fix: CJK replies are silently dropped instead of recovered when the model skips message(action=send) (#115556)

* fix(auto-reply): count CJK sentence terminators in stranded private-final detection

* fix(auto-reply): compare private-final substance thresholds with the CJK-aware estimator

* fix(auto-reply): detect CJK sentence boundaries

---------

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

src/auto-reply/reply/private-message-tool-final.test.ts

@@ -1,5 +1,6 @@
 // Tests private message-tool final delivery and visibility suppression.
 import { describe, expect, it } from "vitest";
+import { estimateStringChars } from "../../utils/cjk-chars.js";
 import { shouldWarnAboutPrivateMessageToolFinal } from "./private-message-tool-final.js";
 
 const base = {
@@ -64,6 +65,75 @@ describe("shouldWarnAboutPrivateMessageToolFinal", () => {
     ).toBe(false);
   });
 
+  // Raw UTF-16 length under-counts CJK about 4x, so these all used to fall below
+  // both thresholds and skip stranded recovery entirely (#115555).
+  it.each([
+    {
+      label: "multi-sentence CJK report",
+      finalText:
+        "近 7 日營收較前期增加 5.09%，已連續兩週回升。最大風險是集中：前五大站台占正營收 86.5%，已超過 85% 觀察門檻。" +
+        "建議先維持成長節奏並優先降低集中風險，不建議只看總額就全面加碼。",
+      expected: true,
+    },
+    {
+      label: "single-sentence CJK paragraph (length alone is substantive)",
+      finalText: `${"字".repeat(150)}。`,
+      expected: true,
+    },
+    {
+      label: "CJK using full-width period U+FF0E",
+      finalText: `${"項".repeat(150)}．`,
+      expected: true,
+    },
+    {
+      label: "CJK using halfwidth ideographic period U+FF61",
+      finalText: `${"項".repeat(150)}｡`,
+      expected: true,
+    },
+    { label: "short CJK acknowledgement", finalText: "沒有需要補充的。已完成。", expected: false },
+    { label: "short CJK single clause", finalText: "已完成", expected: false },
+  ])("$label -> $expected", ({ finalText, expected }) => {
+    expect(shouldWarnAboutPrivateMessageToolFinal({ ...base, finalText })).toBe(expected);
+  });
+
+  it.each([
+    { label: "ideographic full stop", terminator: "。" },
+    { label: "full-width exclamation mark", terminator: "！" },
+    { label: "full-width question mark", terminator: "？" },
+    { label: "full-width full stop", terminator: "．" },
+    { label: "half-width ideographic full stop", terminator: "｡" },
+  ])("flags a medium-length CJK reply with $label", ({ terminator }) => {
+    const finalText =
+      `第一項設定已完成，請檢查通知狀態${terminator}` +
+      `第二項資料已同步，稍後即可收到訊息${terminator}`;
+    const estimatedChars = estimateStringChars(finalText);
+
+    expect(estimatedChars).toBeGreaterThanOrEqual(120);
+    expect(estimatedChars).toBeLessThan(280);
+    expect(shouldWarnAboutPrivateMessageToolFinal({ ...base, finalText })).toBe(true);
+  });
+
+  it.each([
+    {
+      label: "accented Latin stays on raw length",
+      finalText: `Le café est prêt. ${"x".repeat(100)}`,
+      expected: false,
+    },
+    {
+      label: "Cyrillic stays on raw length",
+      finalText: `Готово. ${"x".repeat(100)}`,
+      expected: false,
+    },
+    {
+      label: "emoji stays on raw length",
+      finalText: `Done ✅ Shipped 🚀 ${"x".repeat(100)}`,
+      expected: false,
+    },
+  ])("non-CJK non-ASCII is unaffected: $label", ({ finalText, expected }) => {
+    expect(finalText.length).toBeLessThan(280);
+    expect(shouldWarnAboutPrivateMessageToolFinal({ ...base, finalText })).toBe(expected);
+  });
+
   it("does not flag empty or whitespace-only final text", () => {
     expect(shouldWarnAboutPrivateMessageToolFinal({ ...base, finalText: "" })).toBe(false);
     expect(shouldWarnAboutPrivateMessageToolFinal({ ...base, finalText: "   \n " })).toBe(false);

src/auto-reply/reply/private-message-tool-final.ts

@@ -1,5 +1,6 @@
 /** Detects and logs long private finals when message-tool-only delivery was expected. */
 import { createSubsystemLogger } from "../../logging/subsystem.js";
+import { estimateStringChars } from "../../utils/cjk-chars.js";
 import type { SourceReplyDeliveryMode } from "../get-reply-options.types.js";
 import { isSilentReplyText } from "../tokens.js";
 
