feat(macos): handle system sleep/wake and screen sleep/wake lifecycle events

[jsmestad]

Summary

The macOS frontend does not respond to system sleep/wake or screen sleep/wake events. This can cause stale state after wake (files changed on disk, LSP connections dropped, git status outdated) and wasted GPU rendering while screens are asleep.

Motivation

• After waking from sleep, open files may have been modified externally — the editor should detect and handle this
• LSP connections may have timed out during sleep and need reconnection
• Git status is likely stale after wake
• Metal rendering should pause when screens sleep to avoid unnecessary GPU work
• BEAM heartbeat/timers should be paused during sleep to prevent false timeout detection

Notifications to Handle

Notification	Action
NSWorkspace.willSleepNotification	Flush unsaved state, pause BEAM heartbeat/timers, notify BEAM of impending sleep
NSWorkspace.didWakeNotification	Trigger file staleness checks, reconnect LSP, refresh git status, resume timers
NSWorkspace.screensDidSleepNotification	Pause Metal rendering loop (stop setNeedsDisplay / display link)
NSWorkspace.screensDidWakeNotification	Resume Metal rendering, force a full re-render

Implementation Notes

• Register observers on NSWorkspace.shared.notificationCenter (not the default center)
• willSleep fires before the system actually sleeps — use this window to flush
• didWake may fire before network is fully available — LSP reconnection should retry with backoff
• Screen sleep/wake is independent of system sleep — screens can sleep on idle timeout while the system stays awake
• Consider sending a protocol message to BEAM on sleep/wake so it can pause/resume its own background work

Acceptance Criteria

• Metal rendering pauses when screens sleep and resumes on wake
• BEAM is notified of sleep/wake transitions
• No rendering artifacts or stale frames after wake
• File modification detection runs after system wake

🤖 Generated with Claude Code