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. Queried Opus 5.5, which conjured up tinynudge in one shot; just 30 lines of Swift, 54k compiled:

// tinynudge: Prevent sleep with 1px cursor nudges when idle and a caffeinate-style power assertion
// Build: swiftc -O tinynudge.swift -o tinynudge && strip tinynudge    Usage: tinynudge [seconds] (default 60, Ctrl-C to quit)
import ApplicationServices
import IOKit.pwr_mgt

setbuf(stdout, nil)
let interval = max(1, Double(CommandLine.arguments.dropFirst().first ?? "") ?? 60)

var assertion = IOPMAssertionID(0)
IOPMAssertionCreateWithName(kIOPMAssertionTypePreventUserIdleDisplaySleep as CFString,
                            IOPMAssertionLevel(kIOPMAssertionLevelOn), "tinynudge" as CFString, &assertion)

if !AXIsProcessTrustedWithOptions([kAXTrustedCheckOptionPrompt.takeUnretainedValue(): true] as CFDictionary) {
    print("tinynudge: Grant Terminal Accessibility access (\"Device Control and Data Access\" on macOS 27+) in System Settings → Privacy & Security, then rerun.")
}
print("tinynudge: every \(Int(interval))s when idle. Ctrl-C to quit.")

let anyInput = CGEventType(rawValue: ~0)!
func move(_ p: CGPoint) {
    CGEvent(mouseEventSource: nil, mouseType: .mouseMoved, mouseCursorPosition: p, mouseButton: .left)?.post(tap: .cghidEventTap)
}

while true {
    sleep(UInt32(interval))
    // Only nudge if the mouse/keyboard hasn't been touched for at least half an interval.
    guard CGEventSource.secondsSinceLastEventType(.hidSystemState, eventType: anyInput) >= interval / 2 else { continue }
    guard let p = CGEvent(source: nil)?.location else { continue }
    move(CGPoint(x: p.x + 1, y: p.y))
    move(p)
}

Checks input idle time every N seconds (default: 60). If idle for at least N seconds, 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. Keeps the display awake without Accessibility access; released on exit.

❧ 2026-10-01