Writing
6 min read
The third montage, from the weeks around launch: the Android alert that silently drops its fourth button, a keyboard trap hiding in one prop, an HTTP 431 caused by cookies, sessions that survived a failed refresh badly, and the day the app got a space in its name.
5 min read
Two CSS systems, one cascade, and two one-line changes that each silently erased every input outline in the app. How CSS cascade layers make MUI and Tailwind coexist, why 'prepend: true' inverted the layer order, and why the bug only appeared behind the login.
6 min read
The web console shares the phone app's identity pool — so a valid sign-in proves nothing about belonging there. Building the front door that sends non-admins straight back out, the deletion queue with its runbook inline, tables that share one set of defaults, and the dark-mode fix that lived in a colour-maths exception.
5 min read
A support question — 'did my receipt save?' — needs an audit trail. This one carries no user text ever, logs one row per action rather than per write, never logs from inside a mutation, and introduced the repo's first secondary indexes along with the one screen that must never load everything.
6 min read
Without over-the-air updates, a shipped build can't hear you. In-app announcements are the one channel left — with version targeting against what users actually run, severity that picks the shape, a force-update wall that fails open by construction, and two surprises device testing found.
5 min read
The app spoke 19 languages while its emails stayed English, because two senders fire where no profile row exists. Cognito's standard locale attribute fixed that — and declaring it broke every branch deploy with 'Invalid AttributeDataType', because a user pool's schema is frozen at creation and the sandbox never said so.
6 min read
From zero i18n and 660 hard-coded strings to nineteen languages in two tiers — per-user language that roams, Arabic flipping the shell right-to-left with a font swap that needed zero call-site changes, six plural categories, and a translation pipeline whose limiter is review, not tokens.
6 min read
Store review turned 'file a request' into 'actually delete it'. Three deletion lanes done properly: a server-side Lambda whose order of operations is the design, a guest email round-trip that can't become an email oracle, and admin deletion that doesn't rewrite history.
5 min read
Two weeks before launch, the whole backend moved to a brand-new AWS account. What moves, what can't (Cognito users), what a fresh account makes free (the table rename), and the two quiet gotchas — a webhook that kept building in the old account, and env vars that don't come along.
6 min read
Canny Cart went live in the App Store and Google Play on 27 August. The two things that decided the date weren't code, the highest-consequence failure was silent, and the one rejection that arrived was about a permission button — here's the runbook, honestly.
6 min read
Receipt scanning felt like homework because the app asked 'which list?' before it would save anything. The fix inverts the order: save first, link later — with a pending flag, provisional matches, and a one-time enrichment that keeps the snapshot immutable.
4 min read
Cognito's default verification and reset emails look like a phishing test. One customMessage Lambda brands all of them — and three things will silently stop your emails if you get them wrong, plus the one line that keeps the trigger out of dependency trouble.
6 min read
The second polish montage, with a spine: three screens sharing one hook that wasn't actually shared, an Android crash traced through logcat to a recycled bitmap, sheets that swallowed the back button, and the account-switch leak hiding in a persisted cache.
5 min read
The default tab was a 12-line placeholder for months, because Home had nothing to own. It shipped as pure composition — no backend, no schema, no rebuild — held together by two rules that stop a dashboard from becoming a dumping ground.
6 min read
Dev environments run on toy data or on a GDPR incident. The third option: mirror every production write into dev through a masking Lambda that fakes PII deterministically — same user, same fake identity, forever — with push tokens nulled, never copied.
5 min read
Before v1 could ship, both stores handed over the same unglamorous list: a real website, real legal pages, and a real account-deletion path. What review actually requires, and the design decisions hiding inside the boring parts.
5 min read
Notifications are where good apps become annoying, so every one had to pass a test: what would I thank the app for telling me? Local-first scheduling, token hygiene on shared devices, cold-start deep links, and broadcasts that can't drift from their source.
5 min read
iPad support in seven small phases, built on one decision: a 640pt centered content column that no phone is wide enough to trigger — so every change was tablet-only by construction. Plus the App Store rejection code the plan caught before submission day.
5 min read
npm ci failed on Missing: @opentelemetry/core@2.0.0 — four times, for a package version nothing asked for. A debugging war story about bundled dependencies, lockfile dialects, and published tarballs that are internally incoherent.
6 min read
Point the camera at the handwritten list on the fridge and get editable items. Almost pure assembly — the interesting parts are which pipeline it reuses, why the photo gets deleted, and two Android traps that had nothing to do with vision.
6 min read
The per-list budget from the MVP was measuring the wrong thing. Moving budgets onto a monthly map — with a carry-forward rule that stops editing the past from rewriting the present — and a headline that survives clearing your list.
6 min read
Clearing the Done section felt like losing your history — but the record already existed as soft-deleted rows nothing read. One timestamp, three time semantics, and a documented exception to a house convention turned clearing into archiving.
