diff --git a/src/infra/update-check.test.ts b/src/infra/update-check.test.ts
index 7bd78f77dd3f..3c9bb3fd8576 100644
--- a/src/infra/update-check.test.ts
+++ b/src/infra/update-check.test.ts
@@ -3,6 +3,7 @@ import fs from "node:fs/promises";
 import http from "node:http";
 import type { AddressInfo } from "node:net";
 import path from "node:path";
+import { pathToFileURL } from "node:url";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { runCommandWithTimeout } from "../process/exec.js";
 import { withTempDir } from "../test-helpers/temp-dir.js";
@@ -19,6 +20,25 @@ import {
 
 const mockHttp = useMockHttp();
 
+async function runGit(cwd: string, ...args: string[]): Promise<string> {
+  const result = await runCommandWithTimeout(["git", ...args], { cwd, timeoutMs: 5000 });
+  if (result.code !== 0) {
+    throw new Error(result.stderr || `git ${args.join(" ")} failed`);
+  }
+  return result.stdout.trim();
+}
+
+async function initGitRepo(root: string): Promise<void> {
+  await fs.mkdir(root, { recursive: true });
+  await runGit(root, "init", "--initial-branch=main");
+  await runGit(root, "config", "user.name", "OpenClaw Test");
+  await runGit(root, "config", "user.email", "test@openclaw.invalid");
+}
+
+async function commitGit(root: string, message: string): Promise<void> {
+  await runGit(root, "commit", "--allow-empty", "--message", message);
+}
+
 afterEach(() => {
   vi.restoreAllMocks();
 });
@@ -606,6 +626,112 @@ describe("formatGitInstallLabel", () => {
 });
 
