fix(agent-core,memory-core): keep compaction summary and memory snippet truncation UTF-16 safe (#102542)

* fix(agent-core,memory-core): keep compaction summary and memory snippet truncation UTF-16 safe

* fix: make compaction and memory truncation UTF-16 safe

---------

Co-authored-by: Peter Steinberger <steipete@gmail.com>

packages/agent-core/package.json

@@ -96,6 +96,7 @@
   },
   "dependencies": {
     "@openclaw/ai": "workspace:*",
+    "@openclaw/normalization-core": "workspace:*",
     "typebox": "1.3.3"
   }
 }

packages/agent-core/src/harness/compaction/utils.test.ts

@@ -33,4 +33,18 @@ describe("serializeConversation", () => {
 
     expect(serializeConversation(messages)).toBe(`[Tool result]: ${expected}`);
   });
+
+  it("keeps truncated tool results UTF-16 safe and reports the exact omitted count", () => {
+    const prefix = "a".repeat(1_999);
+    const messages = [
+      {
+        role: "toolResult",
+        content: [{ type: "toolResult", content: `${prefix}🚀tail` }],
+      },
+    ] as unknown as Message[];
+
+    expect(serializeConversation(messages)).toBe(
+      `[Tool result]: ${prefix}\n\n[... 6 more characters truncated]`,
+    );
+  });
 });

packages/agent-core/src/harness/compaction/utils.ts

@@ -1,4 +1,5 @@
 // Agent Core helper module supports utils behavior.
+import { truncateUtf16Safe } from "@openclaw/normalization-core/utf16-slice";
 import type { Message } from "../../../../llm-core/src/index.js";
 import type { AgentMessage } from "../../types.js";
 
@@ -105,8 +106,9 @@ function truncateForSummary(text: string, maxChars: number): string {
   if (text.length <= maxChars) {
     return text;
   }
-  const truncatedChars = text.length - maxChars;
-  return `${text.slice(0, maxChars)}\n\n[... ${truncatedChars} more characters truncated]`;
+  const sliced = truncateUtf16Safe(text, maxChars);
+  const truncatedChars = text.length - sliced.length;
+  return `${sliced}\n\n[... ${truncatedChars} more characters truncated]`;
 }
 
 /** Extract text that compaction both estimates and includes in summary prompts. */