R.

Blog

Practical notes on design and code.

AI

How do I choose which prompt prefix to cache versus re-run to cut LLM latency?

Choose which parts of an LLM prompt belong in a reusable prefix, which parts should stay volatile, and how OpenAI's documented caching modes, keys, and lifetimes affect latency and reuse.

November 1, 2026About 14 min read
Programming

How should I surface and handle AggregateError.errors when Promise.any() rejects so failures are actionable?

Label Promise.any() inputs before you call it, then inspect AggregateError.errors in input order so each failure can drive a retry, fallback, or fatal decision.

October 31, 2026About 14 min read
CSS

When should I use overflow-clip-margin to let decorative paint escape while keeping overflow: clip?

Use `overflow: clip` for a hard clipping boundary, then add `overflow-clip-margin` only when the extra paint is decorative and must remain visible without creating a scroll container.

October 31, 2026About 16 min read
UI/UX

How do I use IntersectionObserver rootMargin and thresholds to preload assets just before visibility without jitter?

Use rootMargin and threshold arrays together so IntersectionObserver preloads just before visibility, then add a tiny stability check so resize-driven jitter does not retrigger the same asset.

October 29, 2026About 15 min read
Architecture

How do I use CREATE POLICY per-command USING vs WITH CHECK to allow safe INSERTs that set owner while blocking later owner UPDATEs?

Use separate PostgreSQL row-security policies for INSERT and UPDATE so a row can be created with an owner and later edited without making the owner column mutable.

October 29, 2026About 17 min read
Programming

When should I use LockManager.request() to serialize work across tabs instead of in-memory locks?

Use LockManager.request() when same-origin tabs or workers need browser-coordinated mutual exclusion. Learn why in-memory locks stop at one JavaScript heap, how exclusive and shared requests behave, and what the callback boundary does and does not guarantee.

October 26, 2026About 15 min read
UI/UX

When should I use contentBoxSize vs borderBoxSize in ResizeObserverEntry?

Choose the ResizeObserverEntry field that matches the edge you are actually testing: layout size, border-inclusive size, or device-pixel size. This article maps box sizing, transforms, and scrollbars to the property that best answers each diagnostic question.

October 25, 2026About 11 min read
CSS

Why doesn't scroll snapping happen — is it the container-type, axis, or snap strictness?

Diagnose scroll snapping by checking the scroll container axis, the child snap alignment, and whether proximity is too soft for the behavior you expect.

October 24, 2026About 13 min read
Architecture

When should I use SERIALIZABLE vs SELECT FOR UPDATE or advisory locks to prevent lost updates?

Compare PostgreSQL SERIALIZABLE transactions, SELECT FOR UPDATE, and transaction-scoped advisory locks so you can choose the narrowest mechanism that owns the conflict and understand whether the result will retry or wait.

October 22, 2026About 16 min read
DevOps

How can I ensure Compose services wait for a backend to be ready without brittle sleep loops?

Use Compose healthchecks and `depends_on` conditions to wait for real backend readiness instead of guessing with sleep loops.

October 21, 2026About 11 min read
Programming

How do I make an IndexedDB upgrade/migration atomic and recoverable across versionchange and transaction aborts?

Use an IndexedDB versionchange transaction as the only place schema and record moves happen, then add a durable migration marker and recovery check so an interrupted upgrade can be retried safely instead of leaving a half-moved database behind.

October 19, 2026About 15 min read
AI

How should teams evolve function schemas and Structured Outputs without breaking live conversations?

Version the model-facing schema, normalize accepted payloads into one canonical server shape, and use strict validation to evolve OpenAI function calling and Structured Outputs without breaking older conversations.

October 17, 2026About 15 min read