Merge pull request #42 from Ravens2121/master

feat(kiro): 新增授权码登录流程，优化邮箱获取与官方 Thinking 模式解析 预支持

cmd/server/main.go

@@ -78,6 +78,7 @@ func main() {
 	var kiroLogin bool
 	var kiroGoogleLogin bool
 	var kiroAWSLogin bool
+	var kiroAWSAuthCode bool
 	var kiroImport bool
 	var githubCopilotLogin bool
 	var projectID string
@@ -101,6 +102,7 @@ func main() {
 	flag.BoolVar(&kiroLogin, "kiro-login", false, "Login to Kiro using Google OAuth")
 	flag.BoolVar(&kiroGoogleLogin, "kiro-google-login", false, "Login to Kiro using Google OAuth (same as --kiro-login)")
 	flag.BoolVar(&kiroAWSLogin, "kiro-aws-login", false, "Login to Kiro using AWS Builder ID (device code flow)")
+	flag.BoolVar(&kiroAWSAuthCode, "kiro-aws-authcode", false, "Login to Kiro using AWS Builder ID (authorization code flow, better UX)")
 	flag.BoolVar(&kiroImport, "kiro-import", false, "Import Kiro token from Kiro IDE (~/.aws/sso/cache/kiro-auth-token.json)")
 	flag.BoolVar(&githubCopilotLogin, "github-copilot-login", false, "Login to GitHub Copilot using device flow")
 	flag.StringVar(&projectID, "project_id", "", "Project ID (Gemini only, not required)")
@@ -513,6 +515,10 @@ func main() {
 		// Users can explicitly override with --no-incognito
 		setKiroIncognitoMode(cfg, useIncognito, noIncognito)
 		cmd.DoKiroAWSLogin(cfg, options)
+	} else if kiroAWSAuthCode {
+		// For Kiro auth with authorization code flow (better UX)
+		setKiroIncognitoMode(cfg, useIncognito, noIncognito)
+		cmd.DoKiroAWSAuthCodeLogin(cfg, options)
 	} else if kiroImport {
 		cmd.DoKiroImport(cfg, options)
 	} else {

internal/auth/kiro/codewhisperer_client.go

@@ -0,0 +1,166 @@
+// Package kiro provides CodeWhisperer API client for fetching user info.
+package kiro
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/config"
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/util"
+	log "github.com/sirupsen/logrus"
+)
+
+const (
+	codeWhispererAPI = "https://codewhisperer.us-east-1.amazonaws.com"
+	kiroVersion      = "0.6.18"
+)
+
+// CodeWhispererClient handles CodeWhisperer API calls.
+type CodeWhispererClient struct {
+	httpClient *http.Client
+	machineID  string
+}
+
+// UsageLimitsResponse represents the getUsageLimits API response.
+type UsageLimitsResponse struct {
+	DaysUntilReset     *int                `json:"daysUntilReset,omitempty"`
+	NextDateReset      *float64            `json:"nextDateReset,omitempty"`
+	UserInfo           *UserInfo           `json:"userInfo,omitempty"`
+	SubscriptionInfo   *SubscriptionInfo   `json:"subscriptionInfo,omitempty"`
+	UsageBreakdownList []UsageBreakdown    `json:"usageBreakdownList,omitempty"`
+}
+
+// UserInfo contains user information from the API.
+type UserInfo struct {
+	Email  string `json:"email,omitempty"`
+	UserID string `json:"userId,omitempty"`
+}
+
+// SubscriptionInfo contains subscription details.
+type SubscriptionInfo struct {
+	SubscriptionTitle string `json:"subscriptionTitle,omitempty"`
+	Type              string `json:"type,omitempty"`
+}
+
+// UsageBreakdown contains usage details.
+type UsageBreakdown struct {
+	UsageLimit                 *int     `json:"usageLimit,omitempty"`
+	CurrentUsage               *int     `json:"currentUsage,omitempty"`
+	UsageLimitWithPrecision    *float64 `json:"usageLimitWithPrecision,omitempty"`
+	CurrentUsageWithPrecision  *float64 `json:"currentUsageWithPrecision,omitempty"`
+	NextDateReset              *float64 `json:"nextDateReset,omitempty"`
+	DisplayName                string   `json:"displayName,omitempty"`
+	ResourceType               string   `json:"resourceType,omitempty"`
+}
+
+// NewCodeWhispererClient creates a new CodeWhisperer client.
+func NewCodeWhispererClient(cfg *config.Config, machineID string) *CodeWhispererClient {
+	client := &http.Client{Timeout: 30 * time.Second}
+	if cfg != nil {
+		client = util.SetProxy(&cfg.SDKConfig, client)
+	}
+	if machineID == "" {
+		machineID = uuid.New().String()
+	}
+	return &CodeWhispererClient{
+		httpClient: client,
+		machineID:  machineID,
+	}
+}
+
+// generateInvocationID generates a unique invocation ID.
+func generateInvocationID() string {
+	return uuid.New().String()
+}
+
+// GetUsageLimits fetches usage limits and user info from CodeWhisperer API.
+// This is the recommended way to get user email after login.
+func (c *CodeWhispererClient) GetUsageLimits(ctx context.Context, accessToken string) (*UsageLimitsResponse, error) {
+	url := fmt.Sprintf("%s/getUsageLimits?isEmailRequired=true&origin=AI_EDITOR&resourceType=AGENTIC_REQUEST", codeWhispererAPI)
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create request: %w", err)
+	}
+
+	// Set headers to match Kiro IDE
+	xAmzUserAgent := fmt.Sprintf("aws-sdk-js/1.0.0 KiroIDE-%s-%s", kiroVersion, c.machineID)
+	userAgent := fmt.Sprintf("aws-sdk-js/1.0.0 ua/2.1 os/windows lang/js md/nodejs#20.16.0 api/codewhispererruntime#1.0.0 m/E KiroIDE-%s-%s", kiroVersion, c.machineID)
+
+	req.Header.Set("Authorization", "Bearer "+accessToken)
+	req.Header.Set("x-amz-user-agent", xAmzUserAgent)
+	req.Header.Set("User-Agent", userAgent)
+	req.Header.Set("amz-sdk-invocation-id", generateInvocationID())
+	req.Header.Set("amz-sdk-request", "attempt=1; max=1")
+	req.Header.Set("Connection", "close")
+
+	log.Debugf("codewhisperer: GET %s", url)
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("request failed: %w", err)
+	}
+	defer resp.Body.Close()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read response: %w", err)
+	}
+
+	log.Debugf("codewhisperer: status=%d, body=%s", resp.StatusCode, string(body))
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("API returned status %d: %s", resp.StatusCode, string(body))
+	}
+
+	var result UsageLimitsResponse
+	if err := json.Unmarshal(body, &result); err != nil {
+		return nil, fmt.Errorf("failed to parse response: %w", err)
+	}
+
+	return &result, nil
+}
+
+// FetchUserEmailFromAPI fetches user email using CodeWhisperer getUsageLimits API.
+// This is more reliable than JWT parsing as it uses the official API.
+func (c *CodeWhispererClient) FetchUserEmailFromAPI(ctx context.Context, accessToken string) string {
+	resp, err := c.GetUsageLimits(ctx, accessToken)
+	if err != nil {
+		log.Debugf("codewhisperer: failed to get usage limits: %v", err)
+		return ""
+	}
+
+	if resp.UserInfo != nil && resp.UserInfo.Email != "" {
+		log.Debugf("codewhisperer: got email from API: %s", resp.UserInfo.Email)
+		return resp.UserInfo.Email
+	}
+
+	log.Debugf("codewhisperer: no email in response")
+	return ""
+}
+
+// FetchUserEmailWithFallback fetches user email with multiple fallback methods.
+// Priority: 1. CodeWhisperer API  2. userinfo endpoint  3. JWT parsing
+func FetchUserEmailWithFallback(ctx context.Context, cfg *config.Config, accessToken string) string {
+	// Method 1: Try CodeWhisperer API (most reliable)
+	cwClient := NewCodeWhispererClient(cfg, "")
+	email := cwClient.FetchUserEmailFromAPI(ctx, accessToken)
+	if email != "" {
+		return email
+	}
+
+	// Method 2: Try SSO OIDC userinfo endpoint
+	ssoClient := NewSSOOIDCClient(cfg)
+	email = ssoClient.FetchUserEmail(ctx, accessToken)
+	if email != "" {
+		return email
+	}
+
+	// Method 3: Fallback to JWT parsing
+	return ExtractEmailFromJWT(accessToken)
+}

internal/auth/kiro/oauth.go

@@ -163,6 +163,13 @@ func (o *KiroOAuth) LoginWithBuilderID(ctx context.Context) (*KiroTokenData, err
 	return ssoClient.LoginWithBuilderID(ctx)
 }
 
+// LoginWithBuilderIDAuthCode performs OAuth login with AWS Builder ID using authorization code flow.
+// This provides a better UX than device code flow as it uses automatic browser callback.
+func (o *KiroOAuth) LoginWithBuilderIDAuthCode(ctx context.Context) (*KiroTokenData, error) {
+	ssoClient := NewSSOOIDCClient(o.cfg)
+	return ssoClient.LoginWithBuilderIDAuthCode(ctx)
+}
+
 // exchangeCodeForToken exchanges the authorization code for tokens.
 func (o *KiroOAuth) exchangeCodeForToken(ctx context.Context, code, codeVerifier, redirectURI string) (*KiroTokenData, error) {
 	payload := map[string]string{

internal/auth/kiro/sso_oidc.go

@@ -3,9 +3,14 @@ package kiro
 
 import (
 	"context"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
 	"encoding/json"
 	"fmt"
+	"html"
 	"io"
+	"net"
 	"net/http"
 	"strings"
 	"time"
@@ -25,6 +30,13 @@ const (
 	
