Dispatches from the work in progress
1. The ask: tell ops the moment a pet tag order is paid Our company sells pet tags (QR tags that clip onto a pet's collar) through a Flutter mobile app. The operations team wanted to know the moment a tag order was paid, instead of checking an
A Query is not automatically cheap. In a test partition of 6,000 pet documents, a Query that filtered on pet_id read all 6,000 items and used 319 read capacity units to return 3. The same request against a composite sort key, OWNER#<owner>#PET#<
For a stacked shipping carton, C flute is the safer pick over B and E. In our illustrative sizing of a 400 × 300 × 200 mm carton, with the same 5.6 kN/m edge crush grade on all three, C flute carried 2,460 N of lab box compression strength,
Three background jobs, none of them serving a single user request, consumed nearly all of the DynamoDB read capacity on our production account. One scheduler table absorbed a GetItem count in the millions over a single week. A second job read a full batch from every index shard on every
When One Field Breaks the Contract: Fixing Pet Allergy Data Types A field that stores a pet’s allergies might look simple. It could be a list of strings, such as ["Chicken", "Peanuts"]. But what happens when one part of the system expects a list, another
The reliable way to send large files over MQTT is to not put them in MQTT at all. AWS IoT Core caps a single publish at 128 KB, so on our pet bowl the MQTT connection carries only a small request, the cloud answers with a presigned S3 POST, and
Few of our smart bowls went deaf for hours while every dashboard stayed green. The cause was one assumption almost every MQTT client invites you to make. They kept sending weight readings every few seconds. The fleet view showed them online. The cloud could see every one of them. But
A screw in a plastic joint loses clamp load through stress relaxation, and in our illustrative model (hypothetical values) a bare M4 screw head on unfilled plastic keeps only 76 percent of its torque after 1,000 hours. Spreading the load with a flat washer lifts that to 86 percent,
A dog trots up to its bowl, takes a few bites, looks around and goes back for more. To the dog, it's just lunch. To us, it's a handful of new files. Our smart bowl, EverBowl, has two cameras, a thermal camera, a microphone and a
A dog's life stage should change as it gets older. But storing a value like "Adult" in a database does not make it change automatically. We solved this by storing the dog's date of birth and deriving its life stage whenever the profile is
To save and resume a multi-step form in a Flutter app, treat a half-finished record as its own kind of object. Keep it out of the list the rest of the app reads, and let one opt-in server parameter bring it back. In the Hoomanely app that took 1 new
Antenna placement for coexisting radios is set by an isolation budget, not by whatever board edge is left over. On Eversense, our board with LoRa, GPS and a Wi-Fi/BLE combo radio, moving the three antennas to separate edges and restoring each ground clearance raised LoRa-to-GPS isolation from 8 dB
One QR Tag, Three Lives: Designing for a Code That Never Changes Scan the disc on a dog's collar and a web page opens. Usually that page has one job: help a stranger get a lost pet home. It shows the pet, lets the owner know their tag
How we isolate tenants on DynamoDB without row-level security: tenant-leading keys, a repository floor, IAM LeadingKeys, and the GSI read that regressed isolation while getting faster.
Auto exposure and auto white balance on a microcontroller camera can run as a small firmware loop on top of the chip's hardware image signal processor (ISP), with no host and no image library. On our new camera module, a once-per-second loop meters the processed image, steers sensor
