diff --git a/internal/runtime/executor/helps/thinking_providers.go b/internal/runtime/executor/helps/thinking_providers.go
index a776136fd..013f93e34 100644
--- a/internal/runtime/executor/helps/thinking_providers.go
+++ b/internal/runtime/executor/helps/thinking_providers.go
@@ -8,4 +8,5 @@ import (
 	_ "github.com/router-for-me/CLIProxyAPI/v7/internal/thinking/provider/geminicli"
 	_ "github.com/router-for-me/CLIProxyAPI/v7/internal/thinking/provider/kimi"
 	_ "github.com/router-for-me/CLIProxyAPI/v7/internal/thinking/provider/openai"
+	_ "github.com/router-for-me/CLIProxyAPI/v7/internal/thinking/provider/xai"
 )
diff --git a/internal/runtime/executor/xai_executor.go b/internal/runtime/executor/xai_executor.go
index 5661328d2..ef46a1314 100644
--- a/internal/runtime/executor/xai_executor.go
+++ b/internal/runtime/executor/xai_executor.go
@@ -487,7 +487,7 @@ func (e *XAIExecutor) prepareResponsesRequest(ctx context.Context, req cliproxye
 	body := sdktranslator.TranslateRequest(from, to, baseModel, bytes.Clone(req.Payload), stream)
 
 	var err error
-	body, err = thinking.ApplyThinking(body, req.Model, from.String(), to.String(), e.Identifier())
+	body, err = thinking.ApplyThinking(body, req.Model, from.String(), e.Identifier(), e.Identifier())
 	if err != nil {
 		return nil, err
 	}
diff --git a/internal/runtime/executor/xai_executor_test.go b/internal/runtime/executor/xai_executor_test.go
index a75f13474..5579cd904 100644
--- a/internal/runtime/executor/xai_executor_test.go
+++ b/internal/runtime/executor/xai_executor_test.go
@@ -196,6 +196,48 @@ func TestXAIExecutorOmitsUnsupportedReasoningEffort(t *testing.T) {
 	}
 }
 
+func TestXAIExecutorAppliesThinkingSuffix(t *testing.T) {
+	var gotBody []byte
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		var errRead error
+		gotBody, errRead = io.ReadAll(r.Body)
+		if errRead != nil {
+			t.Fatalf("read body: %v", errRead)
+		}
+		w.Header().Set("Content-Type", "text/event-stream")
+		_, _ = w.Write([]byte("data: {\"type\":\"response.completed\",\"response\":{\"id\":\"resp_1\",\"object\":\"response\",\"created_at\":0,\"status\":\"completed\",\"model\":\"grok-4.3\",\"output\":[{\"type\":\"message\",\"role\":\"assistant\",\"content\":[{\"type\":\"output_text\",\"text\":\"ok\"}]}]}}\n\n"))
+	}))
+	defer server.Close()
+
+	exec := NewXAIExecutor(&config.Config{})
+	auth := &cliproxyauth.Auth{
+		Provider: "xai",
+		Attributes: map[string]string{
+			"base_url":  server.URL,
+			"auth_kind": "oauth",
+		},
+		Metadata: map[string]any{"access_token": "xai-token"},
+	}
+
+	_, err := exec.Execute(context.Background(), auth, cliproxyexecutor.Request{
+		Model:   "grok-4.3(low)",
+		Payload: []byte(`{"model":"grok-4.3","input":"hello"}`),
+	}, cliproxyexecutor.Options{
+		SourceFormat: sdktranslator.FormatOpenAIResponse,
+		Stream:       false,
+	})
+	if err != nil {
+		t.Fatalf("Execute() error = %v", err)
+	}
+
+	if got := gjson.GetBytes(gotBody, "model").String(); got != "grok-4.3" {
+		t.Fatalf("model = %q, want grok-4.3; body=%s", got, string(gotBody))
+	}
+	if got := gjson.GetBytes(gotBody, "reasoning.effort").String(); got != "low" {
+		t.Fatalf("reasoning.effort = %q, want low; body=%s", got, string(gotBody))
+	}
+}
+
 func TestXAIExecutorExecuteStreamFiltersToolSearchTool(t *testing.T) {
 	var gotBody []byte
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
diff --git a/internal/thinking/apply.go b/internal/thinking/apply.go
index d422a8d8b..e8a078319 100644
--- a/internal/thinking/apply.go
+++ b/internal/thinking/apply.go
@@ -18,6 +18,7 @@ var providerAppliers = map[string]ProviderApplier{
 	"codex":       nil,
 	"antigravity": nil,
 	"kimi":        nil,
+	"xai":         nil,
 }
 