@@ -8,7 +9,8 @@ const privateFinalReplyLogger = createSubsystemLogger("source-reply/private-fina
 const LONG_PRIVATE_FINAL_MIN_CHARS = 280;
 const MULTI_SENTENCE_PRIVATE_FINAL_MIN_CHARS = 120;
 const MULTI_SENTENCE_TERMINATOR_MIN_COUNT = 2;
-const SENTENCE_TERMINATOR_REGEX = /[.!?]+(?:\s|$)/g;
+// CJK sentence marks do not require following whitespace; keep ASCII's boundary rule.
+const SENTENCE_TERMINATOR_REGEX = /[.!?]+(?:\s|$)|[。！？．｡]+/gu;
 
 /**
  * `message_tool_only` allows the model to stay silent by simply not calling the
@@ -34,12 +36,16 @@ export function shouldWarnAboutPrivateMessageToolFinal(params: {
   if (!trimmed || isSilentReplyText(trimmed)) {
     return false;
   }
-  if (trimmed.length >= LONG_PRIVATE_FINAL_MIN_CHARS) {
+  // Both thresholds are substance proxies, so they must be compared against the
+  // shared CJK-aware estimate: raw UTF-16 length under-counts CJK about 4x, which
+  // kept substantive CJK finals below both branches and skipped stranded recovery.
+  const estimatedChars = estimateStringChars(trimmed);
+  if (estimatedChars >= LONG_PRIVATE_FINAL_MIN_CHARS) {
     return true;
   }
   const sentenceTerminatorCount = countSentenceLikeTerminators(trimmed);
   return (
-    trimmed.length >= MULTI_SENTENCE_PRIVATE_FINAL_MIN_CHARS &&
+    estimatedChars >= MULTI_SENTENCE_PRIVATE_FINAL_MIN_CHARS &&
     sentenceTerminatorCount >= MULTI_SENTENCE_TERMINATOR_MIN_COUNT
   );
 }

src/auto-reply/reply/stranded-reply-recovery.test.ts

@@ -85,6 +85,34 @@ describe("resolveStrandedReplyRecovery", () => {
     }
   });
 
+  it("creates the same retry for a substantive CJK private final", () => {
+    // Full-width terminators carry no trailing whitespace, so a CJK reply of the
+    // same shape used to score zero sentence terminators and skip recovery entirely.
+    const base = createMockFollowupRun({ prompt: "question" });
+    const substantiveCjkFinal =
+      "近 7 日營收較前期增加 5.09%，已連續兩週回升。最大風險是集中：前五大站台占正營收 86.5%，已超過 85% 觀察門檻。" +
+      "近 30 日最大單一產品占 44.2%，亦超過 40% 門檻。建議先維持成長節奏並優先降低集中風險，不建議只看總額就全面加碼。" +
+      "成長主因仍待業務確認，我尚未取得該線的回覆。";
+
+    const recovery = resolveStrandedReplyRecovery({
+      base,
+      finalText: substantiveCjkFinal,
+      sourceReplyDeliveryMode: "message_tool_only",
+      sendPolicyDenied: false,
+      successfulSourceReplyDelivery: false,
+      isHeartbeat: false,
+      isRoomEvent: false,
+    });
+
+    expect(recovery.kind).toBe("retry");
+    if (recovery.kind === "retry") {
+      expect(recovery.run.strandedReplyRetry).toBe(true);
+      expect(recovery.run.disableCollectBatching).toBe(true);
+      expect(recovery.run.prompt).toContain(substantiveCjkFinal);
+      expect(recovery.run.prompt).toContain("message(action=send)");
+    }
+  });
+
   it("returns a diagnostic rather than a second retry", () => {
     const base = createMockFollowupRun({ prompt: "question", strandedReplyRetry: true });