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Sergey Chernyshev

@sergeyche.dev
580 followers 178 following 503 posts

I care about UX speed and organize NY UX Speed and Web Performance meetup

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Sergey Chernyshev @sergeyche.dev · 30/09/2026
Looking forward to @folkcomputer.bsky.social open house tonight. Ready to be amazed and immerse into physical computing practice and ask a million questions of existing practitioners.
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Rick Viscomi @rviscomi.dev · 29/09/2026
v0.0.191 of Modern Web Guidance is out and it's a big one! *16* new guides covering: web components by @castastrophe.bsky.social Cross-Origin Storage by @tomayac.com security by @rowan.fyi UI and PWA by @jamessw.com and @sturobson.com Wasm by @sbc100.bsky.social github.com/GoogleChrome...
accessible-web-components: Make custom elements accessible by default, setting roles and ARIA state via the ElementInternals ARIA mixin, managing focus with delegatesFocus, and keeping ARIA relationships within a single shadow root.
custom-elements: Define, register, and manage the lifecycle of autonomous custom elements, covering constructor rules, lifecycle callbacks, upgrade timing, attribute/property reflection, and naming conventions.
form-associated-custom-elements: Make a custom control participate natively in forms with formAssociated and ElementInternals, submitting its own value, integrating with constraint validation, and reacting to reset, disable, and state-restore.
prerendering-custom-elements: Server-render a custom element, then hydrate it in place without re-rendering or a flash of unstyled content.
shadow-dom: Encapsulate a component's DOM and styles with Shadow DOM, construct the tree efficiently with HTML templates, and project consumer content with slots.
styling-web-components: Style across the shadow boundary with :host selectors, inherited and custom properties for theming, ::slotted and ::part, and cascade layers and container queries inside components.
web-components: Orientation and cross-cutting principles for authoring and using Web Components, covering Custom Elements, Shadow DOM, templates and slots, Declarative Shadow DOM, styling across the shadow boundary, Form-Associated Custom Elements, and accessibility requirements. Use this guide when building reusable UI components, design systems, or server-rendered custom elements.
avoid-redundant-large-asset-downloads: Avoid re-downloading and re-storing large shared assets, such as AI models, Wasm modules, or fully-bundled JavaScript libraries, that a visitor's browser may already hold from an unrelated site.
load-shared-resources-declaratively: Serve popular, unmodified scripts, stylesheets, and JavaScript modules from a shared cross-origin cache using markup or import syntax alone, witho…New Guides
migrate-web-app-origin: Transfer an installed web app to a new origin while preserving user configuration and OS-level shortcuts.
local-network-access: Access resources on a user's local network or loopback interface from a public web application.
trusted-types: Help prevent DOM-based XSS attacks by ensuring all untrusted content is sanitized before being inserted into the page.
responsive-table: Build a data table that presents tabular data with proper header semantics, and remains readable and navigable on small screens and with assistive technologies.
spatial-navigation: Implement accessible spatial navigation using arrow keys that works correctly in different layout modes (grid etc)
cpp-on-the-web: Compile C/C++ to WebAssembly using Emscripten

Updated the animated-select-picker guide to advise using standard value attributes on <option> elements to ensure standard form submission behavior.
Updated the branded-select-styling guide to emphasize retaining standard value attributes on <option> elements to preserve default form submission behaviors.
Updated the custom-select-picker-layouts guide with guidance on using :open::picker(select) selectors, customizing the ::checkmark pseudo-element, wrapping <selectedcontent> in a <button>, and managing keyboard navigation and accessibility constraints for grid layouts.
Updated the rich-media-picker guide to clarify that standard value attributes should be maintained on <option> elements to preserve form submission functionality.
Updated the out-of-order-html-streaming guide to document the full suite of static and streaming DOM insertion methods, detailing built-in sanitizer behaviors, WritableStream integration, and processing instruction marker practices.
Updated the sanitize-untrusted-html guide to detail node manipulation patterns using Document.parseHTML() to avoid mutation XSS, explain child preservation rules via replaceWithChildrenElements, and provide aligned DOMPurify fallback configurations.
Updated…Removed the prevent-text-wrapping guide.

HTML processing instructions: Added Chrome 150 and Edge 150 support in out-of-order-html-streaming.

