Phase 0: Add monthly credit replenishment Celery Beat task

- Created billing/tasks.py with replenish_monthly_credits task
- Task runs on first day of each month at midnight
- Adds plan.included_credits to all active accounts
- Creates CreditTransaction records for audit trail
- Configured in celery.py beat_schedule
- Handles errors gracefully and logs all operations

backend/igny8_core/modules/billing/tasks.py

@@ -0,0 +1,99 @@
+"""
+Celery tasks for billing operations
+"""
+import logging
+from celery import shared_task
+from django.utils import timezone
+from django.db import transaction
+from igny8_core.auth.models import Account
+from .services import CreditService
+
+logger = logging.getLogger(__name__)
+
+
+@shared_task(name='igny8_core.modules.billing.tasks.replenish_monthly_credits')
+def replenish_monthly_credits():
+    """
+    Replenish monthly credits for all active accounts.
+    Runs on the first day of each month at midnight.
+    
+    For each active account with a plan:
+    - Adds plan.included_credits to account.credits
+    - Creates a CreditTransaction record
+    - Logs the replenishment
+    """
+    logger.info("=" * 80)
+    logger.info("MONTHLY CREDIT REPLENISHMENT TASK STARTED")
+    logger.info(f"Timestamp: {timezone.now()}")
+    logger.info("=" * 80)
+    
+    # Get all active accounts with plans
+    accounts = Account.objects.filter(
+        status='active',
+        plan__isnull=False
+    ).select_related('plan')
+    
+    total_accounts = accounts.count()
+    logger.info(f"Found {total_accounts} active accounts with plans")
+    
+    replenished = 0
+    skipped = 0
+    errors = 0
+    
+    for account in accounts:
+        try:
+            plan = account.plan
+            
+            # Get monthly credits from plan
+            monthly_credits = plan.included_credits or plan.credits_per_month or 0
+            
+            if monthly_credits <= 0:
+                logger.info(f"Account {account.id} ({account.name}): Plan has no included credits, skipping")
+                skipped += 1
+                continue
+            
+            # Add credits using CreditService
+            with transaction.atomic():
+                new_balance = CreditService.add_credits(
+                    account=account,
+                    amount=monthly_credits,
+                    transaction_type='subscription',
+                    description=f"Monthly credit replenishment - {plan.name} plan",
+                    metadata={
+                        'plan_id': plan.id,
+                        'plan_name': plan.name,
+                        'monthly_credits': monthly_credits,
+                        'replenishment_date': timezone.now().isoformat()
+                    }
+                )
+            
+            logger.info(
+                f"Account {account.id} ({account.name}): "
+                f"Added {monthly_credits} credits (balance: {new_balance})"
+            )
+            replenished += 1
+            
+        except Exception as e:
+            logger.error(
+                f"Account {account.id} ({account.name}): "
+                f"Failed to replenish credits: {str(e)}",
+                exc_info=True
+            )
+            errors += 1
+    
+    logger.info("=" * 80)
+    logger.info("MONTHLY CREDIT REPLENISHMENT TASK COMPLETED")
+    logger.info(f"Total accounts: {total_accounts}")
+    logger.info(f"Replenished: {replenished}")
+    logger.info(f"Skipped: {skipped}")
+    logger.info(f"Errors: {errors}")
+    logger.info("=" * 80)
+    
+    return {
+        'success': True,
+        'total_accounts': total_accounts,
+        'replenished': replenished,
+        'skipped': skipped,
+        'errors': errors
+    }
+