fix: filter out orphaned tool results from history and current context

internal/translator/kiro/openai/kiro_openai_request.go

@@ -578,6 +578,7 @@ func processOpenAIMessages(messages gjson.Result, modelID, origin string) ([]Kir
 
 	// Truncate history if too long to prevent Kiro API errors
 	history = truncateHistoryIfNeeded(history)
+	history, currentToolResults = filterOrphanedToolResults(history, currentToolResults)
 
 	return history, currentUserMsg, currentToolResults
 }
@@ -593,6 +594,61 @@ func truncateHistoryIfNeeded(history []KiroHistoryMessage) []KiroHistoryMessage
 	return history[len(history)-kiroMaxHistoryMessages:]
 }
 
+func filterOrphanedToolResults(history []KiroHistoryMessage, currentToolResults []KiroToolResult) ([]KiroHistoryMessage, []KiroToolResult) {
+	// Remove tool results with no matching tool_use in retained history.
+	// This happens after truncation when the assistant turn that produced tool_use
+	// is dropped but a later user/tool_result survives.
+	validToolUseIDs := make(map[string]bool)
+	for _, h := range history {
+		if h.AssistantResponseMessage == nil {
+			continue
+		}
+		for _, tu := range h.AssistantResponseMessage.ToolUses {
+			validToolUseIDs[tu.ToolUseID] = true
+		}
+	}
+
+	for i, h := range history {
+		if h.UserInputMessage == nil || h.UserInputMessage.UserInputMessageContext == nil {
+			continue
+		}
+		ctx := h.UserInputMessage.UserInputMessageContext
+		if len(ctx.ToolResults) == 0 {
+			continue
+		}
+
+		filtered := make([]KiroToolResult, 0, len(ctx.ToolResults))
+		for _, tr := range ctx.ToolResults {
+			if validToolUseIDs[tr.ToolUseID] {
+				filtered = append(filtered, tr)
+				continue
+			}
+			log.Debugf("kiro-openai: dropping orphaned tool_result in history[%d]: toolUseId=%s (no matching tool_use)", i, tr.ToolUseID)
+		}
+		ctx.ToolResults = filtered
+		if len(ctx.ToolResults) == 0 && len(ctx.Tools) == 0 {
+			h.UserInputMessage.UserInputMessageContext = nil
+		}
+	}
+
+	if len(currentToolResults) > 0 {
+		filtered := make([]KiroToolResult, 0, len(currentToolResults))
+		for _, tr := range currentToolResults {
+			if validToolUseIDs[tr.ToolUseID] {
+				filtered = append(filtered, tr)
+				continue
+			}
+			log.Debugf("kiro-openai: dropping orphaned tool_result in currentMessage: toolUseId=%s (no matching tool_use)", tr.ToolUseID)
+		}
+		if len(filtered) != len(currentToolResults) {
+			log.Infof("kiro-openai: dropped %d orphaned tool_result(s) from currentMessage", len(currentToolResults)-len(filtered))
+		}
+		currentToolResults = filtered
+	}
+
+	return history, currentToolResults
+}
+
 // buildUserMessageFromOpenAI builds a user message from OpenAI format and extracts tool results
 func buildUserMessageFromOpenAI(msg gjson.Result, modelID, origin string) (KiroUserInputMessage, []KiroToolResult) {
 	content := msg.Get("content")

internal/translator/kiro/openai/kiro_openai_request_test.go

@@ -384,3 +384,57 @@ func TestAssistantEndsConversation(t *testing.T) {
 		t.Error("Expected a 'Continue' message to be created when assistant is last")
 	}
 }
+
+func TestFilterOrphanedToolResults_RemovesHistoryAndCurrentOrphans(t *testing.T) {
+	history := []KiroHistoryMessage{
+		{
+			AssistantResponseMessage: &KiroAssistantResponseMessage{
+				Content: "assistant",
+				ToolUses: []KiroToolUse{
+					{ToolUseID: "keep-1", Name: "Read", Input: map[string]interface{}{}},
+				},
+			},
+		},
+		{
+			UserInputMessage: &KiroUserInputMessage{
+				Content: "user-with-mixed-results",
+				UserInputMessageContext: &KiroUserInputMessageContext{
+					ToolResults: []KiroToolResult{
+						{ToolUseID: "keep-1", Status: "success", Content: []KiroTextContent{{Text: "ok"}}},
+						{ToolUseID: "orphan-1", Status: "success", Content: []KiroTextContent{{Text: "bad"}}},
+					},
+				},
+			},
+		},
+		{
+			UserInputMessage: &KiroUserInputMessage{
+				Content: "user-only-orphans",
+				UserInputMessageContext: &KiroUserInputMessageContext{
+					ToolResults: []KiroToolResult{
+						{ToolUseID: "orphan-2", Status: "success", Content: []KiroTextContent{{Text: "bad"}}},
+					},
+				},
+			},
+		},
+	}
+
+	currentToolResults := []KiroToolResult{
+		{ToolUseID: "keep-1", Status: "success", Content: []KiroTextContent{{Text: "ok"}}},
+		{ToolUseID: "orphan-3", Status: "success", Content: []KiroTextContent{{Text: "bad"}}},
+	}
+
+	filteredHistory, filteredCurrent := filterOrphanedToolResults(history, currentToolResults)
+
+	ctx1 := filteredHistory[1].UserInputMessage.UserInputMessageContext
+	if ctx1 == nil || len(ctx1.ToolResults) != 1 || ctx1.ToolResults[0].ToolUseID != "keep-1" {
+		t.Fatalf("expected mixed history message to keep only keep-1, got: %+v", ctx1)
+	}
+
+	if filteredHistory[2].UserInputMessage.UserInputMessageContext != nil {
+		t.Fatalf("expected orphan-only history context to be removed")
+	}
+
+	if len(filteredCurrent) != 1 || filteredCurrent[0].ToolUseID != "keep-1" {
+		t.Fatalf("expected current tool results to keep only keep-1, got: %+v", filteredCurrent)
+	}
+}