 	// Polling interval
 	pollInterval = 5 * time.Second
+	
+	// Authorization code flow callback
+	authCodeCallbackPath = "/oauth/callback"
+	authCodeCallbackPort = 19877
+	
+	// User-Agent to match official Kiro IDE
+	kiroUserAgent = "KiroIDE"
 )
 
 // SSOOIDCClient handles AWS SSO OIDC authentication.
@@ -73,13 +85,11 @@ type CreateTokenResponse struct {
 
 // RegisterClient registers a new OIDC client with AWS.
 func (c *SSOOIDCClient) RegisterClient(ctx context.Context) (*RegisterClientResponse, error) {
-	// Generate unique client name for each registration to support multiple accounts
-	clientName := fmt.Sprintf("CLI-Proxy-API-%d", time.Now().UnixNano())
-	
 	payload := map[string]interface{}{
-		"clientName": clientName,
+		"clientName": "Kiro IDE",
 		"clientType": "public",
-		"scopes":     []string{"codewhisperer:completions", "codewhisperer:analysis", "codewhisperer:conversations"},
+		"scopes":     []string{"codewhisperer:completions", "codewhisperer:analysis", "codewhisperer:conversations", "codewhisperer:transformations", "codewhisperer:taskassist"},
+		"grantTypes": []string{"urn:ietf:params:oauth:grant-type:device_code", "refresh_token"},
 	}
 
 	body, err := json.Marshal(payload)
@@ -92,6 +102,7 @@ func (c *SSOOIDCClient) RegisterClient(ctx context.Context) (*RegisterClientResp
 		return nil, err
 	}
 	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("User-Agent", kiroUserAgent)
 
 	resp, err := c.httpClient.Do(req)
 	if err != nil {
@@ -135,6 +146,7 @@ func (c *SSOOIDCClient) StartDeviceAuthorization(ctx context.Context, clientID,
 		return nil, err
 	}
 	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("User-Agent", kiroUserAgent)
 
 	resp, err := c.httpClient.Do(req)
 	if err != nil {
@@ -179,6 +191,7 @@ func (c *SSOOIDCClient) CreateToken(ctx context.Context, clientID, clientSecret,
 		return nil, err
 	}
 	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("User-Agent", kiroUserAgent)
 
 	resp, err := c.httpClient.Do(req)
 	if err != nil {
@@ -240,6 +253,7 @@ func (c *SSOOIDCClient) RefreshToken(ctx context.Context, clientID, clientSecret
 		return nil, err
 	}
 	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("User-Agent", kiroUserAgent)
 
 	resp, err := c.httpClient.Do(req)
 	if err != nil {
@@ -370,8 +384,8 @@ func (c *SSOOIDCClient) LoginWithBuilderID(ctx context.Context) (*KiroTokenData,
 			fmt.Println("Fetching profile information...")
 			profileArn := c.fetchProfileArn(ctx, tokenResp.AccessToken)
 
-			// Extract email from JWT access token
-			email := ExtractEmailFromJWT(tokenResp.AccessToken)
+			// Fetch user email (tries CodeWhisperer API first, then userinfo endpoint, then JWT parsing)
+			email := FetchUserEmailWithFallback(ctx, c.cfg, tokenResp.AccessToken)
 			if email != "" {
 				fmt.Printf("  Logged in as: %s\n", email)
 			}
@@ -399,6 +413,68 @@ func (c *SSOOIDCClient) LoginWithBuilderID(ctx context.Context) (*KiroTokenData,
 	return nil, fmt.Errorf("authorization timed out")
 }
 
+// FetchUserEmail retrieves the user's email from AWS SSO OIDC userinfo endpoint.
+// Falls back to JWT parsing if userinfo fails.
+func (c *SSOOIDCClient) FetchUserEmail(ctx context.Context, accessToken string) string {
+	// Method 1: Try userinfo endpoint (standard OIDC)
+	email := c.tryUserInfoEndpoint(ctx, accessToken)
+	if email != "" {
+		return email
+	}
+
+	// Method 2: Fallback to JWT parsing
+	return ExtractEmailFromJWT(accessToken)
+}
+
+// tryUserInfoEndpoint attempts to get user info from AWS SSO OIDC userinfo endpoint.
+func (c *SSOOIDCClient) tryUserInfoEndpoint(ctx context.Context, accessToken string) string {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, ssoOIDCEndpoint+"/userinfo", nil)
+	if err != nil {
+		return ""
+	}
+	req.Header.Set("Authorization", "Bearer "+accessToken)
+	req.Header.Set("Accept", "application/json")
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		log.Debugf("userinfo request failed: %v", err)
+		return ""
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		respBody, _ := io.ReadAll(resp.Body)
+		log.Debugf("userinfo endpoint returned status %d: %s", resp.StatusCode, string(respBody))
+		return ""
+	}
+
+	respBody, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return ""
+	}
+
+	log.Debugf("userinfo response: %s", string(respBody))
+
+	var userInfo struct {
+		Email             string `json:"email"`
+		Sub               string `json:"sub"`
+		PreferredUsername string `json:"preferred_username"`
+		Name              string `json:"name"`
+	}
+
+	if err := json.Unmarshal(respBody, &userInfo); err != nil {
+		return ""
+	}
+
+	if userInfo.Email != "" {
+		return userInfo.Email
+	}
+	if userInfo.PreferredUsername != "" && strings.Contains(userInfo.PreferredUsername, "@") {
+		return userInfo.PreferredUsername
+	}
+	return ""
+}
+
 // fetchProfileArn retrieves the profile ARN from CodeWhisperer API.
 // This is needed for file naming since AWS SSO OIDC doesn't return profile info.
 func (c *SSOOIDCClient) fetchProfileArn(ctx context.Context, accessToken string) string {
@@ -525,3 +601,323 @@ func (c *SSOOIDCClient) tryListCustomizations(ctx context.Context, accessToken s
 
