fix(kiro): fix translator format mismatch for OpenAI protocol

Amp-Thread-ID: https://ampcode.com/threads/T-019b092b-f2de-72a1-b428-72511c0de628
Co-authored-by: Amp <amp@ampcode.com>

internal/translator/kiro/claude/kiro_claude.go

@@ -1,14 +1,11 @@
 // Package claude provides translation between Kiro and Claude formats.
-// Since Kiro uses Claude-compatible format internally, translations are mostly pass-through.
-// However, SSE events require proper "event: <type>" prefix for Claude clients.
+// Since Kiro executor generates Claude-compatible SSE format internally (with event: prefix),
+// translations are pass-through.
 package claude
 
 import (
 	"bytes"
 	"context"
-	"strings"
-
-	"github.com/tidwall/gjson"
 )
 
 // ConvertClaudeRequestToKiro converts Claude request to Kiro format.
@@ -18,52 +15,10 @@ func ConvertClaudeRequestToKiro(modelName string, inputRawJSON []byte, stream bo
 }
 
 // ConvertKiroResponseToClaude converts Kiro streaming response to Claude format.
-// It adds the required "event: <type>" prefix for SSE compliance with Claude clients.
-// Input format: "data: {\"type\":\"message_start\",...}"
-// Output format: "event: message_start\ndata: {\"type\":\"message_start\",...}"
+// Kiro executor already generates complete SSE format with "event:" prefix,
+// so this is a simple pass-through.
 func ConvertKiroResponseToClaude(ctx context.Context, model string, originalRequest, request, rawResponse []byte, param *any) []string {
-	raw := string(rawResponse)
-
-	// Handle multiple data blocks (e.g., message_delta + message_stop)
-	lines := strings.Split(raw, "\n\n")
-	var results []string
-
-	for _, line := range lines {
-		line = strings.TrimSpace(line)
-		if line == "" {
-			continue
-		}
-
-		// Extract event type from JSON and add "event:" prefix
-		formatted := addEventPrefix(line)
-		if formatted != "" {
-			results = append(results, formatted)
-		}
-	}
-
-	if len(results) == 0 {
-		return []string{raw}
-	}
-
-	return results
-}
-
-// addEventPrefix extracts the event type from the data line and adds the event: prefix.
-// Input: "data: {\"type\":\"message_start\",...}"
-// Output: "event: message_start\ndata: {\"type\":\"message_start\",...}"
-func addEventPrefix(dataLine string) string {
-	if !strings.HasPrefix(dataLine, "data: ") {
-		return dataLine
-	}
-
-	jsonPart := strings.TrimPrefix(dataLine, "data: ")
-	eventType := gjson.Get(jsonPart, "type").String()
-
-	if eventType == "" {
-		return dataLine
-	}
-
-	return "event: " + eventType + "\n" + dataLine
+	return []string{string(rawResponse)}
 }
 
 // ConvertKiroResponseToClaudeNonStream converts Kiro non-streaming response to Claude format.

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

@@ -4,6 +4,7 @@ package chat_completions
 import (
 	"context"
 	"encoding/json"
+	"strings"
 	"time"
 
 	"github.com/google/uuid"
@@ -13,15 +14,58 @@ import (
 // ConvertKiroResponseToOpenAI converts Kiro streaming response to OpenAI SSE format.
 // Handles Claude SSE events: content_block_start, content_block_delta, input_json_delta,
 // content_block_stop, message_delta, and message_stop.
+// Input may be in SSE format: "event: xxx\ndata: {...}" or raw JSON.
 func ConvertKiroResponseToOpenAI(ctx context.Context, model string, originalRequest, request, rawResponse []byte, param *any) []string {
-	root := gjson.ParseBytes(rawResponse)
+	raw := string(rawResponse)
+	var results []string
+
+	// Handle SSE format: extract JSON from "data: " lines
+	// Input format: "event: message_start\ndata: {...}"
+	lines := strings.Split(raw, "\n")
+	for _, line := range lines {
+		line = strings.TrimSpace(line)
+		if strings.HasPrefix(line, "data: ") {
+			jsonPart := strings.TrimPrefix(line, "data: ")
+			chunks := convertClaudeEventToOpenAI(jsonPart, model)
+			results = append(results, chunks...)
+		} else if strings.HasPrefix(line, "{") {
+			// Raw JSON (backward compatibility)
+			chunks := convertClaudeEventToOpenAI(line, model)
+			results = append(results, chunks...)
+		}
+	}
+
+	return results
+}
+
+// convertClaudeEventToOpenAI converts a single Claude JSON event to OpenAI format
+func convertClaudeEventToOpenAI(jsonStr string, model string) []string {
+	root := gjson.Parse(jsonStr)
 	var results []string
 
 	eventType := root.Get("type").String()
 
 	switch eventType {
 	case "message_start":
-		// Initial message event - could emit initial chunk if needed
+		// Initial message event - emit initial chunk with role
+		response := map[string]interface{}{
+			"id":      "chatcmpl-" + uuid.New().String()[:24],
+			"object":  "chat.completion.chunk",
+			"created": time.Now().Unix(),
+			"model":   model,
+			"choices": []map[string]interface{}{
+				{
+					"index": 0,
+					"delta": map[string]interface{}{
+						"role":    "assistant",
+						"content": "",
+					},
+					"finish_reason": nil,
+				},
+			},
+		}
+		result, _ := json.Marshal(response)
+		results = append(results, string(result))
 		return results
 
 	case "content_block_start":