标签：#EV

When engineers talk about visual regression or website change monitoring, pixel-level diffing algorithms (like pixelmatch or Euclidean RGB distance) are usually the default solution. However, in real-world web environments, pixel-by-pixel comparisons fundamentally fail under normal user interactions and dynamic rendering conditions: Elastic Layout Shifts: A single 20px dynamic banner inserted at the top of a page pushes every subsequent DOM element down, causing 100% of the downstream pixels to fail a pixelmatch test, even if the content itself hasn't changed. Sub-Pixel Anti-Aliasing Jitter: Operating systems (macOS vs. Linux vs. Windows) render font glyphs with subtle sub-pixel anti-aliasing variations, creating thousands of false-positive pixel deltas. Semantic vs. Cosmetic Changes: Changing a single word in a paragraph should trigger a localized alert, but a minor color gradient shift in a hero image shouldn't trigger an emergency notification. At PageWatch.tech , we solved this by combining classical Structural Similarity (SSIM) , ORB Feature Alignment , and Siamese Neural Networks (SNN) for latent-space semantic comparison. In this article, I will dive into the mathematics, neural network architectures, and TypeScript implementation of our computer vision diff pipeline. 🧮 1. Beyond Pixel Comparison: Structural Similarity Index (SSIM) Unlike raw Mean Squared Error (MSE), SSIM measures visual change based on human perception across three dimensions: Luminance , Contrast , and Structure . Mathematically, the SSIM between two image windows $x$ and $y$ is defined as: $$\text{SSIM}(x, y) = \frac{(2\mu_x\mu_y + C_1)(2\sigma_{xy} + C_2)}{(\mu_x^2 + \mu_y^2 + C_1)(\sigma_x^2 + \sigma_y^2 + C_2)}$$ Where: $\mu_x, \mu_y$ are the local pixel mean intensities. $\sigma_x^2, \sigma_y^2$ are the local variances. $\sigma_{xy}$ is the covariance between $x$ and $y$. $C_1, C_2$ are stabilization constants. TypeScript Implementation of SSIM Window Sliding Below is a snippet of how

The car manufacturer is planning a big push into electric vehicles.

Charing your phone in the car may technically use energy, but not enough to give a second thought.

It's impossible to talk about a new Xbox game without also talking about the state of Xbox. Microsoft's gaming division is in freefall: Recent headlines are dominated by extensive layoffs, decimated studios, and confusing strategies, most of which stem from years of bad decisions and expensive acquisitions. But it wasn't always that way. Through its […]

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Letting a stranger contact a car owner without giving them the number There is a small, very common problem in Indian cities that turns out to be a surprisingly good systems design exercise. A car is parked badly. It is blocking a gate, a driveway, another car. Someone needs the owner to move it, right now. The traditional fix is a phone number written on a sticker on the windscreen. That works. It also means a stranger — any stranger, forever — has the owner's personal number. Why the sticker is worse than it looks Once a number is visible on a windscreen, a few things follow: It gets scraped. Numbers on vehicles end up in marketing lists. It cannot be revoked. Change your number and every sticker you own is now wrong. It has no context. A 2am call could be a genuine emergency or someone who saw the number three months ago. It is a safety issue for some owners in a way it is not for others. A number attached to a vehicle, at a known parking spot, at predictable times, is more information than most people realise they are publishing. So the requirement is oddly specific: a stranger must be able to reach the owner, immediately, without ever learning how to reach them again. That constraint is what makes this interesting. The naive version, and why it fails First instinct: put a QR code on the vehicle that opens a page with a "call owner" button, and put the number behind the button. This solves nothing. The number is still in the page source. Anyone who wants it can get it, and now you have added a scan step for the honest majority while stopping none of the dishonest minority. Second instinct: put a contact form behind the QR. The stranger types a message, the owner gets a notification. Better on privacy, useless in practice. The person needs the car moved in the next ninety seconds. They are not filling in a form and waiting for an email. If the fast path is not there, they go back to writing an angry note. The real requirement is synchronous contact with asynchron

