diff --git a/internal/registry/model_definitions_test.go b/internal/registry/model_definitions_test.go
index f7ce02bc..03223a15 100644
--- a/internal/registry/model_definitions_test.go
+++ b/internal/registry/model_definitions_test.go
@@ -49,6 +49,42 @@ func TestWithXAIBuiltinsAddsVideoModel(t *testing.T) {
 	}
 }
 
+func TestValidateModelsCatalogAllowsMissingSections(t *testing.T) {
+	data := validTestModelsCatalog()
+	data.XAI = nil
+
+	if err := validateModelsCatalog(data); err != nil {
+		t.Fatalf("validateModelsCatalog() error = %v", err)
+	}
+}
+
+func TestValidateModelsCatalogRejectsInvalidDefinitions(t *testing.T) {
+	data := validTestModelsCatalog()
+	data.Claude = []*ModelInfo{{ID: ""}}
+
+	if err := validateModelsCatalog(data); err == nil {
+		t.Fatal("expected invalid model definition error")
+	}
+}
+
+func validTestModelsCatalog() *staticModelsJSON {
+	models := []*ModelInfo{{ID: "test-model"}}
+	return &staticModelsJSON{
+		Claude:      models,
+		Gemini:      models,
+		Vertex:      models,
+		GeminiCLI:   models,
+		AIStudio:    models,
+		CodexFree:   models,
+		CodexTeam:   models,
+		CodexPlus:   models,
+		CodexPro:    models,
+		Kimi:        models,
+		Antigravity: models,
+		XAI:         models,
+	}
+}
+
 func findModelInfo(models []*ModelInfo, id string) *ModelInfo {
 	for _, model := range models {
 		if model != nil && model.ID == id {
diff --git a/internal/registry/model_updater.go b/internal/registry/model_updater.go
index ac0caffe..fbc65bbf 100644
--- a/internal/registry/model_updater.go
+++ b/internal/registry/model_updater.go
@@ -349,7 +349,8 @@ func validateModelsCatalog(data *staticModelsJSON) error {
 
 func validateModelSection(section string, models []*ModelInfo) error {
 	if len(models) == 0 {
-		return fmt.Errorf("%s section is empty", section)
+		log.Warnf("models catalog: %s section is empty, continuing without those model definitions", section)
+		return nil
 	}
 
 	seen := make(map[string]struct{}, len(models))
diff --git a/internal/runtime/executor/xai_executor.go b/internal/runtime/executor/xai_executor.go
index 3060eaf5..95f71805 100644
--- a/internal/runtime/executor/xai_executor.go
+++ b/internal/runtime/executor/xai_executor.go
@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"bytes"
 	"context"
+	"encoding/json"
 	"fmt"
 	"io"
 	"net/http"
@@ -767,9 +768,79 @@ func normalizeXAIInputReasoningItems(body []byte) []byte {
 			updated = updatedBody
 		}
 	}
+	return mergeAdjacentXAIInputReasoningSummaries(updated)
+}
+
+func mergeAdjacentXAIInputReasoningSummaries(body []byte) []byte {
+	input := gjson.GetBytes(body, "input")
+	if !input.Exists() || !input.IsArray() {
+		return body
+	}
+
+	changed := false
+	items := make([]json.RawMessage, 0, len(input.Array()))
+	for _, item := range input.Array() {
+		if len(items) > 0 && canMergeXAIReasoningSummary(items[len(items)-1], item) {
+			merged, ok := appendXAIReasoningSummary(items[len(items)-1], item.Get("summary").Array())
+			if ok {
+				items[len(items)-1] = json.RawMessage(merged)
+				changed = true
+				continue
+			}
+		}
+		items = append(items, json.RawMessage(item.Raw))
+	}
+	if !changed {
+		return body
+	}
+
+	rawInput, errMarshal := json.Marshal(items)
+	if errMarshal != nil {
+		return body
+	}
+	updated, errSet := sjson.SetRawBytes(body, "input", rawInput)
+	if errSet != nil {
+		return body
+	}
 	return updated
 }
 
