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Build log

Home Assistant deep-dives, card build logs, and automation write-ups.

FILTER
28 Apr 2026
Building a TRV heat demand aggregator in Home Assistant

TRVs report valve position, not demand. Here is how I built a sensor that aggregates per-room heat demand into something the boiler can act on.

HA
14 Apr 2026
Why I rewrote the calendar card from scratch (twice)

The first rewrite fixed the layout. The second fixed time zones. Here is what I learned about building Lovelace cards that actually handle real calendar data.

build log
2 Apr 2026
F1 race status lighting with Govee and govee2mqtt

Race status from a public API, piped through MQTT, mapped to Govee light effects. The lights go green on race start, safety-car yellow on VSC, and red on a red flag.

automation
20 Mar 2026
Building a word clock card with ResizeObserver

An 11×10 letter grid that shows the time in English. The challenge was making it fit any tile size without JavaScript-driven font sizing.

build log
10 Mar 2026
Getting a custom card accepted into HACS

The HACS submission checklist is longer than it looks. Here is what caught me out and how to get through the review without back-and-forth.

HA
28 Feb 2026
Home Assistant entities, devices, and areas — what actually matters

Three concepts that beginners conflate and experts take for granted. Getting this mental model right makes everything else click.

HA