 	return ""
 }
+
+// RegisterClientForAuthCode registers a new OIDC client for authorization code flow.
+func (c *SSOOIDCClient) RegisterClientForAuthCode(ctx context.Context, redirectURI string) (*RegisterClientResponse, error) {
+	payload := map[string]interface{}{
+		"clientName":   "Kiro IDE",
+		"clientType":   "public",
+		"scopes":       []string{"codewhisperer:completions", "codewhisperer:analysis", "codewhisperer:conversations", "codewhisperer:transformations", "codewhisperer:taskassist"},
+		"grantTypes":   []string{"authorization_code", "refresh_token"},
+		"redirectUris": []string{redirectURI},
+		"issuerUrl":    builderIDStartURL,
+	}
+
+	body, err := json.Marshal(payload)
+	if err != nil {
+		return nil, err
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, ssoOIDCEndpoint+"/client/register", strings.NewReader(string(body)))
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("User-Agent", kiroUserAgent)
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	respBody, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		log.Debugf("register client for auth code failed (status %d): %s", resp.StatusCode, string(respBody))
+		return nil, fmt.Errorf("register client failed (status %d)", resp.StatusCode)
+	}
+
+	var result RegisterClientResponse
+	if err := json.Unmarshal(respBody, &result); err != nil {
+		return nil, err
+	}
+
+	return &result, nil
+}
+
+// AuthCodeCallbackResult contains the result from authorization code callback.
+type AuthCodeCallbackResult struct {
+	Code  string
+	State string
+	Error string
+}
+
+// startAuthCodeCallbackServer starts a local HTTP server to receive the authorization code callback.
+func (c *SSOOIDCClient) startAuthCodeCallbackServer(ctx context.Context, expectedState string) (string, <-chan AuthCodeCallbackResult, error) {
+	// Try to find an available port
+	listener, err := net.Listen("tcp", fmt.Sprintf("127.0.0.1:%d", authCodeCallbackPort))
+	if err != nil {
+		// Try with dynamic port
+		log.Warnf("sso oidc: default port %d is busy, falling back to dynamic port", authCodeCallbackPort)
+		listener, err = net.Listen("tcp", "127.0.0.1:0")
+		if err != nil {
+			return "", nil, fmt.Errorf("failed to start callback server: %w", err)
+		}
+	}
+
+	port := listener.Addr().(*net.TCPAddr).Port
+	redirectURI := fmt.Sprintf("http://127.0.0.1:%d%s", port, authCodeCallbackPath)
+	resultChan := make(chan AuthCodeCallbackResult, 1)
+
+	server := &http.Server{
+		ReadHeaderTimeout: 10 * time.Second,
+	}
+
+	mux := http.NewServeMux()
+	mux.HandleFunc(authCodeCallbackPath, func(w http.ResponseWriter, r *http.Request) {
+		code := r.URL.Query().Get("code")
+		state := r.URL.Query().Get("state")
+		errParam := r.URL.Query().Get("error")
+
+		// Send response to browser
+		w.Header().Set("Content-Type", "text/html; charset=utf-8")
+		if errParam != "" {
+			w.WriteHeader(http.StatusBadRequest)
+			fmt.Fprintf(w, `<!DOCTYPE html>
+<html><head><title>Login Failed</title></head>
+<body><h1>Login Failed</h1><p>Error: %s</p><p>You can close this window.</p></body></html>`, html.EscapeString(errParam))
+			resultChan <- AuthCodeCallbackResult{Error: errParam}
+			return
+		}
+
+		if state != expectedState {
+			w.WriteHeader(http.StatusBadRequest)
+			fmt.Fprint(w, `<!DOCTYPE html>
+<html><head><title>Login Failed</title></head>
+<body><h1>Login Failed</h1><p>Invalid state parameter</p><p>You can close this window.</p></body></html>`)
+			resultChan <- AuthCodeCallbackResult{Error: "state mismatch"}
+			return
+		}
+
+		fmt.Fprint(w, `<!DOCTYPE html>
+<html><head><title>Login Successful</title></head>
+<body><h1>Login Successful!</h1><p>You can close this window and return to the terminal.</p>
+<script>window.close();</script></body></html>`)
+		resultChan <- AuthCodeCallbackResult{Code: code, State: state}
+	})
+
+	server.Handler = mux
+
+	go func() {
+		if err := server.Serve(listener); err != nil && err != http.ErrServerClosed {
+			log.Debugf("auth code callback server error: %v", err)
+		}
+	}()
+
+	go func() {
+		select {
+		case <-ctx.Done():
+		case <-time.After(10 * time.Minute):
+		case <-resultChan:
+		}
+		_ = server.Shutdown(context.Background())
+	}()
+
+	return redirectURI, resultChan, nil
+}
+
+// generatePKCEForAuthCode generates PKCE code verifier and challenge for authorization code flow.
+func generatePKCEForAuthCode() (verifier, challenge string, err error) {
+	b := make([]byte, 32)
+	if _, err := rand.Read(b); err != nil {
+		return "", "", fmt.Errorf("failed to generate random bytes: %w", err)
+	}
+	verifier = base64.RawURLEncoding.EncodeToString(b)
+	h := sha256.Sum256([]byte(verifier))
+	challenge = base64.RawURLEncoding.EncodeToString(h[:])
+	return verifier, challenge, nil
+}
+
+// generateStateForAuthCode generates a random state parameter.
+func generateStateForAuthCode() (string, error) {
+	b := make([]byte, 16)
+	if _, err := rand.Read(b); err != nil {
+		return "", err
+	}
+	return base64.RawURLEncoding.EncodeToString(b), nil
+}
+
+// CreateTokenWithAuthCode exchanges authorization code for tokens.
+func (c *SSOOIDCClient) CreateTokenWithAuthCode(ctx context.Context, clientID, clientSecret, code, codeVerifier, redirectURI string) (*CreateTokenResponse, error) {
+	payload := map[string]string{
+		"clientId":     clientID,
+		"clientSecret": clientSecret,
+		"code":         code,
+		"codeVerifier": codeVerifier,
+		"redirectUri":  redirectURI,
+		"grantType":    "authorization_code",
+	}
+
+	body, err := json.Marshal(payload)
+	if err != nil {
+		return nil, err
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, ssoOIDCEndpoint+"/token", strings.NewReader(string(body)))
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("User-Agent", kiroUserAgent)
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	respBody, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		log.Debugf("create token with auth code failed (status %d): %s", resp.StatusCode, string(respBody))
+		return nil, fmt.Errorf("create token failed (status %d)", resp.StatusCode)
+	}
+
+	var result CreateTokenResponse
+	if err := json.Unmarshal(respBody, &result); err != nil {
+		return nil, err
+	}
+
+	return &result, nil
+}
+
+// LoginWithBuilderIDAuthCode performs the authorization code flow for AWS Builder ID.
+// This provides a better UX than device code flow as it uses automatic browser callback.
+func (c *SSOOIDCClient) LoginWithBuilderIDAuthCode(ctx context.Context) (*KiroTokenData, error) {
+	fmt.Println("\n╔══════════════════════════════════════════════════════════╗")
+	fmt.Println("║     Kiro Authentication (AWS Builder ID - Auth Code)      ║")
+	fmt.Println("╚══════════════════════════════════════════════════════════╝")
+
+	// Step 1: Generate PKCE and state
+	codeVerifier, codeChallenge, err := generatePKCEForAuthCode()
+	if err != nil {
+		return nil, fmt.Errorf("failed to generate PKCE: %w", err)
+	}
+
+	state, err := generateStateForAuthCode()
+	if err != nil {
+		return nil, fmt.Errorf("failed to generate state: %w", err)
+	}
+
+	// Step 2: Start callback server
+	fmt.Println("\nStarting callback server...")
+	redirectURI, resultChan, err := c.startAuthCodeCallbackServer(ctx, state)
+	if err != nil {
+		return nil, fmt.Errorf("failed to start callback server: %w", err)
+	}
+	log.Debugf("Callback server started, redirect URI: %s", redirectURI)
+
+	// Step 3: Register client with auth code grant type
+	fmt.Println("Registering client...")
+	regResp, err := c.RegisterClientForAuthCode(ctx, redirectURI)
+	if err != nil {
+		return nil, fmt.Errorf("failed to register client: %w", err)
+	}
+	log.Debugf("Client registered: %s", regResp.ClientID)
+
+	// Step 4: Build authorization URL
+	scopes := "codewhisperer:completions,codewhisperer:analysis,codewhisperer:conversations"
+	authURL := fmt.Sprintf("%s/authorize?response_type=code&client_id=%s&redirect_uri=%s&scopes=%s&state=%s&code_challenge=%s&code_challenge_method=S256",
+		ssoOIDCEndpoint,
+		regResp.ClientID,
+		redirectURI,
+		scopes,
+		state,
+		codeChallenge,
+	)
+
+	// Step 5: Open browser
+	fmt.Println("\n════════════════════════════════════════════════════════════")
+	fmt.Println("  Opening browser for authentication...")
+	fmt.Println("════════════════════════════════════════════════════════════")
+	fmt.Printf("\n  URL: %s\n\n", authURL)
+
+	// Set incognito mode
+	if c.cfg != nil {
+		browser.SetIncognitoMode(c.cfg.IncognitoBrowser)
+	} else {
+		browser.SetIncognitoMode(true)
+	}
+
+	if err := browser.OpenURL(authURL); err != nil {
+		log.Warnf("Could not open browser automatically: %v", err)
+		fmt.Println("  ⚠ Could not open browser automatically.")
+		fmt.Println("  Please open the URL above in your browser manually.")
+	} else {
+		fmt.Println("  (Browser opened automatically)")
+	}
+
+	fmt.Println("\n  Waiting for authorization callback...")
+
+	// Step 6: Wait for callback
+	select {
+	case <-ctx.Done():
+		browser.CloseBrowser()
+		return nil, ctx.Err()
+	case <-time.After(10 * time.Minute):
+		browser.CloseBrowser()
+		return nil, fmt.Errorf("authorization timed out")
+	case result := <-resultChan:
+		if result.Error != "" {
+			browser.CloseBrowser()
+			return nil, fmt.Errorf("authorization failed: %s", result.Error)
+		}
+
+		fmt.Println("\n✓ Authorization received!")
+
+		// Close browser
+		if err := browser.CloseBrowser(); err != nil {
+			log.Debugf("Failed to close browser: %v", err)
+		}
+
+		// Step 7: Exchange code for tokens
+		fmt.Println("Exchanging code for tokens...")
+		tokenResp, err := c.CreateTokenWithAuthCode(ctx, regResp.ClientID, regResp.ClientSecret, result.Code, codeVerifier, redirectURI)
+		if err != nil {
+			return nil, fmt.Errorf("failed to exchange code for tokens: %w", err)
+		}
+
+		fmt.Println("\n✓ Authentication successful!")
+
+		// Step 8: Get profile ARN
+		fmt.Println("Fetching profile information...")
+		profileArn := c.fetchProfileArn(ctx, tokenResp.AccessToken)
+
+		// Fetch user email (tries CodeWhisperer API first, then userinfo endpoint, then JWT parsing)
+		email := FetchUserEmailWithFallback(ctx, c.cfg, tokenResp.AccessToken)
+		if email != "" {
+			fmt.Printf("  Logged in as: %s\n", email)
+		}
+
+		expiresAt := time.Now().Add(time.Duration(tokenResp.ExpiresIn) * time.Second)
+
+		return &KiroTokenData{
+			AccessToken:  tokenResp.AccessToken,
+			RefreshToken: tokenResp.RefreshToken,
+			ProfileArn:   profileArn,
+			ExpiresAt:    expiresAt.Format(time.RFC3339),
+			AuthMethod:   "builder-id",
+			Provider:     "AWS",
+			ClientID:     regResp.ClientID,
+			ClientSecret: regResp.ClientSecret,
+			Email:        email,
+		}, nil
+	}
+}

internal/cmd/kiro_login.go

@@ -116,6 +116,54 @@ func DoKiroAWSLogin(cfg *config.Config, options *LoginOptions) {
 	fmt.Println("Kiro AWS authentication successful!")
 }
 
+// DoKiroAWSAuthCodeLogin triggers Kiro authentication with AWS Builder ID using authorization code flow.
+// This provides a better UX than device code flow as it uses automatic browser callback.
+//
+// Parameters:
+//   - cfg: The application configuration
+//   - options: Login options including prompts
+func DoKiroAWSAuthCodeLogin(cfg *config.Config, options *LoginOptions) {
+	if options == nil {
+		options = &LoginOptions{}
+	}
+
+	// Note: Kiro defaults to incognito mode for multi-account support.
+	// Users can override with --no-incognito if they want to use existing browser sessions.
+
+	manager := newAuthManager()
+
+	// Use KiroAuthenticator with AWS Builder ID login (authorization code flow)
+	authenticator := sdkAuth.NewKiroAuthenticator()
+	record, err := authenticator.LoginWithAuthCode(context.Background(), cfg, &sdkAuth.LoginOptions{
+		NoBrowser: options.NoBrowser,
+		Metadata:  map[string]string{},
+		Prompt:    options.Prompt,
+	})
+	if err != nil {
+		log.Errorf("Kiro AWS authentication (auth code) failed: %v", err)
+		fmt.Println("\nTroubleshooting:")
+		fmt.Println("1. Make sure you have an AWS Builder ID")
+		fmt.Println("2. Complete the authorization in the browser")
+		fmt.Println("3. If callback fails, try: --kiro-aws-login (device code flow)")
+		return
+	}
+
+	// Save the auth record
+	savedPath, err := manager.SaveAuth(record, cfg)
+	if err != nil {
+		log.Errorf("Failed to save auth: %v", err)
+		return
+	}
+
+	if savedPath != "" {
+		fmt.Printf("Authentication saved to %s\n", savedPath)
+	}
+	if record != nil && record.Label != "" {
+		fmt.Printf("Authenticated as %s\n", record.Label)
+	}
+	fmt.Println("Kiro AWS authentication successful!")
+}
+
 // DoKiroImport imports Kiro token from Kiro IDE's token file.
 // This is useful for users who have already logged in via Kiro IDE
 // and want to use the same credentials in CLI Proxy API.

