diff --git a/src/auth/xai/constants.ts b/src/auth/xai/constants.ts
index e8e13c0f7..38d07933a 100644
--- a/src/auth/xai/constants.ts
+++ b/src/auth/xai/constants.ts
@@ -19,11 +19,13 @@ export const XAI_SCOPES = ["openid", "profile", "email", "offline_access", "grok
 // API key). They authenticate against the CLI chat proxy, which exposes the
 // OpenAI-compatible /v1/chat/completions surface.
 export const XAI_BASE_URL = "https://cli-chat-proxy.grok.com/v1";
-// The grok CLI (which our OAuth scope mirrors) exposes only two models: Grok 4.5
-// (Grok Build's default coding model) and Composer 2.5 Fast. Mirror `grok models`
-// exactly — other model ids are rejected for grok-cli OAuth credentials.
+// Grok-cli OAuth credentials only accept model ids the CLI chat proxy serves.
+// Keep the catalog aligned with Grok Build / xAI listings; default stays the
+// last CLI-advertised coding model until the proxy is confirmed to accept a
+// newer flagship as the session default.
 export const XAI_DEFAULT_MODELS = [
   "grok-4.5",
+  "grok-4.6",
   "grok-composer-2.5-fast",
 ] as const;
 
diff --git a/src/config/xai-providers.test.ts b/src/config/xai-providers.test.ts
index f20c18aca..6fc1b782a 100644
--- a/src/config/xai-providers.test.ts
+++ b/src/config/xai-providers.test.ts
@@ -12,9 +12,10 @@ import {
 } from "./xai-providers.js";
 
 describe("xAI OAuth provider projection", () => {
-  test("default models mirror grok CLI catalog", () => {
-    expect([...XAI_DEFAULT_MODELS]).toEqual(["grok-4.5", "grok-composer-2.5-fast"]);
-    expect(XAI_DEFAULT_MODELS[0]).toBe("grok-4.5");
+  test("default models include Grok 4.6 while defaulting to the CLI coding model", () => {
+    const models: string[] = [...XAI_DEFAULT_MODELS];
+    expect(models).toEqual(["grok-4.5", "grok-4.6", "grok-composer-2.5-fast"]);
+    expect(models[0]).toBe("grok-4.5");
   });
 
   const profile: XaiProfile = {
diff --git a/src/subagent/provider-family.test.ts b/src/subagent/provider-family.test.ts
index ef65d359f..bcdba7513 100644
--- a/src/subagent/provider-family.test.ts
+++ b/src/subagent/provider-family.test.ts
@@ -85,6 +85,7 @@ describe("isKimiLeafProvider", () => {
 describe("detectModelFamily", () => {
   test("detects grok, kimi, and default", () => {
     expect(detectModelFamily({ providerName: "xai/default", model: "grok-4.5" })).toBe("grok");
+    expect(detectModelFamily({ providerName: "xai/default", model: "grok-4.6" })).toBe("grok");
     expect(detectModelFamily({ providerName: "moonshot", model: "kimi-k2" })).toBe("kimi");
     expect(detectModelFamily({ providerName: "anthropic", model: "claude-sonnet-4" })).toBe("default");
   });