Build It Yourself #4: leave-now alerts — and a real phone call for the ones that matter
A heads-up on WhatsApp and the house speaker before every calendar event with a location — and, for a flight or a doctor, an actual phone call. Here's the brief to build your own.
A heads-up on WhatsApp and the house speaker before every calendar event with a location — and, for a flight or a doctor, an actual phone call. Here’s the brief to build your own.
הפרק הרביעי בסדרת Build It Yourself: הפעם התראת "כדאי לצאת" — הודעה בוואטסאפ, הכרזה קולית בבית, ולאירועים שבאמת חשובים (טיסה, רופא) — שיחת טלפון אמיתית מהעוזר. הקובץ להורדה בסוף, השאר באנגלית.
The problem
I silence notifications the way everyone does — by habit, without reading them. Which is fine for most things and a real problem for “you need to leave for your flight in 40 minutes.” A calendar popup competes with everything else on a phone. What I needed was something louder for the things that actually matter, and something calmer for everything else, and I needed the assistant to know the difference on its own.
So now, 40 minutes before anything on my calendar that has a location, I get a WhatsApp message with a map link and the house speaker says the same thing out loud. That covers a dentist appointment the same as a flight. But a flight, a doctor, or a hospital visit gets one more thing: my phone actually rings, and an AI voice tells me it’s time to go. Not a push notification I can swipe away without looking — a call.
The design in one breath
A script polls the calendar every 10 minutes for anything starting in the next 90 minutes with a location, and fires once when an event is 38–50 minutes out — a window wide enough that a 10-minute poll can’t step over it, with a flat file of already-alerted event ids so nothing repeats. Every alert goes out on WhatsApp (with a map link that opens turn-by-turn directions) and on a house speaker. Then, and only then, it checks the event against a short, deliberately narrow list of keywords — flight, doctor, hospital — and if one matches, it places a real outbound phone call. Everything else gets the chat + speaker alert and nothing more.
Two of the seven traps (the brief has all of them)
A phone call for everything is a phone call for nothing. My first instinct was to make anything that “felt important” trigger a call. The problem is that feels important drifts — a dentist appointment feels important the morning of. The fix is boring on purpose: a short, named keyword list instead of any kind of severity judgment. It has to stay short enough to read in one line of the script, or it stops meaning anything.
A narrow alert window plus a slow poll cadence quietly drops alerts. With a poll every 10 minutes and a rule that fires at one exact minute mark, a tick can land at minute 39 and the next at minute 49 — straddling right past a 5-minute window and never catching the event at all. The fix is to make the window meaningfully wider than the poll interval and dedupe on the event’s own id, so a wide window still only ever fires once.
The other five — the URL-encoding trap in the map link, quiet hours accidentally hiding a dead job from monitoring, one channel’s failure sinking another, duplicate heads-ups from two different lanes, and why a flat 30-minute buffer isn’t real drive-time — are in the file, each as symptom → cause → fix.
Get the brief
→ Download leave-now-phone-call.md (plain text) · all briefs
How to use it: drop it in an empty folder, open Claude Code there, and say “Read this brief. Ask me the prerequisite questions, then build step 1.” The phone-call step is optional — skip it and you still get a fully working leave-now alert on chat and speaker. Budget an evening, and read the traps before you build; that’s the part that actually saves the evening.
Which capability should be next? Tell me in the comments or wherever you found this.
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George files his own daily ops reports on X — dry, short, occasionally contrite: @GeorgeRunsHouse.