fix(native-hook-relay): use truncateUtf16Safe for hook display text truncation (#102467)

lsr911 · claude · steipete · web-flow · commit 4fa3118049c1 · 2026-07-09T08:03:19.000+01:00
* fix(tool-policy-audit): use truncateUtf16Safe for audit field truncation

Replace naive .slice(0, MAX) with truncateUtf16Safe() to prevent
surrogate pair splitting in tool policy audit log output.

Co-Authored-By: Claude &lt;noreply@anthropic.com&gt;

* fix(native-hook-relay): use truncateUtf16Safe for hook display text truncation

Replace naive .slice(0, N) truncation with truncateUtf16Safe() in:
- truncateText() helper (covers 4 call sites for tool display text)
- Inline hook result truncation (...[truncated] suffix)

Prevents surrogate pair splitting in native hook relay display
output (tool names, commands, descriptions shown to users).

Co-Authored-By: Claude &lt;noreply@anthropic.com&gt;

* test(agents): cover hook relay UTF-16 boundaries

---------

Co-authored-by: Claude &lt;noreply@anthropic.com&gt;
Co-authored-by: Peter Steinberger &lt;steipete@gmail.com&gt;
diff --git a/src/agents/harness/native-hook-relay.test.ts b/src/agents/harness/native-hook-relay.test.ts
@@ -1370,6 +1370,32 @@ describe("native hook relay registry", () => {
     expect(String(rawPayload.tool_response)).toContain("[truncated]");
   });
 
+  it("retains payload snapshots without splitting surrogate pairs", async () => {
+    const relay = registerNativeHookRelay({
+      provider: "codex",
+      sessionId: "session-1",
+      runId: "run-1",
+      allowedEvents: ["post_tool_use"],
+    });
+
+    await invokeNativeHookRelay({
+      provider: "codex",
+      relayId: relay.relayId,
+      event: "post_tool_use",
+      rawPayload: {
+        tool_response: `${"a".repeat(3_999)}😀tail`,
+      },
+    });
+
+    const [recorded] = testing.getNativeHookRelayInvocationsForTests();
+    const rawPayload = readRecordField(
+      requireRecord(recorded, "native hook relay invocation"),
+      "rawPayload",
+      "invocation raw payload",
+    );
+    expect(rawPayload.tool_response).toBe(`${"a".repeat(3_999)}...[truncated]`);
+  });
+
   it("removes retained invocations when a relay is unregistered", async () => {
     const relay = registerNativeHookRelay({
       provider: "codex",
@@ -3407,6 +3433,20 @@ describe("native hook relay registry", () => {
       }),
     ).toContain("(1 omitted)");
   });
+
+  it("truncates PermissionRequest approval previews without splitting surrogate pairs", () => {
+    expect(
+      testing.formatPermissionApprovalDescriptionForTests({
+        provider: "codex",
+        sessionId: "session-1",
+        runId: "run-1",
+        toolName: "exec",
+        toolInput: {
+          command: `${"a".repeat(236)}😀tail`,
+        },
+      }),
+    ).toBe(`Tool: exec\nCommand: ${"a".repeat(236)}...`);
+  });
 });
 
 describe("native hook relay command builder", () => {
diff --git a/src/agents/harness/native-hook-relay.ts b/src/agents/harness/native-hook-relay.ts
@@ -24,6 +24,7 @@ import {
   asDateTimestampMs,
   resolveExpiresAtMsFromDurationMs,
 } from "@openclaw/normalization-core/number-coercion";
+import { truncateUtf16Safe } from "@openclaw/normalization-core/utf16-slice";
 import type { OpenClawConfig } from "../../config/types.openclaw.js";
 import { toErrorObject } from "../../infra/errors.js";
 import { resolveOpenClawPackageRootSync } from "../../infra/openclaw-root.js";
@@ -1925,11 +1926,14 @@ function snapshotString(value: string, state: { remainingStringLength: number })
     MAX_NATIVE_HOOK_RELAY_HISTORY_STRING_LENGTH,
     state.remainingStringLength,
   );
-  state.remainingStringLength -= limit;
   if (limit >= value.length) {
+    state.remainingStringLength -= limit;
     return value;
   }
-  return `${value.slice(0, limit)}...[truncated]`;
+  const prefix = truncateUtf16Safe(value, limit);
+  // Charge the retained prefix; a safe boundary may back up one code unit.
+  state.remainingStringLength -= prefix.length;
+  return `${prefix}...[truncated]`;
 }
 
 function normalizeNativeHookInvocation(params: {
@@ -2223,7 +2227,7 @@ function truncateText(value: string, maxLength: number): string {
   if (value.length <= maxLength) {
     return value;
   }
-  return `${value.slice(0, Math.max(0, maxLength - 3))}...`;
+  return `${truncateUtf16Safe(value, Math.max(0, maxLength - 3))}...`;
 }
 
 function resolveOpenClawCliExecutable(): string {