+func canMergeXAIReasoningSummary(previous json.RawMessage, current gjson.Result) bool {
+	previousItem := gjson.ParseBytes(previous)
+	if previousItem.Get("type").String() != "reasoning" || current.Get("type").String() != "reasoning" {
+		return false
+	}
+	if !previousItem.Get("summary").IsArray() || !current.Get("summary").IsArray() {
+		return false
+	}
+	if len(current.Get("summary").Array()) == 0 {
+		return false
+	}
+	for name := range current.Map() {
+		if name != "type" && name != "summary" {
+			return false
+		}
+	}
+	return true
+}
+
+func appendXAIReasoningSummary(previous json.RawMessage, currentSummary []gjson.Result) ([]byte, bool) {
+	updated := []byte(previous)
+	summary := gjson.GetBytes(updated, "summary")
+	if !summary.IsArray() {
+		return previous, false
+	}
+	nextIndex := len(summary.Array())
+	for i, item := range currentSummary {
+		updatedItem, errSet := sjson.SetRawBytes(updated, fmt.Sprintf("summary.%d", nextIndex+i), []byte(item.Raw))
+		if errSet != nil {
+			return previous, false
+		}
+		updated = updatedItem
+	}
+	return updated, true
+}
+
 func removeXAIEncryptedReasoningInclude(body []byte) []byte {
 	include := gjson.GetBytes(body, "include")
 	if !include.Exists() || !include.IsArray() {
diff --git a/internal/runtime/executor/xai_executor_test.go b/internal/runtime/executor/xai_executor_test.go
index 59bdbe78..8cc85070 100644
--- a/internal/runtime/executor/xai_executor_test.go
+++ b/internal/runtime/executor/xai_executor_test.go
@@ -55,7 +55,7 @@ func TestXAIExecutorExecuteShapesResponsesRequest(t *testing.T) {
 
 	_, err := exec.Execute(context.Background(), auth, cliproxyexecutor.Request{
 		Model:   "grok-4.3",
-		Payload: []byte(`{"model":"grok-4.3","input":[{"type":"reasoning","summary":[{"type":"summary_text","text":"test"}],"content":null,"encrypted_content":null},{"role":"user","content":"hello"}],"include":["reasoning.encrypted_content"],"reasoning":{"effort":"high"},"tools":[{"type":"tool_search"},{"type":"image_generation"},{"type":"custom","name":"apply_patch"},{"type":"custom","name":"custom_lookup"},{"type":"function","name":"lookup"},{"type":"web_search","external_web_access":true,"search_content_types":["text","image"]},{"type":"namespace","name":"codex_app","description":"Tools in the codex_app namespace.","tools":[{"type":"function","name":"automation_update"},{"type":"custom","name":"namespace_custom"},{"type":"tool_search"}]}]}`),
+		Payload: []byte(`{"model":"grok-4.3","input":[{"type":"reasoning","summary":[{"type":"summary_text","text":"test"}],"content":null,"encrypted_content":null},{"type":"reasoning","summary":[{"type":"summary_text","text":"second"}]},{"role":"user","content":"hello"}],"include":["reasoning.encrypted_content"],"reasoning":{"effort":"high"},"tools":[{"type":"tool_search"},{"type":"image_generation"},{"type":"custom","name":"apply_patch"},{"type":"custom","name":"custom_lookup"},{"type":"function","name":"lookup"},{"type":"web_search","external_web_access":true,"search_content_types":["text","image"]},{"type":"namespace","name":"codex_app","description":"Tools in the codex_app namespace.","tools":[{"type":"function","name":"automation_update"},{"type":"custom","name":"namespace_custom"},{"type":"tool_search"}]}]}`),
 	}, cliproxyexecutor.Options{
 		SourceFormat: sdktranslator.FormatOpenAIResponse,
 		Stream:       false,
@@ -100,6 +100,15 @@ func TestXAIExecutorExecuteShapesResponsesRequest(t *testing.T) {
 	if got := gjson.GetBytes(gotBody, "input.0.summary.0.text").String(); got != "test" {
 		t.Fatalf("input.0.summary.0.text = %q, want test; body=%s", got, string(gotBody))
 	}
+	if got := gjson.GetBytes(gotBody, "input.0.summary.1.text").String(); got != "second" {
+		t.Fatalf("input.0.summary.1.text = %q, want second; body=%s", got, string(gotBody))
+	}
+	if got := gjson.GetBytes(gotBody, "input.1.role").String(); got != "user" {
+		t.Fatalf("input.1.role = %q, want user; body=%s", got, string(gotBody))
+	}
+	if gjson.GetBytes(gotBody, "input.2").Exists() {
+		t.Fatalf("input.2 exists, want consecutive reasoning item merged; body=%s", string(gotBody))
+	}
 	tools := gjson.GetBytes(gotBody, "tools").Array()
 	if len(tools) != 5 {
 		t.Fatalf("tools length = %d, want 5; body=%s", len(tools), string(gotBody))
@@ -206,7 +215,7 @@ func TestXAIExecutorExecuteStreamFiltersToolSearchTool(t *testing.T) {
 
