diff --git a/docs/providers/xai.md b/docs/providers/xai.md
index 8640586c4530..473742d21e1f 100644
--- a/docs/providers/xai.md
+++ b/docs/providers/xai.md
@@ -187,6 +187,14 @@ metadata without joining the published inventory. Their pricing remains unknown,
 recorded as zero until the manifest includes them. Zero is an unavailable estimate, not a claim that
 the provider charges nothing.
 
+Thinking levels follow xAI's
+[documented release rule](https://docs.x.ai/developers/model-capabilities/text/reasoning)
+rather than a fixed model list. Grok 4.5 and later accept `low`, `medium`, and
+`high`; Grok 4.6 and later add `xhigh`. The default is `high`, and reasoning cannot
+be turned off. A newer release id such as `grok-4.8`, its `-latest` alias, or a
+dated snapshot gets these levels and image input before the manifest lists it.
+Variant ids such as `-fast` keep reasoning effort off.
+
 ## Feature coverage
 
 The bundled plugin maps supported xAI APIs onto OpenClaw's shared provider and
diff --git a/extensions/xai/model-id.ts b/extensions/xai/model-id.ts
index 9c190a37aae1..d81f6581979e 100644
--- a/extensions/xai/model-id.ts
+++ b/extensions/xai/model-id.ts
@@ -1,17 +1,33 @@
 // Xai plugin module implements model id behavior.
+
+// A Grok release id: plain, `-latest`, or a dated snapshot (grok-4.7, grok-5, grok-4.8-0115).
+// Other suffixes (fast, mini, reasoning variants) name models with their own contracts.
+const XAI_GROK_RELEASE_ID = /^grok-(\d+)(?:\.(\d+))?(?:-(?:latest|\d{4}))?$/u;
+
+/**
+ * xAI documents reasoning effort from Grok 4.5 and xhigh "on grok-4.6 and later", so
+ * compare release numbers: new Grok releases work before the manifest lists them.
+ */
+export function isXaiGrokReleaseAtLeast(id: string, minimum: readonly [number, number]): boolean {
+  const match = XAI_GROK_RELEASE_ID.exec(normalizeXaiModelId(id.trim().toLowerCase()));
+  if (!match) {
+    return false;
+  }
+  const major = Number(match[1]);
+  const minor = Number(match[2] ?? 0);
+  // Grok 4.20 predates Grok 4.3 despite its number and has no reasoning effort control.
+  if (major === 4 && minor === 20) {
+    return false;
+  }
+  return major > minimum[0] || (major === minimum[0] && minor >= minimum[1]);
+}
+
 export function isXaiXhighModelId(id: string): boolean {
-  const normalized = normalizeXaiModelId(id.trim().toLowerCase());
-  return normalized === "grok-4.7" || normalized === "grok-4.6";
+  return isXaiGrokReleaseAtLeast(id, [4, 6]);
 }
 
 export function isXaiFrontierModelId(id: string): boolean {
-  const normalized = normalizeXaiModelId(id.trim().toLowerCase());
-  return (
-    normalized === "grok-4.7" ||
-    normalized === "grok-4.6" ||
-    normalized === "grok-4.5" ||
-    normalized.startsWith("grok-4.5-")
-  );
+  return isXaiGrokReleaseAtLeast(id, [4, 5]);
 }
 
 export function normalizeXaiModelId(id: string): string {
diff --git a/extensions/xai/provider-policy-api.test.ts b/extensions/xai/provider-policy-api.test.ts
index 63e334e78646..a4fbe5cd014b 100644
--- a/extensions/xai/provider-policy-api.test.ts
+++ b/extensions/xai/provider-policy-api.test.ts
@@ -50,6 +50,10 @@ describe("xai provider thinking policy", () => {
     ["x-ai", "grok-4.7"],
     ["xai", "grok-4.6"],
     ["x-ai", "grok-4.6"],
+    // Releases newer than the manifest follow xAI's "grok-4.6 and later" rule.
+    ["xai", "grok-4.8"],
+    ["xai", "grok-4.8-latest"],
+    ["xai", "grok-5"],
   ])("exposes xhigh reasoning for %s/%s", (provider, modelId) => {
     expect(resolveThinkingProfile({ provider, modelId })).toEqual({
       levels: [{ id: "low" }, { id: "medium" }, { id: "high" }, { id: "xhigh" }],
@@ -95,6 +99,10 @@ describe("xai provider thinking policy", () => {
     ["x-ai", "grok-build-0.1"],
     ["x-ai", "grok-4.20-0309-reasoning"],
     ["x-ai", "grok-4.20-beta-latest-reasoning"],
+    // Grok 4.20 predates 4.3, and variant suffixes are separate model contracts.
+    ["xai", "grok-4.20"],
+    ["xai", "grok-4-0709"],
+    ["xai", "grok-4.8-fast"],
   ])("does not advertise configurable reasoning for %s/%s", (provider, modelId) => {
     expect(resolveThinkingProfile({ provider, modelId })).toEqual({
       levels: [{ id: "off" }],
diff --git a/extensions/xai/responses-tool-policy.test.ts b/extensions/xai/responses-tool-policy.test.ts
index 69aafe3ff5b6..615a8c1be172 100644
--- a/extensions/xai/responses-tool-policy.test.ts
+++ b/extensions/xai/responses-tool-policy.test.ts
@@ -39,25 +39,25 @@ const callers = [
   },
 ];
 
