diff --git a/src/adapters/cursor/effort-map.ts b/src/adapters/cursor/effort-map.ts
index 1dc70a793..e4b838a28 100644
--- a/src/adapters/cursor/effort-map.ts
+++ b/src/adapters/cursor/effort-map.ts
@@ -35,10 +35,9 @@ const CURSOR_MODEL_EFFORT_TIERS: Record<string, readonly string[]> = {
   // cursor-grok-4.5-{low,medium,high}-fast. The bare Fast id returns not_found.
   "grok-4.5": ["low", "medium", "high"],
   "grok-4.5-fast": ["low", "medium", "high"],
-  // 260813 preemptive: grok-4.6 tiers mirrored from grok-4.5 ahead of Cursor's lineup update,
-  // so the suffix/wire handling is already correct the day the slugs appear.
-  "grok-4.6": ["low", "medium", "high"],
-  "grok-4.6-fast": ["low", "medium", "high"],
+  // Cursor Agent CLI lists low, medium, high, and xhigh for Grok 4.6.
+  "grok-4.6": ["low", "medium", "high", "xhigh"],
+  "grok-4.6-fast": ["low", "medium", "high", "xhigh"],
   "gpt-5.1": ["low", "high"],
   "gpt-5.1-codex-max": ["low", "medium", "high", "xhigh"],
   "gpt-5.1-codex-mini": ["low", "high"],
diff --git a/tests/cursor-effort-suffix.test.ts b/tests/cursor-effort-suffix.test.ts
index 2d4c627f0..d81c8aa9f 100644
--- a/tests/cursor-effort-suffix.test.ts
+++ b/tests/cursor-effort-suffix.test.ts
@@ -135,6 +135,13 @@ describe("Cursor per-model reasoning-effort suffix", () => {
     }
   });
 
+  test("grok-4.6 exposes Cursor's xhigh tier", () => {
+    expect(modelIdFor("cursor/grok-4.6", "low")).toBe("cursor-grok-4.6-low");
+    expect(modelIdFor("cursor/grok-4.6", "high")).toBe("cursor-grok-4.6-high");
+    expect(modelIdFor("cursor/grok-4.6", "xhigh")).toBe("cursor-grok-4.6-xhigh");
+    expect(cursorModelEffortLadder("grok-4.6")).toEqual(["low", "medium", "high", "xhigh"]);
+  });
+
   test("kimi-k3 maps to its live effort-suffixed variants", () => {
     expect(modelIdFor("cursor/kimi-k3", "low")).toBe("kimi-k3-low");
     expect(modelIdFor("cursor/kimi-k3", "medium")).toBe("kimi-k3-high");