+				if source.Exists() {
+					width := source.Get("width").Float()
+					height := source.Get("height").Float()
+					if width > 0 && height > 0 {
+						tokens := estimateImageTokens(width, height)
+						addIfNotEmpty(segments, fmt.Sprintf("[IMAGE:%d tokens]", tokens))
+					} else {
+						// No dimensions available, use default estimate
+						addIfNotEmpty(segments, "[IMAGE:1000 tokens]")
+					}
+				} else {
+					// No source info, use default estimate
+					addIfNotEmpty(segments, "[IMAGE:1000 tokens]")
+				}
+			case "tool_use":
+				addIfNotEmpty(segments, part.Get("id").String())
+				addIfNotEmpty(segments, part.Get("name").String())
+				if input := part.Get("input"); input.Exists() {
+					addIfNotEmpty(segments, input.Raw)
+				}
+			case "tool_result":
+				addIfNotEmpty(segments, part.Get("tool_use_id").String())
+				collectClaudeContent(part.Get("content"), segments)
+			case "thinking":
+				addIfNotEmpty(segments, part.Get("thinking").String())
+			default:
+				// For unknown types, try to extract any text content
+				if part.Type == gjson.String {
+					addIfNotEmpty(segments, part.String())
+				} else if part.Type == gjson.JSON {
+					addIfNotEmpty(segments, part.Raw)
+				}
+			}
+			return true
+		})
+	}
+}
+
+// collectClaudeTools extracts text from Claude's tools array.
+func collectClaudeTools(tools gjson.Result, segments *[]string) {
+	if !tools.Exists() || !tools.IsArray() {
+		return
+	}
+	tools.ForEach(func(_, tool gjson.Result) bool {
+		addIfNotEmpty(segments, tool.Get("name").String())
+		addIfNotEmpty(segments, tool.Get("description").String())
+		if inputSchema := tool.Get("input_schema"); inputSchema.Exists() {
+			addIfNotEmpty(segments, inputSchema.Raw)
+		}
+		return true
+	})
 }
 
 // buildOpenAIUsageJSON returns a minimal usage structure understood by downstream translators.

internal/util/proxy.go

@@ -8,6 +8,7 @@ import (
 	"net"
 	"net/http"
 	"net/url"
+	"time"
 
 	"github.com/router-for-me/CLIProxyAPI/v6/sdk/config"
 	log "github.com/sirupsen/logrus"
@@ -36,15 +37,25 @@ func SetProxy(cfg *config.SDKConfig, httpClient *http.Client) *http.Client {
 				log.Errorf("create SOCKS5 dialer failed: %v", errSOCKS5)
 				return httpClient
 			}
-			// Set up a custom transport using the SOCKS5 dialer.
+			// Set up a custom transport using the SOCKS5 dialer with optimized connection pooling
 			transport = &http.Transport{
 				DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
 					return dialer.Dial(network, addr)
 				},
+				MaxIdleConns:        100,
+				MaxIdleConnsPerHost: 20, // Increased from default 2 to support more concurrent users
+				MaxConnsPerHost:     0, // No limit on max concurrent connections per host
+				IdleConnTimeout:     90 * time.Second,
 			}
 		} else if proxyURL.Scheme == "http" || proxyURL.Scheme == "https" {
-			// Configure HTTP or HTTPS proxy.
+			// Configure HTTP or HTTPS proxy with optimized connection pooling
-			transport = &http.Transport{Proxy: http.ProxyURL(proxyURL)}
+			transport = &http.Transport{
+				Proxy:               http.ProxyURL(proxyURL),
+				MaxIdleConns:        100,
+				MaxIdleConnsPerHost: 20, // Increased from default 2 to support more concurrent users
+				MaxConnsPerHost:     0, // No limit on max concurrent connections per host
+				IdleConnTimeout:     90 * time.Second,
+			}
 		}
 	}
 	// If a new transport was created, apply it to the HTTP client.