Watermarking a PDF — adding semi-transparent text over pages — sounds like something only desktop software handles. But with pdf-lib and a bit of canvas math, you can build a fully browser-based watermark tool. This post walks through the implementation details, including text rendering, rotation, and multi-page support. Why client-side? Traditional watermark tools upload your file, process it on a server, and send the result back. For documents that might be confidential or contain sensitive information, this introduces an unnecessary privacy risk. A browser-based approach: Processes everything locally Keeps files on the user's device Works offline after loading Avoids server-side bandwidth costs The stack Vue 3 + Composition API pdf-lib for PDF manipulation and watermarks PDF.js ( pdfjs-dist ) for preview rendering Vite for bundling Adding a text watermark pdf-lib provides a built-in PDFDocument.embedFont() method for custom fonts and page.drawText() for placing text. Here's how to add a rotated, semi-transparent watermark across all pages: < script setup lang= "ts" > import { ref } from ' vue ' import { PDFDocument , rgb , StandardFonts } from ' pdf-lib ' const file = ref < File | null > ( null ) const watermarkText = ref ( ' DRAFT ' ) const opacity = ref ( 0.3 ) const fontSize = ref ( 72 ) const rotationDeg = ref ( - 45 ) const applying = ref ( false ) async function handleFileUpload ( selected : File ) { file . value = selected } async function applyWatermark () { if ( ! file . value ) return applying . value = true try { const arrayBuffer = await file . value . arrayBuffer () const pdfDoc = await PDFDocument . load ( arrayBuffer ) // Embed the Helvetica font — required for correct rendering const helveticaFont = await pdfDoc . embedFont ( StandardFonts . HelveticaBold ) const pages = pdfDoc . getPages () pages . forEach (( page ) => { const { width , height } = page . getSize () page . drawText ( watermarkText . value , { x : ( width - helveticaFont . widthOfT

Hi, my name is Dan, I'm a frontend engineer and open-source maintainer. I've spent the last couple of years building Nano Kit — a lightweight, modular state management ecosystem for modern web apps: signals-based stores , a router , data fetching , i18n , and SSR support , all built on the same tiny reactive core. It recently hit 1.0 , and in this post I want to give you four honest reasons to try it. 1. It's fast At the heart of Nano Kit is a push-pull reactivity system based on the algorithm from alien-signals — one of the fastest signal implementations in the JavaScript ecosystem. I didn't use alien-signals directly, though. Nano Kit needed things it doesn't provide, so I built a dedicated fork called Agera : Signal lifecycles — you can listen to signal activation and deactivation, which powers Nano Kit's mountable stores (run setup logic on first listener, clean up on last). Real tree-shaking — Agera is designed so that only the code you use ends up in your bundle; alien-signals is not well tree-shakable. The result keeps almost all of alien-signals' raw speed. Here is how @nano_kit/store compares to other popular state management libraries in a reactivity benchmark : Library Latency avg (ns) Throughput avg (ops/s) alien-signals 294.00 ± 2.24% 3,559,763 @nano_kit/store 303.55 ± 0.75% 3,365,816 svelte/store 428.58 ± 0.61% 2,479,118 rxjs 454.74 ± 0.07% 2,250,397 nanostores 1,373.2 ± 5.96% 952,399 mobx 3,474.7 ± 1.86% 306,094 valtio 5,041.3 ± 11.46% 254,109 jotai 9,454.6 ± 16.45% 157,853 effector 24,885 ± 11.78% 62,744 @reatom/core 59,430 ± 15.61% 22,741 Benchmark was run on AMD Ryzen 5 PRO 3400G with Node.js v24.14.1 That's ~3.5× faster than nanostores and an order of magnitude faster than most atomic state managers — while shipping lifecycles and mountable stores on top. 2. It's small Nano Kit exists largely because of Nano Stores . I love its philosophy: atomic stores, mountable resources, logic moved out of components, and an obsessive focus on bundle size. Nan

In 1996, Bandai sold 82 million Tamagotchis. Kids carried egg-shaped plastic keychains everywhere, frantically pressing three buttons to feed, clean, and play with a pixelated blob that would literally die if you ignored it during math class. It was the first time millions of people felt genuine emotional attachment to a piece of software. 30 years later, I rebuilt that entire experience — in the browser, with TypeScript, zero dependencies, completely open source. No app store. No download. No install. Just open a tab and adopt your pet. And in the process, I learned more about state machines, game loops, and emotional design than any computer science course ever taught me. Why Build a Virtual Pet in 2025? Three reasons: 1. Nostalgia Is a Distribution Hack People share things that trigger childhood memories. It's not rational — it's emotional. A browser-based Tamagotchi hits a nerve that no todo app or dashboard ever will. When I shared an early prototype, the response wasn't "cool tech stack." It was: "OH MY GOD I used to cry when mine died in second grade" That emotional reaction is worth more than any Product Hunt launch. 2. Game State Machines Are Criminally Underrated Every tutorial teaches state machines with traffic lights or toggle buttons. Boring. Useless. Forgettable. A virtual pet has dozens of interconnected states , real-time decay, evolution paths, conditional transitions, and edge cases that force you to actually think about state architecture. After building this, implementing complex UI flows in production apps felt trivial. 3. Not Everything Needs to Be a SaaS The indie dev world is obsessed with "revenue-generating side projects." Sometimes you should build something purely because it makes people smile. The best projects are the ones you'd use even if nobody else existed. Meet Your New Pet When you open Tamagochi, you get an egg. It hatches. A tiny pixelated creature appears. It has needs. Meet them, and it thrives. Ignore them, and... well, game

