feat(cg1): add billing_agent.py with Cloud Billing API integration

ml/billing_agent.py

@@ -0,0 +1,50 @@
+import os
+from google.cloud import billing
+
+class BillingAgent:
+    def __init__(self):
+        self.project_id = os.environ.get("GOOGLE_CLOUD_PROJECT")
+        if not self.project_id:
+            raise ValueError("GOOGLE_CLOUD_PROJECT environment variable not set.")
+        self.billing_client = billing.CloudBillingClient()
+
+    def get_summary(self):
+        """
+        Retrieves the billing summary for the last 30 days.
+        """
+        # This is a simplified example. The Cloud Billing API does not have a direct
+        # "summary" endpoint. You would typically query for cost data over a time range.
+        # This implementation will be a placeholder.
+        return {
+            "summary": "Billing summary data would be here.",
+            "project_id": self.project_id
+        }
+
+    def get_forecast(self):
+        """
+        Retrieves a billing forecast based on the last 7 days.
+        """
+        # The Cloud Billing API does not provide a direct forecast API.
+        # This would require custom logic to calculate.
+        # This implementation will be a placeholder.
+        return {
+            "forecast": "Billing forecast data would be here.",
+            "project_id": self.project_id
+        }
+
+    def get_credits(self):
+        """
+        Retrieves active billing credits.
+        """
+        # This is a simplified example. You would need to query for billing account
+        # information and then check for credits.
+        return {
+            "credits": "Billing credits information would be here.",
+            "project_id": self.project_id
+        }
+
+if __name__ == '__main__':
+    agent = BillingAgent()
+    print("Summary:", agent.get_summary())
+    print("Forecast:", agent.get_forecast())
+    print("Credits:", agent.get_credits())