https://itsnas.me/writing Thoughts, tutorials, and engineering notes from real-world projects. en Wed, 23 Sep 2026 10:00:00 GMT https://itsnas.me/writing/instrument-a-service-with-wide-events https://itsnas.me/writing/instrument-a-service-with-wide-events Wed, 23 Sep 2026 10:00:00 GMT You're about to add logging to a new service, or you're staring at an existing one where every incident turns into a grep-and-guess session across a dozen disconnected log lines. Replace the step-by-step logs with one wide event per request. https://itsnas.me/writing/wide-event-logger https://itsnas.me/writing/wide-event-logger Wed, 23 Sep 2026 09:30:00 GMT A tiny `createEvent(name, seed)` that accumulates fields over the life of a request via `.set()` and emits exactly one structured log line via `.emit()`, so a request that touches ten steps still produces one row instead of ten. https://itsnas.me/writing/your-logging-sucks https://itsnas.me/writing/your-logging-sucks Wed, 23 Sep 2026 09:00:00 GMT A checkout endpoint with a log line at every step looks like good observability, right up until a customer says "my payment failed" and you have thirteen unrelated lines from thirteen unrelated requests to sort through. The fix isn't more logs, it's one wide event per request instead. https://itsnas.me/writing/cut-a-slow-n-plus-one-query-down https://itsnas.me/writing/cut-a-slow-n-plus-one-query-down Fri, 18 Sep 2026 14:00:00 GMT An endpoint that queries once per parent row instead of once per request looks fine with ten rows and falls over with ten thousand. Batch the per-row lookups into one query and the round trips disappear. https://itsnas.me/writing/what-breaks-1k-to-1m-requests-per-second https://itsnas.me/writing/what-breaks-1k-to-1m-requests-per-second Thu, 17 Sep 2026 09:00:00 GMT The same endpoint, run through four traffic tiers. At 1k req/s almost any design survives. At 10k the database and the single instance give first. At 100k the cache and the load balancer become the systems under test. At 1M the architecture itself has to change, because the failure mode is no longer capacity, it's correlated behavior across clients you don't control. https://itsnas.me/writing/migrating-schema-per-tenant-databases-at-scale https://itsnas.me/writing/migrating-schema-per-tenant-databases-at-scale Sat, 12 Sep 2026 15:00:00 GMT Choosing physical tenant isolation over a shared, RLS-scoped schema buys two new problems: knowing where a tenant's data actually lives, and running one migration correctly hundreds of times instead of once. Neither has an app-code fix, both need their own infrastructure. https://itsnas.me/writing/designing-multi-tenant-apis-that-scale https://itsnas.me/writing/designing-multi-tenant-apis-that-scale Sat, 12 Sep 2026 09:00:00 GMT A missing tenant filter is a data leak, not a crash. Row-level security fixes that structurally, but rate limits, connection pools, and error codes built for one instance break the same quiet way once the API runs as several. https://itsnas.me/writing/why-payment-retries-need-idempotency https://itsnas.me/writing/why-payment-retries-need-idempotency Fri, 11 Sep 2026 09:00:00 GMT A plain payment endpoint looks correct until you trace what a double-click, a timed-out request, or a redelivered webhook actually does to it. Each one turns one payment into two. Idempotency keys are the fix, at two layers most write-ups skip. https://itsnas.me/writing/next-route-rendering-strategy https://itsnas.me/writing/next-route-rendering-strategy Tue, 01 Sep 2026 17:30:00 GMT An App Router route is prerendered by default and silently turns dynamic the moment you read something request-specific. Knowing which bucket a route belongs in (and what forces it out) is the difference between an instant page and a server render on every hit. https://itsnas.me/writing/retryable-write-endpoint https://itsnas.me/writing/retryable-write-endpoint Tue, 01 Sep 2026 17:00:00 GMT A client that retries a POST after a timeout can create the resource twice or charge a card twice. An idempotency key lets the server spot the retry and replay the first response instead of doing the work again. https://itsnas.me/writing/first-15-minutes-of-a-prod-incident https://itsnas.me/writing/first-15-minutes-of-a-prod-incident Tue, 01 Sep 2026 16:30:00 GMT Something's on fire in production and you're the one holding it. Your job for the next fifteen minutes is to shrink the impact and coordinate the response, not to find the root cause. https://itsnas.me/writing/retry-backoff https://itsnas.me/writing/retry-backoff Tue, 01 Sep 2026 15:00:00 GMT A generic `retry(task, options)` that re-runs a failing async task with exponential backoff and full jitter, an optional `shouldRetry` predicate, and a cap on any single delay. https://itsnas.me/writing/typed-event-emitter https://itsnas.me/writing/typed-event-emitter Tue, 01 Sep 2026 14:00:00 GMT A ~20-line pub/sub where the event names and each event's payload type come from one map, so `on` and `emit` are fully checked against it and `on` returns its own unsubscribe. https://itsnas.me/writing/assert-never https://itsnas.me/writing/assert-never Tue, 01 Sep 2026 13:00:00 GMT A one-line helper that makes a `switch` over a discriminated union a compile error the moment a case is added and left unhandled, with a runtime