diff --git a/internal/runtime/executor/xai_executor_execute.go b/internal/runtime/executor/xai_executor_execute.go
index 72f769729..48a6aca9d 100644
--- a/internal/runtime/executor/xai_executor_execute.go
+++ b/internal/runtime/executor/xai_executor_execute.go
@@ -94,16 +94,21 @@ func (e *XAIExecutor) Execute(ctx context.Context, auth *cliproxyauth.Auth, req
 		if len(eventData) == 0 {
 			continue
 		}
-		switch gjson.GetBytes(eventData, "type").String() {
+		eventType := gjson.GetBytes(eventData, "type").String()
+		switch eventType {
 		case "response.output_item.done":
 			xaiCollectOutputItemDone(eventData, outputItemsByIndex, &outputItemsFallback)
-		case "response.completed":
+		case "response.completed", "response.incomplete":
 			if detail, ok := helps.ParseCodexUsage(eventData); ok {
 				reporter.Publish(ctx, detail)
 			}
 			completedData := xaiPatchCompletedOutput(eventData, outputItemsByIndex, outputItemsFallback)
 			completedData = xaiNormalizeReasoningSummaryData(completedData)
-			cacheXAIReasoningReplayFromCompleted(ctx, prepared.replayScope, completedData)
+			if eventType == "response.completed" {
+				// A truncated turn carries no replayable terminal state, so only a
+				// completed response may refresh the reasoning replay cache.
+				cacheXAIReasoningReplayFromCompleted(ctx, prepared.replayScope, completedData)
+			}
 			var param any
 			out := sdktranslator.TranslateNonStream(ctx, prepared.to, prepared.responseFormat, req.Model, prepared.originalPayload, prepared.body, completedData, &param)
 			if prepared.responseFormat == sdktranslator.FormatOpenAIResponse {
@@ -113,7 +118,7 @@ func (e *XAIExecutor) Execute(ctx context.Context, auth *cliproxyauth.Auth, req
 		}
 	}
 
-	return resp, statusErr{code: http.StatusRequestTimeout, msg: "xai stream error: stream disconnected before response.completed"}
+	return resp, statusErr{code: http.StatusRequestTimeout, msg: "xai stream error: stream disconnected before response.completed or response.incomplete"}
 }
 
 func (e *XAIExecutor) executeCompact(ctx context.Context, auth *cliproxyauth.Auth, req cliproxyexecutor.Request, opts cliproxyexecutor.Options) (resp cliproxyexecutor.Response, err error) {
diff --git a/internal/runtime/executor/xai_executor_stream.go b/internal/runtime/executor/xai_executor_stream.go
index 4dad2c51f..2b5f3e86f 100644
--- a/internal/runtime/executor/xai_executor_stream.go
+++ b/internal/runtime/executor/xai_executor_stream.go
@@ -121,13 +121,17 @@ func (e *XAIExecutor) ExecuteStream(ctx context.Context, auth *cliproxyauth.Auth
 					switch normalizedEventName {
 					case "response.output_item.done":
 						xaiCollectOutputItemDone(eventData, outputItemsByIndex, &outputItemsFallback)
-					case "response.completed":
+					case "response.completed", "response.incomplete":
 						if detail, ok := helps.ParseCodexUsage(eventData); ok {
 							reporter.Publish(ctx, detail)
 						}
 						eventData = xaiPatchCompletedOutput(eventData, outputItemsByIndex, outputItemsFallback)
 						eventData = xaiNormalizeReasoningSummaryData(eventData)
-						cacheXAIReasoningReplayFromCompleted(ctx, prepared.replayScope, eventData)
+						if normalizedEventName == "response.completed" {
+							// A truncated turn carries no replayable terminal state, so only a
+							// completed response may refresh the reasoning replay cache.
+							cacheXAIReasoningReplayFromCompleted(ctx, prepared.replayScope, eventData)
+						}
 						normalizedEventName = gjson.GetBytes(eventData, "type").String()
 					}
 
diff --git a/internal/runtime/executor/xai_executor_test.go b/internal/runtime/executor/xai_executor_test.go
index 15de2a67a..8be5a3d54 100644
--- a/internal/runtime/executor/xai_executor_test.go
+++ b/internal/runtime/executor/xai_executor_test.go
@@ -656,6 +656,96 @@ func TestXAIExecutorExecuteFiltersInternalXSearchCalls(t *testing.T) {
 	}
 }
 