One of the biggest mistakes beginners make when learning Terraform is treating their local machine as the deployment server. A typical workflow looks like this: terraform init terraform plan terraform apply While this approach is perfectly fine for learning, it quickly becomes problematic when working on real-world projects with multiple engineers. Consider these questions: Who deployed the infrastructure? Was the infrastructure reviewed before deployment? Can someone else reproduce the deployment? What happens if the engineer's laptop is lost or misconfigured? How do we know exactly what changed? These are some of the reasons Infrastructure as Code (IaC) is almost always integrated with Continuous Integration and Continuous Deployment (CI/CD) pipelines in professional environments. In this article, we'll build a simple Terraform CI/CD pipeline using GitHub Actions. Instead of focusing only on the YAML syntax, we'll first understand why each stage exists and how they work together to produce safe, repeatable infrastructure deployments. What is Terraform CI/CD? Terraform CI/CD is the process of automating the validation, planning, and deployment of infrastructure whenever changes are made to Terraform code. Instead of running Terraform commands manually from a developer's laptop, a CI/CD platform executes those commands automatically in a controlled environment. The workflow typically looks like this: Developer │ ▼ Git Push │ ▼ GitHub Repository │ ▼ GitHub Actions │ ▼ Terraform Init │ ▼ Terraform Validate │ ▼ Terraform Plan │ ▼ Manual Approval │ ▼ Terraform Apply │ ▼ AWS Infrastructure This approach provides consistency, visibility, and security while reducing the chances of human error. Why Not Run Terraform Manually? Running Terraform from your laptop works well for personal projects, but it introduces several risks in a team environment. Manual Deployment CI/CD Deployment Requires someone to remember every command Runs automatically Easy to skip validation Validat

In 2023, Bitly's free plan gave you 100 links per month with full analytics. In 2025, they slashed it to 5 links per month . Five. And they started showing full-screen interstitial ads before redirecting — even on links you created years ago. In 2026, their cheapest paid plan is $10/month — just to shorten links without ads. I was paying $120/year to turn long URLs into short ones. A problem that takes 3 lines of code to solve. So I solved it myself. For free. Forever. Introducing ZipLink ZipLink is a fast, self-hostable URL shortener built with Next.js and Firebase. Deploy it once, use it forever. No monthly fees. No link limits. No ads. No "upgrade to unlock analytics." Your links. Your data. Your domain. Your rules. https://yourdomain.com/abc123 → https://some-really-long-url.com/path/to/thing?utm=whatever That's it. That's the product. Except you own it completely. The State of URL Shorteners in 2026 (It's Embarrassing) Let me show you what the "industry leaders" are charging for what is essentially a database lookup: The Comparison Table Feature Bitly Rebrandly Short.io Dub.co TinyURL Pro ZipLink Monthly cost $10-$300/mo $13-$349/mo $19-$149/mo $24-$299/mo $9.99/mo $0 Annual cost $96-$2,388/yr $156-$4,188/yr $228-$1,788/yr $288-$3,588/yr $119.88/yr $0 Free tier links 5/month 10/month 1,000 total 25/month Unlimited (no analytics) Unlimited Custom domain Paid only Free (1 domain) Required Paid only Paid only Yes (yours) Click analytics Paid only Paid only Free (basic) Paid only Paid only Full, free Link expiration Paid only Paid only Yes Yes No Yes Password protection Enterprise only Paid only Paid Paid No Yes API access Paid only Paid only Yes Yes Paid Full, free QR codes 2 free, then paid Paid Yes Paid Paid Unlimited Self-hostable No No No Yes (complex) No Yes (simple) Data ownership Their servers Their servers Their servers Their servers Their servers Your Firebase Ads/interstitials Yes (free tier) No No No Yes (free tier) Never Links disappear if you stop pay

GoPro's Wireless Mic System nails the basics, but it has some frustrating flaws.

