fix: render telegram draft streams with markdown html

src/telegram/bot-message-dispatch.ts

@@ -26,6 +26,7 @@ import type { TelegramStreamMode } from "./bot/types.js";
 import type { TelegramInlineButtons } from "./button-types.js";
 import { resolveTelegramDraftStreamingChunking } from "./draft-chunking.js";
 import { createTelegramDraftStream } from "./draft-stream.js";
+import { renderTelegramHtmlText } from "./format.js";
 import { editMessageTelegram } from "./send.js";
 import { cacheSticker, describeStickerImage } from "./sticker-cache.js";
 
@@ -101,6 +102,15 @@ export const dispatchTelegramMessage = async ({
   } = context;
 
   const draftMaxChars = Math.min(textLimit, 4096);
+  const tableMode = resolveMarkdownTableMode({
+    cfg,
+    channel: "telegram",
+    accountId: route.accountId,
+  });
+  const renderDraftPreview = (text: string) => ({
+    text: renderTelegramHtmlText(text, { tableMode }),
+    parseMode: "HTML" as const,
+  });
   const accountBlockStreamingEnabled =
     typeof telegramCfg.blockStreaming === "boolean"
       ? telegramCfg.blockStreaming
@@ -117,6 +127,7 @@ export const dispatchTelegramMessage = async ({
         thread: threadSpec,
         replyToMessageId: draftReplyToMessageId,
         minInitialChars: draftMinInitialChars,
+        renderText: renderDraftPreview,
         log: logVerbose,
         warn: logVerbose,
       })
@@ -129,6 +140,7 @@ export const dispatchTelegramMessage = async ({
         thread: threadSpec,
         replyToMessageId: draftReplyToMessageId,
         minInitialChars: draftMinInitialChars,
+        renderText: renderDraftPreview,
         log: logVerbose,
         warn: logVerbose,
       })
@@ -259,11 +271,6 @@ export const dispatchTelegramMessage = async ({
     channel: "telegram",
     accountId: route.accountId,
   });
-  const tableMode = resolveMarkdownTableMode({
-    cfg,
-    channel: "telegram",
-    accountId: route.accountId,
-  });
   const chunkMode = resolveChunkMode(cfg, "telegram", route.accountId);
 
   // Handle uncached stickers: get a dedicated vision description before dispatch

src/telegram/draft-stream.test.ts

@@ -133,6 +133,26 @@ describe("createTelegramDraftStream", () => {
     expect(api.sendMessage).toHaveBeenCalledTimes(2);
     expect(api.sendMessage).toHaveBeenLastCalledWith(123, "After thinking", undefined);
   });
+
+  it("supports rendered previews with parse_mode", async () => {
+    const api = createMockDraftApi();
+    const stream = createTelegramDraftStream({
+      // oxlint-disable-next-line typescript/no-explicit-any
+      api: api as any,
+      chatId: 123,
+      renderText: (text) => ({ text: `<i>${text}</i>`, parseMode: "HTML" }),
+    });
+
+    stream.update("hello");
+    await stream.flush();
+    expect(api.sendMessage).toHaveBeenCalledWith(123, "<i>hello</i>", { parse_mode: "HTML" });
+
+    stream.update("hello again");
+    await stream.flush();
+    expect(api.editMessageText).toHaveBeenCalledWith(123, 17, "<i>hello again</i>", {
+      parse_mode: "HTML",
+    });
+  });
 });
 
 describe("draft stream initial message debounce", () => {

src/telegram/draft-stream.ts

@@ -15,6 +15,11 @@ export type TelegramDraftStream = {
   forceNewMessage: () => void;
 };
 
+type TelegramDraftPreview = {
+  text: string;
+  parseMode?: "HTML";
+};
+
 export function createTelegramDraftStream(params: {
   api: Bot["api"];
   chatId: number;
@@ -24,6 +29,8 @@ export function createTelegramDraftStream(params: {
   throttleMs?: number;
   /** Minimum chars before sending first message (debounce for push notifications) */
   minInitialChars?: number;
+  /** Optional preview renderer (e.g. markdown -> HTML + parse mode). */
+  renderText?: (text: string) => TelegramDraftPreview;
   log?: (message: string) => void;
   warn?: (message: string) => void;
 }): TelegramDraftStream {
@@ -42,6 +49,7 @@ export function createTelegramDraftStream(params: {
 
   let streamMessageId: number | undefined;
   let lastSentText = "";
+  let lastSentParseMode: "HTML" | undefined;
   let stopped = false;
   let isFinal = false;
 
@@ -63,24 +71,43 @@ export function createTelegramDraftStream(params: {
       );
       return false;
     }
-    if (trimmed === lastSentText) {
+    const rendered = params.renderText?.(trimmed) ?? { text: trimmed };
+    const renderedText = rendered.text.trimEnd();
+    const renderedParseMode = rendered.parseMode;
+    if (!renderedText) {
+      return false;
+    }
+    if (renderedText === lastSentText && renderedParseMode === lastSentParseMode) {
       return true;
     }
 
     // Debounce first preview send for better push notification quality.
     if (typeof streamMessageId !== "number" && minInitialChars != null && !isFinal) {
-      if (trimmed.length < minInitialChars) {
+      if (renderedText.length < minInitialChars) {
         return false;
       }
     }
 
-    lastSentText = trimmed;
+    lastSentText = renderedText;
+    lastSentParseMode = renderedParseMode;
     try {
       if (typeof streamMessageId === "number") {
-        await params.api.editMessageText(chatId, streamMessageId, trimmed);
+        if (renderedParseMode) {
+          await params.api.editMessageText(chatId, streamMessageId, renderedText, {
+            parse_mode: renderedParseMode,
+          });
+        } else {
+          await params.api.editMessageText(chatId, streamMessageId, renderedText);
+        }
         return true;
       }
-      const sent = await params.api.sendMessage(chatId, trimmed, replyParams);
+      const sendParams = renderedParseMode
+        ? {
+            ...replyParams,
+            parse_mode: renderedParseMode,
+          }
+        : replyParams;
+      const sent = await params.api.sendMessage(chatId, renderedText, sendParams);
       const sentMessageId = sent?.message_id;
       if (typeof sentMessageId !== "number" || !Number.isFinite(sentMessageId)) {
         stopped = true;
@@ -138,6 +165,7 @@ export function createTelegramDraftStream(params: {
   const forceNewMessage = () => {
     streamMessageId = undefined;
     lastSentText = "";
+    lastSentParseMode = undefined;
     loop.resetPending();
   };