feat: add reminder service for todos

Adds a background reminder loop that checks every 5 minutes for overdue
todos and sends Telegram notifications.

Changes:
- Add last_reminded_at column to todos table with auto-migration
- Add listTodosDueForReminder to find overdue, unreminded todos
- Add markReminderSent to update reminder timestamp
- Add user_chats table to map user_id -> chat_id for notifications
- Add recordUserChat called on each message to track chat IDs
- Add reminderLoop forked in runTelegramBot
- 24-hour anti-spam interval between reminders per todo

1 files changed, 75 insertions, 0 deletions

diff --git a/Omni/Agent/Telegram.hs b/Omni/Agent/Telegram.hs
index f1c71e6..27b3ccf 100644
--- a/Omni/Agent/Telegram.hs
+++ b/Omni/Agent/Telegram.hs
@@ -43,6 +43,12 @@ module Omni.Agent.Telegram
     checkOllama,
     pullEmbeddingModel,
 
+    -- * Reminders
+    reminderLoop,
+    checkAndSendReminders,
+    recordUserChat,
+    lookupChatId,
+
     -- * System Prompt
     telegramSystemPrompt,
 
@@ -62,6 +68,7 @@ import qualified Data.Text as Text
 import Data.Time (getCurrentTime, utcToLocalTime)
 import Data.Time.Format (defaultTimeLocale, formatTime)
 import Data.Time.LocalTime (getCurrentTimeZone)
+import qualified Database.SQLite.Simple as SQL
 import qualified Network.HTTP.Client as HTTPClient
 import qualified Network.HTTP.Simple as HTTP
 import qualified Omni.Agent.Engine as Engine
@@ -578,12 +585,78 @@ telegramSystemPrompt =
       "ALWAYS include a text response to the user after using tools. never end your turn with only tool calls."
     ]
 
+initUserChatsTable :: SQL.Connection -> IO ()
+initUserChatsTable conn =
+  SQL.execute_
+    conn
+    "CREATE TABLE IF NOT EXISTS user_chats (\
+    \  user_id TEXT PRIMARY KEY,\
+    \  chat_id INTEGER NOT NULL,\
+    \  last_seen_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP\
+    \)"
+
+recordUserChat :: Text -> Int -> IO ()
+recordUserChat uid chatId = do
+  now <- getCurrentTime
+  Memory.withMemoryDb <| \conn -> do
+    initUserChatsTable conn
+    SQL.execute
+      conn
+      "INSERT INTO user_chats (user_id, chat_id, last_seen_at) \
+      \VALUES (?, ?, ?) \
+      \ON CONFLICT(user_id) DO UPDATE SET \
+      \  chat_id = excluded.chat_id, \
+      \  last_seen_at = excluded.last_seen_at"
+      (uid, chatId, now)
+
+lookupChatId :: Text -> IO (Maybe Int)
+lookupChatId uid =
+  Memory.withMemoryDb <| \conn -> do
+    initUserChatsTable conn
+    rows <-
+      SQL.query
+        conn
+        "SELECT chat_id FROM user_chats WHERE user_id = ?"
+        (SQL.Only uid)
+    pure (listToMaybe (map SQL.fromOnly rows))
+
+reminderLoop :: TelegramConfig -> IO ()
+reminderLoop tgConfig =
+  forever <| do
+    threadDelay (5 * 60 * 1000000)
+    checkAndSendReminders tgConfig
+
+checkAndSendReminders :: TelegramConfig -> IO ()
+checkAndSendReminders tgConfig = do
+  todos <- Todos.listTodosDueForReminder
+  forM_ todos <| \td -> do
+    mChatId <- lookupChatId (Todos.todoUserId td)
+    case mChatId of
+      Nothing -> pure ()
+      Just chatId -> do
+        let title = Todos.todoTitle td
+            dueStr = case Todos.todoDueDate td of
+              Just d -> " (due: " <> tshow d <> ")"
+              Nothing -> ""
+            msg =
+              "⏰ reminder: \""
+                <> title
+                <> "\""
+                <> dueStr
+                <> "\nreply when you finish and i'll mark it complete."
+        sendMessage tgConfig chatId msg
+        Todos.markReminderSent (Todos.todoId td)
+        putText <| "Sent reminder for todo " <> tshow (Todos.todoId td) <> " to chat " <> tshow chatId
+
 -- | Run the Telegram bot main loop.
 runTelegramBot :: TelegramConfig -> Provider.Provider -> IO ()
 runTelegramBot tgConfig provider = do
   putText "Starting Telegram bot..."
   offsetVar <- newTVarIO 0
 
+  _ <- forkIO (reminderLoop tgConfig)
+  putText "Reminder loop started (checking every 5 minutes)"
+
   let engineCfg =
         Engine.defaultEngineConfig
           { Engine.engineOnToolCall = \toolName args ->
@@ -639,6 +712,8 @@ handleAuthorizedMessage ::
   Int ->
   IO ()
 handleAuthorizedMessage tgConfig provider engineCfg msg uid userName chatId = do
+  recordUserChat uid chatId
+
   pdfContent <- case tmDocument msg of
     Just doc | isPdf doc -> do
       putText <| "Processing PDF: " <> fromMaybe "(unnamed)" (tdFileName doc)