Fix: poll sleep state off the main thread (menu bar icon didn't appear)

StateMonitor ran the synchronous XPC read on the main thread (initial poll in
applicationDidFinishLaunching + a main-run-loop timer). When the helper is
unreachable (e.g. a fresh install before the Login Items approval), each read
blocked the main thread for the full timeout, starving the run loop so SwiftUI
never installed the MenuBarExtra — the process ran with no menu-bar icon.

poll() now runs read() on a background queue and delivers onObserved back on
main, with an in-flight guard to coalesce overlapping ticks. Regression test
proves poll() no longer blocks its caller.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: iamdadzilla

Sources/MacsomniaCore/StateMonitor.swift

@@ -7,15 +7,28 @@ public final class StateMonitor {
     private let read: () -> Bool?
     private let onObserved: (Bool) -> Void
     private var timer: Timer?
+    private let workQueue = DispatchQueue(label: "com.macsomnia.statemonitor")
+    private var inFlight = false   // touched only on the main thread
 
     public init(read: @escaping () -> Bool?, onObserved: @escaping (Bool) -> Void) {
         self.read = read
         self.onObserved = onObserved
     }
 
+    /// Call on the main thread. `read()` may block (synchronous XPC to the
+    /// privileged helper), so it runs on a background queue and never stalls the
+    /// caller's run loop — otherwise a slow/unreachable helper at launch would
+    /// keep SwiftUI from ever installing the menu-bar item. `onObserved` is
+    /// delivered back on the main thread. Overlapping ticks are coalesced.
     public func poll() {
-        if let value = read() {
-            onObserved(value)
+        if inFlight { return }
+        inFlight = true
+        workQueue.async { [weak self] in
+            let value = self?.read()
+            DispatchQueue.main.async {
+                self?.inFlight = false
+                if let value { self?.onObserved(value) }
+            }
         }
     }
 

Tests/MacsomniaCoreTests/StateMonitorTests.swift

@@ -3,16 +3,35 @@ import XCTest
 
 final class StateMonitorTests: XCTestCase {
     func testPollForwardsObservedValue() {
+        let exp = expectation(description: "observed")
         var observed: [Bool] = []
-        let monitor = StateMonitor(read: { true }, onObserved: { observed.append($0) })
+        let monitor = StateMonitor(read: { true }, onObserved: { observed.append($0); exp.fulfill() })
         monitor.poll()
+        wait(for: [exp], timeout: 2)
         XCTAssertEqual(observed, [true])
     }
 
     func testPollSkipsWhenReadReturnsNil() {
-        var observed: [Bool] = []
-        let monitor = StateMonitor(read: { nil }, onObserved: { observed.append($0) })
+        let exp = expectation(description: "should not observe")
+        exp.isInverted = true
+        let monitor = StateMonitor(read: { nil }, onObserved: { _ in exp.fulfill() })
+        monitor.poll()
+        wait(for: [exp], timeout: 0.3)
+    }
+
+    /// `read()` can block (synchronous XPC to the privileged helper). `poll()`
+    /// must run it off the caller's thread — otherwise a slow/unreachable helper
+    /// blocks the main run loop at launch and the menu-bar item never appears.
+    func testPollDoesNotBlockCaller() {
+        let exp = expectation(description: "observed")
+        let monitor = StateMonitor(
+            read: { Thread.sleep(forTimeInterval: 0.5); return true },
+            onObserved: { _ in exp.fulfill() }
+        )
+        let start = Date()
         monitor.poll()
-        XCTAssertTrue(observed.isEmpty)
+        let elapsed = Date().timeIntervalSince(start)
+        XCTAssertLessThan(elapsed, 0.1, "poll() must not block its caller while read() runs")
+        wait(for: [exp], timeout: 2)
     }
 }