diff --git a/src/acp/event-mapper.test.ts b/src/acp/event-mapper.test.ts
index 88650811a53a..8d599b455fd5 100644
--- a/src/acp/event-mapper.test.ts
+++ b/src/acp/event-mapper.test.ts
@@ -1,6 +1,6 @@
 /** Tests ACP tool-call location extraction limits. */
 import { describe, expect, it } from "vitest";
-import { extractToolCallLocations } from "./event-mapper.js";
+import { extractToolCallLocations, formatToolTitle } from "./event-mapper.js";
 
 describe("extractToolCallLocations", () => {
   it("enforces the global node visit cap across nested structures", () => {
@@ -18,3 +18,13 @@ describe("extractToolCallLocations", () => {
     expect(locations).toEqual([{ path: "/tmp/file-0.txt" }, { path: "/tmp/file-1.txt" }]);
   });
 });
+
+describe("formatToolTitle", () => {
+  it("does not split surrogate pairs when truncating argument values", () => {
+    const title = formatToolTitle("exec", {
+      command: `${"x".repeat(99)}🚀tail`,
+    });
+
+    expect(title).toBe(`exec: command: ${"x".repeat(99)}...`);
+  });
+});
diff --git a/src/acp/event-mapper.ts b/src/acp/event-mapper.ts
index 2862a8ae21cd..3a7b5600d90c 100644
--- a/src/acp/event-mapper.ts
+++ b/src/acp/event-mapper.ts
@@ -14,6 +14,7 @@ import {
   normalizeOptionalString,
   readStringValue,
 } from "@openclaw/normalization-core/string-coerce";
+import { truncateUtf16Safe } from "@openclaw/normalization-core/utf16-slice";
 
 type GatewayAttachment = {
   type: string;
@@ -309,7 +310,7 @@ export function formatToolTitle(
   }
   const parts = Object.entries(args).map(([key, value]) => {
     const raw = typeof value === "string" ? value : JSON.stringify(value);
-    const safe = raw.length > 100 ? `${raw.slice(0, 100)}...` : raw;
+    const safe = raw.length > 100 ? `${truncateUtf16Safe(raw, 100)}...` : raw;
     return `${key}: ${safe}`;
   });
   // Sanitize at the source so session updates and permission requests never