A four-column table titled "Benchmark Evaluations" comparing unguided versus guided pass rates across 132 tasks and 1,124 assertions.

Row 1: codex_cli (gpt-5.6-sol) achieved a 59% unguided pass rate and an 81% guided pass rate, an uplift of +22 percentage points.

Row 2: claude_code (claude-sonnet-5) achieved a 54% unguided pass rate and an 87% guided pass rate, an uplift of +33 percentage points.

Row 3: antigravity (gemini-3.8-flash-medium) achieved a 65% unguided pass rate and a 91% guided pass rate, an uplift of +26 percentage points.
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Sergey Chernyshev @sergeyche.dev · 29/09/2026
Last few early-ish tickets left. I can't wait to be there and seeing you all!
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Sergey Chernyshev @sergeyche.dev · 29/09/2026
Just watched the video by @kevinpowell.co about AI impact on our jobs: www.youtube.com/watch?v=1aW7... I feel like many of us might be having "AI burnout" - a new type of burnout that we in software industry didn't see before. The analogy of moving from hand-crafted to conveyor belts seems right.
youtube.com
We're all fed up
YouTube video by General Musings with Kevin Powell
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Sergey Chernyshev @sergeyche.dev · 28/09/2026
Not so small step for Bsky, giant leap for mankind/ATproto ;)
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Sergey Chernyshev @sergeyche.dev · 28/09/2026
This has been in the works for a bit, happy to see BEACON dataset now available in RUM Archive. /cc @paulcalvano.bsky.social
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NY Web Performance @nywebperf.com · 20/09/2026
We'd love to welcome @loim.dev to the organizing team as Social Media Manager! 🎉 🎉 🎉 🎉 🎉 If you'll see event announcements on here or other platforms or get our event emails, know that Liam is the one driving these efforts. If you'd like to join the team, reach out here: www.nywebperformance.org
nywebperformance.org
Meet Our Organizer Team
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NY Web Performance @nywebperf.com · 19/09/2026
Slides from Sufian Rhazi's "Speed is a shape (why React is slow)" talk: github.com/nywebperf/sp... You can find Sufian at abstract.properties Video coming soon to our YouTube! #webperformance #nyc #reactjs
github.com
speaker-slides/2026-09-17-Sufian-Rhazi/Speed is a shape.pdf at main · nywebperf/speaker-slides
Contribute to nywebperf/speaker-slides development by creating an account on GitHub.
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Sergey Chernyshev @sergeyche.dev · 18/09/2026
Is it just me or YouTube is playing at 10x speed or something?
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Chrome for Developers @developer.chrome.com · 17/09/2026
Modern Web Guidance v0.0.187 brings new and updated guides and Codex plugin support → goo.gle/4harAXQ ✨ New guides: progress rings, scrollspy nav menus, loading spinners 📝 Updated guidance to avoid bfcache breakage and unwanted inline layout gaps 🔌 Added plugin manifest support for Codex
goo.gle
Release v0.0.187 · GoogleChrome/modern-web-guidance
Release Notes: v0.0.187 🆕 New Guides Introduced a new guide for progress-ring detailing how to build accessible, customizable circular progress indicators that visually communicate task completion...
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NY Web Performance @nywebperf.com · 17/09/2026
Tonight at 6:00PM @ Cloudflare: "Speed is a shape (why React is slow)" with Sufian Rhazi. If you RSVPed, we'll see you there! nywebperf.com/e/315924565/... #webperformance #nyc #reactjs
nywebperf.com
Speed is a shape (why React is slow), Thu, Sep 17, 2026, 6:00 PM | Meetup
If we take a step back from flame charts and performance profiles to ask "**what does React need to do**?" we can see that it's not one particular thing that makes your Rea
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Sergey Chernyshev @sergeyche.dev · 17/09/2026
I've given a short spiel about UX Speed at W3C RUM Community Group session (following a presentation by @njansma.bsky.social about Agentic Browsers). Here's a deep link to my part of the talk, but I recommend listening to the whole thing: drive.google.com/file/d/1bqQn...
drive.google.com
2026-09-09 RUMCG Meeting Recording
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Sergey Chernyshev @sergeyche.dev · 15/09/2026
The next question is - will there be a multi-account app that lets you do your split personality / corporate brand posting? Currently picking the identity in @bsky.app works well, but can be improved upon for those who‘s job it is to maintain many accounts.
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Sergey Chernyshev @sergeyche.dev · 15/09/2026
