diff --git a/extensions/line/src/message-cards.test.ts b/extensions/line/src/message-cards.test.ts
index db9b216e2d1a..538c7584b4d8 100644
--- a/extensions/line/src/message-cards.test.ts
+++ b/extensions/line/src/message-cards.test.ts
@@ -51,13 +51,13 @@ describe("createButtonTemplate", () => {
     expect((template.template as { text: string }).text.length).toBe(60);
   });
 
-  it("keeps longer text when thumbnail is provided", () => {
+  it("truncates text to 60 chars when title and thumbnail are provided", () => {
     const longText = "x".repeat(100);
     const template = createButtonTemplate("Title", longText, [messageAction("OK")], {
       thumbnailImageUrl: "https://example.com/thumb.jpg",
     });
 
-    expect((template.template as { text: string }).text.length).toBe(100);
+    expect((template.template as { text: string }).text.length).toBe(60);
   });
 });
 
@@ -77,12 +77,67 @@ describe("createCarouselColumn", () => {
     expect(column.actions.length).toBe(3);
   });
 
-  it("truncates text to 120 characters", () => {
+  it("truncates text to 120 characters when no title or image is set", () => {
     const longText = "x".repeat(150);
     const column = createCarouselColumn({ text: longText, actions: [messageAction("OK")] });
 
     expect(column.text.length).toBe(120);
   });
+
+  it("truncates text to 60 characters when a title is set", () => {
+    const longText = "x".repeat(150);
+    const column = createCarouselColumn({
+      title: "Title",
+      text: longText,
+      actions: [messageAction("OK")],
+    });
+
+    expect(column.text.length).toBe(60);
+  });
+
+  it("does not split an emoji grapheme at the 60-code-unit boundary", () => {
+    const text = `${"x".repeat(59)}👨‍👩‍👧‍👦after`;
+    const column = createCarouselColumn({
+      title: "Title",
+      text,
+      actions: [messageAction("OK")],
+    });
+
+    expect(column.text).toBe("x".repeat(59));
+  });
+
+  it("keeps required text when the first grapheme exceeds the limit", () => {
+    const text = `😀${"\u0301".repeat(59)}`;
+    const column = createCarouselColumn({
+      title: "Title",
+      text,
+      actions: [messageAction("OK")],
+    });
+
+    expect(column.text.length).toBe(60);
+    expect(column.text.startsWith("😀")).toBe(true);
+  });
+
+  it("uses the compact limit when a whitespace-only title is present", () => {
+    const column = createCarouselColumn({
+      title: " ",
+      text: "x".repeat(150),
+      actions: [messageAction("OK")],
+    });
+
+    expect(column.text).toBe("x".repeat(60));
+  });
+
+  it("truncates text to 60 characters when a thumbnail image is set", () => {
+    const longText = "x".repeat(150);
+    const column = createCarouselColumn({
+      text: longText,
+      thumbnailImageUrl: "https://example.com/thumb.jpg",
+      actions: [messageAction("OK")],
+    });
+
+    expect(column.text.length).toBe(60);
+  });
 });
 
 describe("carousel column limits", () => {
@@ -131,6 +186,20 @@ describe("createProductCarousel", () => {
       .columns;
     expect(columns[0].actions[0].type).toBe(expectedType);
   });
+
+  it("preserves the complete price when truncating a long description", () => {
+    const template = createProductCarousel([
+      {
+        title: "Product",
+        description: "x".repeat(59),
+        price: "$12.99",
+      },
+    ]);
+    const columns = (template.template as { columns: Array<{ text: string }> }).columns;
+
+    expect(columns[0].text).toBe(`${"x".repeat(53)}\n$12.99`);
+    expect(columns[0].text.length).toBe(60);
+  });
 });
 
 describe("flex cards", () => {
diff --git a/extensions/line/src/template-messages.ts b/extensions/line/src/template-messages.ts
index 357bf3bed281..9e5060aba4b6 100644
--- a/extensions/line/src/template-messages.ts
+++ b/extensions/line/src/template-messages.ts
@@ -13,6 +13,9 @@ type CarouselColumn = messagingApi.CarouselColumn;
 type ImageCarouselTemplate = messagingApi.ImageCarouselTemplate;
 type ImageCarouselColumn = messagingApi.ImageCarouselColumn;
 