sdk/auth/kiro.go

@@ -47,8 +47,9 @@ func (a *KiroAuthenticator) Provider() string {
 }
 
 // RefreshLead indicates how soon before expiry a refresh should be attempted.
+// Set to 5 minutes to match Antigravity and avoid frequent refresh checks while still ensuring timely token refresh.
 func (a *KiroAuthenticator) RefreshLead() *time.Duration {
-	d := 30 * time.Minute
+	d := 5 * time.Minute
 	return &d
 }
 
@@ -103,7 +104,8 @@ func (a *KiroAuthenticator) Login(ctx context.Context, cfg *config.Config, opts
 			"source":      "aws-builder-id",
 			"email":       tokenData.Email,
 		},
-		NextRefreshAfter: expiresAt.Add(-30 * time.Minute),
+		// NextRefreshAfter is aligned with RefreshLead (5min)
+		NextRefreshAfter: expiresAt.Add(-5 * time.Minute),
 	}
 
 	if tokenData.Email != "" {
@@ -165,7 +167,8 @@ func (a *KiroAuthenticator) LoginWithGoogle(ctx context.Context, cfg *config.Con
 			"source":      "google-oauth",
 			"email":       tokenData.Email,
 		},
-		NextRefreshAfter: expiresAt.Add(-30 * time.Minute),
+		// NextRefreshAfter is aligned with RefreshLead (5min)
+		NextRefreshAfter: expiresAt.Add(-5 * time.Minute),
 	}
 
 	if tokenData.Email != "" {
@@ -227,7 +230,8 @@ func (a *KiroAuthenticator) LoginWithGitHub(ctx context.Context, cfg *config.Con
 			"source":      "github-oauth",
 			"email":       tokenData.Email,
 		},
-		NextRefreshAfter: expiresAt.Add(-30 * time.Minute),
+		// NextRefreshAfter is aligned with RefreshLead (5min)
+		NextRefreshAfter: expiresAt.Add(-5 * time.Minute),
 	}
 
 	if tokenData.Email != "" {
@@ -291,7 +295,8 @@ func (a *KiroAuthenticator) ImportFromKiroIDE(ctx context.Context, cfg *config.C
 			"source":      "kiro-ide-import",
 			"email":       tokenData.Email,
 		},
-		NextRefreshAfter: expiresAt.Add(-30 * time.Minute),
+		// NextRefreshAfter is aligned with RefreshLead (5min)
+		NextRefreshAfter: expiresAt.Add(-5 * time.Minute),
 	}
 
 	// Display the email if extracted
@@ -351,7 +356,8 @@ func (a *KiroAuthenticator) Refresh(ctx context.Context, cfg *config.Config, aut
 	updated.Metadata["refresh_token"] = tokenData.RefreshToken
 	updated.Metadata["expires_at"] = tokenData.ExpiresAt
 	updated.Metadata["last_refresh"] = now.Format(time.RFC3339) // For double-check optimization
-	updated.NextRefreshAfter = expiresAt.Add(-30 * time.Minute)
+	// NextRefreshAfter is aligned with RefreshLead (5min)
+	updated.NextRefreshAfter = expiresAt.Add(-5 * time.Minute)
 
 	return updated, nil
 }

sdk/cliproxy/auth/manager.go

@@ -40,7 +40,7 @@ type RefreshEvaluator interface {
 const (
 	refreshCheckInterval  = 5 * time.Second
 	refreshPendingBackoff = time.Minute
-	refreshFailureBackoff = 5 * time.Minute
+	refreshFailureBackoff = 1 * time.Minute
 	quotaBackoffBase      = time.Second
 	quotaBackoffMax       = 30 * time.Minute
 )
@@ -1471,7 +1471,9 @@ func (m *Manager) refreshAuth(ctx context.Context, id string) {
 		updated.Runtime = auth.Runtime
 	}
 	updated.LastRefreshedAt = now
-	updated.NextRefreshAfter = time.Time{}
+	// Preserve NextRefreshAfter set by the Authenticator
+	// If the Authenticator set a reasonable refresh time, it should not be overwritten
+	// If the Authenticator did not set it (zero value), shouldRefresh will use default logic
 	updated.LastError = nil
 	updated.UpdatedAt = now
 	_, _ = m.Update(ctx, updated)