fix(auto-reply): truncate user-facing text on UTF-16 boundary (#97299)

zenglingbiao · web-flow · commit 1b8b8500cee0 · 2026-06-27T20:39:32.000Z
Summary: - The PR imports `truncateUtf16Safe` and uses it for the Codex usage-limit preview and verbose working-label truncation paths in auto-reply. - PR surface: Source +2. Total +2 across 2 files. - Reproducibility: yes. Current main uses raw `slice(0, N)` at both reported user-facing truncation sites, and ... ludes terminal before/after output showing dangling surrogates before the fix and safe truncation after it. Automerge notes: - No ClawSweeper repair was needed after automerge opt-in. Validation: - ClawSweeper review passed for head 74a0a32. - Required merge gates passed before the squash merge. Prepared head SHA: 74a0a32 Review: #97299 (comment) Co-authored-by: zenglingbiao <zeng.lingbiao@xydigit.com> Approved-by: takhoffman
diff --git a/src/auto-reply/reply/agent-runner-execution.ts b/src/auto-reply/reply/agent-runner-execution.ts
@@ -87,6 +87,7 @@ import { CommandLaneClearedError, GatewayDrainingError } from "../../process/com
 import { CommandLane } from "../../process/lanes.js";
 import { defaultRuntime } from "../../runtime.js";
 import { shouldPreserveUserFacingSessionStateForInputProvenance } from "../../sessions/input-provenance.js";
+import { truncateUtf16Safe } from "../../shared/utf16-slice.js";
 import {
   isMarkdownCapableMessageChannel,
   resolveMessageChannel,
@@ -753,7 +754,7 @@ function extractCodexUsageLimitMessage(text: string): string | undefined {
   if (!message) {
     return undefined;
   }
-  return message.length > 500 ? `${message.slice(0, 497)}...` : message;
+  return message.length > 500 ? `${truncateUtf16Safe(message, 497)}...` : message;
 }
 
 function isPureTransientRateLimitSummary(err: unknown): boolean {
diff --git a/src/auto-reply/reply/dispatch-from-config.ts b/src/auto-reply/reply/dispatch-from-config.ts
@@ -95,6 +95,7 @@ import { isAcpSessionKey } from "../../routing/session-key.js";
 import { resolveSendPolicy } from "../../sessions/send-policy.js";
 import { createLazyImportLoader } from "../../shared/lazy-promise.js";
 import { resolveSilentReplyPolicyFromPolicies } from "../../shared/silent-reply-policy.js";
+import { truncateUtf16Safe } from "../../shared/utf16-slice.js";
 import { createTtsDirectiveTextStreamCleaner } from "../../tts/directives.js";
 import {
   normalizeTtsAutoMode,
@@ -2565,7 +2566,7 @@ export async function dispatchReplyFromConfig(
       if (collapsed.length <= 80) {
         return collapsed;
       }
-      return `${collapsed.slice(0, 77).trimEnd()}...`;
+      return `${truncateUtf16Safe(collapsed, 77).trimEnd()}...`;
     };
     const formatPlanUpdateText = (payload: { explanation?: string; steps?: string[] }) => {
       const explanation = payload.explanation?.replace(/\s+/g, " ").trim();