internal/runtime/executor/kiro_executor.go

@@ -1293,17 +1293,66 @@ func (e *KiroExecutor) parseEventStream(body io.Reader) (string, []kiroclaude.Ki
 				log.Debugf("kiro: parseEventStream found stopReason in messageStopEvent: %s", stopReason)
 			}
 
-		case "messageMetadataEvent":
-			// Handle message metadata events which may contain token counts
-			if metadata, ok := event["messageMetadataEvent"].(map[string]interface{}); ok {
+		case "messageMetadataEvent", "metadataEvent":
+			// Handle message metadata events which contain token counts
+			// Official format: { tokenUsage: { outputTokens, totalTokens, uncachedInputTokens, cacheReadInputTokens, cacheWriteInputTokens, contextUsagePercentage } }
+			var metadata map[string]interface{}
+			if m, ok := event["messageMetadataEvent"].(map[string]interface{}); ok {
+				metadata = m
+			} else if m, ok := event["metadataEvent"].(map[string]interface{}); ok {
+				metadata = m
+			} else {
+				metadata = event // event itself might be the metadata
+			}
+
+			// Check for nested tokenUsage object (official format)
+			if tokenUsage, ok := metadata["tokenUsage"].(map[string]interface{}); ok {
+				// outputTokens - precise output token count
+				if outputTokens, ok := tokenUsage["outputTokens"].(float64); ok {
+					usageInfo.OutputTokens = int64(outputTokens)
+					log.Infof("kiro: parseEventStream found precise outputTokens in tokenUsage: %d", usageInfo.OutputTokens)
+				}
+				// totalTokens - precise total token count
+				if totalTokens, ok := tokenUsage["totalTokens"].(float64); ok {
+					usageInfo.TotalTokens = int64(totalTokens)
+					log.Infof("kiro: parseEventStream found precise totalTokens in tokenUsage: %d", usageInfo.TotalTokens)
+				}
+				// uncachedInputTokens - input tokens not from cache
+				if uncachedInputTokens, ok := tokenUsage["uncachedInputTokens"].(float64); ok {
+					usageInfo.InputTokens = int64(uncachedInputTokens)
+					log.Infof("kiro: parseEventStream found uncachedInputTokens in tokenUsage: %d", usageInfo.InputTokens)
+				}
+				// cacheReadInputTokens - tokens read from cache
+				if cacheReadTokens, ok := tokenUsage["cacheReadInputTokens"].(float64); ok {
+					// Add to input tokens if we have uncached tokens, otherwise use as input
+					if usageInfo.InputTokens > 0 {
+						usageInfo.InputTokens += int64(cacheReadTokens)
+					} else {
+						usageInfo.InputTokens = int64(cacheReadTokens)
+					}
+					log.Debugf("kiro: parseEventStream found cacheReadInputTokens in tokenUsage: %d", int64(cacheReadTokens))
+				}
+				// contextUsagePercentage - can be used as fallback for input token estimation
+				if ctxPct, ok := tokenUsage["contextUsagePercentage"].(float64); ok {
+					upstreamContextPercentage = ctxPct
+					log.Debugf("kiro: parseEventStream found contextUsagePercentage in tokenUsage: %.2f%%", ctxPct)
+				}
+			}
+
+			// Fallback: check for direct fields in metadata (legacy format)
+			if usageInfo.InputTokens == 0 {
 				if inputTokens, ok := metadata["inputTokens"].(float64); ok {
 					usageInfo.InputTokens = int64(inputTokens)
 					log.Debugf("kiro: parseEventStream found inputTokens in messageMetadataEvent: %d", usageInfo.InputTokens)
 				}
+			}
+			if usageInfo.OutputTokens == 0 {
 				if outputTokens, ok := metadata["outputTokens"].(float64); ok {
 					usageInfo.OutputTokens = int64(outputTokens)
 					log.Debugf("kiro: parseEventStream found outputTokens in messageMetadataEvent: %d", usageInfo.OutputTokens)
 				}
+			}
+			if usageInfo.TotalTokens == 0 {
 				if totalTokens, ok := metadata["totalTokens"].(float64); ok {
 					usageInfo.TotalTokens = int64(totalTokens)
 					log.Debugf("kiro: parseEventStream found totalTokens in messageMetadataEvent: %d", usageInfo.TotalTokens)
@@ -1356,6 +1405,78 @@ func (e *KiroExecutor) parseEventStream(body io.Reader) (string, []kiroclaude.Ki
 					usageInfo.InputTokens, usageInfo.OutputTokens)
 			}
 
+		case "meteringEvent":
+			// Handle metering events from Kiro API (usage billing information)
+			// Official format: { unit: string, unitPlural: string, usage: number }
+			if metering, ok := event["meteringEvent"].(map[string]interface{}); ok {
+				unit := ""
+				if u, ok := metering["unit"].(string); ok {
+					unit = u
+				}
+				usageVal := 0.0
+				if u, ok := metering["usage"].(float64); ok {
+					usageVal = u
+				}
+				log.Infof("kiro: parseEventStream received meteringEvent: usage=%.2f %s", usageVal, unit)
+				// Store metering info for potential billing/statistics purposes
+				// Note: This is separate from token counts - it's AWS billing units
+			} else {
+				// Try direct fields
+				unit := ""
+				if u, ok := event["unit"].(string); ok {
+					unit = u
+				}
+				usageVal := 0.0
+				if u, ok := event["usage"].(float64); ok {
+					usageVal = u
+				}
+				if unit != "" || usageVal > 0 {
+					log.Infof("kiro: parseEventStream received meteringEvent (direct): usage=%.2f %s", usageVal, unit)
+				}
+			}
+
+		case "error", "exception", "internalServerException", "invalidStateEvent":
+			// Handle error events from Kiro API stream
+			errMsg := ""
+			errType := eventType
+
+			// Try to extract error message from various formats
+			if msg, ok := event["message"].(string); ok {
+				errMsg = msg
+			} else if errObj, ok := event[eventType].(map[string]interface{}); ok {
+				if msg, ok := errObj["message"].(string); ok {
+					errMsg = msg
+				}
+				if t, ok := errObj["type"].(string); ok {
+					errType = t
+				}
+			} else if errObj, ok := event["error"].(map[string]interface{}); ok {
+				if msg, ok := errObj["message"].(string); ok {
+					errMsg = msg
+				}
+				if t, ok := errObj["type"].(string); ok {
+					errType = t
+				}
+			}
+
+			// Check for specific error reasons
+			if reason, ok := event["reason"].(string); ok {
+				errMsg = fmt.Sprintf("%s (reason: %s)", errMsg, reason)
+			}
+
+			log.Errorf("kiro: parseEventStream received error event: type=%s, message=%s", errType, errMsg)
+
+			// For invalidStateEvent, we may want to continue processing other events
+			if eventType == "invalidStateEvent" {
+				log.Warnf("kiro: invalidStateEvent received, continuing stream processing")
+				continue
+			}
+
+			// For other errors, return the error
+			if errMsg != "" {
+				return "", nil, usageInfo, stopReason, fmt.Errorf("kiro API error (%s): %s", errType, errMsg)
+			}
+
 		default:
 			// Check for contextUsagePercentage in any event
 			if ctxPct, ok := event["contextUsagePercentage"].(float64); ok {
@@ -1693,30 +1814,14 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 	// IMPORTANT: This must persist across all TranslateStream calls
 	var translatorParam any
 
-	// 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>
-	pendingEndTagChars := 0      // Number of chars that might be start of </thinking>
-	isThinkingBlockOpen := false // Track if thinking content block is open
+	// Thinking mode state tracking - tag-based parsing for <thinking> tags in content
+	inThinkBlock := false       // Whether we're currently inside a <thinking> block
+	isThinkingBlockOpen := false // Track if thinking content block SSE event is open
 	thinkingBlockIndex := -1     // Index of the thinking content block
-	var accumulatedThinkingContent strings.Builder // Accumulate thinking content for signature generation
+	var accumulatedThinkingContent strings.Builder // Accumulate thinking content for token counting
 
-	// Code block state tracking for heuristic thinking tag parsing
-	// When inside a markdown code block, <thinking> tags should NOT be parsed
-	// This prevents false positives when the model outputs code examples containing these tags
-	inCodeBlock := false
-	codeFenceType := "" // Track which fence type opened the block ("```" or "~~~")
-
-	// Inline code state tracking - when inside backticks, don't parse thinking tags
-	// This handles cases like `<thinking>` being discussed in text
-	inInlineCode := false
-
-	// Track if we've seen any non-whitespace content before a thinking tag
-	// Real thinking blocks from Kiro always start at the very beginning of the response
-	// If we see content before <thinking>, subsequent <thinking> tags are likely discussion text
-	hasSeenNonThinkingContent := false
-	thinkingBlockCompleted := false // Track if we've already completed a thinking block
+	// Buffer for handling partial tag matches at chunk boundaries
+	var pendingContent strings.Builder // Buffer content that might be part of a tag
 
