fix: rich messages follow-ups — reply_parameters, send latch, opt-in default

- Use reply_parameters per the sendRichMessage spec instead of the
  undocumented reply_to_message_id scalar (silently ignored -> reply
  anchor quietly dropped).
- Latch rich sends off after an endpoint-capability failure (old PTB /
  server without sendRichMessage) so every later reply doesn't pay a
  doomed extra roundtrip; per-message BadRequests do NOT latch.
- Default rich_messages to OFF (opt-in) while the day-old Bot API 10.1
  endpoint is validated live; revert the prompt-hint table guidance
  until the default flips on.
- Tests: reply_parameters shape, send-latch behavior, BadRequest
  non-latch; rich tests opt in explicitly via extra.

tests/agent/test_prompt_builder.py

@@ -877,20 +877,6 @@ class TestPromptBuilderConstants:
         # check that this test is calibrated correctly).
         assert "include MEDIA:" in PLATFORM_HINTS["telegram"]
 
-    def test_telegram_hint_encourages_rich_markdown(self):
-        # Regression: Telegram now supports Bot API 10.1 Rich Messages, so the
-        # hint must encourage tables / task lists / rich Markdown and must no
-        # longer forbid tables. The adapter sends final replies via
-        # sendRichMessage with raw markdown (see test_telegram_rich_messages).
-        hint = PLATFORM_HINTS["telegram"]
-        lowered = hint.lower()
-        assert "Telegram has NO table syntax" not in hint
-        assert "table" in lowered
-        assert "task list" in lowered
-        assert "rich markdown" in lowered
-        # Local media delivery guidance must remain intact.
-        assert "include MEDIA:" in hint
-
     def test_platform_hints_mattermost(self):
         hint = PLATFORM_HINTS["mattermost"]
         assert "Mattermost" in hint

tests/gateway/test_telegram_rich_messages.py

@@ -27,8 +27,17 @@ RICH_CONTENT = "## Results\n\n| Case | Status |\n|---|---|\n| rich | ✅ |\n\n-
 
 
 def _make_adapter(extra=None):
-    """Build a TelegramAdapter with a mock bot wired for the rich path."""
-    config = PlatformConfig(enabled=True, token="fake-token", extra=extra or {})
+    """Build a TelegramAdapter with a mock bot wired for the rich path.
+
+    Rich messages are opt-in (default off) while the Bot API 10.1 endpoint
+    is validated live, so tests that exercise the rich path enable it
+    explicitly here; opt-out tests pass their own ``extra``.
+    """
+    config = PlatformConfig(
+        enabled=True,
+        token="fake-token",
+        extra={"rich_messages": True} if extra is None else extra,
+    )
     adapter = TelegramAdapter(config)
     bot = MagicMock()
     # do_api_request as an AsyncMock makes inspect.iscoroutinefunction(...) True,
@@ -133,6 +142,44 @@ async def test_unknown_endpoint_error_falls_back_to_legacy():
     adapter._bot.send_message.assert_awaited()
 
 
+@pytest.mark.asyncio
+async def test_capability_error_latches_rich_send_off():
+    """Endpoint-missing errors latch rich off so later sends skip the
+    doomed extra roundtrip entirely."""
+    adapter = _make_adapter()
+    adapter._bot.do_api_request = AsyncMock(side_effect=RuntimeError("Method not found"))
+
+    result = await adapter.send("12345", RICH_CONTENT)
+    assert result.success is True
+    assert adapter._rich_send_disabled is True
+
+    # Second send skips rich entirely (no second do_api_request call).
+    adapter._bot.do_api_request.reset_mock()
+    adapter._bot.send_message.reset_mock()
+    result2 = await adapter.send("12345", RICH_CONTENT)
+    assert result2.success is True
+    adapter._bot.do_api_request.assert_not_called()
+    adapter._bot.send_message.assert_awaited()
+
+
+@pytest.mark.asyncio
+async def test_per_message_bad_request_does_not_latch_off():
+    """A parser/limit BadRequest is per-message — rich must stay enabled
+    for subsequent messages."""
+    adapter = _make_adapter()
+    adapter._bot.do_api_request = AsyncMock(side_effect=BadRequest("can't parse rich message"))
+
+    result = await adapter.send("12345", RICH_CONTENT)
+    assert result.success is True
+    assert adapter._rich_send_disabled is False
+
+    # Next message re-attempts rich.
+    adapter._bot.do_api_request = AsyncMock(return_value=SimpleNamespace(message_id=124))
+    result2 = await adapter.send("12345", RICH_CONTENT)
+    assert result2.success is True
+    adapter._bot.do_api_request.assert_awaited_once()
+
+
 @pytest.mark.asyncio
 @pytest.mark.parametrize("exc", [TimedOut("timed out"), NetworkError("connection reset")])
 async def test_transient_rich_error_does_not_legacy_resend(exc):
@@ -184,13 +231,17 @@ async def test_routing_direct_messages_topic_id_drops_message_thread_id():
 
 
 @pytest.mark.asyncio
-async def test_reply_to_propagates_as_scalar():
+async def test_reply_to_propagates_as_reply_parameters():
     adapter = _make_adapter()
 
     await adapter.send("-100123", RICH_CONTENT, reply_to="999")
 
     api_kwargs = _rich_api_kwargs(adapter)
-    assert api_kwargs["reply_to_message_id"] == 999
+    # Spec: sendRichMessage documents reply_parameters (ReplyParameters), not
+    # the legacy reply_to_message_id scalar — unknown params are silently
+    # ignored, which would quietly drop the reply anchor.
+    assert api_kwargs["reply_parameters"] == {"message_id": 999}
+    assert "reply_to_message_id" not in api_kwargs
 
 
 @pytest.mark.asyncio