Wake iso's display for hands calls while it sleeps

hands/Sources/byre-hands/Display.swift

@@ -0,0 +1,42 @@
+import CoreGraphics
+import IOKit.pwr_mgt
+import ScreenCaptureKit
+
+func displayAsleep() -> Bool {
+    let id = CGMainDisplayID()
+    return CGDisplayIsAsleep(id) != 0 || CGDisplayBounds(id).width == 0
+}
+
+func displayCapturable() async -> Bool {
+    if displayAsleep() {
+        return false
+    }
+    // Without Screen Recording this throws; stop waiting so tools that don't capture still run.
+    guard let content = try? await SCShareableContent.excludingDesktopWindows(false, onScreenWindowsOnly: true) else {
+        return true
+    }
+    return content.displays.contains(where: { $0.displayID == CGMainDisplayID() })
+}
+
+func withDisplayAwake<T>(_ body: () async throws -> T) async throws -> T {
+    var hold = IOPMAssertionID(0)
+    IOPMAssertionCreateWithName(kIOPMAssertionTypePreventUserIdleDisplaySleep as CFString, IOPMAssertionLevel(kIOPMAssertionLevelOn), "byre-hands" as CFString, &hold)
+    defer {
+        IOPMAssertionRelease(hold)
+    }
+    if displayAsleep() {
+        var wake = IOPMAssertionID(0)
+        IOPMAssertionDeclareUserActivity("byre-hands" as CFString, kIOPMUserActiveLocal, &wake)
+        defer {
+            IOPMAssertionRelease(wake)
+        }
+        let deadline = ContinuousClock.now + .seconds(10)
+        while !(await displayCapturable()) {
+            if ContinuousClock.now > deadline {
+                throw ToolError("the display didn't wake within 10s")
+            }
+            try await Task.sleep(for: .milliseconds(100))
+        }
+    }
+    return try await body()
+}

hands/Sources/byre-hands/Server.swift

@@ -101,7 +101,7 @@ struct Server {
             return ["content": [Content.text("unknown tool: \(name)").json], "isError": true]
         }
         do {
-            let content = try await tool.run(args)
+            let content = try await withDisplayAwake { try await tool.run(args) }
             return ["content": content.map { $0.json }]
         } catch let e as ToolError {
             return ["content": [Content.text(e.message).json], "isError": true]