 	// Pre-calculate input tokens from request if possible
 	// Kiro uses Claude format, so try Claude format first, then OpenAI format, then fallback
@@ -1820,57 +1925,10 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 				currentToolUse = nil
 			}
 
-			// Flush any pending tag characters at EOF
-			// These are partial tag prefixes that were held back waiting for more data
-			// Since no more data is coming, output them as regular text
-			var pendingText string
-			if pendingStartTagChars > 0 {
-				pendingText = kirocommon.ThinkingStartTag[:pendingStartTagChars]
-				log.Debugf("kiro: flushing pending start tag chars at EOF: %q", pendingText)
-				pendingStartTagChars = 0
-			}
-			if pendingEndTagChars > 0 {
-				pendingText += kirocommon.ThinkingEndTag[:pendingEndTagChars]
-				log.Debugf("kiro: flushing pending end tag chars at EOF: %q", pendingText)
-				pendingEndTagChars = 0
-			}
-
-			// Output pending text if any
-			if pendingText != "" {
-				// If we're in a thinking block, output as thinking content
-				if inThinkBlock && isThinkingBlockOpen {
-					thinkingEvent := kiroclaude.BuildClaudeThinkingDeltaEvent(pendingText, thinkingBlockIndex)
-					sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, thinkingEvent, &translatorParam)
-					for _, chunk := range sseData {
-						if chunk != "" {
-							out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunk + "\n\n")}
-						}
-					}
-					// Accumulate thinking content for signature generation
-					accumulatedThinkingContent.WriteString(pendingText)
-				} else {
-					// Output as regular text
-					if !isTextBlockOpen {
-						contentBlockIndex++
-						isTextBlockOpen = true
-						blockStart := kiroclaude.BuildClaudeContentBlockStartEvent(contentBlockIndex, "text", "", "")
-						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")}
-							}
-						}
-					}
-
-					claudeEvent := kiroclaude.BuildClaudeStreamEvent(pendingText, contentBlockIndex)
-					sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, claudeEvent, &translatorParam)
-					for _, chunk := range sseData {
-						if chunk != "" {
-							out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunk + "\n\n")}
-						}
-					}
-				}
-			}
+			// DISABLED: Tag-based pending character flushing
+			// This code block was used for tag-based thinking detection which has been
+			// replaced by reasoningContentEvent handling. No pending tag chars to flush.
+			// Original code preserved in git history.
 			break
 		}
 
@@ -1954,6 +2012,76 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 				log.Debugf("kiro: streamToChannel found stopReason in messageStopEvent: %s", upstreamStopReason)
 			}
 
+		case "meteringEvent":
+			// Handle metering events from Kiro API (usage billing information)
+			// Official format: { unit: string, unitPlural: string, usage: number }
+			if metering, ok := event["meteringEvent"].(map[string]interface{}); ok {
+				unit := ""
+				if u, ok := metering["unit"].(string); ok {
+					unit = u
+				}
+				usageVal := 0.0
+				if u, ok := metering["usage"].(float64); ok {
+					usageVal = u
+				}
+				upstreamCreditUsage = usageVal
+				hasUpstreamUsage = true
+				log.Infof("kiro: streamToChannel received meteringEvent: usage=%.4f %s", usageVal, unit)
+			} else {
+				// Try direct fields (event is meteringEvent itself)
+				if unit, ok := event["unit"].(string); ok {
+					if usage, ok := event["usage"].(float64); ok {
+						upstreamCreditUsage = usage
+						hasUpstreamUsage = true
+						log.Infof("kiro: streamToChannel received meteringEvent (direct): usage=%.4f %s", usage, unit)
+					}
+				}
+			}
+
+		case "error", "exception", "internalServerException":
+			// Handle error events from Kiro API stream
+			errMsg := ""
+			errType := eventType
+
+			// Try to extract error message from various formats
+			if msg, ok := event["message"].(string); ok {
+				errMsg = msg
+			} else if errObj, ok := event[eventType].(map[string]interface{}); ok {
+				if msg, ok := errObj["message"].(string); ok {
+					errMsg = msg
+				}
+				if t, ok := errObj["type"].(string); ok {
+					errType = t
+				}
+			} else if errObj, ok := event["error"].(map[string]interface{}); ok {
+				if msg, ok := errObj["message"].(string); ok {
+					errMsg = msg
+				}
+			}
+
+			log.Errorf("kiro: streamToChannel received error event: type=%s, message=%s", errType, errMsg)
+
+			// Send error to the stream and exit
+			if errMsg != "" {
+				out <- cliproxyexecutor.StreamChunk{
+					Err: fmt.Errorf("kiro API error (%s): %s", errType, errMsg),
+				}
+				return
+			}
+
+		case "invalidStateEvent":
+			// Handle invalid state events - log and continue (non-fatal)
+			errMsg := ""
+			if msg, ok := event["message"].(string); ok {
+				errMsg = msg
+			} else if stateEvent, ok := event["invalidStateEvent"].(map[string]interface{}); ok {
+				if msg, ok := stateEvent["message"].(string); ok {
+					errMsg = msg
+				}
+			}
+			log.Warnf("kiro: streamToChannel received invalidStateEvent: %s, continuing", errMsg)
+			continue
+
 		default:
 			// Check for upstream usage events from Kiro API
 			// Format: {"unit":"credit","unitPlural":"credits","usage":1.458}
@@ -2110,266 +2238,22 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 					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
-
-				// If we have pending start tag chars from previous chunk, prepend them
-				if pendingStartTagChars > 0 {
-					remaining = kirocommon.ThinkingStartTag[:pendingStartTagChars] + remaining
-					pendingStartTagChars = 0
-				}
-
-				// If we have pending end tag chars from previous chunk, prepend them
-				if pendingEndTagChars > 0 {
-					remaining = kirocommon.ThinkingEndTag[:pendingEndTagChars] + remaining
-					pendingEndTagChars = 0
-				}
-
-				for len(remaining) > 0 {
-					// CRITICAL FIX: Only parse <thinking> tags when thinking mode was enabled in the request.
-					// When thinking is NOT enabled, <thinking> tags in responses should be treated as
-					// regular text content, not as thinking blocks. This prevents normal text content
-					// from being incorrectly parsed as thinking when the model outputs <thinking> tags
-					// without the user requesting thinking mode.
-					if !thinkingEnabled {
-						// Thinking not enabled - emit all content as regular text without parsing tags
-						if remaining != "" {
-							if !isTextBlockOpen {
-								contentBlockIndex++
-								isTextBlockOpen = true
-								blockStart := kiroclaude.BuildClaudeContentBlockStartEvent(contentBlockIndex, "text", "", "")
-								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")}
-									}
-								}
-							}
-
-							claudeEvent := kiroclaude.BuildClaudeStreamEvent(remaining, contentBlockIndex)
-							sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, claudeEvent, &translatorParam)
-							for _, chunk := range sseData {
-								if chunk != "" {
-									out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunk + "\n\n")}
-								}
-							}
-						}
-						break // Exit the for loop - all content processed as text
-					}
-
-					// HEURISTIC FIX: Track code block and inline code state to avoid parsing <thinking> tags
-					// inside code contexts. When the model outputs code examples containing these tags,
-					// they should be treated as text.
-					if !inThinkBlock {
-						// Check for inline code backticks first (higher priority than code fences)
-						// This handles cases like `<thinking>` being discussed in text
-						backtickIdx := strings.Index(remaining, kirocommon.InlineCodeMarker)
-						thinkingIdx := strings.Index(remaining, kirocommon.ThinkingStartTag)
-
-						// If backtick comes before thinking tag, handle inline code
-						if backtickIdx >= 0 && (thinkingIdx < 0 || backtickIdx < thinkingIdx) {
-							if inInlineCode {
-								// Closing backtick - emit content up to and including backtick, exit inline code
-								textToEmit := remaining[:backtickIdx+1]
-								if textToEmit != "" {
-									if !isTextBlockOpen {
-										contentBlockIndex++
-										isTextBlockOpen = true
-										blockStart := kiroclaude.BuildClaudeContentBlockStartEvent(contentBlockIndex, "text", "", "")
-										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")}
-											}
-										}
-									}
-									claudeEvent := kiroclaude.BuildClaudeStreamEvent(textToEmit, contentBlockIndex)
-									sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, claudeEvent, &translatorParam)
-									for _, chunk := range sseData {
-										if chunk != "" {
-											out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunk + "\n\n")}
-										}
-									}
-								}
-								remaining = remaining[backtickIdx+1:]
-								inInlineCode = false
-								continue
-							} else {
-								// Opening backtick - emit content before backtick, enter inline code
-								textToEmit := remaining[:backtickIdx+1]
-								if textToEmit != "" {
-									if !isTextBlockOpen {
-										contentBlockIndex++
-										isTextBlockOpen = true
-										blockStart := kiroclaude.BuildClaudeContentBlockStartEvent(contentBlockIndex, "text", "", "")
-										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")}
-											}
-										}
-									}
-									claudeEvent := kiroclaude.BuildClaudeStreamEvent(textToEmit, contentBlockIndex)
-									sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, claudeEvent, &translatorParam)
-									for _, chunk := range sseData {
-										if chunk != "" {
-											out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunk + "\n\n")}
-										}
-									}
-								}
-								remaining = remaining[backtickIdx+1:]
-								inInlineCode = true
-								continue
-							}
-						}
-
-						// If inside inline code, emit all content as text (don't parse thinking tags)
-						if inInlineCode {
-							if remaining != "" {
-								if !isTextBlockOpen {
-									contentBlockIndex++
-									isTextBlockOpen = true
-									blockStart := kiroclaude.BuildClaudeContentBlockStartEvent(contentBlockIndex, "text", "", "")
-									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")}
-										}
-									}
-								}
-								claudeEvent := kiroclaude.BuildClaudeStreamEvent(remaining, contentBlockIndex)
-								sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, claudeEvent, &translatorParam)
-								for _, chunk := range sseData {
-									if chunk != "" {
-										out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunk + "\n\n")}
-									}
-								}
-							}
-							break // Exit loop - remaining content is inside inline code
-						}
-
-						// Check for code fence markers (``` or ~~~) to toggle code block state
-						fenceIdx := strings.Index(remaining, kirocommon.CodeFenceMarker)
-						altFenceIdx := strings.Index(remaining, kirocommon.AltCodeFenceMarker)
-
-						// Find the earliest fence marker
-						earliestFenceIdx := -1
-						earliestFenceType := ""
-						if fenceIdx >= 0 && (altFenceIdx < 0 || fenceIdx < altFenceIdx) {
-							earliestFenceIdx = fenceIdx
-							earliestFenceType = kirocommon.CodeFenceMarker
-						} else if altFenceIdx >= 0 {
-							earliestFenceIdx = altFenceIdx
-							earliestFenceType = kirocommon.AltCodeFenceMarker
-						}
-
-						if earliestFenceIdx >= 0 {
-							// Check if this fence comes before any thinking tag
-							thinkingIdx := strings.Index(remaining, kirocommon.ThinkingStartTag)
-							if inCodeBlock {
-								// Inside code block - check if this fence closes it
-								if earliestFenceType == codeFenceType {
-									// This fence closes the code block
-									// Emit content up to and including the fence as text
-									textToEmit := remaining[:earliestFenceIdx+len(earliestFenceType)]
-									if textToEmit != "" {
-										if !isTextBlockOpen {
-											contentBlockIndex++
-											isTextBlockOpen = true
-											blockStart := kiroclaude.BuildClaudeContentBlockStartEvent(contentBlockIndex, "text", "", "")
-											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")}
-												}
-											}
-										}
-										claudeEvent := kiroclaude.BuildClaudeStreamEvent(textToEmit, contentBlockIndex)
-										sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, claudeEvent, &translatorParam)
-										for _, chunk := range sseData {
-											if chunk != "" {
-												out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunk + "\n\n")}
-											}
-										}
-									}
-									remaining = remaining[earliestFenceIdx+len(earliestFenceType):]
-									inCodeBlock = false
-									codeFenceType = ""
-									log.Debugf("kiro: exited code block")
-									continue
-								}
-							} else if thinkingIdx < 0 || earliestFenceIdx < thinkingIdx {
-								// Not in code block, and fence comes before thinking tag (or no thinking tag)
-								// Emit content up to and including the fence as text, then enter code block
-								textToEmit := remaining[:earliestFenceIdx+len(earliestFenceType)]
-								if textToEmit != "" {
-									if !isTextBlockOpen {
-										contentBlockIndex++
-										isTextBlockOpen = true
-										blockStart := kiroclaude.BuildClaudeContentBlockStartEvent(contentBlockIndex, "text", "", "")
-										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")}
-											}
-										}
-									}
-									claudeEvent := kiroclaude.BuildClaudeStreamEvent(textToEmit, contentBlockIndex)
-									sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, claudeEvent, &translatorParam)
-									for _, chunk := range sseData {
-										if chunk != "" {
-											out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunk + "\n\n")}
-										}
-									}
-								}
-								remaining = remaining[earliestFenceIdx+len(earliestFenceType):]
-								inCodeBlock = true
-								codeFenceType = earliestFenceType
-								log.Debugf("kiro: entered code block with fence: %s", earliestFenceType)
-								continue
-							}
-						}
-
-						// If inside code block, emit all content as text (don't parse thinking tags)
-						if inCodeBlock {
-							if remaining != "" {
-								if !isTextBlockOpen {
-									contentBlockIndex++
-									isTextBlockOpen = true
-									blockStart := kiroclaude.BuildClaudeContentBlockStartEvent(contentBlockIndex, "text", "", "")
-									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")}
-										}
-									}
-								}
-								claudeEvent := kiroclaude.BuildClaudeStreamEvent(remaining, contentBlockIndex)
-								sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, claudeEvent, &translatorParam)
-								for _, chunk := range sseData {
-									if chunk != "" {
-										out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunk + "\n\n")}
-									}
-								}
-							}
-							break // Exit loop - all remaining content is inside code block
-						}
-					}
+					// TAG-BASED THINKING PARSING: Parse <thinking> tags from content
+					// Combine pending content with new content for processing
+					pendingContent.WriteString(contentDelta)
+					processContent := pendingContent.String()
+					pendingContent.Reset()
 
