tinynudge: macOS mouse jiggler

Casting about for a software alternative to CRU's Mouse Jiggler MJ-3, stumbled upon WakeyWakey, move-mouse-macOS, and MoveMouse, but sought something simpler. Generated tinynudge with Opus 5.5 in one pass, then refined it with GPT-6 Astra, yielding 33 lines of Swift that compile to a 55k executable:

// Build: swiftc -O tinynudge.swift -o tinynudge && strip tinynudge
// Run: ./tinynudge [positive whole seconds] (default 60; Ctrl-C to quit)
import ApplicationServices
import IOKit.pwr_mgt

func fail(_ message: String) -> Never {
    fputs("tinynudge: \(message)\n", stderr)
    exit(1)
}
guard CommandLine.arguments.count <= 2,
      let interval = UInt32(CommandLine.arguments.dropFirst().first ?? "60"), interval > 0
else { fail("Usage: tinynudge [positive whole seconds]") }
guard AXIsProcessTrustedWithOptions([kAXTrustedCheckOptionPrompt.takeUnretainedValue(): true] as CFDictionary)
else { fail("Grant Device Control and Data Access (formerly Accessibility) access in System Settings → Privacy & Security, then rerun.") }

var assertion = IOPMAssertionID(0)
let result = IOPMAssertionCreateWithName(
    kIOPMAssertionTypePreventUserIdleDisplaySleep as CFString,
    IOPMAssertionLevel(kIOPMAssertionLevelOn), "tinynudge" as CFString, &assertion)
guard result == kIOReturnSuccess else { fail("Display-sleep assertion failed (\(result)).") }
setbuf(stdout, nil)
print("tinynudge: active (interval: \(interval)s, check: \(interval / 2)s). Ctrl-C to quit.")

let anyInput = CGEventType(rawValue: UInt32.max)!
while true {
    sleep(interval)
    guard CGEventSource.secondsSinceLastEventType(.hidSystemState, eventType: anyInput) >= Double(interval) / 2,
          let p = CGEvent(source: nil)?.location else { continue }
    for position in [CGPoint(x: p.x + 1, y: p.y), p] {
        CGEvent(mouseEventSource: nil, mouseType: .mouseMoved,
                mouseCursorPosition: position, mouseButton: .left)?.post(tap: .cghidEventTap)
    }
}

Checks input idle time every N seconds (default: 60). If idle for at least half that interval, moves the cursor 1px right and back. Requires Accessibility access ("Device Control and Data Access" in macOS 27+); prompts if your terminal lacks it.

Separately, holds a caffeinate -d-style power assertion, visible as tinynudge in pmset -g assertions; released on exit.

Tested in macOS 26 Tahoe and 27 Golden Gate.

❧ 2026-10-01