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>

extensions/memory-core/src/short-term-promotion.test.ts

@@ -3588,4 +3588,70 @@ describe("short-term promotion", () => {
       });
     });
   });
+  describe("UTF-16 snippet bounds", () => {
+    it("stores a complete-code-point short-term recall snippet", async () => {
+      await withTempWorkspace(async (workspaceDir) => {
+        const prefix = "y".repeat(testing.SHORT_TERM_RECALL_MAX_SNIPPET_CHARS - 1);
+        await recordShortTermRecalls({
+          workspaceDir,
+          query: "utf16 recall",
+          results: [
+            {
+              path: "memory/2026-04-03.md",
+              source: "memory",
+              startLine: 1,
+              endLine: 1,
+              score: 0.9,
+              snippet: `${prefix}🚀tail`,
+            },
+          ],
+        });
+
+        const entries = Object.values(await readRecallStoreEntries(workspaceDir));
+        expect(entries).toHaveLength(1);
+        expect(readEntrySnippet(entries[0])).toBe(prefix);
+      });
+    });
+
+    it("writes a complete-code-point promoted MEMORY.md snippet", async () => {
+      await withTempWorkspace(async (workspaceDir) => {
+        const prefix = "a".repeat(7);
+        const snippet = `${prefix}🚀tail`;
+        await writeDailyMemoryNote(workspaceDir, "2026-04-03", [snippet]);
+        await recordShortTermRecalls({
+          workspaceDir,
+          query: "utf16 promotion",
+          results: [
+            {
+              path: "memory/2026-04-03.md",
+              source: "memory",
+              startLine: 1,
+              endLine: 1,
+              score: 0.9,
+              snippet,
+            },
+          ],
+        });
+        const ranked = await rankShortTermPromotionCandidates({
+          workspaceDir,
+          minScore: 0,
+          minRecallCount: 0,
+          minUniqueQueries: 0,
+        });
+
+        await applyShortTermPromotions({
+          workspaceDir,
+          candidates: ranked,
+          minScore: 0,
+          minRecallCount: 0,
+          minUniqueQueries: 0,
+          maxPromotedSnippetTokens: 2,
+        });
+
+        const memoryText = await fs.readFile(path.join(workspaceDir, "MEMORY.md"), "utf-8");
+        expect(memoryText).toContain(`- ${prefix}... [`);
+        expect(memoryText).not.toContain("🚀");
+      });
+    });
+  });
 });

extensions/memory-core/src/short-term-promotion.ts

@@ -16,6 +16,7 @@ import {
   normalizeStringEntries,
   uniqueStrings,
 } from "openclaw/plugin-sdk/string-coerce-runtime";
+import { truncateUtf16Safe } from "openclaw/plugin-sdk/text-utility-runtime";
 import {
   deriveConceptTags,
   MAX_CONCEPT_TAGS,
@@ -359,7 +360,7 @@ function truncateShortTermSnippet(snippet: string): string {
   if (snippet.length <= SHORT_TERM_RECALL_MAX_SNIPPET_CHARS) {
     return snippet;
   }
-  return snippet.slice(0, SHORT_TERM_RECALL_MAX_SNIPPET_CHARS).trimEnd();
+  return truncateUtf16Safe(snippet, SHORT_TERM_RECALL_MAX_SNIPPET_CHARS).trimEnd();
 }
 
 function enforceShortTermRecallSnippetCap(store: ShortTermRecallStore): void {
@@ -2351,7 +2352,7 @@ function truncatePromotedSnippet(snippet: string, maxTokens: number): string {
   if (limit === 0 || snippet.length <= limit) {
     return snippet;
   }
-  const hardLimit = snippet.slice(0, limit);
+  const hardLimit = truncateUtf16Safe(snippet, limit);
   const sentenceBoundary = Math.max(
     hardLimit.lastIndexOf(". "),
     hardLimit.lastIndexOf("! "),

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. */

pnpm-lock.yaml

@@ -1864,6 +1864,9 @@ importers:
       '@openclaw/ai':
         specifier: workspace:*
         version: link:../ai
+      '@openclaw/normalization-core':
+        specifier: workspace:*
+        version: link:../normalization-core
       typebox:
         specifier: 1.3.3
         version: 1.3.3