fix(telegram): sanitize failover alert errors

apps/api/tests/test_failover_alerter.py

@@ -19,6 +19,8 @@ from src.services.failover_alerter import (
     DEDUP_TTL_SEC,
     QUOTA_DEDUP_TTL_SEC,
     FailoverAlerter,
+    _lines_from_list,
+    _sanitize_telegram_error,
     configure_alerter,
     get_failover_alerter,
     reset_failover_alerter,
@@ -231,3 +233,19 @@ async def test_memory_dedup_max_size_gc():
 
     # GC 後：999 個 stale entry 被清除，只剩 fresh:key + trigger:gc:key
     assert len(alerter._memory_dedup) <= 3  # fresh + trigger + 可能有邊界差1
+
+
+def test_lines_from_list_escapes_markdown_v2_numbered_periods() -> None:
+    rendered = _lines_from_list(["修復 node-exporter-110"])
+
+    assert "1\\." in rendered
+    assert "node\\-exporter\\-110" in rendered
+
+
+def test_sanitize_telegram_error_redacts_bot_token_url() -> None:
+    raw = "HTTP error for https://api.telegram.org/bot123456:SECRET/sendMessage"
+
+    sanitized = _sanitize_telegram_error(raw)
+
+    assert "SECRET" not in sanitized
+    assert "bot<redacted>" in sanitized

apps/api/tests/test_telegram_gateway_error_sanitizer.py

@@ -0,0 +1,12 @@
+from __future__ import annotations
+
+from src.services.telegram_gateway import _sanitize_telegram_error
+
+
+def test_telegram_gateway_sanitizes_bot_token_url() -> None:
+    raw = "Client error for https://api.telegram.org/bot123456:SECRET/sendMessage"
+
+    sanitized = _sanitize_telegram_error(raw)
+
+    assert "SECRET" not in sanitized
+    assert "bot<redacted>" in sanitized