01 · Writing
Notes from building things.
Operator postmortems: decisions, metrics, and what broke. The kind of specific, load-bearing failure that only shows up when you ship and operate your own software. Mostly what the numbers said, what I decided, and what I’d change.
- 6 min
A hang fix made my paywall load zero products on every cold launch
Making the purchase service configure asynchronously fixed a launch hang and opened a race. The paywall asked for products on the first frame, a guard clause returned silently, and the app cached that failure for the whole session.
- 5 min
Grafting an MTP sidecar onto my local model for a lossless 1.48x
The MTP builds that get you speculative decoding on Apple Silicon are not the model I run. Mine had the speed head stripped out during quantization. Grafting one back on took a 555MB file and got 1.48x, and it stays lossless.
- 6 min
Three kernel panics getting a 284B model onto a 128GB Mac
DeepSeek-V4-Flash is a 284B-parameter MoE model. My Mac has 128GB of unified memory. Getting them to run together took three real kernel panics before I found the config that holds. The answer was pure CPU, not the GPU.
- 5 min
A ratio metric and an absolute-diff tolerance froze my dashboard for three days
Every health check stayed green while a metric sat frozen for 72 hours. The culprit was a threshold constant named NUMERIC_TOLERANCE_PERCENT that compared absolute values.
- 4 min
Apple renamed one word in a report, and my analytics silently fabricated installs
A substring match on a report named "App Store Downloads" stopped matching when Apple renamed it to "App Downloads." The fallback returned zero rows, which got read as a clean zero. A separate aggregation quirk on top of that is what pushed counts to 70x.