https://sabinsth.com Blog posts, project write-ups, notes, snippets, TIL and case studies from Sabin Shrestha. en-us https://sabinsth.com/til/2026-08-23-stripe-webhook-idempotency https://sabinsth.com/til/2026-08-23-stripe-webhook-idempotency Sun, 23 Aug 2026 00:00:00 GMT TIL that Stripe can and will deliver the same webhook event more than once, and a handler that reacts to checkout.session.completed by granting access will happily grant it twice — the fix was recording processed event IDs and treating the handler as a set operation, not an append. TIL https://sabinsth.com/til/2026-08-21-presigned-urls-secure-file-downloads https://sabinsth.com/til/2026-08-21-presigned-urls-secure-file-downloads Fri, 21 Aug 2026 00:00:00 GMT TIL how to replace a guessable direct-download link with a permission-checked, time-limited presigned URL, so the object storage path a purchased asset actually lives at is never sent to the client. TIL https://sabinsth.com/til/2026-08-20-sse-instead-of-websockets-live-vote-counts https://sabinsth.com/til/2026-08-20-sse-instead-of-websockets-live-vote-counts Thu, 20 Aug 2026 00:00:00 GMT TIL that live vote tallies only need server-to-client push, not a full-duplex protocol — swapping a hand-rolled WebSocket setup for Server-Sent Events dropped the reconnection logic entirely and simplified the reverse proxy config. TIL https://sabinsth.com/til/2026-08-19-live-poll-results-server-sent-events https://sabinsth.com/til/2026-08-19-live-poll-results-server-sent-events Wed, 19 Aug 2026 00:00:00 GMT TIL that once vote writes were race-free, the results screen still felt dead until a manual refresh — switching from client polling to Server-Sent Events made results update instantly without the bidirectional complexity WebSockets would have added for a channel that only ever sends in one direction. TIL https://sabinsth.com/til/2026-08-18-preventing-duplicate-votes-mongodb https://sabinsth.com/til/2026-08-18-preventing-duplicate-votes-mongodb Tue, 18 Aug 2026 00:00:00 GMT TIL that a 'check if the user already voted, then write' guard is racy under concurrent requests — the fix was a unique compound index plus an atomic $inc, so MongoDB rejects the duplicate instead of the app trying to catch it first. TIL https://sabinsth.com/til/color-scheme-dark-leaks-into-print-pdf https://sabinsth.com/til/color-scheme-dark-leaks-into-print-pdf Mon, 17 Aug 2026 00:00:00 GMT TIL that setting color-scheme: dark once on html/body for a dark-themed site makes the browser paint its default canvas background dark everywhere that property cascades — including print and PDF output — unless @media print resets it. TIL https://sabinsth.com/til/webhook-idempotency-deterministic-ids https://sabinsth.com/til/webhook-idempotency-deterministic-ids Sun, 16 Aug 2026 00:00:00 GMT TIL that webhook delivery is at-least-once, not exactly-once. Instead of trying to prevent duplicate deliveries, derive a deterministic ID from the event and let the receiver refuse to redo work it already did. TIL https://sabinsth.com/blog/sprout-feedback-to-git-branch-nextjs-supabase https://sabinsth.com/blog/sprout-feedback-to-git-branch-nextjs-supabase Sat, 15 Aug 2026 00:00:00 GMT A template that wires a public feedback form straight into GitHub — every submission becomes a git branch via Claude Code, with no human touching the pipeline in between. Blog https://sabinsth.com/til/2026-08-15-mdx-jsx-expression-attributes-lose-value https://sabinsth.com/til/2026-08-15-mdx-jsx-expression-attributes-lose-value Sat, 15 Aug 2026 00:00:00 GMT TIL that generating attr={"..."} into MDX source instead of attr="..." made a prop come back as an empty object on every render, with no error anywhere in the pipeline — found while writing the Obsidian-callout preprocessor for this site. TIL https://sabinsth.com/til/fuse-js-search-across-content-collections https://sabinsth.com/til/fuse-js-search-across-content-collections Fri, 14 Aug 2026 00:00:00 GMT TIL that a single flat Fuse.js index with weighted keys is enough to search blog posts, TIL entries, projects, case studies, and snippets together — no separate index or backend needed per collection. TIL https://sabinsth.com/til/2026-08-13-websocket-broadcast-dead-connections https://sabinsth.com/til/2026-08-13-websocket-broadcast-dead-connections Thu, 13 Aug 2026 00:00:00 GMT TIL that looping over every connected WebSocket client and sending a message throws on the first one that's already gone, which silently drops the update