+					// Process content looking for thinking tags
+					for len(processContent) > 0 {
 					if inThinkBlock {
-						// Inside thinking block - look for </thinking> end tag
-						// CRITICAL FIX: Skip </thinking> tags that are not the real end tag
-						// This prevents false positives when thinking content discusses these tags
-						// Pass current code block/inline code state for accurate detection
-						endIdx := findRealThinkingEndTag(remaining, inCodeBlock, inInlineCode)
-						
+						// We're inside a thinking block, look for </thinking>
+						endIdx := strings.Index(processContent, kirocommon.ThinkingEndTag)
 						if endIdx >= 0 {
-							// Found end tag - emit any content before end tag, then close block
-							thinkContent := remaining[:endIdx]
-							if thinkContent != "" {
-								// TRUE STREAMING: Emit thinking content immediately
-								// Start thinking block if not open
+							// Found end tag - emit thinking content before the tag
+							thinkingText := processContent[:endIdx]
+							if thinkingText != "" {
+								// Ensure thinking block is open
 								if !isThinkingBlockOpen {
 									contentBlockIndex++
 									thinkingBlockIndex = contentBlockIndex
@@ -2382,22 +2266,16 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 										}
 									}
 								}
-
-								// Send thinking delta immediately
-								thinkingEvent := kiroclaude.BuildClaudeThinkingDeltaEvent(thinkContent, thinkingBlockIndex)
+								// Send thinking delta
+								thinkingEvent := kiroclaude.BuildClaudeThinkingDeltaEvent(thinkingText, thinkingBlockIndex)
 								sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, thinkingEvent, &translatorParam)
 								for _, chunk := range sseData {
 									if chunk != "" {
 										out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunk + "\n\n")}
 									}
 								}
-								// Accumulate thinking content for signature generation
-								accumulatedThinkingContent.WriteString(thinkContent)
+								accumulatedThinkingContent.WriteString(thinkingText)
 							}
-
-							// Note: Partial tag handling is done via pendingEndTagChars
-							// When the next chunk arrives, the partial tag will be reconstructed
-
 							// Close thinking block
 							if isThinkingBlockOpen {
 								blockStop := kiroclaude.BuildClaudeThinkingBlockStopEvent(thinkingBlockIndex)
@@ -2408,31 +2286,25 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 									}
 								}
 								isThinkingBlockOpen = false
-								accumulatedThinkingContent.Reset() // Reset for potential next thinking block
 							}
-
 							inThinkBlock = false
-							thinkingBlockCompleted = true // Mark that we've completed a thinking block
-							remaining = remaining[endIdx+len(kirocommon.ThinkingEndTag):]
-							log.Debugf("kiro: exited thinking block, subsequent <thinking> tags will be treated as text")
+							processContent = processContent[endIdx+len(kirocommon.ThinkingEndTag):]
+							log.Debugf("kiro: closed thinking block, remaining content: %d chars", len(processContent))
 						} else {
-							// No end tag found - TRUE STREAMING: emit content immediately
-							// Only save potential partial tag length for next iteration
-							pendingEnd := kiroclaude.PendingTagSuffix(remaining, kirocommon.ThinkingEndTag)
-
-							// Calculate content to emit immediately (excluding potential partial tag)
-							var contentToEmit string
-							if pendingEnd > 0 {
-								contentToEmit = remaining[:len(remaining)-pendingEnd]
-								// Save partial tag length for next iteration (will be reconstructed from thinkingEndTag)
-								pendingEndTagChars = pendingEnd
-							} else {
-								contentToEmit = remaining
+							// No end tag found - check for partial match at end
+							partialMatch := false
+							for i := 1; i < len(kirocommon.ThinkingEndTag) && i <= len(processContent); i++ {
+								if strings.HasSuffix(processContent, kirocommon.ThinkingEndTag[:i]) {
+									// Possible partial tag at end, buffer it
+									pendingContent.WriteString(processContent[len(processContent)-i:])
+									processContent = processContent[:len(processContent)-i]
+									partialMatch = true
+									break
 								}
-
-							// TRUE STREAMING: Emit thinking content immediately
-							if contentToEmit != "" {
-								// Start thinking block if not open
+							}
+							if !partialMatch || len(processContent) > 0 {
+								// Emit all as thinking content
+								if processContent != "" {
 									if !isThinkingBlockOpen {
 										contentBlockIndex++
 										thinkingBlockIndex = contentBlockIndex
@@ -2445,47 +2317,37 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 											}
 										}
 									}
-
-								// Send thinking delta immediately - TRUE STREAMING!
-								thinkingEvent := kiroclaude.BuildClaudeThinkingDeltaEvent(contentToEmit, thinkingBlockIndex)
+									thinkingEvent := kiroclaude.BuildClaudeThinkingDeltaEvent(processContent, thinkingBlockIndex)
 									sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, thinkingEvent, &translatorParam)
 									for _, chunk := range sseData {
 										if chunk != "" {
 											out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunk + "\n\n")}
 										}
 									}
-								// Accumulate thinking content for signature generation
-								accumulatedThinkingContent.WriteString(contentToEmit)
+									accumulatedThinkingContent.WriteString(processContent)
 								}
-
-							remaining = ""
+							}
+							processContent = ""
 						}
 					} else {
-						// Outside thinking block - look for <thinking> start tag
-						// CRITICAL FIX: Only parse <thinking> tags at the very beginning of the response
-						// or if we haven't completed a thinking block yet.
-						// After a thinking block is completed, subsequent <thinking> tags are likely
-						// discussion text (e.g., "Kiro returns `<thinking>` tags") and should NOT be parsed.
-						startIdx := -1
-						if !thinkingBlockCompleted && !hasSeenNonThinkingContent {
-							startIdx = strings.Index(remaining, kirocommon.ThinkingStartTag)
-							// If there's non-whitespace content before the tag, it's not a real thinking block
-							if startIdx > 0 {
-								textBefore := remaining[:startIdx]
-								if strings.TrimSpace(textBefore) != "" {
-									// There's real content before the tag - this is discussion text, not thinking
-									hasSeenNonThinkingContent = true
-									startIdx = -1
-									log.Debugf("kiro: found <thinking> tag after non-whitespace content, treating as text")
-								}
-							}
-						}
+						// Not in thinking block, look for <thinking>
+						startIdx := strings.Index(processContent, kirocommon.ThinkingStartTag)
 						if startIdx >= 0 {
-							// Found start tag - emit text before it and switch to thinking mode
-							textBefore := remaining[:startIdx]
+							// Found start tag - emit text content before the tag
+							textBefore := processContent[:startIdx]
 							if textBefore != "" {
-								// Only whitespace before thinking tag is allowed
-								// Start text content block if needed
+								// Close thinking block if open
+								if isThinkingBlockOpen {
+									blockStop := kiroclaude.BuildClaudeThinkingBlockStopEvent(thinkingBlockIndex)
+									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")}
+										}
+									}
+									isThinkingBlockOpen = false
+								}
+								// Ensure text block is open
 								if !isTextBlockOpen {
 									contentBlockIndex++
 									isTextBlockOpen = true
@@ -2497,7 +2359,7 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 										}
 									}
 								}
-
+								// Send text delta
 								claudeEvent := kiroclaude.BuildClaudeStreamEvent(textBefore, contentBlockIndex)
 								sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, claudeEvent, &translatorParam)
 								for _, chunk := range sseData {
@@ -2506,8 +2368,7 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 									}
 								}
 							}
-
-							// Close text block before starting thinking block
+							// Close text block before entering thinking
 							if isTextBlockOpen {
 								blockStop := kiroclaude.BuildClaudeContentBlockStopEvent(contentBlockIndex)
 								sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, blockStop, &translatorParam)
@@ -2518,26 +2379,24 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 								}
 								isTextBlockOpen = false
 							}
-
 							inThinkBlock = true
-							remaining = remaining[startIdx+len(kirocommon.ThinkingStartTag):]
+							processContent = processContent[startIdx+len(kirocommon.ThinkingStartTag):]
 							log.Debugf("kiro: entered thinking block")
 						} else {
-							// No start tag found - check for partial start tag at buffer end
-							// Only check for partial tags if we haven't completed a thinking block yet
-							pendingStart := 0
-							if !thinkingBlockCompleted && !hasSeenNonThinkingContent {
-								pendingStart = kiroclaude.PendingTagSuffix(remaining, kirocommon.ThinkingStartTag)
+							// No start tag found - check for partial match at end
+							partialMatch := false
+							for i := 1; i < len(kirocommon.ThinkingStartTag) && i <= len(processContent); i++ {
+								if strings.HasSuffix(processContent, kirocommon.ThinkingStartTag[:i]) {
+									// Possible partial tag at end, buffer it
+									pendingContent.WriteString(processContent[len(processContent)-i:])
+									processContent = processContent[:len(processContent)-i]
+									partialMatch = true
+									break
 								}
-							if pendingStart > 0 {
-								// Emit text except potential partial tag
-								textToEmit := remaining[:len(remaining)-pendingStart]
-								if textToEmit != "" {
-									// Mark that we've seen non-thinking content
-									if strings.TrimSpace(textToEmit) != "" {
-										hasSeenNonThinkingContent = true
 							}
-									// Start text content block if needed
+							if !partialMatch || len(processContent) > 0 {
+								// Emit all as text content
+								if processContent != "" {
 									if !isTextBlockOpen {
 										contentBlockIndex++
 										isTextBlockOpen = true
@@ -2549,8 +2408,7 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 											}
 										}
 									}
-
-									claudeEvent := kiroclaude.BuildClaudeStreamEvent(textToEmit, contentBlockIndex)
+									claudeEvent := kiroclaude.BuildClaudeStreamEvent(processContent, contentBlockIndex)
 									sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, claudeEvent, &translatorParam)
 									for _, chunk := range sseData {
 										if chunk != "" {
@@ -2558,38 +2416,8 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 										}
 									}
 								}
-								pendingStartTagChars = pendingStart
-								remaining = ""
-							} else {
-								// No partial tag - emit all as text
-								if remaining != "" {
-									// Mark that we've seen non-thinking content
-									if strings.TrimSpace(remaining) != "" {
-										hasSeenNonThinkingContent = true
-									}
-									// Start text content block if needed
-									if !isTextBlockOpen {
-										contentBlockIndex++
-										isTextBlockOpen = true
-										blockStart := kiroclaude.BuildClaudeContentBlockStartEvent(contentBlockIndex, "text", "", "")
-										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")}
-											}
-										}
-									}
-
-									claudeEvent := kiroclaude.BuildClaudeStreamEvent(remaining, contentBlockIndex)
-									sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, claudeEvent, &translatorParam)
-									for _, chunk := range sseData {
-										if chunk != "" {
-											out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunk + "\n\n")}
-										}
-									}
-								}
-								remaining = ""
 							}
+							processContent = ""
 						}
 					}
 					}
@@ -2658,6 +2486,80 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 				}
 			}
 
