ACS Developer Sandbox automatic plan upgrade behavior in Titanium SDK 8.0‑9.x

Goal: Keep a low‑traffic Appcelerator Titanium app on the free ArrowDB (ACS) developer sandbox to avoid unexpected billing while still using SDK 8.0‑9.x.

Constraints/uncertainty: The free sandbox provides up to 1 M API calls per month, but the switch to the paid plan occurs automatically and silently when the quota is exceeded, with no CLI or build‑log notification. Additionally, Titanium SDK 10+ removed the explicit acs sandbox flag, so relying on the legacy acs enabled=\"false\" mode=\"dev\" configuration may generate warnings or be ignored, making the cost‑saving behavior unreliable.

How can developers programmatically detect when the free sandbox quota is approaching its limit? Is there a supported CLI command or ACS API to query current usage and remaining quota? What configuration should be used in SDK 10+ to retain the free sandbox behavior without triggering build warnings or falling back to paid services?