Trying out @mu.social - added web app to home screen and it seems to work fine. Very refreshing to be able to natively use a different UI for the same social network.
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Sergey Chernyshev @sergeyche.dev · 15/09/2026
When working noon-8 (e.g. west coast company / east coast home office) is an option would that be your preference? Especially during good weather seasons/weeks when you enjoy it or miss it? I had been shifting my hours sometimes as of late for other reasons but is this a normal thing people do?
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NY Web Performance @nywebperf.com · 12/09/2026
This Thursday, September 17 at 6:00PM: "Speed is a shape (why React is slow)" with Sufian Rhazi RSVP: nywebperf.com/e/315924565/... ⚠️ RSVPs close September 15 #webperformance #nyc #reactjs
nywebperf.com
Speed is a shape (why React is slow), Thu, Sep 17, 2026, 6:00 PM | Meetup
If we take a step back from flame charts and performance profiles to ask "**what does React need to do**?" we can see that it's not one particular thing that makes your Rea
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IGDA NYC @igdanyc.bsky.social · 08/09/2026
Sept 22: Level Up Tuesday! Speaker Matt has made maps and mods for Doom and other video games for over 30 years! "A Critique on Critique: How to Handle Feedback" explores how to categorize and gather feedback. RSVP HERE for free entry to the game club: www.coexistgaming.com/event-detail...
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Joan León @nucliweb.net · 07/09/2026
P75 is green: LCP 1.58s, INP 176ms, CLS 0.01. P90: LCP 2.68s, INP 352ms, CLS 0.17. 15% of visits get a noticeably worse experience. Product Performance doesn't end once you pass CrUX: if P75 is good, work on P90. #WebPerf #CoreWebVitals #RUM #ProductPerformance
DebugBear RUM dashboard showing Core Web Vitals at the P75 percentile: Largest Contentful Paint 1.58s, Interaction to Next Paint 176ms, and Cumulative Layout Shift 0.01, all flagged green on the score bar.DebugBear RUM dashboard showing Core Web Vitals at the P90 percentile: Largest Contentful Paint 2.68s, Interaction to Next Paint 352ms, and Cumulative Layout Shift 0.17, all flagged orange or red on the score bar.
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WebPerformance Report @webperfreport.bsky.social · 06/09/2026
⚡Featured posts this week: ✨ Submit your proposals for Interop 2027: @rachelandrew.co.uk ✨ Reading a performance profile: @nucliweb.net ✨ HTML over WebSockets: @androsfenollosa.bsky.social ✨ Intro to Web UX and Speed Optimization: @sergeyche.dev 🙏 Special thanks to the authors! #webperf
WebPerformance Report performance email preview highlighting optimization scores, Perf Links, and Core Web Vitals metrics on a colorful gradient background.
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Ryan Townsend @twnsnd.com · 03/09/2026
Can 2027 be the year we finally get all the Core Web Vitals in all browsers? 🙏 Work your magic folks: github.com/web-platform... #webperf
Bernie Sanders meme captioned “I am one again asking for CLS”
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NY Web Performance @nywebperf.com · 02/09/2026
Join us in 2 weeks on September 17 at 6:00PM for "Speed is a shape (why React is slow)" with Sufian Rhazi RSVP: nywebperf.com/e/315924565/... #webperformance #nyc #meetup
nywebperf.com
Speed is a shape (why React is slow), Thu, Sep 17, 2026, 6:00 PM | Meetup
If we take a step back from flame charts and performance profiles to ask "**what does React need to do**?" we can see that it's not one particular thing that makes your Rea
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Sergey Chernyshev @sergeyche.dev · 02/09/2026
Multi-tasking in software space have always been hard as you need to keep mental models of multiple things active in your head at the same time. AI-assisted multi-tasking is even harder.
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performance.now() conference @perfnow.nl · 01/09/2026
Three new speakers were announced for perfnow.nl ! Aleth Gueguen about native web and PWAs. @adactio.com about long-term performance: not milliseconds but decades Risko Ruus about regression testing and other QA Tickets: perfnow.nl/tickets.html See you in November in Amsterdam!
perfnow.nl
performance.now(); 19th and 20th of November 2026, Amsterdam
On 19th and 20th of November 2026, the seventh edition of performance.now() will take place in Amsterdam—a single track conference, covering today’s most important web performance insights.
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Rachel Andrew @rachelandrew.co.uk · 01/09/2026
