fix: handle Write tool truncation when content exceeds API limits

When the Kiro/AWS CodeWhisperer API receives a Write tool request with content
that exceeds transmission limits, it truncates the tool input. This can result in:
- Empty input buffer (no input transmitted at all)
- Missing 'content' field in the parsed JSON
- Incomplete JSON that fails to parse

This fix detects these truncation scenarios and converts them to Bash tool calls
that echo an error message. This allows Claude Code to execute the Bash command,
see the error output, and the agent can then retry with smaller chunks.

Changes:
- kiro_claude_tools.go: Detect three truncation scenarios in ProcessToolUseEvent:
  1. Empty input buffer (no input transmitted)
  2. JSON parse failure with file_path but no content field
  3. Successfully parsed JSON missing content field
  When detected, emit a special '__truncated_write__' marker tool use

- kiro_executor.go: Handle '__truncated_write__' markers in streamToChannel:
  1. Extract file_path from the marker for context
  2. Create a Bash tool_use that echoes an error message
  3. Include retry guidance (700-line chunks recommended)
  4. Set hasToolUses=true to ensure stop_reason='tool_use' for agent continuation

This ensures the agent continues and can retry with smaller file chunks instead
of failing silently or showing errors to the user.

internal/runtime/executor/kiro_executor.go

@@ -2332,8 +2332,8 @@ func (e *KiroExecutor) extractEventTypeFromBytes(headers []byte) string {
 func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out chan<- cliproxyexecutor.StreamChunk, targetFormat sdktranslator.Format, model string, originalReq, claudeBody []byte, reporter *usageReporter, thinkingEnabled bool) {
 	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 upstreamStopReason string // Track stop_reason from upstream events
+	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)
@@ -3111,12 +3111,88 @@ func (e *KiroExecutor) streamToChannel(ctx context.Context, body io.Reader, out
 			_ = signature // Signature can be used for verification if needed
 
 		case "toolUseEvent":
+			// Debug: log raw toolUseEvent payload for large tool inputs
+			if log.IsLevelEnabled(log.DebugLevel) {
+				payloadStr := string(payload)
+				if len(payloadStr) > 500 {
+					payloadStr = payloadStr[:500] + "...[truncated]"
+				}
+				log.Debugf("kiro: raw toolUseEvent payload (%d bytes): %s", len(payload), payloadStr)
+			}
 			// Handle dedicated tool use events with input buffering
 			completedToolUses, newState := kiroclaude.ProcessToolUseEvent(event, currentToolUse, processedIDs)
 			currentToolUse = newState
 
 			// Emit completed tool uses
 			for _, tu := range completedToolUses {
+				// Check for truncated write marker - emit as a Bash tool that echoes the error
+				// This way Claude Code will execute it, see the error, and the agent can retry
+				if tu.Name == "__truncated_write__" {
+					filePath := ""
+					if fp, ok := tu.Input["file_path"].(string); ok && fp != "" {
+						filePath = fp
+					}
+
+					// Create a Bash tool that echoes the error message
+					// This will be executed by Claude Code and the agent will see the result
+					var errorMsg string
+					if filePath != "" {
+						errorMsg = fmt.Sprintf("echo '[WRITE TOOL ERROR] The file content for \"%s\" is too large to be transmitted by the upstream API. You MUST retry by writing the file in smaller chunks: First use Write to create the file with the first 700 lines, then use multiple Edit operations to append the remaining content in chunks of ~700 lines each.'", filePath)
+					} else {
+						errorMsg = "echo '[WRITE TOOL ERROR] The file content is too large to be transmitted by the upstream API. The Write tool input was truncated. You MUST retry by writing the file in smaller chunks: First use Write to create the file with the first 700 lines, then use multiple Edit operations to append the remaining content in chunks of ~700 lines each.'"
+					}
+
+					log.Warnf("kiro: converting truncated write to Bash echo for file: %s", filePath)
+
+					hasToolUses = true
+
+					// Close text block if open
+					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
+					}
+
+					contentBlockIndex++
+
+					// Emit as Bash tool_use
+					blockStart := kiroclaude.BuildClaudeContentBlockStartEvent(contentBlockIndex, "tool_use", tu.ToolUseID, "Bash")
+					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")}
+						}
+					}
+
+					// Emit the Bash command as input
+					bashInput := map[string]interface{}{
+						"command": errorMsg,
+					}
+					inputJSON, _ := json.Marshal(bashInput)
+					inputDelta := kiroclaude.BuildClaudeInputJsonDeltaEvent(string(inputJSON), contentBlockIndex)
+					sseData = sdktranslator.TranslateStream(ctx, sdktranslator.FromString("kiro"), targetFormat, model, originalReq, claudeBody, inputDelta, &translatorParam)
+					for _, chunk := range sseData {
+						if chunk != "" {
+							out <- cliproxyexecutor.StreamChunk{Payload: []byte(chunk + "\n\n")}
+						}
+					}
+
+					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")}
+						}
+					}
+
+					continue // Skip the normal tool_use emission
+				}
+
 				hasToolUses = true
 
 				// Close text block if open