diff --git a/ex/app/__init__.py b/ex/app/__init__.py
index 3e568a5..c82e899 100644
--- a/ex/app/__init__.py
+++ b/ex/app/__init__.py
@@ -9,7 +9,7 @@ import bleach
 import markdown
 
 app = Flask(__name__)
-app.secret_key = 'exam-secret-key-2026'
+app.secret_key = os.environ.get('SECRET_KEY', 'exam-secret-key-2026')
 
 _ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 app.config['UPLOAD_FOLDER'] = os.path.join(os.path.dirname(__file__), 'static', 'uploads')
diff --git a/ex/run.py b/ex/run.py
index baf4072..df0ab23 100644
--- a/ex/run.py
+++ b/ex/run.py
@@ -8,4 +8,4 @@ if __name__ == '__main__':
     with app.app_context():
         if not os.path.exists(app.config['DATABASE']):
             init_db()
-    app.run(debug=True)
+    app.run(debug=os.environ.get('FLASK_DEBUG') == '1')
diff --git a/hws/hw-2/circle_square_mk.py b/hws/hw-2/circle_square_mk.py
index aee448a..8d65bf2 100644
--- a/hws/hw-2/circle_square_mk.py
+++ b/hws/hw-2/circle_square_mk.py
@@ -1,5 +1,4 @@
 import random
-import math
 
 def circle_square_mk(r, n):
     inside = 0
diff --git a/hws/hw-2/people_sort.py b/hws/hw-2/people_sort.py
index 4aa1026..9cc95fd 100644
--- a/hws/hw-2/people_sort.py
+++ b/hws/hw-2/people_sort.py
@@ -1,4 +1,3 @@
-import operator
 
 def person_lister(f):
     def inner(people):
diff --git a/hws/hw-2/test.py b/hws/hw-2/test.py
index 8c36270..c442e94 100644
--- a/hws/hw-2/test.py
+++ b/hws/hw-2/test.py
@@ -2,7 +2,6 @@ import pytest
 import math
 import os
 import subprocess
-import tempfile
 from fact import fact_it, fact_rec
 from show_employee import show_employee
 from sum_and_sub import sum_and_sub
@@ -11,7 +10,7 @@ from my_sum import my_sum
 from email_validation import fun
 from fibonacci import fibonacci
 from average_scores import compute_average_scores
-from plane_angle import Point, plane_angle
+from plane_angle import Point
 from complex_numbers import Complex
 from circle_square_mk import circle_square_mk
 from log_decorator import function_logger
diff --git a/labs/lab-1/app/app.py b/labs/lab-1/app/app.py
index 78ecf20..a48f193 100644
--- a/labs/lab-1/app/app.py
+++ b/labs/lab-1/app/app.py
@@ -1,3 +1,4 @@
+import os
 import random
 from flask import Flask, render_template
 from faker import Faker
@@ -48,4 +49,4 @@ def about():
     return render_template('about.html', title='Об авторе')
 
 if __name__ == '__main__':
-    app.run(debug=True)
+    app.run(debug=os.environ.get('FLASK_DEBUG') == '1')
diff --git a/labs/lab-2/app/app.py b/labs/lab-2/app/app.py
index b4d9913..4d37b53 100644
--- a/labs/lab-2/app/app.py
+++ b/labs/lab-2/app/app.py
@@ -1,3 +1,4 @@
+import os
 import re
 import random
 from flask import Flask, render_template, request
@@ -104,4 +105,4 @@ def phone():
     )
 
 if __name__ == '__main__':
-    app.run(debug=True)
+    app.run(debug=os.environ.get('FLASK_DEBUG') == '1')
diff --git a/labs/lab-3/app/app.py b/labs/lab-3/app/app.py
index fbddca7..e7be760 100644
--- a/labs/lab-3/app/app.py
+++ b/labs/lab-3/app/app.py
@@ -1,3 +1,4 @@
+import os
 import re
 import random
 from flask import Flask, render_template, request, session, redirect, url_for, flash
@@ -8,7 +9,7 @@ fake = Faker('ru_RU')
 
 app = Flask(__name__)
 application = app
-app.secret_key = '1234567890secret'
+app.secret_key = os.environ.get('SECRET_KEY', '1234567890secret')
 
 login_manager = LoginManager()
 login_manager.init_app(app)
@@ -166,4 +167,4 @@ def phone():
     )
 
 if __name__ == '__main__':
-    app.run(debug=True)
+    app.run(debug=os.environ.get('FLASK_DEBUG') == '1')
diff --git a/labs/lab-4/app/app.py b/labs/lab-4/app/app.py
index 4e8dc16..7c29ea6 100644
--- a/labs/lab-4/app/app.py
+++ b/labs/lab-4/app/app.py
@@ -1,7 +1,8 @@
+import os
 import re
 import random
 from datetime import datetime
-from flask import Flask, render_template, request, session, redirect, url_for, flash, abort
+from flask import Flask, render_template, request, session, redirect, url_for, flash
 from flask_login import LoginManager, UserMixin, login_user, logout_user, login_required, current_user
 from flask_sqlalchemy import SQLAlchemy
 from flask_bcrypt import Bcrypt
@@ -11,7 +12,7 @@ fake = Faker('ru_RU')
 
 app = Flask(__name__)
 application = app
-app.secret_key = '1234567890secret'
+app.secret_key = os.environ.get('SECRET_KEY', '1234567890secret')
 app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///users.db'
 app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
 
