diff --git a/tests/unit/test_yaml_jinja2_expressions.py b/tests/unit/test_yaml_jinja2_expressions.py
new file mode 100644
index 00000000..d9bbfce5
--- /dev/null
+++ b/tests/unit/test_yaml_jinja2_expressions.py
@@ -0,0 +1,379 @@
+#!/usr/bin/env python3
+"""
+Test that Jinja2 expressions within YAML files are valid.
+This catches issues like inline comments in Jinja2 expressions within YAML task files.
+"""
+import re
+import sys
+from pathlib import Path
+
+import yaml
+from jinja2 import Environment, StrictUndefined, TemplateSyntaxError
+
+
+def find_yaml_files_with_jinja2():
+    """Find all YAML files that might contain Jinja2 expressions."""
+    yaml_files = []
+
+    # Look for YAML files in roles that are likely to have Jinja2
+    patterns = [
+        'roles/**/tasks/*.yml',
+        'roles/**/defaults/*.yml',
+        'roles/**/vars/*.yml',
+        'playbooks/*.yml',
+        '*.yml'
+    ]
+
+    skip_dirs = {'.git', '.venv', 'venv', '.env', 'configs'}
+
+    for pattern in patterns:
+        for path in Path('.').glob(pattern):
+            if not any(skip_dir in path.parts for skip_dir in skip_dirs):
+                yaml_files.append(path)
+
+    return sorted(yaml_files)
+
+
+def extract_jinja2_expressions(content):
+    """Extract all Jinja2 expressions from text content."""
+    expressions = []
+
+    # Find {{ ... }} expressions (variable interpolations)
+    for match in re.finditer(r'\{\{(.+?)\}\}', content, re.DOTALL):
+        expressions.append({
+            'type': 'variable',
+            'content': match.group(1),
+            'full': match.group(0),
+            'start': match.start(),
+            'end': match.end()
+        })
+
+    # Find {% ... %} expressions (control structures)
+    for match in re.finditer(r'\{%(.+?)%\}', content, re.DOTALL):
+        expressions.append({
+            'type': 'control',
+            'content': match.group(1),
+            'full': match.group(0),
+            'start': match.start(),
+            'end': match.end()
+        })
+
+    return expressions
+
+
+def find_line_number(content, position):
+    """Find the line number for a given position in content."""
+    return content[:position].count('\n') + 1
+
+
+def validate_jinja2_expression(expression, context_vars=None):
+    """
+    Validate a single Jinja2 expression.
+    Returns (is_valid, error_message)
+    """
+    if context_vars is None:
+        context_vars = get_test_variables()
+
+    # First check for inline comments - this is the main issue we want to catch
+    if '#' in expression['content']:
+        # Check if the # is within a list or dict literal
+        content = expression['content']
+        # Remove strings to avoid false positives
+        cleaned = re.sub(r'"[^"]*"', '""', content)
+        cleaned = re.sub(r"'[^']*'", "''", cleaned)
+
+        # Look for # that appears to be a comment
+        # The # should have something before it (not at start) and something after (the comment text)
+        # Also check for # at the start of a line within the expression
+        if '#' in cleaned:
+            # Check each line in the cleaned expression
+            for line in cleaned.split('\n'):
+                line = line.strip()
+                if '#' in line:
+                    # If # appears and it's not escaped (\#)
+                    hash_idx = line.find('#')
+                    if hash_idx >= 0:
+                        # Check if it's escaped
+                        if hash_idx == 0 or line[hash_idx-1] != '\\':
+                            # This looks like an inline comment
+                            return False, "Inline comment (#) found in Jinja2 expression - comments must be outside expressions"
+
+    try:
+        env = Environment(undefined=StrictUndefined)
+
+        # Add common Ansible filters (expanded list)
+        env.filters['bool'] = lambda x: bool(x)
+        env.filters['default'] = lambda x, d='': x if x else d
+        env.filters['to_uuid'] = lambda x: 'mock-uuid'
+        env.filters['b64encode'] = lambda x: 'mock-base64'
+        env.filters['b64decode'] = lambda x: 'mock-decoded'
+        env.filters['version'] = lambda x, op: True
+        env.filters['ternary'] = lambda x, y, z=None: y if x else (z if z is not None else '')
+        env.filters['regex_replace'] = lambda x, p, r: x
+        env.filters['difference'] = lambda x, y: list(set(x) - set(y))
+        env.filters['strftime'] = lambda fmt, ts: 'mock-timestamp'
+        env.filters['int'] = lambda x: int(x) if x else 0
+        env.filters['list'] = lambda x: list(x)
+        env.filters['map'] = lambda x, *args: x
+        env.tests['version'] = lambda x, op: True
+
+        # Wrap the expression in appropriate delimiters for parsing
+        if expression['type'] == 'variable':
+            template_str = '{{' + expression['content'] + '}}'
+        else:
+            template_str = '{%' + expression['content'] + '%}'
+
+        # Try to compile the template
+        template = env.from_string(template_str)
+
+        # Try to render it with test variables
+        # This will catch undefined variables and runtime errors
+        template.render(**context_vars)
+
+        return True, None
+
+    except TemplateSyntaxError as e:
+        # Check for the specific inline comment issue
+        if '#' in expression['content']:
+            # Check if the # is within a list or dict literal
+            content = expression['content']
+            # Remove strings to avoid false positives
+            cleaned = re.sub(r'"[^"]*"', '""', content)
+            cleaned = re.sub(r"'[^']*'", "''", cleaned)
+
+            # Look for # that appears to be a comment (not in string, not escaped)
+            if re.search(r'[^\\\n]#[^\}]', cleaned):
+                return False, "Inline comment (#) found in Jinja2 expression - comments must be outside expressions"
+
+        return False, f"Syntax error: {e.message}"
+
+    except Exception as e:
+        # Be lenient - we mainly care about inline comments and basic syntax
+        # Ignore runtime errors (undefined vars, missing attributes, etc.)