-it.each(callers)(
-  "keeps the $name default request within supported reasoning efforts",
-  async ({ run }) => {
-    const request = vi.fn<typeof fetch>(async () =>
-      Response.json({ output_text: "fixture result" }),
-    );
-    vi.stubGlobal("fetch", withFetchPreconnect(request));
-    await run("grok-4.7");
-    expect(request).toHaveBeenCalledOnce();
-    const init = request.mock.calls[0]?.[1];
-    expect(init).toEqual(expect.objectContaining({ body: expect.any(String) }));
-    const body = new Request("https://api.x.ai/v1/responses", init);
-    expect(await body.json()).toMatchObject({
-      model: "grok-4.7",
-      store: false,
-      reasoning: { effort: "low" },
-    });
-  },
-);
+// Releases newer than the setup default keep its tool effort.
+it.each(
+  callers.flatMap(({ name, run }) =>
+    ["grok-4.7", "grok-4.8"].map((model) => ({ name, run, model })),
+  ),
+)("keeps the $name $model request within supported reasoning efforts", async ({ run, model }) => {
+  const request = vi.fn<typeof fetch>(async () => Response.json({ output_text: "fixture result" }));
+  vi.stubGlobal("fetch", withFetchPreconnect(request));
+  await run(model);
+  expect(request).toHaveBeenCalledOnce();
+  const init = request.mock.calls[0]?.[1];
+  expect(init).toEqual(expect.objectContaining({ body: expect.any(String) }));
+  const body = new Request("https://api.x.ai/v1/responses", init);
+  expect(await body.json()).toMatchObject({
+    model,
+    store: false,
+    reasoning: { effort: "low" },
+  });
+});
 
 it.each(callers)("preserves an explicit model and omitted effort for $name", async ({ run }) => {
   const request = vi.fn<typeof fetch>(async () => Response.json({ output_text: "fixture result" }));
diff --git a/extensions/xai/runtime-model-compat.test.ts b/extensions/xai/runtime-model-compat.test.ts
index 08e130c51382..d5e3c8e118cc 100644
--- a/extensions/xai/runtime-model-compat.test.ts
+++ b/extensions/xai/runtime-model-compat.test.ts
@@ -24,7 +24,7 @@ describe("xai runtime model compat", () => {
     });
   });
 
-  it.each(["grok-4.7", "grok-4.6"])("preserves %s xhigh reasoning", (id) => {
+  it.each(["grok-4.8", "grok-4.7", "grok-4.6"])("preserves %s xhigh reasoning", (id) => {
     const model = applyXaiRuntimeModelCompat({
       id,
       provider: "xai",
diff --git a/extensions/xai/src/responses-tool-shared.ts b/extensions/xai/src/responses-tool-shared.ts
index 3c2e4929d7ed..05781e1044f5 100644
--- a/extensions/xai/src/responses-tool-shared.ts
+++ b/extensions/xai/src/responses-tool-shared.ts
@@ -8,6 +8,7 @@ import {
 } from "openclaw/plugin-sdk/string-coerce-runtime";
 import { truncateUtf16Safe } from "openclaw/plugin-sdk/text-utility-runtime";
 import { resolveXaiCatalogEntry } from "../model-definitions.js";
+import { isXaiGrokReleaseAtLeast } from "../model-id.js";
 import { applyXaiRuntimeModelCompat } from "../runtime-model-compat.js";
 import type { XaiWebSearchResponse } from "./web-search-response.types.js";
 
@@ -64,9 +65,7 @@ export function resolveXaiToolDefaultReasoningEffort(
   preferred: "none" | "low",
 ): "none" | "low" | undefined {
   // Per-model tool defaults must survive changes to the setup default.
-  return model === "grok-4.3" || model === "grok-4.6" || model === "grok-4.7"
-    ? preferred
-    : undefined;
+  return model === "grok-4.3" || isXaiGrokReleaseAtLeast(model, [4, 6]) ? preferred : undefined;
 }
 
 function buildXaiResponsesToolBody(params: {
diff --git a/extensions/xai/supported-capabilities.test.ts b/extensions/xai/supported-capabilities.test.ts
index a28defe2dca4..f56849c0caf6 100644
--- a/extensions/xai/supported-capabilities.test.ts
+++ b/extensions/xai/supported-capabilities.test.ts
@@ -34,6 +34,7 @@ it.each([
   { id: "grok-3-mini-fast", reasoning: true, input: ["text"], maxTokens: 64_000 },
   { id: "grok-4.20-reasoning", reasoning: true, input: ["text", "image"], maxTokens: 30_000 },
   { id: "grok-4.20-non-reasoning", reasoning: false, input: ["text", "image"], maxTokens: 30_000 },
+  { id: "grok-4.8", reasoning: true, input: ["text", "image"], maxTokens: 64_000 },
 ])(
   "keeps supported capabilities separate from inventory and pricing for $id",
   ({ id, ...capabilities }) => {