throw as the safety net for data that violated the types at the edges. https://itsnas.me/writing/result-type https://itsnas.me/writing/result-type Tue, 01 Sep 2026 12:00:00 GMT A `Result<T, E>` union plus `tryCatch` wrappers that turn a throwing call into a value the caller has to inspect: the failure path becomes part of the return type instead of an invisible jump. https://itsnas.me/writing/use-local-storage https://itsnas.me/writing/use-local-storage Tue, 01 Sep 2026 11:00:00 GMT A `localStorage`-backed `useState` built on `useSyncExternalStore`: no hydration mismatch under SSR, live updates when another tab writes, and live updates when another hook on the same page writes. https://itsnas.me/writing/use-controllable-state https://itsnas.me/writing/use-controllable-state Tue, 01 Sep 2026 10:00:00 GMT One hook that lets a component be driven from outside (`value` + `onChange`) or manage its own state (`defaultValue`), the same two-mode contract a native `<input>` has, while the component body only ever reads one value and calls one setter. https://itsnas.me/writing/use-toggle https://itsnas.me/writing/use-toggle Tue, 01 Sep 2026 09:00:00 GMT A boolean `useState` that hands back `on` / `off` / `toggle` instead of a raw setter, so call sites read as intent. Every function, and the controls object itself, stays referentially stable, safe to pass as props or list as effect dependencies without retriggering anything downstream. https://itsnas.me/writing/ai-agent-skills-dev-workflow https://itsnas.me/writing/ai-agent-skills-dev-workflow Wed, 26 Aug 2026 18:00:00 GMT An AI agent produces plausible, well-formatted code that quietly drifts from what was asked. The fix is a loop with a durable spec: a real GitHub issue the agent must reference, and a two-axis review (standards vs. spec) that runs against it before the PR opens. https://itsnas.me/writing/building-a-typed-fetch-factory https://itsnas.me/writing/building-a-typed-fetch-factory Tue, 25 Aug 2026 10:00:00 GMT How a single createFetcher factory infers request/response types from an OpenAPI schema and layers in caching, retries, and cancellation, and why each piece is built the way it is. https://itsnas.me/writing/typed-fetch-factory https://itsnas.me/writing/typed-fetch-factory Tue, 25 Aug 2026 09:15:00 GMT A reusable fetch factory that infers request/response types from an OpenAPI schema and adds in-memory caching, retry with backoff, and AbortController support, no per-endpoint boilerplate, no `any`. https://itsnas.me/writing/hashing-and-the-birthday-paradox https://itsnas.me/writing/hashing-and-the-birthday-paradox Wed, 19 Aug 2026 09:00:00 GMT A hash space that looks astronomically large can still produce collisions with a surprisingly small number of items, the same math behind the birthday paradox, applied to hashing. https://itsnas.me/writing/valid-triangle-number https://itsnas.me/writing/valid-triangle-number Sat, 15 Aug 2026 09:00:00 GMT Sort the side lengths, fix the largest one at a time, and let the gap between two pointers count every valid pair against it in one step instead of testing them one by one. https://itsnas.me/writing/3sum https://itsnas.me/writing/3sum Fri, 14 Aug 2026 09:00:00 GMT Sort the array, fix one value as a moving target, and reuse the exact two-pointer proof from Two Sum II to sweep the rest, with a couple of extra duplicate-skipping rules layered on top. https://itsnas.me/writing/two-sum-ii https://itsnas.me/writing/two-sum-ii Thu, 13 Aug 2026 09:00:00 GMT A sorted array, two pointers closing in from both ends, and a proof that whichever side is off-target can be ruled out entirely rather than retried against a smaller search space. https://itsnas.me/writing/container-with-most-water https://itsnas.me/writing/container-with-most-water Wed, 12 Aug 2026 09:00:00 GMT A row of walls, two pointers starting at the widest container, and a proof that moving the taller wall can never beat what you already have, so only the shorter side is ever worth moving. https://itsnas.me/writing/two-pointers https://itsnas.me/writing/two-pointers Tue, 11 Aug 2026 09:00:00 GMT Two indices walking through one ordered structure, discarding the side that cannot improve the answer at every step and replacing a nested loop with a single pass. https://itsnas.me/writing/ai-without-losing-engineering-judgment https://itsnas.me/writing/ai-without-losing-engineering-judgment Tue, 17 Mar 2026 09:30:00 GMT AI can speed up delivery, but engineers still own architecture, quality, and decisions. A simple workflow to ship faster without outsourcing judgment. https://itsnas.me/writing/plan-for-2026 https://itsnas.me/writing/plan-for-2026 Thu, 01 Jan 2026 00:00:00 GMT It's 2026, and I'm still working as a Senior Software Engineer, setting some ambitious goals for myself and writing about it as tech keeps changing under our feet. https://itsnas.me/writing/disecting-my-portfolio https://itsnas.me/writing/disecting-my-portfolio Sat, 12 Apr 2025 16:00:00 GMT It took me 3 years to build my portfolio. The process was bitter yet rewarding. Learnt many things and adopted good habbits. https://itsnas.me/writing/welcome https://itsnas.me/writing/welcome Sun, 06 Apr 2025 14:40:00 GMT The name's Nas. Software Engineer based in UK, with Computer Science degree from King's College London University.