fix(auth): garder l identite Discord du cote verifie

app/supporting_scripts/schema_report.py

@@ -29,10 +29,13 @@ Usage
     # Also look for the seeded admin/password account (SEC-003)
     python app/supporting_scripts/schema_report.py --check-seed-accounts
 
+    # Find Discord identities that must be reconciled before UNIQUE (SEC-012)
+    python app/supporting_scripts/schema_report.py --check-discord-identities
+
 Exit codes
 ----------
     0  the live schema matches the models
-    1  drift found — the report says what
+    1  drift or requested data risk found — the report says what
     2  could not connect or read the catalogue
 
 Reading the output
@@ -315,6 +318,42 @@ def find_seed_accounts(engine):
     return results
 
 
+def find_duplicate_discord_identities(engine):
+    """Discord snowflakes claimed by more than one account (SEC-012).
+
+    New links are now refused in application code, but existing production
+    rows predate that guard. These groups must be reconciled before Alembic
+    can add the database-level UNIQUE constraint.
+
+    Returns:
+        list[tuple]: (discord_user_id, comma-separated usernames, count).
+    """
+    from sqlalchemy import text
+
+    with engine.connect() as connection:
+        rows = connection.execute(
+            text(
+                'SELECT discord_user_id, COUNT(*) AS account_count '
+                'FROM users '
+                "WHERE discord_user_id IS NOT NULL AND discord_user_id <> '' "
+                'GROUP BY discord_user_id HAVING COUNT(*) > 1 '
+                'ORDER BY discord_user_id'
+            )
+        ).fetchall()
+
+        duplicates = []
+        for discord_user_id, account_count in rows:
+            usernames = connection.execute(
+                text(
+                    'SELECT username FROM users '
+                    'WHERE discord_user_id = :discord_user_id ORDER BY username'
+                ),
+                {'discord_user_id': discord_user_id},
+            ).scalars()
+            duplicates.append((discord_user_id, ', '.join(usernames), account_count))
+    return duplicates
+
+
 def main(argv=None):
     parser = argparse.ArgumentParser(description=__doc__.split('\n')[0])
     parser.add_argument(
@@ -327,6 +366,11 @@ def main(argv=None):
         action='store_true',
         help='Also look for the admin/password account seeded by clear_db.py (SEC-003).',
     )
+    parser.add_argument(
+        '--check-discord-identities',
+        action='store_true',
+        help='Find duplicate Discord IDs that block the SEC-012 UNIQUE constraint.',
+    )
     args = parser.parse_args(argv)
 
     if not args.url:
@@ -375,9 +419,24 @@ def main(argv=None):
                 )
                 print(f'  {username} ({role}): {verdict}')
 
+    duplicate_discord_identities = []
+    if args.check_discord_identities:
+        print('\n' + '=' * 78)
+        print('Duplicate Discord identities (SEC-012)')
+        print('=' * 78)
+        try:
+            duplicate_discord_identities = find_duplicate_discord_identities(engine)
+        except SQLAlchemyError as exc:
+            print(f'Could not check: {exc}')
+        else:
+            if not duplicate_discord_identities:
+                print('No Discord identity is shared by multiple accounts.')
+            for discord_user_id, usernames, account_count in duplicate_discord_identities:
+                print(f'  {discord_user_id}: {account_count} accounts ({usernames})')
+
     blocking = sum(1 for f in findings if f.severity == BLOCKING)
     print(f'\n{len(findings)} finding(s), {blocking} blocking.')
-    return 1 if findings else 0
+    return 1 if findings or duplicate_discord_identities else 0
 
 
 if __name__ == '__main__':  # pragma: no cover