Two a11y engineering roles (one of them early career!) at Apple in London in the team my daughter manages. These sound like excellent roles to share with UK a11y folks. jobs.apple.com/en-gb/detail... jobs.apple.com/en-gb/detail...
jobs.apple.com
Accessibility Engineer (Web Accessibility SME) - Jobs at Apple (UK)
Apply for a Accessibility Engineer (Web Accessibility SME) job at Apple. Read about the role and find out if it’s right for you.
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Mateusz Krzeszowiak @krzksz.bsky.social · 28/08/2026
We made Shopify storefronts faster with automatic Early Hints. By finding and preloading render-blocking resources, we improved p75 FCP by 76ms and LCP by 100ms. No merchant or theme changes required. performance.shopify.com/blogs/blog/f...
performance.shopify.com
Faster Shopify storefronts with automatic Early Hints
We recently changed how Shopify uses Early Hints on storefronts. Instead of relying only on resource hints added by theme authors, we now scan generated HTML and automatically identify resources that ...
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Sergey Chernyshev @sergeyche.dev · 28/08/2026
3^3 wedding anniversary and 2^5 since we met
maracuya mousse and caramel flan for desert
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NY Web Performance @nywebperf.com · 26/08/2026
Get ready for "Speed is a shape (why React is slow)" with Sufian Rhazi on September 17 at 6:00PM! RSVP: nywebperf.com/e/315924565/... #webperformance #nyc #meetup #uxspeed #react
nywebperf.com
Speed is a shape (why React is slow), Thu, Sep 17, 2026, 6:00 PM | Meetup
If we take a step back from flame charts and performance profiles to ask "**what does React need to do**?" we can see that it's not one particular thing that makes your Rea
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Stefan Judis @stefanjudis.com · 06/08/2026
With Chrome 151, soft navigations entered the mainstream. If you haven't heard the term, a soft navigation is anything that: - is initiated by a user action - results in a visible URL change - results in a visible paint developer.chrome...
Code snippet: const observer = new PerformanceObserver(console.log); observer.observe({ type: 'soft-navigation', buffered: true });
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jenn schiffer 😎 @jennschiffer.com · 22/08/2026
had a v nice time meeting and socializing irl with folks! i am home now to recharge after a v busy 24 hours. btw i wanna shout out @bnb.im who is djing set at @wonderville.nyc tonight! and if you are in town monday night, you can catch me co-ceo’ing robot karaoke there
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Sergey Chernyshev @sergeyche.dev · 22/08/2026
And a live lexicon leaderboard!
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Sergey Chernyshev @sergeyche.dev · 22/08/2026
Fun game + AR + atproto integration!
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Sergey Chernyshev @sergeyche.dev · 22/08/2026
i'm at @atproto.nyc community day 2026 [fhf1pqww] #atprotonyc
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Sergey Chernyshev @sergeyche.dev · 21/08/2026
If coding using AI became so much cheaper, then maybe we should not be writing code and concentrate on defining requirements and constraints as a “source” of our applications and let the agentic workflow “compile” it into code and then production executable systems. #borderless
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[object Object] @zeigenvector.bsky.social · 19/08/2026
As job searches sometimes go, I have found myself starting a fresh round of searching! Let me know if you need a Staff+ Frontend Platform girlie to round out your team! ⚡️🩵✨ If you’re curious what I’ve done in the past, check out my talk about my time at Slack: www.youtube.com/watch?v=f-B2...
youtube.com
Several components are rendering | Jenna Zeigen | LeadDev New York 2024
YouTube video by LeadDev
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Sergey Chernyshev @sergeyche.dev · 19/08/2026
I wonder if imposter syndrome is increasing as we rely on AI more and more in our daily work…
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Sergey Chernyshev @sergeyche.dev · 17/08/2026
I want to take a quick “poll” among the software engineers in the “room”: Q: do you like reviewing PRs?
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atproto.nyc @atproto.nyc · 15/08/2026
make sure you pick up a ticket if you’ve not already!! we can’t wait to see you
events.atmosphere.tickets
Get tickets to atproto.nyc community day 2026
Sat, Aug 22, 2026, 10:00 AM EDT · Recurse Center
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Sergey Chernyshev @sergeyche.dev · 15/08/2026
