fix(telegram): honor message.quote for partial-quote reply context

When a Telegram user replies using the native quote feature to select
only part of a prior message, _build_message_event was injecting the
ENTIRE replied-to message into reply_to_text via
message.reply_to_message.text/caption. python-telegram-bot exposes
the user-selected substring as message.quote (TextQuote.text); we now
prefer that and fall back to the full replied-to text only when no
native quote is present.

The agent-visible "[Replying to: \"...\"]" prefix can otherwise expand
the user's narrow quote into the full prior message, causing the agent
to act on unrelated actionable-looking text the user did not select
(e.g. multi-item briefings where the user quotes one bullet but the
prefix injects every bullet). Falls back cleanly when message.quote
is absent (PTB <21 or replies that don't quote a substring).

Fixes #22619

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

gateway/platforms/telegram.py

@@ -4026,12 +4026,28 @@ class TelegramAdapter(BasePlatformAdapter):
             chat_topic=chat_topic,
         )
         
-        # Extract reply context if this message is a reply
+        # Extract reply context if this message is a reply.
+        # Prefer Telegram's native partial quote (message.quote, TextQuote)
+        # so a user replying to a single selected substring of a prior
+        # multi-section message doesn't get the whole replied-to message
+        # injected into the agent's context — which can cause the agent
+        # to act on unrelated actionable-looking text the user didn't
+        # quote (#22619). Fall back to the full replied-to message text
+        # / caption when no native quote is present.
         reply_to_id = None
         reply_to_text = None
         if message.reply_to_message:
             reply_to_id = str(message.reply_to_message.message_id)
-            reply_to_text = message.reply_to_message.text or message.reply_to_message.caption or None
+            quote = getattr(message, "quote", None)
+            quote_text = getattr(quote, "text", None) if quote is not None else None
+            if quote_text:
+                reply_to_text = quote_text
+            else:
+                reply_to_text = (
+                    message.reply_to_message.text
+                    or message.reply_to_message.caption
+                    or None
+                )
 
         # Per-channel/topic ephemeral prompt
         from gateway.platforms.base import resolve_channel_prompt

tests/gateway/test_telegram_reply_quote.py

@@ -0,0 +1,144 @@
+"""Tests for Telegram native partial-quote handling in _build_message_event.
+
+When a Telegram user replies using Telegram's native quote feature to
+select only part of a prior message, the adapter must use ``message.quote.text``
+(the user-selected substring) rather than ``message.reply_to_message.text``
+(the entire replied-to message). Otherwise the agent receives the full prior
+message as ``reply_to_text``, which can cause it to act on unrelated
+actionable-looking text the user did not quote (#22619).
+"""
+
+import sys
+from types import SimpleNamespace
+from unittest.mock import MagicMock
+
+from gateway.config import PlatformConfig
+
+
+def _ensure_telegram_mock():
+    if "telegram" in sys.modules and hasattr(sys.modules["telegram"], "__file__"):
+        return
+
+    telegram_mod = MagicMock()
+    telegram_mod.ext.ContextTypes.DEFAULT_TYPE = type(None)
+    telegram_mod.constants.ParseMode.MARKDOWN_V2 = "MarkdownV2"
+    telegram_mod.constants.ChatType.GROUP = "group"
+    telegram_mod.constants.ChatType.SUPERGROUP = "supergroup"
+    telegram_mod.constants.ChatType.CHANNEL = "channel"
+    telegram_mod.constants.ChatType.PRIVATE = "private"
+
+    for name in ("telegram", "telegram.ext", "telegram.constants", "telegram.request"):
+        sys.modules.setdefault(name, telegram_mod)
+
+
+_ensure_telegram_mock()
+
+from gateway.platforms.telegram import TelegramAdapter  # noqa: E402
+
+
+def _make_adapter():
+    return TelegramAdapter(PlatformConfig(enabled=True, token="***", extra={}))
+
+
+def _make_message(
+    text="follow-up",
+    reply_to_text=None,
+    reply_to_caption=None,
+    reply_to_id=42,
+    quote_text=None,
+):
+    chat = SimpleNamespace(id=111, type="private", title=None, full_name="Alice")
+    user = SimpleNamespace(id=42, full_name="Alice")
+
+    reply_to_message = None
+    if reply_to_text is not None or reply_to_caption is not None:
+        reply_to_message = SimpleNamespace(
+            message_id=reply_to_id,
+            text=reply_to_text,
+            caption=reply_to_caption,
+        )
+
+    quote = None
+    if quote_text is not None:
+        quote = SimpleNamespace(text=quote_text)
+
+    return SimpleNamespace(
+        chat=chat,
+        from_user=user,
+        text=text,
+        message_thread_id=None,
+        message_id=1001,
+        reply_to_message=reply_to_message,
+        quote=quote,
+        date=None,
+        forum_topic_created=None,
+    )
+
+
+def test_native_partial_quote_used_as_reply_to_text():
+    """When ``message.quote`` is present, prefer the selected substring."""
+    from gateway.platforms.base import MessageType
+
+    adapter = _make_adapter()
+    msg = _make_message(
+        text="mark this one as done",
+        reply_to_text=(
+            "Briefing:\n- Item A: deploy fix\n- Item B: rotate keys\n- Item C: update docs"
+        ),
+        quote_text="Item B: rotate keys",
+    )
+
+    event = adapter._build_message_event(msg, MessageType.TEXT)
+
+    assert event.reply_to_text == "Item B: rotate keys"
+    assert event.reply_to_message_id == "42"
+
+
+def test_full_reply_text_used_when_no_native_quote():
+    """No ``message.quote`` → fall back to the whole replied-to message text."""
+    from gateway.platforms.base import MessageType
+
+    adapter = _make_adapter()
+    msg = _make_message(
+        text="thanks",
+        reply_to_text="Whole prior message body",
+        quote_text=None,
+    )
+
+    event = adapter._build_message_event(msg, MessageType.TEXT)
+
+    assert event.reply_to_text == "Whole prior message body"
+    assert event.reply_to_message_id == "42"
+
+
+def test_caption_fallback_when_no_quote_and_no_text():
+    """Replied-to media message: caption is used when text is absent."""
+    from gateway.platforms.base import MessageType
+
+    adapter = _make_adapter()
+    msg = _make_message(
+        text="see this",
+        reply_to_text=None,
+        reply_to_caption="Photo caption from earlier",
+        quote_text=None,
+    )
+
+    event = adapter._build_message_event(msg, MessageType.TEXT)
+
+    assert event.reply_to_text == "Photo caption from earlier"
+
+
+def test_empty_quote_text_falls_back_to_full_reply():
+    """Defensive: a present-but-empty quote.text shouldn't blank the prefix."""
+    from gateway.platforms.base import MessageType
+
+    adapter = _make_adapter()
+    msg = _make_message(
+        text="follow-up",
+        reply_to_text="Prior message body",
+        quote_text="",
+    )
+
+    event = adapter._build_message_event(msg, MessageType.TEXT)
+
+    assert event.reply_to_text == "Prior message body"