for everyone still connected after it in the list — the fix is a try/except per connection, not around the loop. TIL https://sabinsth.com/til/short-lived-signed-urls-paid-downloads https://sabinsth.com/til/short-lived-signed-urls-paid-downloads Wed, 12 Aug 2026 00:00:00 GMT TIL that a private-looking direct download URL for a purchased file is still a public URL forever, and the fix is generating a signed, expiring link on demand after checking ownership server-side. TIL https://sabinsth.com/til/react-use-optimistic-auto-revert https://sabinsth.com/til/react-use-optimistic-auto-revert Tue, 11 Aug 2026 00:00:00 GMT TIL why React's useOptimistic hook doesn't need explicit rollback code when a server call fails, while a manual optimistic-update hook built on plain useState does. TIL https://sabinsth.com/til/aeo-vs-seo https://sabinsth.com/til/aeo-vs-seo Mon, 10 Aug 2026 00:00:00 GMT TIL: Answer Engine Optimization (AEO) optimizes for being the answer an AI cites, not just ranking in a list of blue links — and most of what makes a Next.js site AEO-friendly is stuff good SEO already wants. TIL https://sabinsth.com/til/mutationobserver-infinite-loop-injected-ui https://sabinsth.com/til/mutationobserver-infinite-loop-injected-ui Mon, 10 Aug 2026 00:00:00 GMT TIL a MutationObserver watching a third-party page fires again on the elements your own extension code just injected, causing an infinite injection loop unless the injection function is idempotent. TIL https://sabinsth.com/blog/nvim-log-insert-plugin https://sabinsth.com/blog/nvim-log-insert-plugin Mon, 27 Jul 2026 00:00:00 GMT A tiny Lua plugin that inserts a detailed console.log — file, line number, function, and variable name — with a single leader keymap. Blog https://sabinsth.com/blog/rrr-stack-docker-compose https://sabinsth.com/blog/rrr-stack-docker-compose Mon, 27 Jul 2026 00:00:00 GMT A service-by-service breakdown of rrr-stack, my one-command Docker Compose setup for Jellyseerr, Prowlarr, Sonarr, Radarr, Lidarr, qBittorrent, Jellyfin, Homepage, and Maintainerr. Blog https://sabinsth.com/blog/self-hosted-home-media-server-docker https://sabinsth.com/blog/self-hosted-home-media-server-docker Mon, 27 Jul 2026 00:00:00 GMT A complete walkthrough of my home server — TrueNAS for backups, Proxmox for virtualization, and a fully automated Docker media stack with the *Arr apps and Jellyfin. Blog https://sabinsth.com/snippets/nextjs-useauth-context https://sabinsth.com/snippets/nextjs-useauth-context Mon, 27 Jul 2026 00:00:00 GMT A React context wrapping an API — login, logout, signup, and password reset — that keeps the client in sync with an httpOnly session cookie by revalidating on mount. Snippets https://sabinsth.com/snippets/redis-clustered-map-pins https://sabinsth.com/snippets/redis-clustered-map-pins Mon, 27 Jul 2026 00:00:00 GMT Serve map pins for whatever bounding box a user is currently viewing, cached in Redis by the exact viewport, with overlapping pins clustered in SQL before they ever leave the server. Snippets https://sabinsth.com/case-studies/clonify-saas-platform https://sabinsth.com/case-studies/clonify-saas-platform Mon, 27 Jul 2026 00:00:00 GMT Rebuilding a digital-products marketplace from WordPress to Next.js and Payload CMS, with a custom JSON caching layer and secure, subscription-aware asset delivery. Case Studies https://sabinsth.com/case-studies/pasal-sms-business-platform https://sabinsth.com/case-studies/pasal-sms-business-platform Mon, 27 Jul 2026 00:00:00 GMT A multi-tenant SaaS platform on Next.js, Express.js and MongoDB that replaces notebook-and-spreadsheet shop record keeping with digital sales, credit, inventory, and analytics tracking. Case Studies https://sabinsth.com/case-studies/photo-pasal-gifting-platform https://sabinsth.com/case-studies/photo-pasal-gifting-platform Mon, 27 Jul 2026 00:00:00 GMT Turning a Messenger-and-phone-calls print shop into a scalable Next.js and Payload CMS e-commerce platform for personalized gifting in Nepal. Case Studies https://sabinsth.com/case-studies/pollarise-social-polling-platform https://sabinsth.com/case-studies/pollarise-social-polling-platform Mon, 27 Jul 2026 00:00:00 GMT A scalable SaaS polling platform on Next.js, Node.js and MongoDB, built to turn opinion-sharing into a fast, social, mobile-first experience rather than a survey form. Case Studies https://sabinsth.com/case-studies/recaho-dispatcher-extension https://sabinsth.com/case-studies/recaho-dispatcher-extension Mon, 27 Jul 