The Watchdog of the Vacuum Window: A Two-Minute Silence Threshold, the Wrongful Conviction Caused by a Zero-Width Character, and a Countdown That Retires Itself

Two construction sites labor day and night, yet even a foreman dozes — and in the vacuum window, a task parked at turn-complete waiting-for-input can sit still for half an hour. What was completed today is a watchdog specialized for the vacuum.

I. The Activity Signal: The Breathing of Log Files

The first cornerstone of the design is unexpectedly plain: each task’s session keeps a live log on disk (a rollout jsonl), written on the AI’s every move — the file’s modification time is its breath. The watchdog takes the pulse every twenty seconds: silence beyond two minutes means it is stuck in the vacuum (verified by measurement: the last record at a stall is indeed the completed model request). Injection does not walk the fragile road of screen coordinates — Windows Accessibility (UIA) locates the controls; and whether the message truly went out is judged by the input box being cleared.

II. Two Wrongful Convictions and One Truth

The first night’s report was all FAIL input not cleared — probe by probe, the exoneration finally landed: the injection chain was sound throughout; focus, click, typing all genuinely took effect. The true culprit was the validation: ZCode’s empty input box is not an empty string but a newline plus a zero-width character, so every success was misjudged as failure, triggering piles of meaningless retries. The injection of 02:13, posthumously a success, had in fact revived the Moyu session stalled for thirty-one minutes. The second case was the reverse: once the write landed but the enter fell short — focus never truly entered the input box. Two cuts fixed it: a real mouse click on the input box before pasting and pressing enter; and failure back-off (three consecutive failures earn a ten-minute cooldown), ending the idle spinning every minute.

III. The Safety Design: Never Interrupt One Who Is Working

The watchdog’s rules of engagement were written finer than its features: yield to the game — the Moyu task actively seizes the game window’s foreground for click batches; while the game is in front and the session logged activity within five minutes, the watchdog stands down — but past five minutes of silence it injects anyway, never permitting a permanent deadlock; yield to the master — only after ZCode has held the foreground a short while (proof the master is operating) is injection permitted, and each focus switch of about a second is logged; no repeats — two injections to the same session are at least three minutes apart, and the global interval is forty-five seconds. The daemon runs independently of the chat window, restarts by double-clicking the bat, and a watchdog.stop file laid in the workspace halts it within seconds.

IV. The Automation That Knows How to Close Shop

The final order came from the master: run only until eight thirty in the morning. The deadline was not entrusted to any external timer but written inside the script itself — checked every twenty seconds, and at the hour it logs one line of deadline reached and exits cleanly. The rarest thing about automation is not how long it can run but knowing when to stop: the sentinel keeps a duty roster, the watchdog a countdown, permissions an expiry — only an automation that can close its own shop deserves to be trusted for the long term.