diff --git a/cli/deploy.py b/cli/deploy.py
index 5e6d040a..9e535cb4 100644
--- a/cli/deploy.py
+++ b/cli/deploy.py
@@ -6,7 +6,6 @@ import os
 import datetime
 import sys
 
-
 def run_ansible_playbook(
     inventory,
     modes,
@@ -81,6 +80,24 @@ def run_ansible_playbook(
     duration = end_time - start_time
     print(f"⏱️ Total execution time: {duration}\n")
 
+def validate_application_ids(inventory, app_ids):
+    """
+    Abort the script if any application IDs are invalid, with detailed reasons.
+    """
+    from utils.valid_deploy_id import ValidDeployId
+    validator = ValidDeployId()
+    invalid = validator.validate(inventory, app_ids)
+    if invalid:
+        print("\n❌ Detected invalid application_id(s):\n")
+        for app_id, status in invalid.items():
+            reasons = []
+            if not status['in_roles']:
+                reasons.append("not defined in roles (cymais)")
+            if not status['in_inventory']:
+                reasons.append("not found in inventory file")
+            print(f"  - {app_id}: " + ", ".join(reasons))
+        sys.exit(1)
+
 
 def main():
     parser = argparse.ArgumentParser(
@@ -150,6 +167,7 @@ def main():
     )
 
     args = parser.parse_args()
+    validate_application_ids(args.inventory, args.id)
 
