Offer grok-4.6 xhigh in the reasoning catalog

src/provider/reasoning-effort.test.ts

@@ -77,6 +77,18 @@ describe("supportedEfforts", () => {
   test("unknown model gets the safe subset", () => {
     expect(supportedEfforts("some-random-model")).toEqual(["low", "medium", "high"]);
   });
+
+  test("grok-4.6 includes xhigh", () => {
+    expect(supportedEfforts("grok-4.6")).toEqual(["low", "medium", "high", "xhigh"]);
+  });
+
+  test("grok-4.5 stays on the unknown-model subset without xhigh", () => {
+    expect(supportedEfforts("grok-4.5")).toEqual(["low", "medium", "high"]);
+  });
+
+  test("grok-composer-2.5-fast stays on the unknown-model subset without xhigh", () => {
+    expect(supportedEfforts("grok-composer-2.5-fast")).toEqual(["low", "medium", "high"]);
+  });
 });
 
 describe("validateEffort", () => {
@@ -97,6 +109,11 @@ describe("validateEffort", () => {
     expect(validateEffort("unknown", "xhigh").ok).toBe(false);
     expect(validateEffort("unknown", "minimal").ok).toBe(false);
   });
+
+  test("accepts xhigh on grok-4.6 and rejects it on grok-4.5", () => {
+    expect(validateEffort("grok-4.6", "xhigh")).toEqual({ ok: true });
+    expect(validateEffort("grok-4.5", "xhigh").ok).toBe(false);
+  });
 });
 
 describe("cycleReasoningEffort", () => {
@@ -118,6 +135,11 @@ describe("cycleReasoningEffort", () => {
     setModelReasoningCapabilities({ "chat-only-model": false });
     expect(cycleReasoningEffort("chat-only-model", "medium")).toBeUndefined();
   });
+
+  test("wraps high to xhigh to low on grok-4.6", () => {
+    expect(cycleReasoningEffort("grok-4.6", "high")).toBe("xhigh");
+    expect(cycleReasoningEffort("grok-4.6", "xhigh")).toBe("low");
+  });
 });
 
 describe("reasoning capability gate", () => {

src/provider/reasoning-effort.ts

@@ -36,6 +36,10 @@ const MAX_EFFORT_CODEX_MODELS: readonly string[] = ["gpt-5.6-sol", "gpt-5.6-terr
 // purpose: these are the levels the broadest range of reasoning models accept.
 const UNKNOWN_MODEL_EFFORTS: readonly ReasoningEffort[] = ["low", "medium", "high"];
 
+// grok-4.6 accepts xhigh; grok-4.5 and composer stay on the unknown-model subset.
+const GROK_46_EFFORTS: readonly ReasoningEffort[] = ["low", "medium", "high", "xhigh"];
+const GROK_46_MODELS: readonly string[] = ["grok-4.6"];
+
 function isKnownOpenAIReasoningModel(model: string): boolean {
   return model.startsWith("gpt-5") || model.startsWith("o1") || model.startsWith("o3") || model.startsWith("o4");
 }
@@ -75,6 +79,9 @@ export function supportedEfforts(
   if (isKnownOpenAIReasoningModel(model)) {
     return [...DEFAULT_EFFORTS];
   }
+  if (GROK_46_MODELS.includes(model)) {
+    return [...GROK_46_EFFORTS];
+  }
   return [...UNKNOWN_MODEL_EFFORTS];
 }