telegram: add cheap pre-filter for group messages

Use Gemini Flash to classify group messages before running the
full Sonnet agent. Skips casual banter to save tokens/cost.

- shouldEngageInGroup: yes/no classifier using gemini-2.0-flash
- Only runs for group chats, private chats skip the filter
- On classifier failure, defaults to engaging (fail-open)

1 files changed, 65 insertions, 3 deletions

diff --git a/Omni/Agent/Telegram.hs b/Omni/Agent/Telegram.hs
index f8afcb7..27d7413 100644
--- a/Omni/Agent/Telegram.hs
+++ b/Omni/Agent/Telegram.hs
@@ -433,11 +433,35 @@ handleAuthorizedMessage tgConfig provider engineCfg msg uid userName chatId = do
 
   let userMessage = replyContext <> baseMessage
 
-  _ <- Memory.saveMessage uid chatId Memory.UserRole (Just userName) userMessage
+  shouldEngage <-
+    if Types.isGroupChat msg
+      then do
+        putText "Checking if should engage (group chat)..."
+        shouldEngageInGroup (Types.tgOpenRouterApiKey tgConfig) userMessage
+      else pure True
 
-  (conversationContext, contextTokens) <- Memory.getConversationContext uid chatId maxConversationTokens
-  putText <| "Conversation context: " <> tshow contextTokens <> " tokens"
+  if not shouldEngage
+    then putText "Skipping group message (pre-filter said no)"
+    else do
+      _ <- Memory.saveMessage uid chatId Memory.UserRole (Just userName) userMessage
 
+      (conversationContext, contextTokens) <- Memory.getConversationContext uid chatId maxConversationTokens
+      putText <| "Conversation context: " <> tshow contextTokens <> " tokens"
+
+      processEngagedMessage tgConfig provider engineCfg msg uid userName chatId userMessage conversationContext
+
+processEngagedMessage ::
+  Types.TelegramConfig ->
+  Provider.Provider ->
+  Engine.EngineConfig ->
+  Types.TelegramMessage ->
+  Text ->
+  Text ->
+  Int ->
+  Text ->
+  Text ->
+  IO ()
+processEngagedMessage tgConfig provider engineCfg msg uid userName chatId userMessage conversationContext = do
   memories <- Memory.recallMemories uid userMessage 5
   let memoryContext = Memory.formatMemoriesForPrompt memories
 
@@ -563,6 +587,44 @@ checkAndSummarize openRouterKey uid chatId = do
         _ <- Memory.summarizeAndArchive uid chatId summary
         putText "Conversation summarized and archived (gemini)"
 
+shouldEngageInGroup :: Text -> Text -> IO Bool
+shouldEngageInGroup openRouterKey messageText = do
+  let gemini = Provider.defaultOpenRouter openRouterKey "google/gemini-2.0-flash-001"
+  result <-
+    Provider.chat
+      gemini
+      []
+      [ Provider.Message
+          Provider.System
+          ( Text.unlines
+              [ "You are a classifier that decides if an AI assistant should respond to a message in a group chat.",
+                "Respond with ONLY 'yes' or 'no' (lowercase, nothing else).",
+                "",
+                "Say 'yes' if:",
+                "- The message is a direct question the assistant could answer",
+                "- The message contains a factual error worth correcting",
+                "- The message mentions the bot or asks for help",
+                "- The message shares a link or document to analyze",
+                "",
+                "Say 'no' if:",
+                "- It's casual banter or chit-chat between people",
+                "- It's a greeting or farewell",
+                "- It's an inside joke or personal conversation",
+                "- It doesn't require or benefit from bot input"
+              ]
+          )
+          Nothing
+          Nothing,
+        Provider.Message Provider.User messageText Nothing Nothing
+      ]
+  case result of
+    Left err -> do
+      putText <| "Engagement check failed: " <> err
+      pure True
+    Right msg -> do
+      let response = Text.toLower (Text.strip (Provider.msgContent msg))
+      pure (response == "yes" || response == "y")
+
 checkOllama :: IO (Either Text ())
 checkOllama = do
   ollamaUrl <- fromMaybe "http://localhost:11434" </ lookupEnv "OLLAMA_URL"