From 27052806eafeb5e5b19195c1159ae77baac47418 Mon Sep 17 00:00:00 2001
From: Ben Sabic <bensabic@users.noreply.github.com>
Date: Sun, 15 Mar 2026 21:36:15 +1100
Subject: [PATCH] fix(telegram): set parse_mode for markdown messages

postMessage and editMessage only set parse_mode when a card was present,
causing markdown messages to render as plain text with visible formatting
characters. Now also sets parse_mode when the message has a markdown field.

Closes #226
---
 .../fix-telegram-markdown-parse-mode.md       |  5 +++
 packages/adapter-telegram/src/index.test.ts   | 32 +++++++++++++++++++
 packages/adapter-telegram/src/index.ts        | 10 ++++--
 3 files changed, 45 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/fix-telegram-markdown-parse-mode.md

diff --git a/.changeset/fix-telegram-markdown-parse-mode.md b/.changeset/fix-telegram-markdown-parse-mode.md
new file mode 100644
index 00000000..51a3210b
--- /dev/null
+++ b/.changeset/fix-telegram-markdown-parse-mode.md
@@ -0,0 +1,5 @@
+---
+"@chat-adapter/telegram": patch
+---
+
+Set `parse_mode` to `"Markdown"` when posting messages with a `markdown` field, not only for card messages
diff --git a/packages/adapter-telegram/src/index.test.ts b/packages/adapter-telegram/src/index.test.ts
index a0d64168..cc5d195f 100644
--- a/packages/adapter-telegram/src/index.test.ts
+++ b/packages/adapter-telegram/src/index.test.ts
@@ -943,6 +943,38 @@ describe("TelegramAdapter", () => {
     expect(sendMessageBody.text).toBe("raw id message");
   });
 
+  it("sets parse_mode for markdown messages", async () => {
+    mockFetch
+      .mockResolvedValueOnce(
+        telegramOk({
+          id: 999,
+          is_bot: true,
+          first_name: "Bot",
+          username: "mybot",
+        })
+      )
+      .mockResolvedValueOnce(telegramOk(sampleMessage()));
+
+    const adapter = createTelegramAdapter({
+      botToken: "token",
+      mode: "webhook",
+      logger: mockLogger,
+      userName: "mybot",
+    });
+
+    await adapter.initialize(createMockChat());
+
+    await adapter.postMessage("telegram:123", {
+      markdown: "**bold** and _italic_",
+    });
+
+    const sendMessageBody = JSON.parse(
+      String((mockFetch.mock.calls[1]?.[1] as RequestInit).body)
+    ) as { parse_mode?: string };
+
+    expect(sendMessageBody.parse_mode).toBe("Markdown");
+  });
+
   it("posts cards with inline keyboard buttons", async () => {
     mockFetch
       .mockResolvedValueOnce(
diff --git a/packages/adapter-telegram/src/index.ts b/packages/adapter-telegram/src/index.ts
index ee2cdd22..272b2e69 100644
--- a/packages/adapter-telegram/src/index.ts
+++ b/packages/adapter-telegram/src/index.ts
@@ -556,7 +556,10 @@ export class TelegramAdapter
 
     const card = extractCard(message);
     const replyMarkup = card ? cardToTelegramInlineKeyboard(card) : undefined;
-    const parseMode = card ? TELEGRAM_MARKDOWN_PARSE_MODE : undefined;
+    const hasMarkdown =
+      typeof message === "object" && message !== null && "markdown" in message;
+    const parseMode =
+      card || hasMarkdown ? TELEGRAM_MARKDOWN_PARSE_MODE : undefined;
     const text = this.truncateMessage(
       convertEmojiPlaceholders(
         card
@@ -642,7 +645,10 @@ export class TelegramAdapter
 
     const card = extractCard(message);
     const replyMarkup = card ? cardToTelegramInlineKeyboard(card) : undefined;
-    const parseMode = card ? TELEGRAM_MARKDOWN_PARSE_MODE : undefined;
+    const hasMarkdown =
+      typeof message === "object" && message !== null && "markdown" in message;
+    const parseMode =
+      card || hasMarkdown ? TELEGRAM_MARKDOWN_PARSE_MODE : undefined;
     const text = this.truncateMessage(
       convertEmojiPlaceholders(
         card