 	result, err := exec.ExecuteStream(context.Background(), auth, cliproxyexecutor.Request{
 		Model:   "grok-4.3",
-		Payload: []byte(`{"model":"grok-4.3","input":[{"type":"reasoning","summary":[{"type":"summary_text","text":"test"}],"content":null,"encrypted_content":null},{"role":"user","content":"hello"}],"tools":[{"type":"tool_search"},{"type":"image_generation"},{"type":"custom","name":"apply_patch"},{"type":"custom","name":"custom_lookup"},{"type":"function","name":"lookup"},{"type":"web_search","external_web_access":true,"search_content_types":["text","image"]},{"type":"namespace","name":"codex_app","description":"Tools in the codex_app namespace.","tools":[{"type":"function","name":"automation_update"},{"type":"custom","name":"namespace_custom"},{"type":"tool_search"}]}]}`),
+		Payload: []byte(`{"model":"grok-4.3","input":[{"type":"reasoning","summary":[{"type":"summary_text","text":"test"}],"content":null,"encrypted_content":null},{"type":"reasoning","summary":[{"type":"summary_text","text":"second"}]},{"role":"user","content":"hello"},{"type":"reasoning","summary":[{"type":"summary_text","text":"separate"}]}],"tools":[{"type":"tool_search"},{"type":"image_generation"},{"type":"custom","name":"apply_patch"},{"type":"custom","name":"custom_lookup"},{"type":"function","name":"lookup"},{"type":"web_search","external_web_access":true,"search_content_types":["text","image"]},{"type":"namespace","name":"codex_app","description":"Tools in the codex_app namespace.","tools":[{"type":"function","name":"automation_update"},{"type":"custom","name":"namespace_custom"},{"type":"tool_search"}]}]}`),
 	}, cliproxyexecutor.Options{
 		SourceFormat: sdktranslator.FormatOpenAIResponse,
 		Stream:       true,
@@ -233,6 +242,15 @@ func TestXAIExecutorExecuteStreamFiltersToolSearchTool(t *testing.T) {
 	if got := gjson.GetBytes(gotBody, "input.0.summary.0.text").String(); got != "test" {
 		t.Fatalf("input.0.summary.0.text = %q, want test; body=%s", got, string(gotBody))
 	}
+	if got := gjson.GetBytes(gotBody, "input.0.summary.1.text").String(); got != "second" {
+		t.Fatalf("input.0.summary.1.text = %q, want second; body=%s", got, string(gotBody))
+	}
+	if got := gjson.GetBytes(gotBody, "input.1.role").String(); got != "user" {
+		t.Fatalf("input.1.role = %q, want user; body=%s", got, string(gotBody))
+	}
+	if got := gjson.GetBytes(gotBody, "input.2.summary.0.text").String(); got != "separate" {
+		t.Fatalf("input.2.summary.0.text = %q, want separate; body=%s", got, string(gotBody))
+	}
 	foundAutomationUpdate := false
 	foundNamespaceCustom := false
 	for i, tool := range tools {