+		case "reasoningContentEvent":
+			// Handle official reasoningContentEvent from Kiro API
+			// This replaces tag-based thinking detection with the proper event type
+			// Official format: { text: string, signature?: string, redactedContent?: base64 }
+			var thinkingText string
+			var signature string
+
+			if re, ok := event["reasoningContentEvent"].(map[string]interface{}); ok {
+				if text, ok := re["text"].(string); ok {
+					thinkingText = text
+				}
+				if sig, ok := re["signature"].(string); ok {
+					signature = sig
+					if len(sig) > 20 {
+						log.Debugf("kiro: reasoningContentEvent has signature: %s...", sig[:20])
+					} else {
+						log.Debugf("kiro: reasoningContentEvent has signature: %s", sig)
+					}
+				}
+			} else {
+				// Try direct fields
+				if text, ok := event["text"].(string); ok {
+					thinkingText = text
+				}
+				if sig, ok := event["signature"].(string); ok {
+					signature = sig
+				}
+			}
+
+			if thinkingText != "" {
+				// Close text block if open before starting thinking block
+				if isTextBlockOpen && contentBlockIndex >= 0 {
+					blockStop := kiroclaude.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")}
+						}
+					}
+					isTextBlockOpen = false
+				}
+
+				// Start thinking block if not already open
+				if !isThinkingBlockOpen {
+					contentBlockIndex++
+					thinkingBlockIndex = contentBlockIndex
+					isThinkingBlockOpen = true
+					blockStart := kiroclaude.BuildClaudeContentBlockStartEvent(thinkingBlockIndex, "thinking", "", "")
+					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 thinking content
+				thinkingEvent := kiroclaude.BuildClaudeThinkingDeltaEvent(thinkingText, thinkingBlockIndex)
+				sseData := sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, thinkingEvent, &translatorParam)
+				for _, chunk := range sseData {
+					if chunk != "" {
+						out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunk + "\n\n")}
+					}
+				}
+
+				// Accumulate for token counting
+				accumulatedThinkingContent.WriteString(thinkingText)
+				log.Debugf("kiro: received reasoningContentEvent, text length: %d, has signature: %v", len(thinkingText), signature != "")
+			}
+
+			// Note: We don't close the thinking block here - it will be closed when we see
+			// the next assistantResponseEvent or at the end of the stream
+			_ = signature // Signature can be used for verification if needed
+
 		case "toolUseEvent":
 			// Handle dedicated tool use events with input buffering
 			completedToolUses, newState := kiroclaude.ProcessToolUseEvent(event, currentToolUse, processedIDs)
@@ -2721,17 +2623,71 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 				totalUsage.OutputTokens = int64(outputTokens)
 			}
 