2026 00:00:00 GMT A Chrome extension that injects a live operational dashboard and workflow automation into an existing dispatch platform, with zero backend access or modification. Case Studies https://sabinsth.com/case-studies/teamenoch-website-nextjs-cms https://sabinsth.com/case-studies/teamenoch-website-nextjs-cms Mon, 27 Jul 2026 00:00:00 GMT Turning a traditional service-business website into an SEO-focused, content-driven Next.js and Payload CMS platform built to generate leads and scale with the business. Case Studies https://sabinsth.com/til/2026-06-18-production-only-bugs https://sabinsth.com/til/2026-06-18-production-only-bugs Thu, 18 Jun 2026 00:00:00 GMT TIL that a bug I couldn't reproduce locally turned out to depend on a real difference between environments — request concurrency — that my local setup structurally couldn't produce, no matter how hard I tried to repro it. TIL https://sabinsth.com/til/2026-06-13-traefik-reverse-proxy https://sabinsth.com/til/2026-06-13-traefik-reverse-proxy Sat, 13 Jun 2026 00:00:00 GMT TIL that manually editing an Nginx config and restarting it for every new service didn't scale past a handful of containers — Traefik's label-based routing removed that step entirely by discovering services automatically. TIL https://sabinsth.com/til/2026-06-09-docker-application-deployment https://sabinsth.com/til/2026-06-09-docker-application-deployment Tue, 09 Jun 2026 00:00:00 GMT TIL that 'works on my machine' stopped being a real category of bug the day I containerized the API, not because Docker is clever but because it removed an entire class of environment-drift I'd been debugging manually. TIL https://sabinsth.com/til/2026-06-06-framer-alongside-development https://sabinsth.com/til/2026-06-06-framer-alongside-development Sat, 06 Jun 2026 00:00:00 GMT TIL that building the Clonify Framer plugin taught me Framer is a genuinely different target than a normal web build — its plugin runtime and code-component model don't map 1:1 onto React conventions. TIL https://sabinsth.com/til/2026-06-02-figma-to-react-components https://sabinsth.com/til/2026-06-02-figma-to-react-components Tue, 02 Jun 2026 00:00:00 GMT TIL that building each screen straight from its Figma frame produced pixel-accurate but unreusable components — the fix was designing the component API from the design system's tokens, not from any one screen. TIL https://sabinsth.com/til/2026-05-31-unreliable-mobile-networks https://sabinsth.com/til/2026-05-31-unreliable-mobile-networks Sun, 31 May 2026 00:00:00 GMT TIL that 'handle offline' undersold the actual problem — the failure mode that hurt drivers most was a flaky, half-connected state, not a clean offline/online boundary. TIL https://sabinsth.com/til/2026-05-26-choosing-object-storage-images https://sabinsth.com/til/2026-05-26-choosing-object-storage-images Tue, 26 May 2026 00:00:00 GMT TIL that storing delivery-proof photos as base64 blobs in MongoDB worked fine at low volume and turned into slow queries and ballooning backups once real usage kicked in. TIL https://sabinsth.com/til/2026-05-23-choosing-nodejs-hosting-saas https://sabinsth.com/til/2026-05-23-choosing-nodejs-hosting-saas Sat, 23 May 2026 00:00:00 GMT TIL that I picked Render for a Node.js API expecting the deciding factor to be price, and the thing that actually mattered day to day turned out to be deploy simplicity and predictable cold-start behavior. TIL https://sabinsth.com/til/2026-05-19-complete-delivery-management-system https://sabinsth.com/til/2026-05-19-complete-delivery-management-system Tue, 19 May 2026 00:00:00 GMT TIL that a system spanning a browser extension, a React Native app, an API, and a database only stayed maintainable solo because I treated the API as the one real product and everything else as a thin client of it. TIL https://sabinsth.com/til/2026-05-16-photo-proof-of-delivery https://sabinsth.com/til/2026-05-16-photo-proof-of-delivery Sat, 16 May 2026 00:00:00 GMT TIL that the hard part of a photo-proof-of-delivery feature isn't the camera or the upload individually — it's making sure a completed delivery can never end up without its proof attached. TIL https://sabinsth.com/til/2026-05-11-dispatch-management-dashboard https://sabinsth.com/til/2026-05-11-dispatch-management-dashboard Mon, 11 May 2026 00:00:00 GMT TIL that a dispatch dashboard built around 'show all the order fields' overwhelmed the person actually using it — the redesign that worked started from what a dispatcher