pr_body.md

Summary

This PR implements four critical safety and monitoring features for the Utility-Drip smart contract:

Features Added

#16 - Max Flow Rate Safety Cap

• Added max_flow_rate_per_hour field to prevent hardware errors from draining wallets
• Users can set custom hourly limits via set_max_flow_rate() function
• Claim function now respects hourly caps to protect against malfunctioning hardware

#12 - Expected Depletion Calculation

• Added calculate_expected_depletion() read-only function
• Predicts when user's balance will reach zero based on current consumption rate
• Improves UX by helping users plan their top-ups

#19 - Emergency Shutdown

• Added emergency_shutdown() function for providers
• Allows immediate disabling of specific meters for leak/hardware tampering scenarios
• Enhances security and provider control

#20 - Heartbeat Monitoring

• Added heartbeat timestamp tracking to Meter struct
• Implemented update_heartbeat() and is_meter_offline() functions
• Meters considered offline if heartbeat > 1 hour old
• Enables IoT connectivity monitoring

Changes Made

• Extended Meter struct with new fields for safety and monitoring
• Added 5 new contract functions
• Updated claim logic to respect flow rate caps
• Added comprehensive test coverage for all new functionality
• All tests passing successfully

Testing

• Added 5 new test cases covering all functionality
• Tests verify max flow rate enforcement, depletion calculation, emergency shutdown, and heartbeat monitoring
• 100% test pass rate

Fixes: #16, #12, #19, #20