-		case "messageMetadataEvent":
-			// Handle message metadata events which may contain token counts
-			if metadata, ok := event["messageMetadataEvent"].(map[string]interface{}); ok {
+		case "messageMetadataEvent", "metadataEvent":
+			// Handle message metadata events which contain token counts
+			// Official format: { tokenUsage: { outputTokens, totalTokens, uncachedInputTokens, cacheReadInputTokens, cacheWriteInputTokens, contextUsagePercentage } }
+			var metadata map[string]interface{}
+			if m, ok := event["messageMetadataEvent"].(map[string]interface{}); ok {
+				metadata = m
+			} else if m, ok := event["metadataEvent"].(map[string]interface{}); ok {
+				metadata = m
+			} else {
+				metadata = event // event itself might be the metadata
+			}
+
+			// Check for nested tokenUsage object (official format)
+			if tokenUsage, ok := metadata["tokenUsage"].(map[string]interface{}); ok {
+				// outputTokens - precise output token count
+				if outputTokens, ok := tokenUsage["outputTokens"].(float64); ok {
+					totalUsage.OutputTokens = int64(outputTokens)
+					hasUpstreamUsage = true
+					log.Infof("kiro: streamToChannel found precise outputTokens in tokenUsage: %d", totalUsage.OutputTokens)
+				}
+				// totalTokens - precise total token count
+				if totalTokens, ok := tokenUsage["totalTokens"].(float64); ok {
+					totalUsage.TotalTokens = int64(totalTokens)
+					log.Infof("kiro: streamToChannel found precise totalTokens in tokenUsage: %d", totalUsage.TotalTokens)
+				}
+				// uncachedInputTokens - input tokens not from cache
+				if uncachedInputTokens, ok := tokenUsage["uncachedInputTokens"].(float64); ok {
+					totalUsage.InputTokens = int64(uncachedInputTokens)
+					hasUpstreamUsage = true
+					log.Infof("kiro: streamToChannel found uncachedInputTokens in tokenUsage: %d", totalUsage.InputTokens)
+				}
+				// cacheReadInputTokens - tokens read from cache
+				if cacheReadTokens, ok := tokenUsage["cacheReadInputTokens"].(float64); ok {
+					// Add to input tokens if we have uncached tokens, otherwise use as input
+					if totalUsage.InputTokens > 0 {
+						totalUsage.InputTokens += int64(cacheReadTokens)
+					} else {
+						totalUsage.InputTokens = int64(cacheReadTokens)
+					}
+					hasUpstreamUsage = true
+					log.Debugf("kiro: streamToChannel found cacheReadInputTokens in tokenUsage: %d", int64(cacheReadTokens))
+				}
+				// contextUsagePercentage - can be used as fallback for input token estimation
+				if ctxPct, ok := tokenUsage["contextUsagePercentage"].(float64); ok {
+					upstreamContextPercentage = ctxPct
+					log.Debugf("kiro: streamToChannel found contextUsagePercentage in tokenUsage: %.2f%%", ctxPct)
+				}
+			}
+
+			// Fallback: check for direct fields in metadata (legacy format)
+			if totalUsage.InputTokens == 0 {
 				if inputTokens, ok := metadata["inputTokens"].(float64); ok {
 					totalUsage.InputTokens = int64(inputTokens)
+					hasUpstreamUsage = true
 					log.Debugf("kiro: streamToChannel found inputTokens in messageMetadataEvent: %d", totalUsage.InputTokens)
 				}
+			}
+			if totalUsage.OutputTokens == 0 {
 				if outputTokens, ok := metadata["outputTokens"].(float64); ok {
 					totalUsage.OutputTokens = int64(outputTokens)
+					hasUpstreamUsage = true
 					log.Debugf("kiro: streamToChannel found outputTokens in messageMetadataEvent: %d", totalUsage.OutputTokens)
 				}
+			}
+			if totalUsage.TotalTokens == 0 {
 				if totalTokens, ok := metadata["totalTokens"].(float64); ok {
 					totalUsage.TotalTokens = int64(totalTokens)
 					log.Debugf("kiro: streamToChannel found totalTokens in messageMetadataEvent: %d", totalUsage.TotalTokens)

internal/translator/kiro/claude/kiro_claude_request.go

@@ -222,20 +222,19 @@ func BuildKiroPayload(claudeBody []byte, modelID, profileArn, origin string, isA
 	kiroTools := convertClaudeToolsToKiro(tools)
 
 	// Thinking mode implementation:
-	// Kiro API doesn't accept max_tokens for thinking. Instead, thinking mode is enabled
-	// by injecting <thinking_mode> and <max_thinking_length> tags into the system prompt.
-	// We use a fixed max_thinking_length value since Kiro handles the actual budget internally.
+	// Kiro API supports official thinking/reasoning mode via <thinking_mode> tag.
+	// When set to "enabled", Kiro returns reasoning content as official reasoningContentEvent
+	// rather than inline <thinking> tags in assistantResponseEvent.
+	// We use a high max_thinking_length to allow extensive reasoning.
 	if thinkingEnabled {
-		thinkingHint := `<thinking_mode>interleaved</thinking_mode>
-<max_thinking_length>200000</max_thinking_length>
-
-IMPORTANT: You MUST use <thinking>...</thinking> tags to show your reasoning process before providing your final response. Think step by step inside the thinking tags.`
+		thinkingHint := `<thinking_mode>enabled</thinking_mode>
+<max_thinking_length>200000</max_thinking_length>`
 		if systemPrompt != "" {
 			systemPrompt = thinkingHint + "\n\n" + systemPrompt
 		} else {
 			systemPrompt = thinkingHint
 		}
-		log.Infof("kiro: injected thinking prompt, has_tools: %v", len(kiroTools) > 0)
+		log.Infof("kiro: injected thinking prompt (official mode), has_tools: %v", len(kiroTools) > 0)
 	}
 
 	// Process messages and build history

internal/translator/kiro/openai/kiro_openai_request.go

@@ -231,20 +231,19 @@ func BuildKiroPayloadFromOpenAI(openaiBody []byte, modelID, profileArn, origin s
 	kiroTools := convertOpenAIToolsToKiro(tools)
 
 	// Thinking mode implementation:
-	// Kiro API doesn't accept max_tokens for thinking. Instead, thinking mode is enabled
-	// by injecting <thinking_mode> and <max_thinking_length> tags into the system prompt.
-	// We use a fixed max_thinking_length value since Kiro handles the actual budget internally.
+	// Kiro API supports official thinking/reasoning mode via <thinking_mode> tag.
+	// When set to "enabled", Kiro returns reasoning content as official reasoningContentEvent
+	// rather than inline <thinking> tags in assistantResponseEvent.
+	// We use a high max_thinking_length to allow extensive reasoning.
 	if thinkingEnabled {
-		thinkingHint := `<thinking_mode>interleaved</thinking_mode>
-<max_thinking_length>200000</max_thinking_length>
-
-IMPORTANT: You MUST use <thinking>...</thinking> tags to show your reasoning process before providing your final response. Think step by step inside the thinking tags.`
+		thinkingHint := `<thinking_mode>enabled</thinking_mode>
+<max_thinking_length>200000</max_thinking_length>`
 		if systemPrompt != "" {
 			systemPrompt = thinkingHint + "\n\n" + systemPrompt
 		} else {
 			systemPrompt = thinkingHint
 		}
-		log.Debugf("kiro-openai: injected thinking prompt")
+		log.Debugf("kiro-openai: injected thinking prompt (official mode)")
 	}
 
 	// Process messages and build history

sdk/auth/kiro.go

@@ -117,6 +117,71 @@ func (a *KiroAuthenticator) Login(ctx context.Context, cfg *config.Config, opts
 	return record, nil
 }
 
+// LoginWithAuthCode performs OAuth login for Kiro with AWS Builder ID using authorization code flow.
+// This provides a better UX than device code flow as it uses automatic browser callback.
+func (a *KiroAuthenticator) LoginWithAuthCode(ctx context.Context, cfg *config.Config, opts *LoginOptions) (*coreauth.Auth, error) {
+	if cfg == nil {
+		return nil, fmt.Errorf("kiro auth: configuration is required")
+	}
+
+	oauth := kiroauth.NewKiroOAuth(cfg)
+
+	// Use AWS Builder ID authorization code flow
+	tokenData, err := oauth.LoginWithBuilderIDAuthCode(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("login failed: %w", err)
+	}
+
+	// Parse expires_at
+	expiresAt, err := time.Parse(time.RFC3339, tokenData.ExpiresAt)
+	if err != nil {
+		expiresAt = time.Now().Add(1 * time.Hour)
+	}
+
+	// Extract identifier for file naming
+	idPart := extractKiroIdentifier(tokenData.Email, tokenData.ProfileArn)
+
+	now := time.Now()
+	fileName := fmt.Sprintf("kiro-aws-%s.json", idPart)
+
+	record := &coreauth.Auth{
+		ID:        fileName,
+		Provider:  "kiro",
+		FileName:  fileName,
+		Label:     "kiro-aws",
+		Status:    coreauth.StatusActive,
+		CreatedAt: now,
+		UpdatedAt: now,
+		Metadata: map[string]any{
+			"type":          "kiro",
+			"access_token":  tokenData.AccessToken,
+			"refresh_token": tokenData.RefreshToken,
+			"profile_arn":   tokenData.ProfileArn,
+			"expires_at":    tokenData.ExpiresAt,
+			"auth_method":   tokenData.AuthMethod,
+			"provider":      tokenData.Provider,
+			"client_id":     tokenData.ClientID,
+			"client_secret": tokenData.ClientSecret,
+			"email":         tokenData.Email,
+		},
+		Attributes: map[string]string{
+			"profile_arn": tokenData.ProfileArn,
+			"source":      "aws-builder-id-authcode",
+			"email":       tokenData.Email,
+		},
+		// NextRefreshAfter is aligned with RefreshLead (5min)
+		NextRefreshAfter: expiresAt.Add(-5 * time.Minute),
+	}
+
+	if tokenData.Email != "" {
+		fmt.Printf("\n✓ Kiro authentication completed successfully! (Account: %s)\n", tokenData.Email)
+	} else {
+		fmt.Println("\n✓ Kiro authentication completed successfully!")
+	}
+
+	return record, nil
+}
+
 // LoginWithGoogle performs OAuth login for Kiro with Google.
 // This uses a custom protocol handler (kiro://) to receive the callback.
 func (a *KiroAuthenticator) LoginWithGoogle(ctx context.Context, cfg *config.Config, opts *LoginOptions) (*coreauth.Auth, error) {