AI got written texts to be 10x more verbose. My text skimming or fast-reading skill that I develop in my brain over the years only speed reading up by 1.5-2x (this is an estimate). I have no idea how to keep up with this. The only way I can think of is to use AI to summarize what has been written.
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Rick Viscomi @rviscomi.dev · 13/08/2026
Nice teardown of how the Modern Web Guidance skill actually works by @nucliweb.net joanleon.dev/en/modern-we... A lot of thought went into being as token-efficient as possible!
joanleon.dev
A skill that knows nothing: the architecture of Modern Web Guidance | Joan León
Modern Web Guidance doesn't keep the knowledge in the skill, it teaches the agent to retrieve it. Local semantic search with MiniLM and TensorFlow.js, guides with their own grader, and empirical calib...
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Bogdan Chadkin @trysound.io · 12/08/2026
Happy to announce that I’m back maintaining SVGO. It’s a tool I use daily, and I’d like to keep it fresh and stable. github.com/svg/svgo If you’d like to support the project, consider donating via OpenCollective.
github.com
GitHub - svg/svgo: SVG Optimizer for Node.js and CLI. ⚙️
SVG Optimizer for Node.js and CLI. ⚙️. Contribute to svg/svgo development by creating an account on GitHub.
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Phil Hawksworth @philhawksworth.dev · 13/08/2026
Great to see that @smashingconf.com continue to offer scholarships and opportunities for volunteers at their events. Heartily recommended. smashingconf.com/scholarship-...
smashingconf.com
Scholarship and Volunteering
Are you a part of an underrepresented group in tech? Or maybe you’d like to help us out during the days and become a volunteer?
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Sergey Chernyshev @sergeyche.dev · 10/08/2026
Last year I’ve built a backup tool for my 360 photos that I post to Google Maps. Now I am thinking it might benefit from at-proto implementation with integrations for WikiShootMe and OpenStreetMap. If only I had mental capacity to take on one more project ;)
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Sergey Chernyshev @sergeyche.dev · 09/08/2026
Upset with myself for being very unproductive at Starbucks on a weekend - spent 3 hours mostly watching YouTube shorts instead of reviewing a ton of side-project PRs made by my AI coder. Maybe I wasn’t in the mood for it, but still feel like I wasted what’s left of my brain after a week of work.
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Sergey Chernyshev @sergeyche.dev · 07/08/2026
Progressive enhancement is the way to build software - use fallbacks for browser that don’t support things yet. Many tweaks are optional - look at Craigslist!
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Sergey Chernyshev @sergeyche.dev · 06/08/2026
Was just chatting with @alexchernyshev.bsky.social about the fact that speaking to your computer is the change that is hard and probably occupies the centers in our brain and vocal chords more than what we are used to. I wonder how many social norms and not tech we will have hard time changing.
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Joan León @nucliweb.net · 03/08/2026
Web performance is a marathon, not a sprint. Ship the fastest site today and in two weeks a third-party script, an unoptimised image or a CDN change will have quietly undone it. Optimising without monitoring doesn't last. 🧵 #WebPerf #RUM #CoreWebVitals
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Barry Pollard @tunetheweb.com · 04/08/2026
Technology, like time, cannot be stopped in it's relentless march forward. Much as us old timers would like to slow down one or the other just a little bit… In light of that, Chrome 153 will come with an updated list of modern devices for emulation mode—with nice categorisation—thanks to @jackf.io
An updated list of modern devices DevTools can emulate now nicely categorised into Mobile, Foldables, Tablets & Desktops, and Smart Displays.
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Sergey Chernyshev @sergeyche.dev · 02/08/2026
Laura got Rudy the dog off the streets, do good and good will come to you: youtu.be/2kOY93THkdQ?...
youtu.be
I Need Your Help Saving This Dog!
YouTube video by Laura Kampf
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Sergey Chernyshev @sergeyche.dev · 30/07/2026
I am feeling that with introduction of AI we might have less obvious changes in SDLC that can be quite useful. For example, the cost of modeling and visualizing system requirements might be so much lower that architectural decisions can be more informed. UX Speed Calculator was one of those tools.
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