+const COMPACT_TEMPLATE_TEXT_LIMIT = 60;
+const graphemeSegmenter = new Intl.Segmenter(undefined, { granularity: "grapheme" });
+
 type TemplatePayloadAction = {
   type?: "uri" | "postback" | "message";
   uri?: string;
@@ -30,6 +33,48 @@ function buildTemplatePayloadAction(action: TemplatePayloadAction): Action {
   return messageAction(action.label, action.data ?? action.label);
 }
 
+function resolveTemplateTextLimit(params: {
+  title?: string;
+  thumbnailImageUrl?: string;
+  textOnlyLimit: number;
+}): number {
+  return params.title !== undefined || params.thumbnailImageUrl !== undefined
+    ? COMPACT_TEMPLATE_TEXT_LIMIT
+    : params.textOnlyLimit;
+}
+
+function truncateTemplateText(text: string, limit: number): string {
+  let result = "";
+  for (const { segment } of graphemeSegmenter.segment(text)) {
+    if (result.length + segment.length > limit) {
+      // A pathological grapheme can exceed LINE's whole field limit. Preserve
+      // graphemes normally, but keep required text non-empty without splitting
+      // a surrogate pair when the first grapheme alone cannot fit.
+      if (!result) {
+        for (const codePoint of segment) {
+          if (result.length + codePoint.length > limit) {
+            break;
+          }
+          result += codePoint;
+        }
+      }
+      break;
+    }
+    result += segment;
+  }
+  return result;
+}
+
+function formatProductCarouselText(description: string, price?: string): string {
+  if (!price) {
+    return description;
+  }
+  const priceText = truncateTemplateText(price, COMPACT_TEMPLATE_TEXT_LIMIT);
+  const descriptionLimit = Math.max(0, COMPACT_TEMPLATE_TEXT_LIMIT - priceText.length - 1);
+  const descriptionText = truncateTemplateText(description, descriptionLimit);
+  return descriptionText ? `${descriptionText}\n${priceText}` : priceText;
+}
+
 /**
  * Create a confirm template (yes/no style dialog)
  */
@@ -68,12 +113,15 @@ export function createButtonTemplate(
     altText?: string;
   },
 ): TemplateMessage {
-  const hasThumbnail = Boolean(options?.thumbnailImageUrl?.trim());
-  const textLimit = hasThumbnail ? 160 : 60;
+  const textLimit = resolveTemplateTextLimit({
+    title,
+    thumbnailImageUrl: options?.thumbnailImageUrl,
+    textOnlyLimit: 160,
+  });
   const template: ButtonsTemplate = {
     type: "buttons",
     title: title.slice(0, 40), // LINE limit
-    text: text.slice(0, textLimit), // LINE limit (60 if no thumbnail, 160 with thumbnail)
+    text: truncateTemplateText(text, textLimit),
     actions: actions.slice(0, 4), // LINE limit: max 4 actions
     thumbnailImageUrl: options?.thumbnailImageUrl,
     imageAspectRatio: options?.imageAspectRatio ?? "rectangle",
@@ -125,9 +173,14 @@ export function createCarouselColumn(params: {
   imageBackgroundColor?: string;
   defaultAction?: Action;
 }): CarouselColumn {
+  // LINE caps a carousel column's text at 60 chars when the column carries a
+  // title or thumbnail image, and 120 chars otherwise. Sending an over-length
+  // text makes LINE reject the whole carousel, so mirror the conditional limit
+  // the buttons template already applies above.
+  const textLimit = resolveTemplateTextLimit({ ...params, textOnlyLimit: 120 });
   return {
     title: params.title?.slice(0, 40),
-    text: params.text.slice(0, 120), // LINE limit
+    text: truncateTemplateText(params.text, textLimit),
     actions: params.actions.slice(0, 3), // LINE limit: max 3 actions per column
     thumbnailImageUrl: params.thumbnailImageUrl,
     imageBackgroundColor: params.imageBackgroundColor,
@@ -256,9 +309,7 @@ export function createProductCarousel(
 
     return createCarouselColumn({
       title: product.title,
-      text: product.price
-        ? `${product.description}\n${product.price}`.slice(0, 120)
-        : product.description,
+      text: formatProductCarouselText(product.description, product.price),
       thumbnailImageUrl: product.imageUrl,
       actions,
     });