fix: Add missing sqlite3 import and improve database connection robustness by verifying and safely closing connections.

Tasks.md

@@ -100,6 +100,22 @@ This document tracks all pending tasks, improvements, and issues identified in t
 - **Description**: `identity.py:42` string comparison for ADMIN_ID could fail if numeric
 - **Action needed**: Fix type handling for user ID comparison
 
+### [BUG-004] Missing sqlite3 import
+- **Status**: DONE
+- **Priority**: High
+- **Description**: `flow_engine.py` missing `sqlite3` import causing NameError
+- **Files affected**: `flow_engine.py`
+- **Action needed**: Add `import sqlite3`
+- **Due**: ASAP
+
+### [BUG-005] Telegram Conflict Error
+- **Status**: DONE
+- **Priority**: High
+- **Description**: `telegram.error.Conflict` indicates multiple bot instances running
+- **Files affected**: Runtime
+- **Action needed**: Kill all orphan processes and restart
+- **Due**: ASAP
+
 ## **Documentation & Testing** 📚
 
 ### [DOC-001] Documentation Consistency

bot/db.py

@@ -15,16 +15,32 @@ local = threading.local()
 
 def get_db_connection():
     """Creates a connection to the SQLite database."""
-    if not hasattr(local, "conn"):
-        local.conn = sqlite3.connect(DATABASE_FILE, check_same_thread=False)
-        local.conn.row_factory = sqlite3.Row
+    if hasattr(local, "conn"):
+        try:
+            # Check if connection is open
+            local.conn.execute("SELECT 1")
+            logger.debug("Reusing existing database connection")
+            return local.conn
+        except sqlite3.ProgrammingError:
+            logger.warning("Detected closed connection in thread-local storage. Recreating.")
+            del local.conn
+    
+    logger.debug("Creating new database connection")
+    local.conn = sqlite3.connect(DATABASE_FILE, check_same_thread=False)
+    local.conn.row_factory = sqlite3.Row
     return local.conn
 
 def close_db_connection():
     """Closes the database connection."""
     if hasattr(local, "conn"):
-        local.conn.close()
-        del local.conn
+        logger.debug("Closing database connection")
+        try:
+            local.conn.close()
+        except Exception as e:
+            logger.error(f"Error closing database connection: {e}")
+        finally:
+            if hasattr(local, "conn"):
+                del local.conn
 
 def setup_database():
     """Sets up the database tables if they don't exist."""

bot/modules/flow_engine.py

@@ -2,6 +2,7 @@
 import json
 import logging
 import os
+import sqlite3
 from bot.db import get_db_connection
 from bot.modules.sales_rag import generate_sales_pitch
 from bot.modules.nfc_tag import generate_nfc_tag