6 min read
A currency symbol is a user property masquerading as a constant. Unwinding one hardcoded £ touched state architecture (two kinds of readers, two stores, one setter), onboarding (guess, then confirm), and product honesty (relabel is never convert).
7 min read
No price API exists, but after weeks of receipt scanning the user owns a dataset nobody sells. Three screens built on it — and the honesty gates, living in selectors not UI, that stop derived numbers from lying.
7 min read
A barcode is an exact input — so the AI's job flips from interpreting to normalising, the lookup becomes a chain of fallbacks with 3-second fuses, and the cache becomes a shared global model that grows coverage exactly where the world's product databases are blank.
8 min read
The headline money feature: photograph a crumpled receipt, extract priced line items with Claude vision, match them to your list, keep the receipt as an immutable record. Plus two war stories: an IAM AccessDenied that looked impossible, and the save that failed silently for a whole session.
6 min read
The money feature didn't need a money model. One new schema field, prices as an attribute of shopping items, sums in pennies, a green/amber/red budget bar — and the offline architecture from Part 7 paying rent.
7 min read
Six fixes too small to blog about, shipped as one deliberate pass: a 12-line parser instead of an LLM, merge-not-duplicate, bulk clear, brand pull-to-refresh, sticky headers that Android never had, and a bug cured by deleting a component.
7 min read
Reusable 'Weekly essentials' lists shipped with one new schema field and zero new tables. The design fork (new model vs status vs flag), the copy-both-ways helper, and the three ripple effects one boolean forced.
6 min read
The feature was one line of SQL: my most-added grocery items, ranked. DynamoDB doesn't have the clause. Here's the client-side aggregation that shipped instead — with explicit scan budgets, honest counts, and a documented exit ramp.
6 min read
Users wanted to reorder and rename the aisle headers on their shopping list. Small problem: the aisles don't exist — they're free-text strings Claude stamps on items. The fix is an old modeling trick: split identity from display.
5 min read
Drag-to-reorder on a grouped React Native list set off a cascade of Android gesture bugs — crash, refresh freeze, header overlap, janky scroll. The fix wasn't debugging harder. It was re-reading the requirement.
6 min read
A grocery app has to work where signal dies — the store. Here's offline-first without a sync engine: React Query pauses, persists, and replays your mutations, made robust by keyed mutation defaults and client-generated IDs.
6 min read
A real 3-way theme setting for Expo + NativeWind: one colorScheme.set() call cascades light/dark/system through your utility classes, the navigation theme, and the native tab bar. Redux holds the choice, AsyncStorage remembers it.
6 min read
Speak your groceries, get a structured, categorised, editable list. The interesting part isn't the LLM — it's the review gate I put between Claude and my database so a bad parse can never silently save.
6 min read
Same commit, opposite outcome: dev deployed clean, main rolled back every time. The log said only 'Validation failed with 1 error(s)'. The cause was a name two branches were quietly fighting over.
3 min read
There is a good chance that you will need to interact with an external API to receive and send data,...
1 min read
An arcade game player wants to climb to the top of the leaderboard and track their ranking. The game...
5 min read
Metro died with a transformFile error that named no file. The trail ended at a @babel/types from 2017, pulled into node_modules by an Amplify dependency. The hunt, and the one-block fix.
7 min read
My Expo app needs three backends — sandbox, dev, prod. The obvious way to hand each build its config hit a 4 KiB wall. Here's the per-environment pattern that replaced it.
4 min read
Voice-first grocery lists on Amplify Gen 2 + Expo, built in public. The stack, what works already, and the three ways it's bitten me so far.
1 min read
Given an array of integers, find the longest subarray where the absolute difference between any two...
2 min read
Interacting with external APIs is often essential, and React Query simplifies this by allowing you to...
2 min read
Building a multipage form in React can be streamlined using React-Hook-Form for form handling and...
1 min read
In this series, I will begin a journey into creating a platform that will allow anyone willing, to...
3 min read
HTML (HyperText Markup Language) is the most basic building block of the Web. It defines the meaning...
2 min read
An avid hiker keeps meticulous records of their hikes. During the last hike that took exactly steps...
2 min read
A teacher asks the class to open their books to a page number. A student can either start turning...
2 min read
Given a 6 X 6 Array arr: 1 1 1 0 0 0 0 1 0 0 0 0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0...
1 min read
There is a large pile of socks that must be paired by color. Given an array of integers representing...
1 min read
Two friends Anna and Brian, are deciding how to split the bill at a dinner. Each will only pay for...
1 min read
Given an array of bird sightings where every element represents a bird type id, determine the id of...
1 min read
The HNG Internship is an ambitious attempt to change the way education is done in Africa. It’s the...