+        error_str = str(e).lower()
+        if any(ignore in error_str for ignore in ['undefined', 'has no attribute', 'no filter']):
+            return True, None  # These are runtime issues, not syntax issues
+        return False, f"Error: {str(e)}"
+
+
+def get_test_variables():
+    """Get a comprehensive set of test variables for expression validation."""
+    return {
+        # Network configuration
+        'IP_subject_alt_name': '10.0.0.1',
+        'server_name': 'algo-vpn',
+        'wireguard_port': 51820,
+        'wireguard_network': '10.19.49.0/24',
+        'wireguard_network_ipv6': 'fd9d:bc11:4021::/64',
+        'strongswan_network': '10.19.48.0/24',
+        'strongswan_network_ipv6': 'fd9d:bc11:4020::/64',
+
+        # Feature flags
+        'ipv6_support': True,
+        'dns_encryption': True,
+        'dns_adblocking': True,
+        'wireguard_enabled': True,
+        'ipsec_enabled': True,
+
+        # OpenSSL/PKI
+        'openssl_constraint_random_id': 'test-uuid-12345',
+        'CA_password': 'test-password',
+        'p12_export_password': 'test-p12-password',
+        'ipsec_pki_path': '/etc/ipsec.d',
+        'ipsec_config_path': '/etc/ipsec.d',
+        'subjectAltName': 'IP:10.0.0.1,DNS:vpn.example.com',
+        'subjectAltName_type': 'IP',
+
+        # Ansible variables
+        'ansible_default_ipv4': {'address': '10.0.0.1'},
+        'ansible_default_ipv6': {'address': '2600:3c01::f03c:91ff:fedf:3b2a'},
+        'ansible_distribution': 'Ubuntu',
+        'ansible_distribution_version': '22.04',
+        'ansible_date_time': {'epoch': '1234567890'},
+
+        # User management
+        'users': ['alice', 'bob', 'charlie'],
+        'all_users': ['alice', 'bob', 'charlie', 'david'],
+
+        # Common variables
+        'item': 'test-item',
+        'algo_provider': 'local',
+        'algo_server_name': 'algo-vpn',
+        'dns_servers': ['1.1.1.1', '1.0.0.1'],
+
+        # OpenSSL version for conditionals
+        'openssl_version': '3.0.0',
+
+        # IPsec configuration
+        'certificate_validity_days': 3650,
+        'ike_cipher': 'aes128gcm16-prfsha512-ecp256',
+        'esp_cipher': 'aes128gcm16-ecp256',
+    }
+
+
+def validate_yaml_file(yaml_path, check_inline_comments_only=False):
+    """
+    Validate all Jinja2 expressions in a YAML file.
+    Returns (has_inline_comments, list_of_inline_comment_errors, list_of_other_errors)
+    """
+    inline_comment_errors = []
+    other_errors = []
+
+    try:
+        with open(yaml_path) as f:
+            content = f.read()
+
+        # First, check if it's valid YAML
+        try:
+            yaml.safe_load(content)
+        except yaml.YAMLError:
+            # YAML syntax error, not our concern here
+            return False, [], []
+
+        # Extract all Jinja2 expressions
+        expressions = extract_jinja2_expressions(content)
+
+        if not expressions:
+            return False, [], []  # No Jinja2 expressions to validate
+
+        # Validate each expression
+        for expr in expressions:
+            is_valid, error = validate_jinja2_expression(expr)
+
+            if not is_valid:
+                line_num = find_line_number(content, expr['start'])
+                error_msg = f"{yaml_path}:{line_num}: {error}"
+
+                # Separate inline comment errors from other errors
+                if error and 'inline comment' in error.lower():
+                    inline_comment_errors.append(error_msg)
+                    # Show context for inline comment errors
+                    if len(expr['full']) < 200:
+                        inline_comment_errors.append(f"  Expression: {expr['full'][:100]}...")
