fix: restore tablet cursor after display sleep/wake

[lhysilicon]

Problem

When the Mac's display idle-sleeps (pmset displaysleep) and then wakes, the tablet keeps showing a live picture but the mouse cursor is gone — and stays gone until the stream is manually restarted.

Root cause

SCStreamConfiguration.showsCursor = true lets ScreenCaptureKit composite the cursor into captured frames. But cursor-only movement over an idle virtual display does not dirty the surface, so ScreenCaptureKit delivers no new frames. The idle keepalive added in 0.6.8 then re-sends the last cached buffer indefinitely and resets lastFrameTime, so the stall-based restart in startFrameMonitor never fires — the tablet is frozen on a stale, cursor-less frame. There was no display sleep/wake handling, so nothing rebuilt the capture.

Confirmed empirically: with a static desktop, sweeping the real cursor across the virtual display's global coordinates produced zero new SCStream frames (the host stayed at the ~1 fps keepalive the whole time).

Fix

1. Prevent the trigger — hold kIOPMAssertionTypePreventUserIdleDisplaySleep while streaming so the display (hence the virtual display) never idle-sleeps. Released in stopStreaming.
2. Recover if sleep happens anyway (manual/forced display sleep, reconnect) — on NSWorkspace.screensDidWakeNotification / didWakeNotification, rebuild the SCStream via a new ScreenCapture.hardRestart(reason:). Guarded by an isStreaming flag + a streamGeneration token so a wake restart can never resurrect a stream that was stopped mid-flight, and debounced 2 s (both notifications can fire on a full-system wake).
3. Defensive — the CGDisplayStream fallback was created with properties: nil, which omits the cursor; it now passes [kCGDisplayStreamShowCursor: true].

Two files changed: MacHost/Sources/ScreenCapture.swift, MacHost/Sources/AppDelegate.swift.

Notes / testing

• I could not produce a local release build to smoke-test: my machine has only Command Line Tools (no full Xcode), and the SwiftUI @State macro does not expand under CLT, which blocks the link (unrelated to this change). In whole-module compilation the two changed files produced no compiler errors — only the pre-existing SwiftUI/toolchain issue in SettingsWindow.swift stopped the final binary. Please verify the build on a full-Xcode setup before merging.
• The display-sleep assertion keeps the main display awake while streaming. If you'd rather preserve idle display-sleep and rely only on the wake-triggered rebuild, gate the assertion on an active client instead of the whole streaming session.
• didChangeScreenParametersNotification was intentionally not hooked: it fires on benign arrangement/resolution changes and on every virtual-display create/destroy, which would cause spurious restarts; screensDidWake is the precise signal for this bug.

🤖 Generated with Claude Code

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[luisdavim]

Is this similar to #42?

[tranvuongquocdat]

Yes, it overlaps #42 a bit — the sleep-prevention part here is unique though, and it looks good. This PR just covers a lot of ground beyond the cursor fix, so would you mind splitting it up? Keep this one focused on the sleep/wake fix and open the rest separately — much easier for me to review and merge quickly that way.

[tranvuongquocdat]

Update: I've pulled the two unique pieces of this branch into main — the display-sleep assertion and the generation-guarded restarts — with the commit credited to you as-is. The rest (ADB status overhaul, settings UI work, the Low-Latency change) is still very welcome as separate PRs where each can get a proper look. Thanks for the solid debugging on this one!