Summary

Adds support for maintaining battery within a percentage range (e.g., battery maintain 70-80) while preserving full backward compatibility with single-value syntax (e.g., battery maintain 80).

Motivation

When using battery maintain 80, the battery constantly cycles between ~79% and ~81%, which still causes some wear. This PR allows users to set a wider range like battery maintain 70-80, letting the battery rest anywhere in that range, reducing charge/discharge cycles.

Changes

Core Functionality

• New validation function valid_percentage_range():

  • Validates NUMBER-NUMBER format
  • Ensures lower < upper
  • Enforces lower ≥ 10 and upper ≤ 100
  • No maximum range spread limit (user choice)

• Updated maintain_synchronous logic:

  • Parses setting into lower_bound and upper_bound
  • Enable charging when battery < lower_bound
  • Disable charging when battery ≥ upper_bound
  • Battery rests freely within the range
  • Fully backward compatible (single values work as before)

• Enhanced status display:

  • Shows "70% - 80%" for ranges
  • Shows "80%" for single values

Documentation

• Updated help message with range examples
• Added README examples and usage notes
• Clarified range syntax in CLI help

Persistence

• Daemon correctly persists ranges across reboots
• Stores range format (e.g., 70-80) in ~/.battery/maintain.percentage
• Recovery logic auto-detects format

Testing

Tested on macOS with the following scenarios:

• ✅ Single value battery maintain 80 works as before
• ✅ Valid ranges work: battery maintain 70-80
• ✅ Invalid ranges rejected:
  • 80-70 (upper < lower)
  • 5-15 (lower < 10)
  • 95-105 (upper > 100)
  • 70-70 (equal values)
• ✅ Status correctly displays ranges: "70% - 80%"
• ✅ Settings persist in daemon across reboots
• ✅ Backward compatibility maintained

CLI-Only Feature

This implementation is CLI-only. GUI support for ranges is deferred to future work.

Example Usage

# Traditional single-value (backward compatible)
battery maintain 80

# New range syntax - lets battery rest between 70-80%
battery maintain 70-80

# Check status
battery status
# Output: Your battery is currently being maintained at 70% - 80%