+                elif not check_inline_comments_only:
+                    other_errors.append(error_msg)
+
+    except Exception as e:
+        if not check_inline_comments_only:
+            other_errors.append(f"{yaml_path}: Error reading file: {e}")
+
+    return len(inline_comment_errors) > 0, inline_comment_errors, other_errors
+
+
+def test_specific_openssl_expressions():
+    """
+    Test the specific expressions that had the inline comment bug.
+    This is a regression test for the exact issue that was reported.
+    """
+    print("\n🔬 Testing specific OpenSSL expressions (regression test)...")
+
+    # The problematic expression that was reported
+    problematic_expr = """{{ [
+  subjectAltName_type + ':' + IP_subject_alt_name + ('/255.255.255.255' if subjectAltName_type == 'IP' else ''),
+  'DNS:' + openssl_constraint_random_id,        # Per-deployment UUID prevents cross-deployment reuse
+  'email:' + openssl_constraint_random_id       # Unique email domain isolates certificate scope
+] + (
+  ['IP:' + ansible_default_ipv6['address'] + '/128'] if ipv6_support else []
+) }}"""
+
+    # The fixed expression (without inline comments)
+    fixed_expr = """{{ [
+  subjectAltName_type + ':' + IP_subject_alt_name + ('/255.255.255.255' if subjectAltName_type == 'IP' else ''),
+  'DNS:' + openssl_constraint_random_id,
+  'email:' + openssl_constraint_random_id
+] + (
+  ['IP:' + ansible_default_ipv6['address'] + '/128'] if ipv6_support else []
+) }}"""
+
+    test_cases = [
+        ('Problematic (with inline comments)', problematic_expr, False),
+        ('Fixed (without inline comments)', fixed_expr, True),
+    ]
+
+    errors = []
+    for name, expr_content, should_pass in test_cases:
+        expr = {
+            'type': 'variable',
+            'content': expr_content[2:-2],  # Remove {{ }}
+            'full': expr_content
+        }
+
+        is_valid, error = validate_jinja2_expression(expr)
+
+        if should_pass and not is_valid:
+            errors.append(f"❌ {name}: Should have passed but failed with: {error}")
+        elif not should_pass and is_valid:
+            errors.append(f"❌ {name}: Should have failed but passed")
+        else:
+            status = "✅" if should_pass else "⚠️"
+            result = "passed" if is_valid else f"failed with: {error}"
+            print(f"  {status} {name}: {result}")
+
+    if errors:
+        print("\n❌ Regression test FAILED:")
+        for error in errors:
+            print(f"    {error}")
+        return False
+    else:
+        print("  ✅ Regression test passed - would have caught the bug!")
+        return True
+
+
+def main():
+    """Main test function."""
+    print("🔍 Validating Jinja2 expressions in YAML files for inline comments...\n")
+
+    # First run the regression test
+    regression_passed = test_specific_openssl_expressions()
+
+    # Find all YAML files
+    yaml_files = find_yaml_files_with_jinja2()
+    print(f"\n📁 Found {len(yaml_files)} YAML files to check")
+
+    all_inline_comment_errors = []
+    files_with_inline_comments = []
+    files_checked = 0
+
+    # Validate each file - focus on inline comments
+    for yaml_file in yaml_files:
+        has_inline_comments, inline_errors, other_errors = validate_yaml_file(yaml_file, check_inline_comments_only=True)
+        files_checked += 1
+
+        if has_inline_comments:
+            files_with_inline_comments.append(yaml_file)
+            all_inline_comment_errors.extend(inline_errors)
+
+    # Report results
+    print(f"\n✅ Checked {files_checked} YAML files for inline comments in Jinja2 expressions")
+
+    if all_inline_comment_errors:
+        print(f"\n❌ Found inline comment issues in {len(files_with_inline_comments)} files:\n")
+        # Show all inline comment errors since these are critical
+        for error in all_inline_comment_errors:
+            print(f"  ERROR: {error}")
+    else:
+        print("\n✅ No inline comments found in Jinja2 expressions!")
+
+    # Check the specific file that had the bug
+    openssl_file = Path('roles/strongswan/tasks/openssl.yml')
+    if openssl_file.exists():
+        print(f"\n🎯 Checking {openssl_file} specifically...")
+        has_inline_comments, inline_errors, other_errors = validate_yaml_file(openssl_file)
+        if not has_inline_comments:
+            print(f"  ✅ {openssl_file} has no inline comments in Jinja2 expressions")
+        else:
+            print(f"  ❌ {openssl_file} has inline comments in Jinja2 expressions:")
+            for error in inline_errors:
+                print(f"    {error}")
+
+    if all_inline_comment_errors or not regression_passed:
+        print("\n❌ Found inline comment issues that need to be fixed")
+        print("💡 Move comments outside of {{ }} and {% %} expressions")
+        return 1
+    else:
+        print("\n✅ All YAML files are free of inline comments in Jinja2 expressions!")
+        return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())