When a new platform team set out on implementing their roadmap through forced workflows with poor documentation, developer experience declined. Success came from simplifying governance, prioritizing what matters, and rolling out compliance incrementally through prevention, detection, and communication. Empathy, focus, and shared purpose drove successful adoption. By Ben Linders

The resulting report is a near-random mixture of real problems and grievances.

Gas prices are up, and US car dealerships are full of hybrids. Customers are going for it.

QCon AI New York 2026 (Dec 15-16) has opened registration at The Westin Jersey City Newport. Six tracks on production AI, chaired by Eder Ignatowicz with Faye Zhang and Wes Reisz. First sessions announced in August, full program by November. By Artenisa Chatziou

The next time you’re locked out of your Google account, you can use your face as part of the account recovery process.

Data preservation layouts are no longer just an exercise in handling routine disk failures; they are a direct line of defense in an active cyber-warfare environment. Far too many system administrators blindly default to writing simple, unencrypted shell scripts tied to legacy system utilities. Operating obsolete data-mirroring procedures introduces severe vulnerabilities to enterprise architectures. Traditional file sync tools completely lack client-side encryption barriers, leaving raw production data completely exposed to third-party infrastructure hosts. Furthermore, standard backup approaches consume vast amounts of unnecessary bandwidth by redundantly transferring identical files over and over again. Restic completely destroys this insecure paradigm. Written from the ground up in Go, Restic enforces client-side AES-256-CTR cryptographic encryption by default, ensuring no plain-text data ever traverses the network interface. Leveraging advanced content-defined chunking algorithms, it performs lightning-fast block-level deduplication to compress your overall storage footprint to a minimum. Phase 1: The Backup Orchestration Myth Understanding the architectural superiority of a native Go-compiled, client-side encrypted backup engine is critical before designing your disaster recovery pipeline: Architectural Metric Legacy Sync Tools BorgBackup Platform Modern Restic Engine Native Cloud S3 Support Requires Rclone Mounts Requires Third-Party Proxy Layers Native Compiled Support Default Cryptography None (Plain-Text Transmissions) Client-Side AES-256 AES-256-CTR Client-Side Data Deduplication File-Level Verification Only Content-Defined Block Level Content-Defined Block Level Cross-Platform Portability Variable Compatibility Strictly UNIX/Linux Constrained Single Static Go Binary Phase 2: The Append-Only Lock Paradox (IAM Fix) The most dangerous operational vulnerability found in generic Linux documentation involves key privileges. Amateurs store fully unconstrained ad

Ink & Switch published bijou64, a variable-length integer encoding where every number has exactly one byte representation, closing the canonicality bug class behind attacks on PKCS#1, JWT libraries, and Bitcoin. The design also decodes two to ten times faster than LEB128. Community ports to Elixir, Go, Perl, and Java followed, while HN commenters debated SIMD performance and residual range checks. By Steef-Jan Wiggers

A background worker sits quietly for weeks, chewing through a job queue without incident, and then one Tuesday afternoon it disappears mid-batch, taking forty in-flight jobs down with it. No stack trace pointing at the offending line, no alert until a customer notices their export never finished. Nine times out of ten, the culprit is one of the most under-discussed failure modes in server-side JavaScript: unhandled promise rejections. They are easy to introduce, easy to miss in code review, and in modern Node.js they no longer just print a warning — they can end your process outright. This post walks through what unhandled promise rejections actually are at the engine level, why they are far more dangerous in long-running Node.js services than in typical web requests, how Node's default behavior around them has shifted over the years, and the concrete patterns you can use to stop them from quietly killing your jobs. What an Unhandled Promise Rejection Actually Is At the JavaScript engine level, a promise is a state machine with three possible states: pending, fulfilled, or rejected. When an async operation fails — a network call times out, a database query throws, a JSON parse blows up — the promise representing that operation transitions to the rejected state and carries a reason, usually an Error object. That's all a rejection is: a value flowing down the promise's error channel instead of its success channel. The engine only considers a rejection "handled" if, by the time it does its bookkeeping (which happens on a microtask checkpoint, not synchronously), there is a .catch() handler, a second argument to .then() , or a surrounding try/catch around an await somewhere in that promise's chain. If none of those exist anywhere in the chain, the rejection is classified as unhandled. This is the precise, narrow definition of unhandled promise rejections: a promise that reaches the rejected state with zero handlers attached anywhere along its chain of consumers. It's wo