 describe("checkUpdateStatus", () => {
+  it("does not report divergence for unrelated histories", async () => {
+    await withTempDir({ prefix: "openclaw-update-check-unrelated-" }, async (base) => {
+      const localRoot = path.join(base, "local");
+      const remoteRoot = path.join(base, "remote");
+      await initGitRepo(localRoot);
+      await commitGit(localRoot, "local history");
+      await initGitRepo(remoteRoot);
+      await commitGit(remoteRoot, "remote history");
+
+      await runGit(localRoot, "remote", "add", "origin", remoteRoot);
+      await runGit(localRoot, "fetch", "origin", "main");
+      await runGit(localRoot, "branch", "--set-upstream-to=origin/main", "main");
+
+      const mergeBase = await runCommandWithTimeout(["git", "merge-base", "HEAD", "origin/main"], {
+        cwd: localRoot,
+        timeoutMs: 5000,
+      });
+      expect(mergeBase.code).toBe(1);
+      expect(
+        await runGit(localRoot, "rev-list", "--left-right", "--count", "HEAD...origin/main"),
+      ).toMatch(/^1\s+1$/u);
+
+      const status = await checkUpdateStatus({
+        root: localRoot,
+        includeRegistry: false,
+        fetchGit: false,
+        timeoutMs: 5000,
+      });
+      expect(status.git).toMatchObject({
+        upstream: "origin/main",
+        ahead: null,
+        behind: null,
+      });
+    });
+  });
+
+  it("reports divergence only when shallow history retains a merge base", async () => {
+    await withTempDir({ prefix: "openclaw-update-check-shallow-" }, async (base) => {
+      const sourceRoot = path.join(base, "source");
+      await initGitRepo(sourceRoot);
+      await commitGit(sourceRoot, "common base");
+      await runGit(sourceRoot, "switch", "--create", "feature");
+      await commitGit(sourceRoot, "feature change");
+      await runGit(sourceRoot, "switch", "main");
+      await commitGit(sourceRoot, "main change");
+
+      const cloneDivergedHistory = async (name: string, depth?: number) => {
+        const cloneRoot = path.join(base, name);
+        const depthArgs = depth ? [`--depth=${depth}`] : [];
+        await runGit(
+          base,
+          "clone",
+          "--quiet",
+          ...depthArgs,
+          "--branch",
+          "feature",
+          pathToFileURL(sourceRoot).href,
+          cloneRoot,
+        );
+        await runGit(
+          cloneRoot,
+          "fetch",
+          "--quiet",
+          ...(depth ? [`--depth=${depth}`] : []),
+          "origin",
+          "+refs/heads/main:refs/remotes/origin/main",
+        );
+        await runGit(
+          cloneRoot,
+          "config",
+          "--add",
+          "remote.origin.fetch",
+          "+refs/heads/main:refs/remotes/origin/main",
+        );
+        await runGit(cloneRoot, "config", "branch.feature.remote", "origin");
+        await runGit(cloneRoot, "config", "branch.feature.merge", "refs/heads/main");
+        return cloneRoot;
+      };
+
+      const readDivergence = async (root: string) => {
+        const status = await checkUpdateStatus({
+          root,
+          includeRegistry: false,
+          fetchGit: false,
+          timeoutMs: 5000,
+        });
+        return { ahead: status.git?.ahead, behind: status.git?.behind };
+      };
+
+      const fullRoot = await cloneDivergedHistory("full");
+      await expect(readDivergence(fullRoot)).resolves.toEqual({ ahead: 1, behind: 1 });
+      await runGit(fullRoot, "remote", "rename", "--", "origin", "-dash");
+      expect(await runGit(fullRoot, "rev-parse", "--abbrev-ref", "@{upstream}")).toBe("-dash/main");
+      await expect(readDivergence(fullRoot)).resolves.toEqual({ ahead: 1, behind: 1 });
+
+      const truncatedRoot = await cloneDivergedHistory("shallow-depth-1", 1);
+      await expect(readDivergence(truncatedRoot)).resolves.toEqual({
+        ahead: null,
+        behind: null,
+      });
+
+      const comparableRoot = await cloneDivergedHistory("shallow-depth-2", 2);
+      await expect(readDivergence(comparableRoot)).resolves.toEqual({ ahead: 1, behind: 1 });
+    });
+  });
+
   it("returns unknown install status when root is missing", async () => {
     await expect(
       checkUpdateStatus({ root: null, includeRegistry: false, timeoutMs: 1000 }),
diff --git a/src/infra/update-check.ts b/src/infra/update-check.ts
index abb0155f7604..6dadfb5e6065 100644
--- a/src/infra/update-check.ts
+++ b/src/infra/update-check.ts
@@ -249,10 +249,28 @@ async function checkGitUpdateStatus(params: {
         .catch(() => false)
     : null;
 
-  const counts =
-    upstream && upstream.length > 0
+  // Freeze the post-fetch upstream for both graph queries. Resolve via @{upstream} rather than
+  // its display name so dashed remotes stay operands on older Git versions. Three-dot rev-list
+  // still counts disconnected or truncated histories, so require a visible common ancestor.
+  const upstreamCommitRes =
+    upstream && sha
       ? await runCommandWithTimeout(
-          ["git", "-C", root, "rev-list", "--left-right", "--count", `HEAD...${upstream}`],
+          ["git", "-C", root, "rev-parse", "--verify", "@{upstream}^{commit}"],
+          { timeoutMs },
+        ).catch(() => null)
+      : null;
+  const upstreamCommit =
+    upstreamCommitRes?.code === 0 ? upstreamCommitRes.stdout.trim() || null : null;
+  const mergeBase =
+    sha && upstreamCommit
+      ? await runCommandWithTimeout(["git", "-C", root, "merge-base", sha, upstreamCommit], {
+          timeoutMs,
+        }).catch(() => null)
+      : null;
+  const counts =
+    sha && upstreamCommit && mergeBase?.code === 0 && mergeBase.stdout.trim().length > 0
+      ? await runCommandWithTimeout(
+          ["git", "-C", root, "rev-list", "--left-right", "--count", `${sha}...${upstreamCommit}`],
           { timeoutMs },
         ).catch(() => null)
       : null;