fix(slack): sanitize generated session IDs

src/google/adk/integrations/slack/slack_runner.py

@@ -15,6 +15,7 @@
 from __future__ import annotations
 
 import logging
+import re
 from typing import Any
 
 from google.adk.runners import Runner
@@ -31,6 +32,13 @@
 
 logger = logging.getLogger("google_adk." + __name__)
 
+_SESSION_ID_UNSAFE_CHARS = re.compile(r"[^A-Za-z0-9_-]")
+
+
+def _to_session_id_part(value: str) -> str:
+  """Converts Slack identifiers into ADK session-id-safe strings."""
+  return _SESSION_ID_UNSAFE_CHARS.sub("_", value)
+
 
 class SlackRunner:
   """Runner for ADK agents on Slack."""
@@ -73,8 +81,14 @@ async def _handle_message(self, event: dict[str, Any], say: Any) -> None:
     if not text or not user_id or not channel_id:
       return
 
-    # In Slack, we can use the channel_id (and optionally thread_ts) as a session ID.
-    session_id = f"{channel_id}-{thread_ts}" if thread_ts else channel_id
+    # In Slack, we can use the channel_id (and optionally thread_ts) as a
+    # session ID. Slack timestamps contain "." but managed session services only
+    # accept letters, numbers, "_" and "-".
+    session_id = (
+        f"{_to_session_id_part(channel_id)}-{_to_session_id_part(thread_ts)}"
+        if thread_ts
+        else _to_session_id_part(channel_id)
+    )
 
     new_message = types.Content(role="user", parts=[types.Part(text=text)])
 

tests/unittests/integrations/slack/test_slack_runner.py

@@ -74,6 +74,39 @@ async def mock_run_async(*args, **kwargs):
         text="Hi user!",
     )
 
+  @patch("google.adk.integrations.slack.slack_runner.logger")
+  async def test_handle_message_sanitizes_slack_thread_ts_session_id(
+      self, mock_logger
+  ):
+    mock_say = AsyncMock()
+    mock_say.return_value = {"ts": "thinking_ts"}
+    event = {
+        "text": "Hello bot",
+        "user": "U12345",
+        "channel": "C67890",
+        "thread_ts": "1234567890.123456",
+        "ts": "1234567899.999999",
+    }
+
+    async def mock_run_async(*args, **kwargs):
+      return
+      yield
+
+    self.mock_runner.run_async.side_effect = mock_run_async
+
+    await self.slack_runner._handle_message(event, mock_say)
+
+    self.mock_runner.run_async.assert_called_once_with(
+        user_id="U12345",
+        session_id="C67890-1234567890_123456",
+        new_message=types.Content(
+            role="user", parts=[types.Part(text="Hello bot")]
+        ),
+    )
+    mock_say.assert_called_once_with(
+        text="_Thinking..._", thread_ts="1234567890.123456"
+    )
+
   @patch("google.adk.integrations.slack.slack_runner.logger")
   async def test_handle_message_multi_turn(self, mock_logger):
     # Setup mocks