Automatic pause when battery low

[nicktallen]

Problem

Self-hosted runners consume significant CPU/memory. When a MacBook is on battery and charge drops low, runners should automatically pause to preserve battery life.

Proposed Solution

Monitor battery level via IOKit/IOPowerSources and auto-pause all runners when:

• Battery drops below a configurable threshold (default: 20%)
• Auto-resume when plugged in or above threshold

Acceptance Criteria

• Detect battery level on macOS
• Configurable low-battery threshold (Settings UI + CLI flag)
• Auto-pause all running runners when threshold hit
• Auto-resume when charging resumes or level recovers
• Menubar notification when auto-pause triggers
• Opt-out toggle in settings

Notes

Listed in README under "Planned Features." Filing to track formally.

[nicktallen]

Triage note — partial scaffolding exists

AppSettings already has a pauseOnBattery: Bool field in Runner.swift (line 168), and there are tests for it in AppSettingsTests.swift. However, no runtime battery monitoring logic has been implemented yet — the field is model-only.

Implementation will need:

• IOPSCopyPowerSourcesInfo() or NSProcessInfo.processInfo.isLowPowerModeEnabled monitoring
• A service that watches battery state and calls pause/resume on RunnerManager
• Settings UI to expose the toggle

The model layer is ready, so this is mostly a services + UI task.

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Automated triage by mac-runner bot

[nicktallen]

Triage note — Data model scaffolding already exists.

AppSettings has a pauseOnBattery: Bool property that's persisted in the JSON config at ~/Library/Application Support/MacRunner/config.json. However:

• No UI toggle in the Settings view yet
• No battery monitoring logic (IOPSCopyPowerSourcesInfo or NSProcessInfo.processInfo.isLowPowerModeEnabled)
• No auto-pause trigger

This pairs naturally with #41 (quiet hours) — AppSettings also has a quietHours: QuietHours? struct (enabled, start, end) in the model but no implementation.