Merge dc013e9 into 2cb482d

wm0018 · web-flow · commit 6cbd2a02ff35 · 2026-07-09T03:42:41.000Z
diff --git a/src/gateway/session-utils.fs.test.ts b/src/gateway/session-utils.fs.test.ts
@@ -2008,6 +2008,20 @@ describe("readSessionPreviewItemsFromTranscript", () => {
     expect(result[0]?.text.endsWith("...")).toBe(true);
   });
 
+  test("keeps preview text valid when the limit bisects an emoji", () => {
+    const sessionId = "preview-truncate-utf16";
+    const lines = [
+      JSON.stringify({
+        message: { role: "assistant", content: `${"t".repeat(196)}🚀xyz` },
+      }),
+    ];
+    writeTranscriptLines(sessionId, lines);
+
+    expect(readPreview(sessionId, 1, 200)).toEqual([
+      { role: "assistant", text: `${"t".repeat(196)}...` },
+    ]);
+  });
+
   test("strips inline directives from preview items", () => {
     const sessionId = "preview-strip-inline-directives";
     const lines = [
diff --git a/src/gateway/session-utils.fs.ts b/src/gateway/session-utils.fs.ts
@@ -20,6 +20,7 @@ import {
 import { jsonUtf8Bytes } from "../infra/json-utf8-bytes.js";
 import { hasInterSessionUserProvenance } from "../sessions/input-provenance.js";
 import { extractAssistantVisibleText } from "../shared/chat-message-content.js";
+import { truncateUtf16Safe } from "../utils.js";
 import { estimateStringChars, estimateTokensFromChars } from "../utils/cjk-chars.js";
 import { stripInlineDirectiveTagsForDisplay } from "../utils/directive-tags.js";
 import { extractToolCallNames, hasToolCall } from "../utils/transcript-tools.js";
@@ -1919,13 +1920,11 @@ function normalizeRole(role: string | undefined, isTool: boolean): SessionPrevie
 }
 
 function truncatePreviewText(text: string, maxChars: number): string {
-  if (maxChars <= 0 || text.length <= maxChars) {
+  if (text.length <= maxChars) {
     return text;
   }
-  if (maxChars <= 3) {
-    return text.slice(0, maxChars);
-  }
-  return `${text.slice(0, maxChars - 3)}...`;
+  // The preview entry point clamps maxChars to at least 20, so the suffix budget stays positive.
+  return `${truncateUtf16Safe(text, maxChars - 3)}...`;
 }
 
 function extractPreviewText(message: TranscriptPreviewMessage): string | null {
diff --git a/src/gateway/session-utils.test.ts b/src/gateway/session-utils.test.ts
@@ -2560,6 +2560,11 @@ describe("deriveSessionTitle", () => {
     expect(result.endsWith("…")).toBe(true);
   });
 
+  test("keeps a derived title valid when the limit bisects an emoji", () => {
+    const entry = { sessionId: "abc123", updatedAt: Date.now() } as SessionEntry;
+    expect(deriveSessionTitle(entry, `${"t".repeat(58)}🚀 extra`)).toBe(`${"t".repeat(58)}…`);
+  });
+
   test("truncates at word boundary when possible", () => {
     const entry = {
       sessionId: "abc123",
diff --git a/src/gateway/session-utils.ts b/src/gateway/session-utils.ts
@@ -93,6 +93,7 @@ import {
   resolveAvatarMime,
 } from "../shared/avatar-policy.js";
 import { resolveNonNegativeNumber } from "../shared/number-coercion.js";
+import { truncateUtf16Safe } from "../utils.js";
 import { normalizeSessionDeliveryFields } from "../utils/delivery-context.shared.js";
 import type { ModelCostConfig } from "../utils/usage-format.js";
 import { estimateUsageCost, resolveModelCostConfig } from "../utils/usage-format.js";
@@ -229,7 +230,7 @@ function truncateTitle(text: string, maxLen: number): string {
   if (text.length <= maxLen) {
     return text;
   }
-  const cut = text.slice(0, maxLen - 1);
+  const cut = truncateUtf16Safe(text, maxLen - 1);
   const lastSpace = cut.lastIndexOf(" ");
   if (lastSpace > maxLen * 0.6) {
     return cut.slice(0, lastSpace) + "…";
