It started with one smart plug. I wanted the lamp in the study to come on at dusk so I would stop walking into the desk. That is the whole brief. A two-pound problem.
Three weekends later I have a Home Assistant instance running in a container, a Zigbee coordinator flashed with the right firmware, an MQTT broker I did not strictly need, and a dashboard that tells me the humidity in a room nobody sits in. The lamp does come on at dusk now, I will grant it that.
The slide is predictable and I walked into it with my eyes open. You start with the cloud integration because it is easy, then you read one forum thread about everything routing through someone else's servers in Frankfurt and you decide, on principle, that the lamp should not need the internet to turn itself on. So you buy a Zigbee stick. Then you discover the stick's default firmware is two years old and the better one needs flashing over a serial adapter you do not own yet.
The thing I did not expect is how good it is once you stop fighting it. The automation engine is genuinely capable, and it runs entirely on a box in my own house, which means it keeps working when the broadband does not. I have a rule that drops the boiler flow temperature when nobody has triggered a motion sensor downstairs for an hour, and another that nags me on my phone if the freezer drifts above a sensible threshold, which it did once, at three in the morning, the night a plug failed. That second one has probably already paid for the whole exercise in spoiled food I did not lose, and it is the kind of thing no off-the-shelf gadget would have told me.
What I would tell my past self: pick local control from the start and accept the upfront cost. Zigbee or Z-Wave, a dedicated coordinator, everything talking on your own network. The cloud route feels faster on day one and then you spend day thirty migrating off it anyway because a vendor sunset an API. Do it once.
The other lesson is to stop when the brief is met. The lamp works. The freezer alarm works. I do not need to know the humidity in the spare room. I will, of course, end up knowing it, because there is a sensor going cheap and a free slot on the dashboard, and that is exactly how a two-pound problem becomes a hobby.