+func TestXAIExecutorExecuteAcceptsResponseIncomplete(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.Header().Set("Content-Type", "text/event-stream")
+		_, _ = w.Write([]byte("data: {\"type\":\"response.output_item.done\",\"output_index\":0,\"item\":{\"id\":\"rs_1\",\"type\":\"reasoning\",\"summary\":[]}}\n\n"))
+		_, _ = w.Write([]byte("data: {\"type\":\"response.incomplete\",\"response\":{\"id\":\"resp_1\",\"object\":\"response\",\"status\":\"incomplete\",\"incomplete_details\":{\"reason\":\"max_output_tokens\"},\"output\":[],\"usage\":{\"input_tokens\":8,\"output_tokens\":1,\"total_tokens\":9}}}\n\n"))
+	}))
+	defer server.Close()
+
+	exec := NewXAIExecutor(&config.Config{})
+	auth := &cliproxyauth.Auth{
+		Provider:   "xai",
+		Attributes: map[string]string{"base_url": server.URL},
+		Metadata:   map[string]any{"access_token": "xai-token"},
+	}
+	resp, err := exec.Execute(context.Background(), auth, cliproxyexecutor.Request{
+		Model:   "grok-4.5",
+		Payload: []byte(`{"model":"grok-4.5","input":"hi","max_output_tokens":1}`),
+	}, cliproxyexecutor.Options{
+		SourceFormat: sdktranslator.FormatOpenAIResponse,
+		Stream:       false,
+	})
+	if err != nil {
+		t.Fatalf("Execute() error = %v", err)
+	}
+	if got := gjson.GetBytes(resp.Payload, "status").String(); got != "incomplete" {
+		t.Fatalf("status = %q, want incomplete; payload=%s", got, resp.Payload)
+	}
+	if got := gjson.GetBytes(resp.Payload, "incomplete_details.reason").String(); got != "max_output_tokens" {
+		t.Fatalf("incomplete reason = %q, want max_output_tokens; payload=%s", got, resp.Payload)
+	}
+	if got := gjson.GetBytes(resp.Payload, "output.#").Int(); got != 1 {
+		t.Fatalf("output length = %d, want 1; payload=%s", got, resp.Payload)
+	}
+}
+
+func TestXAIExecutorExecuteStreamAcceptsResponseIncomplete(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.Header().Set("Content-Type", "text/event-stream")
+		_, _ = fmt.Fprint(w, "event: response.output_item.done\ndata: {\"type\":\"response.output_item.done\",\"output_index\":0,\"item\":{\"id\":\"rs_1\",\"type\":\"reasoning\",\"summary\":[]}}\n\n")
+		_, _ = fmt.Fprint(w, "event: response.incomplete\ndata: {\"type\":\"response.incomplete\",\"response\":{\"id\":\"resp_1\",\"object\":\"response\",\"status\":\"incomplete\",\"incomplete_details\":{\"reason\":\"max_output_tokens\"},\"output\":[],\"usage\":{\"input_tokens\":8,\"output_tokens\":1,\"total_tokens\":9}}}\n\n")
+	}))
+	defer server.Close()
+
+	exec := NewXAIExecutor(&config.Config{})
+	auth := &cliproxyauth.Auth{
+		Provider:   "xai",
+		Attributes: map[string]string{"base_url": server.URL},
+		Metadata:   map[string]any{"access_token": "xai-token"},
+	}
+	result, err := exec.ExecuteStream(context.Background(), auth, cliproxyexecutor.Request{
+		Model:   "grok-4.5",
+		Payload: []byte(`{"model":"grok-4.5","input":"hi","max_output_tokens":1}`),
+	}, cliproxyexecutor.Options{
+		SourceFormat: sdktranslator.FormatOpenAIResponse,
+		Stream:       true,
+	})
+	if err != nil {
+		t.Fatalf("ExecuteStream() error = %v", err)
+	}
+
+	var stream bytes.Buffer
+	for chunk := range result.Chunks {
+		if chunk.Err != nil {
+			t.Fatalf("stream chunk error = %v", chunk.Err)
+		}
+		stream.Write(chunk.Payload)
+		stream.WriteByte('\n')
+	}
+
+	var incomplete gjson.Result
+	for _, line := range strings.Split(stream.String(), "\n") {
+		line = strings.TrimSpace(strings.TrimPrefix(line, "data:"))
+		if !gjson.Valid(line) {
+			continue
+		}
+		if event := gjson.Parse(line); event.Get("type").String() == "response.incomplete" {
+			incomplete = event
+		}
+	}
+	if !incomplete.Exists() {
+		t.Fatalf("no response.incomplete chunk forwarded: %s", stream.String())
+	}
+	if got := incomplete.Get("response.output.#").Int(); got != 1 {
+		t.Fatalf("incomplete output length = %d, want 1; event=%s", got, incomplete.Raw)
+	}
+	if got := incomplete.Get("response.usage.total_tokens").Int(); got != 9 {
+		t.Fatalf("incomplete usage total_tokens = %d, want 9; event=%s", got, incomplete.Raw)
+	}
+}
+
 func TestXAIExecutorPrepareHonorsInjectXSearchConfig(t *testing.T) {
 	t.Parallel()