needs to decide, not what data exists. TIL https://sabinsth.com/til/2026-05-09-regex-delivery-times https://sabinsth.com/til/2026-05-09-regex-delivery-times Sat, 09 May 2026 00:00:00 GMT TIL that a regex tuned against a handful of examples ('DELIVERY TIME: 2:00 PM') broke on real data within a day because of extra whitespace and inconsistent AM/PM casing I hadn't accounted for. TIL https://sabinsth.com/til/2026-05-05-extracting-delivery-info-dynamic-html https://sabinsth.com/til/2026-05-05-extracting-delivery-info-dynamic-html Tue, 05 May 2026 00:00:00 GMT TIL that a content script querying the DOM immediately on page load found nothing, because the POS's order details render client-side, after the content script's own 'document_idle' point had already passed. TIL https://sabinsth.com/til/nextjs-route-handlers-return-plain-responses https://sabinsth.com/til/nextjs-route-handlers-return-plain-responses Sun, 03 May 2026 00:00:00 GMT TIL you don't need NextResponse for a simple Route Handler — a standard Web API Response works fine, which matters for things like hand-rolled RSS/XML endpoints. TIL https://sabinsth.com/projects/recaho-helper-chrome-extension https://sabinsth.com/projects/recaho-helper-chrome-extension Fri, 01 May 2026 00:00:00 GMT Browser extension that improves productivity while working inside Recaho. Projects https://sabinsth.com/til/2026-05-01-pos-integration-without-control https://sabinsth.com/til/2026-05-01-pos-integration-without-control Fri, 01 May 2026 00:00:00 GMT TIL that integrating with a system you don't own means designing for its changes, not just its current behavior — the architecture that survived was the one that assumed the POS would break the integration eventually. TIL https://sabinsth.com/til/2026-04-28-chrome-extension-to-nodejs-api https://sabinsth.com/til/2026-04-28-chrome-extension-to-nodejs-api Tue, 28 Apr 2026 00:00:00 GMT TIL that a fetch call from a content script that worked fine in the console failed silently from the actual extension, because content scripts run in an isolated world with their own CORS and CSP rules. TIL https://sabinsth.com/til/2026-04-23-injecting-ui-into-website https://sabinsth.com/til/2026-04-23-injecting-ui-into-website Thu, 23 Apr 2026 00:00:00 GMT TIL that a naive injected panel kept getting wiped out by the host page's own re-renders — the fix was watching for that, not fighting it, and mounting into a container the host page has no reason to touch. TIL https://sabinsth.com/snippets/use-debounce-hook https://sabinsth.com/snippets/use-debounce-hook Wed, 22 Apr 2026 00:00:00 GMT A small generic hook for debouncing a fast-changing value — search inputs, resize handlers, anything you don't want firing on every keystroke. Snippets https://sabinsth.com/til/2026-04-21-content-script-read-pos-data https://sabinsth.com/til/2026-04-21-content-script-read-pos-data Tue, 21 Apr 2026 00:00:00 GMT TIL that a content script reading order data straight from the DOM breaks every time the POS ships a markup change — the fix was reading from the most stable layer available, not the most convenient one. TIL https://sabinsth.com/til/2026-04-17-chrome-extension-manifest-v3 https://sabinsth.com/til/2026-04-17-chrome-extension-manifest-v3 Fri, 17 Apr 2026 00:00:00 GMT TIL that MV3's move from persistent background pages to event-driven service workers means you can't hold long-lived in-memory state the way old extension tutorials assume — it gets killed and restarted constantly. TIL https://sabinsth.com/til/2026-04-14-api-timestamps-local-time https://sabinsth.com/til/2026-04-14-api-timestamps-local-time Tue, 14 Apr 2026 00:00:00 GMT TIL that hardcoding a UTC+4 offset for timestamps because most orders happened to be local worked right up until a driver or a server ended up in a different timezone. TIL https://sabinsth.com/notes/nextjs-server-client-mental-model https://sabinsth.com/notes/nextjs-server-client-mental-model Fri, 10 Apr 2026 00:00:00 GMT The rule of thumb I actually use when deciding whether a component needs 'use client', and how a Server Component parent can still pass data down to it. Notes https://sabinsth.com/til/2026-04-10-unknownhostexception-android https://sabinsth.com/til/2026-04-10-unknownhostexception-android Fri, 10 Apr 2026 00:00:00 GMT TIL that an Android UnknownHostException on a hostname that resolved fine everywhere else usually isn't a DNS problem at all — it's the app pointed at a hostname that only ever existed on my dev machine. TIL