diff --git a/internal/runtime/executor/xai_executor_request.go b/internal/runtime/executor/xai_executor_request.go
index cc2ff93c2..6ee90d66f 100644
--- a/internal/runtime/executor/xai_executor_request.go
+++ b/internal/runtime/executor/xai_executor_request.go
@@ -97,6 +97,7 @@ func (e *XAIExecutor) prepareResponsesRequestTo(ctx context.Context, req cliprox
 	// Drop choices that point at tools removed by normalizeXAITools before any
 	// configured x_search injection, so no surviving choice references a deleted tool.
 	body = normalizeXAINamespaceToolChoice(body)
+	body = normalizeXAIForcedWebSearchToolChoice(body)
 	body = pruneXAIOrphanedToolChoice(body)
 	body = normalizeXAIToolChoiceForTools(body)
 	if e.cfg != nil && e.cfg.XAI.InjectXSearch {
@@ -584,6 +585,26 @@ func ensureXAINativeXSearchAllowedTools(body []byte) []byte {
 	return body
 }
 
+// normalizeXAIForcedWebSearchToolChoice rewrites Codex's hosted-tool choice
+// into the allowed_tools form accepted by xAI's ModelToolChoice schema.
+func normalizeXAIForcedWebSearchToolChoice(body []byte) []byte {
+	choice := gjson.GetBytes(body, "tool_choice")
+	if !choice.IsObject() || strings.TrimSpace(choice.Get("type").String()) != xaiWebSearchToolType {
+		return body
+	}
+
+	allowedChoice := []byte(`{"type":"allowed_tools","mode":"required","tools":[]}`)
+	allowedChoice, errSetAllowed := sjson.SetRawBytes(allowedChoice, "tools.-1", []byte(choice.Raw))
+	if errSetAllowed != nil {
+		return body
+	}
+	updated, errSetChoice := sjson.SetRawBytes(body, "tool_choice", allowedChoice)
+	if errSetChoice != nil {
+		return body
+	}
+	return updated
+}
+
 // pruneXAIOrphanedToolChoice removes tool_choice entries that no longer match
 // any remaining tool after normalizeXAITools filtering. Forced choices that
 // reference a deleted tool are dropped entirely; allowed_tools lists keep only
diff --git a/internal/runtime/executor/xai_executor_test.go b/internal/runtime/executor/xai_executor_test.go
index 79eb16a36..74548bd89 100644
--- a/internal/runtime/executor/xai_executor_test.go
+++ b/internal/runtime/executor/xai_executor_test.go
@@ -802,6 +802,46 @@ func TestEnsureXAINativeXSearchTool(t *testing.T) {
 	}
 }
 
+func TestXAIExecutorPrepareNormalizesClaudeWebSearchToolChoice(t *testing.T) {
+	t.Parallel()
+
+	exec := NewXAIExecutor(&config.Config{})
+	prepared, errPrepare := exec.prepareResponsesRequest(context.Background(), cliproxyexecutor.Request{
+		Model: "grok-4.5",
+		Payload: []byte(`{
+			"model":"grok-4.5",
+			"max_tokens":4096,
+			"stream":true,
+			"output_config":{"effort":"high"},
+			"thinking":{"type":"disabled"},
+			"messages":[{"role":"user","content":[{"type":"text","text":"Perform a web search"}]}],
+			"tool_choice":{"type":"tool","name":"web_search"},
+			"tools":[{"type":"web_search_20250305","name":"web_search","max_uses":8}]
+		}`),
+	}, cliproxyexecutor.Options{
+		SourceFormat: sdktranslator.FormatClaude,
+		Stream:       true,
+	}, true)
+	if errPrepare != nil {
+		t.Fatalf("prepareResponsesRequest() error = %v", errPrepare)
+	}
+
+	choice := gjson.GetBytes(prepared.body, "tool_choice")
+	if got := choice.Get("type").String(); got != "allowed_tools" {
+		t.Fatalf("tool_choice.type = %q, want allowed_tools; body=%s", got, prepared.body)
+	}
+	if got := choice.Get("mode").String(); got != "required" {
+		t.Fatalf("tool_choice.mode = %q, want required; body=%s", got, prepared.body)
+	}
+	allowed := choice.Get("tools").Array()
+	if len(allowed) != 1 {
+		t.Fatalf("tool_choice.tools length = %d, want 1; body=%s", len(allowed), prepared.body)
+	}
+	if got := allowed[0].Get("type").String(); got != "web_search" {
+		t.Fatalf("tool_choice.tools.0.type = %q, want web_search; body=%s", got, prepared.body)
+	}
+}
+
 func TestPruneXAIOrphanedToolChoice(t *testing.T) {
 	t.Parallel()