     modes = {
         "mode_reset": args.reset,
diff --git a/tests/unit/utils/test_valid_deploy_id.py b/tests/unit/utils/test_valid_deploy_id.py
new file mode 100644
index 00000000..61fa86a6
--- /dev/null
+++ b/tests/unit/utils/test_valid_deploy_id.py
@@ -0,0 +1,116 @@
+# File: tests/unit/utils/test_valid_deploy_id.py
+import os
+import tempfile
+import unittest
+import yaml
+from utils.valid_deploy_id import ValidDeployId
+
+class TestValidDeployId(unittest.TestCase):
+    def setUp(self):
+        # Create a temporary directory for roles
+        self.temp_dir = tempfile.TemporaryDirectory()
+        self.roles_dir = os.path.join(self.temp_dir.name, 'roles')
+        os.makedirs(self.roles_dir)
+
+        # Create a dummy role with application_id 'app1'
+        role_path = os.path.join(self.roles_dir, 'role1', 'vars')
+        os.makedirs(role_path)
+        with open(os.path.join(role_path, 'main.yml'), 'w', encoding='utf-8') as f:
+            yaml.safe_dump({'application_id': 'app1'}, f)
+
+        # Initialize validator with our temp roles_dir
+        self.validator = ValidDeployId(roles_dir=self.roles_dir)
+
+    def tearDown(self):
+        self.temp_dir.cleanup()
+
+    def _write_ini_inventory(self, content):
+        fd, path = tempfile.mkstemp(suffix='.ini')
+        os.close(fd)
+        with open(path, 'w', encoding='utf-8') as f:
+            f.write(content)
+        return path
+
+    def _write_yaml_inventory(self, data):
+        fd, path = tempfile.mkstemp(suffix='.yml')
+        os.close(fd)
+        with open(path, 'w', encoding='utf-8') as f:
+            yaml.safe_dump(data, f)
+        return path
+
+    def test_valid_in_roles_and_ini_inventory(self):
+        # Inventory contains app1 as a host
+        ini_content = """
+        [servers]
+        app1,otherhost
+        """
+        inv = self._write_ini_inventory(ini_content)
+        result = self.validator.validate(inv, ['app1'])
+        self.assertEqual(result, {}, "app1 should be valid when in roles and ini inventory")
+
+    def test_missing_in_roles(self):
+        # Inventory contains app2 but roles only have app1
+        ini_content = """
+        [servers]
+        app2
+        """
+        inv = self._write_ini_inventory(ini_content)
+        result = self.validator.validate(inv, ['app2'])
+        # app2 not in roles, but in inventory
+        expected = {'app2': {'in_roles': False, 'in_inventory': True}}
+        self.assertEqual(result, expected)
+
+    def test_missing_in_inventory_ini(self):
+        # Roles have app1 but inventory does not mention it
+        ini_content = """
+        [servers]
+        otherhost
+        """
+        inv = self._write_ini_inventory(ini_content)
+        result = self.validator.validate(inv, ['app1'])
+        expected = {'app1': {'in_roles': True, 'in_inventory': False}}
+        self.assertEqual(result, expected)
+
+    def test_missing_both_ini(self):
+        # Neither roles nor inventory have appX
+        ini_content = """
+        [servers]
+        otherhost
+        """
+        inv = self._write_ini_inventory(ini_content)
+        result = self.validator.validate(inv, ['appX'])
+        expected = {'appX': {'in_roles': False, 'in_inventory': False}}
+        self.assertEqual(result, expected)
+
+    def test_valid_in_roles_and_yaml_inventory(self):
+        # YAML inventory with app1 as a dict key
+        data = {'app1': {'hosts': ['app1']}, 'group': {'app1': {}}}
+        inv = self._write_yaml_inventory(data)
+        result = self.validator.validate(inv, ['app1'])
+        self.assertEqual(result, {}, "app1 should be valid in roles and yaml inventory")
+
+    def test_missing_in_roles_yaml(self):
+        # YAML inventory has app2 key but roles only have app1
+        data = {'app2': {}}
+        inv = self._write_yaml_inventory(data)
+        result = self.validator.validate(inv, ['app2'])
+        expected = {'app2': {'in_roles': False, 'in_inventory': True}}
+        self.assertEqual(result, expected)
+
+    def test_missing_in_inventory_yaml(self):
+        # Roles have app1 but YAML inventory has no app1
+        data = {'group': {'other': {}}}
+        inv = self._write_yaml_inventory(data)
+        result = self.validator.validate(inv, ['app1'])
+        expected = {'app1': {'in_roles': True, 'in_inventory': False}}
+        self.assertEqual(result, expected)
+
+    def test_missing_both_yaml(self):
+        data = {}
+        inv = self._write_yaml_inventory(data)
+        result = self.validator.validate(inv, ['unknown'])
+        expected = {'unknown': {'in_roles': False, 'in_inventory': False}}
+        self.assertEqual(result, expected)
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/utils/valid_deploy_id.py b/utils/valid_deploy_id.py
new file mode 100644
index 00000000..51ae8e47
--- /dev/null
+++ b/utils/valid_deploy_id.py
@@ -0,0 +1,89 @@
+# File: utils/valid_deploy_id.py
+"""
+Utility for validating deployment application IDs against defined roles and inventory.
+"""
+import os
+import yaml
+import glob
+import configparser
+
+from filter_plugins.get_all_application_ids import get_all_application_ids
+
+class ValidDeployId:
+    def __init__(self, roles_dir='roles'):
+        # Load all known application IDs from roles
+        self.valid_ids = set(get_all_application_ids(roles_dir))
+
+    def validate(self, inventory_path, ids):
+        """
+        Validate a list of application IDs against both role definitions and inventory.
+        Returns a dict mapping invalid IDs to their presence status.
+        Example:
+          {
+            "app1": {"in_roles": False, "in_inventory": True},
+            "app2": {"in_roles": True, "in_inventory": False}
+          }
+        """
+        invalid = {}
+        for app_id in ids:
+            in_roles = app_id in self.valid_ids
+            in_inventory = self._exists_in_inventory(inventory_path, app_id)
+            if not (in_roles and in_inventory):
+                invalid[app_id] = {
+                    'in_roles': in_roles,
+                    'in_inventory': in_inventory
+                }
+        return invalid
+
+    def _exists_in_inventory(self, inventory_path, app_id):
+        _, ext = os.path.splitext(inventory_path)
+        if ext in ('.yml', '.yaml'):
+            return self._search_yaml_keys(inventory_path, app_id)
+        else:
+            return self._search_ini_sections(inventory_path, app_id)
+
+    def _search_ini_sections(self, inventory_path, app_id):
+        """
+        Manually parse INI inventory for sections and host lists.
+        Returns True if app_id matches a section name or a host in a section.
+        """
+        present = False
+        with open(inventory_path, 'r', encoding='utf-8') as f:
+            current_section = None
+            for raw in f:
+                line = raw.strip()
+                # Skip blanks and comments
+                if not line or line.startswith(('#', ';')):
+                    continue
+                # Section header
+                if line.startswith('[') and line.endswith(']'):
+                    current_section = line[1:-1].strip()
+                    if current_section == app_id:
+                        return True
+                    continue
+                # Host or variable line under a section
+                if current_section:
+                    # Split on commas or whitespace
+                    for part in [p.strip() for p in line.replace(',', ' ').split()]:
+                        if part == app_id:
+                            return True
+        return False
+
+    def _search_yaml_keys(self, inventory_path, app_id):
+        with open(inventory_path, 'r', encoding='utf-8') as f:
+            data = yaml.safe_load(f)
+        return self._find_key(data, app_id)
+
+    def _find_key(self, node, key):  # recursive search
+        if isinstance(node, dict):
+            for k, v in node.items():
+                # If key matches and maps to a dict or list, consider it present
+                if k == key and isinstance(v, (dict, list)):
+                    return True
+                if self._find_key(v, key):
+                    return True
+        elif isinstance(node, list):
+            for item in node:
+                if self._find_key(item, key):
+                    return True
+        return False