Your semantics tree is your test API and your accessibility API at once
A testTag is invisible to a screen reader. A contentDescription is not.
All posts
Focus is the input model you don't test until someone plugs in a keyboard
Compose's focus system handles keyboard, D-pad and accessibility navigation. The APIs are small, but modifier order matters, and a form with no focus handling is unusable on any device without a touchscreen.
Nested scroll is a negotiation, and there are four moments to intervene
NestedScrollConnection gives parents four chances to consume scroll deltas around a child. Choosing the wrong one is why collapsing headers collapse late, and why same-axis nesting misbehaves.
The null that meant three different things
Not-yet-loaded, absent, and explicitly-cleared share one representation, and the UI has to guess.
Six weeks of optimisation, and the fix was two lines
Profiling found the hot function. The hot function was called a thousand times for one reason.
Pinch, pan and rotate arrive together, and the centroid is what ties them
Multi-touch gestures produce pan, zoom and rotation simultaneously. The centroid — the point between the fingers — is what makes the transform feel anchored, and ignoring it is the most common photo-viewer bug.
The health check that returned 200 while the service was useless
Proving the process is running keeps a broken instance in the load balancer.
The queue had no maximum, so the failure was memory and not latency
An unbounded buffer converts a throughput problem into an out-of-memory crash.
Swipe-to-dismiss is a state machine with anchors, not a drag handler
Hand-rolled swipe gestures compare a distance threshold and ignore velocity, which is why a fast flick feels wrong. AnchoredDraggableState models discrete positions and settles between them using both distance and speed.
Offset pagination loses rows while you read, and the user never knows
An insert on page 1 shifts every later offset. A keyset cursor is data, not a position.
The webhook that arrived twice, and the order that shipped twice
At-least-once is the contract every provider offers. Your handler is where exactly-once gets built.
Running a model on-device is a memory decision first
Quantisation, mmap and the low-memory killer decide whether your 3B model ships.