 // GetProviderApplier returns the ProviderApplier for the given provider name.
@@ -62,7 +63,7 @@ func IsUserDefinedModel(modelInfo *registry.ModelInfo) bool {
 //   - body: Original request body JSON
 //   - model: Model name, optionally with thinking suffix (e.g., "claude-sonnet-4-5(16384)")
 //   - fromFormat: Source request format (e.g., openai, codex, gemini)
-//   - toFormat: Target provider format for the request body (gemini, gemini-cli, antigravity, claude, openai, codex, kimi)
+//   - toFormat: Target provider format for the request body (gemini, gemini-cli, antigravity, claude, openai, codex, kimi, xai)
 //   - providerKey: Provider identifier used for registry model lookups (may differ from toFormat, e.g., openrouter -> openai)
 //
 // Returns:
@@ -324,7 +325,7 @@ func extractThinkingConfig(body []byte, provider string) ThinkingConfig {
 		return extractGeminiConfig(body, provider)
 	case "openai":
 		return extractOpenAIConfig(body)
-	case "codex":
+	case "codex", "xai":
 		return extractCodexConfig(body)
 	case "kimi":
 		// Kimi uses OpenAI-compatible reasoning_effort format
diff --git a/internal/thinking/provider/xai/apply.go b/internal/thinking/provider/xai/apply.go
new file mode 100644
index 000000000..3938a4325
--- /dev/null
+++ b/internal/thinking/provider/xai/apply.go
@@ -0,0 +1,26 @@
+// Package xai implements thinking configuration for xAI Grok Responses API models.
+//
+// xAI models use the OpenAI Responses API compatible reasoning.effort format
+// with discrete levels.
+package xai
+
+import (
+	"github.com/router-for-me/CLIProxyAPI/v7/internal/thinking"
+	"github.com/router-for-me/CLIProxyAPI/v7/internal/thinking/provider/codex"
+)
+
+// Applier implements thinking.ProviderApplier for xAI models.
+type Applier struct {
+	codex.Applier
+}
+
+var _ thinking.ProviderApplier = (*Applier)(nil)
+
+// NewApplier creates a new xAI thinking applier.
+func NewApplier() *Applier {
+	return &Applier{}
+}
+
+func init() {
+	thinking.RegisterProvider("xai", NewApplier())
+}
diff --git a/internal/thinking/provider/xai/apply_test.go b/internal/thinking/provider/xai/apply_test.go
new file mode 100644
index 000000000..17f99f563
--- /dev/null
+++ b/internal/thinking/provider/xai/apply_test.go
@@ -0,0 +1,51 @@
+package xai
+
+import (
+	"testing"
+
+	"github.com/router-for-me/CLIProxyAPI/v7/internal/registry"
+	"github.com/router-for-me/CLIProxyAPI/v7/internal/thinking"
+	"github.com/tidwall/gjson"
+)
+
+func TestApplySetsReasoningEffort(t *testing.T) {
+	applier := NewApplier()
+	modelInfo := &registry.ModelInfo{
+		ID: "grok-4.3",
+		Thinking: &registry.ThinkingSupport{
+			ZeroAllowed: true,
+			Levels:      []string{"none", "low", "medium", "high"},
+		},
+	}
+
+	out, err := applier.Apply([]byte(`{"input":"hello"}`), thinking.ThinkingConfig{
+		Mode:  thinking.ModeLevel,
+		Level: thinking.LevelHigh,
+	}, modelInfo)
+	if err != nil {
+		t.Fatalf("Apply() error = %v", err)
+	}
+	if got := gjson.GetBytes(out, "reasoning.effort").String(); got != "high" {
+		t.Fatalf("reasoning.effort = %q, want high; body=%s", got, string(out))
+	}
+}
+
+func TestApplyNoneFallsBackToLowestLevelWhenDisableUnsupported(t *testing.T) {
+	applier := NewApplier()
+	modelInfo := &registry.ModelInfo{
+		ID: "grok-3-mini",
+		Thinking: &registry.ThinkingSupport{
+			Levels: []string{"low", "medium", "high"},
+		},
+	}
+
+	out, err := applier.Apply([]byte(`{"input":"hello"}`), thinking.ThinkingConfig{
+		Mode: thinking.ModeNone,
+	}, modelInfo)
+	if err != nil {
+		t.Fatalf("Apply() error = %v", err)
+	}
+	if got := gjson.GetBytes(out, "reasoning.effort").String(); got != "low" {
+		t.Fatalf("reasoning.effort = %q, want low; body=%s", got, string(out))
+	}
+}
diff --git a/internal/thinking/strip.go b/internal/thinking/strip.go
index 1e1712d19..75755b31f 100644
--- a/internal/thinking/strip.go
+++ b/internal/thinking/strip.go
@@ -42,7 +42,7 @@ func StripThinkingConfig(body []byte, provider string) []byte {
 			"reasoning_effort",
 			"thinking",
 		}
-	case "codex":
+	case "codex", "xai":
 		paths = []string{"reasoning.effort"}
 	default:
 		return body
diff --git a/internal/thinking/types.go b/internal/thinking/types.go
index 39868a02f..987ababc6 100644
--- a/internal/thinking/types.go
+++ b/internal/thinking/types.go
@@ -1,7 +1,7 @@
 // Package thinking provides unified thinking configuration processing.
 //
 // This package offers a unified interface for parsing, validating, and applying
-// thinking configurations across various AI providers (Claude, Gemini, OpenAI, Codex, Antigravity, Kimi).
+// thinking configurations across various AI providers (Claude, Gemini, OpenAI, Codex, Antigravity, Kimi, xAI).
 package thinking
 
 import "github.com/router-for-me/CLIProxyAPI/v7/internal/registry"
diff --git a/internal/thinking/validate.go b/internal/thinking/validate.go
index 2baa93f1d..909a2eeaa 100644
--- a/internal/thinking/validate.go
+++ b/internal/thinking/validate.go
@@ -357,7 +357,7 @@ func isGeminiFamily(provider string) bool {
 
 func isOpenAIFamily(provider string) bool {
 	switch provider {
-	case "openai", "openai-response", "codex":
+	case "openai", "openai-response", "codex", "xai":
 		return true
 	default:
 		return false