@@ -447,4 +448,4 @@ def change_password():
 
 
 if __name__ == '__main__':
-    app.run(debug=True)
+    app.run(debug=os.environ.get('FLASK_DEBUG') == '1')
diff --git a/labs/lab-4/requirements.txt b/labs/lab-4/requirements.txt
index bf65c86..2233e55 100644
--- a/labs/lab-4/requirements.txt
+++ b/labs/lab-4/requirements.txt
@@ -7,6 +7,7 @@ MarkupSafe==2.1.1
 python-dateutil==2.8.2
 six==1.16.0
 Werkzeug==2.0.3
-Flask-Login
-Flask-SQLAlchemy
-Flask-Bcrypt
\ No newline at end of file
+Flask-Login==0.6.3
+Flask-SQLAlchemy==2.5.1
+SQLAlchemy==1.4.54
+Flask-Bcrypt==1.0.1
diff --git a/labs/lab-5/app/app.py b/labs/lab-5/app/app.py
index 7925e29..04de1e6 100644
--- a/labs/lab-5/app/app.py
+++ b/labs/lab-5/app/app.py
@@ -1,8 +1,9 @@
+import os
 import re
 import random
 from functools import wraps
 from datetime import datetime
-from flask import Flask, render_template, request, session, redirect, url_for, flash, abort
+from flask import Flask, render_template, request, session, redirect, url_for, flash
 from flask_login import LoginManager, UserMixin, login_user, logout_user, login_required, current_user
 from flask_sqlalchemy import SQLAlchemy
 from flask_bcrypt import Bcrypt
@@ -12,7 +13,7 @@ fake = Faker('ru_RU')
 
 app = Flask(__name__)
 application = app
-app.secret_key = '1234567890secret'
+app.secret_key = os.environ.get('SECRET_KEY', '1234567890secret')
 app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///users.db'
 app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
 
@@ -515,4 +516,4 @@ with app.app_context():
 
 
 if __name__ == '__main__':
-    app.run(debug=True)
+    app.run(debug=os.environ.get('FLASK_DEBUG') == '1')
diff --git a/labs/lab-5/app/visit_logs.py b/labs/lab-5/app/visit_logs.py
index 5dfa963..6628ff5 100644
--- a/labs/lab-5/app/visit_logs.py
+++ b/labs/lab-5/app/visit_logs.py
@@ -51,7 +51,7 @@ def index():
         return redirect(url_for('index'))
 
     m = _get_app_module()
-    db, VisitLog = m.db, m.VisitLog
+    VisitLog = m.VisitLog
 
     page = request.args.get('page', 1, type=int)
     per_page = 10
diff --git a/labs/lab-5/requirements.txt b/labs/lab-5/requirements.txt
index bf65c86..2233e55 100644
--- a/labs/lab-5/requirements.txt
+++ b/labs/lab-5/requirements.txt
@@ -7,6 +7,7 @@ MarkupSafe==2.1.1
 python-dateutil==2.8.2
 six==1.16.0
 Werkzeug==2.0.3
-Flask-Login
-Flask-SQLAlchemy
-Flask-Bcrypt
\ No newline at end of file
+Flask-Login==0.6.3
+Flask-SQLAlchemy==2.5.1
+SQLAlchemy==1.4.54
+Flask-Bcrypt==1.0.1
diff --git a/labs/lab-6/app/config.py b/labs/lab-6/app/config.py
index ea62ca6..a57756c 100644
--- a/labs/lab-6/app/config.py
+++ b/labs/lab-6/app/config.py
@@ -1,6 +1,6 @@
 import os
 
-SECRET_KEY = 'secret-key'
+SECRET_KEY = os.environ.get('SECRET_KEY', 'secret-key')
 
 SQLALCHEMY_DATABASE_URI = 'sqlite:///project.db'
 SQLALCHEMY_TRACK_MODIFICATIONS = False
diff --git a/labs/lab-6/app/models.py b/labs/lab-6/app/models.py
index 7954fca..6fb666e 100644
--- a/labs/lab-6/app/models.py
+++ b/labs/lab-6/app/models.py
@@ -1,7 +1,6 @@
 import os
-from typing import Optional, Union, List
+from typing import Optional, List
 from datetime import datetime
-import sqlalchemy as sa
 from werkzeug.security import check_password_hash, generate_password_hash
 from flask_login import UserMixin
 from flask import url_for