feat(nimbus): Send channel notifications in slack DMs

experimenter/experimenter/slack/notification.py

@@ -15,18 +15,46 @@ def _get_slack_client():
     return WebClient(token=settings.SLACK_AUTH_TOKEN)
 
 
-def _get_user_mentions(client, emails):
-    mentions = []
+def _lookup_users(client, emails):
+    user_ids = []
     for email in emails:
         if not email:
             continue
         try:
             response = client.users_lookupByEmail(email=email)
-            mentions.append(f"<@{response['user']['id']}>")
+            user_id = response["user"]["id"]
+            user_ids.append(user_id)
         except SlackApiError as e:
             logger.warning(f"Could not find Slack user for {email}: {e}")
             continue
-    return " ".join(mentions)
+    return user_ids
+
+
+def _is_user_in_channel(client, user_id, channel):
+    try:
+        response = client.conversations_members(channel=channel)
+        return user_id in response.get("members", [])
+    except SlackApiError as e:
+        logger.warning(f"Failed to check if user {user_id} is in channel {channel}: {e}")
+        return False
+
+
+def _send_dm_to_user(client, user_id, message, channel_message_link=None):
+    try:
+        conversation = client.conversations_open(users=[user_id])
+        channel_id = conversation["channel"]["id"]
+
+        # Add channel message link if provided
+        dm_message = message
+        if channel_message_link:
+            dm_message = f"{message}\n\nView in channel: {channel_message_link}"
+
+        client.chat_postMessage(
+            channel=channel_id, text=dm_message, unfurl_links=False, unfurl_media=False
+        )
+        logger.info(f"DM sent to user {user_id}")
+    except SlackApiError as e:
+        logger.warning(f"Failed to send DM to user {user_id}: {e}")
 
 
 def send_slack_notification(
@@ -47,13 +75,22 @@ def send_slack_notification(
 
     channel = settings.SLACK_NIMBUS_CHANNEL
 
-    requesting_user_mention = ""
+    all_user_ids = []
+
+    requesting_user_ids = []
     if requesting_user_email:
-        requesting_user_mention = _get_user_mentions(client, [requesting_user_email])
+        requesting_user_ids = _lookup_users(client, [requesting_user_email])
+        all_user_ids.extend(requesting_user_ids)
         # Exclude requesting_user_email from email_addresses to avoid duplicate mentions
         email_addresses = [e for e in email_addresses if e and e != requesting_user_email]
 
-    mentions = _get_user_mentions(client, email_addresses)
+    mentioned_user_ids = _lookup_users(client, email_addresses)
+    all_user_ids.extend(mentioned_user_ids)
+
+    requesting_user_mention = (
+        f"<@{requesting_user_ids[0]}>" if requesting_user_ids else ""
+    )
+    mentions = " ".join(f"<@{user_id}>" for user_id in mentioned_user_ids)
 
     if requesting_user_mention:
         message = (
@@ -67,10 +104,29 @@ def send_slack_notification(
         message = f"{message} {mentions}"
 
     try:
-        client.chat_postMessage(
+        response = client.chat_postMessage(
             channel=channel, text=message, unfurl_links=False, unfurl_media=False
         )
         logger.info(f"Slack notification sent for experiment {experiment.name}")
+
+        # Get the permalink to the channel message
+        channel_message_link = None
+        try:
+            permalink_response = client.chat_getPermalink(
+                channel=channel, message_ts=response["ts"]
+            )
+            channel_message_link = permalink_response["permalink"]
+        except SlackApiError as e:
+            logger.warning(f"Could not get permalink for channel message: {e}")
+
+        for user_id in all_user_ids:
+            if not _is_user_in_channel(client, user_id, channel):
+                _send_dm_to_user(client, user_id, message, channel_message_link)
+            else:
+                logger.info(
+                    f"Skipping DM to user {user_id} - already in channel {channel}"
+                )
+
     except SlackApiError as e:
         logger.error(f"Failed to send Slack notification for {experiment.name}: {e}")
         raise