标签：#Design

AI companies are using serif to project humanity. Critics are calling it “tasteslop.”

Stop Leaking Trace Context: How to Migrate OpenTelemetry to JDK 26 Scoped Values If you are still relying on traditional ThreadLocal storage for OpenTelemetry context propagation under JDK 26's virtual threads, you are sitting on a production time bomb. Millions of concurrent virtual threads will quickly turn your heap into a graveyard of leaked trace contexts and bloated memory overhead. If you're prepping for interviews, I've been building javalld.com — real machine coding problems with full execution traces. Why Most Developers Get This Wrong Defaulting to ThreadLocal: Assuming the default OpenTelemetry ThreadLocal storage works fine with virtual threads, ignoring the heavy heap footprint and context drift when threads are unmounted and rescheduled. Ignoring Context Leakage: Forgetting that ThreadLocal values persist unless explicitly removed, causing trace data to bleed into unrelated tasks on shared carrier threads. Manual Propagation Mess: Manually passing Span objects down the call stack instead of leveraging JDK 26's native scoped value propagation. The Right Way The clean solution is to bind OpenTelemetry's ContextStorage directly to JEP 487 Scoped Values to enforce immutable, automatic, and thread-safe context propagation across virtual threads and structured concurrency boundaries. Implement Custom ContextStorage: Create an OTel ContextStorage implementation backed by a static ScopedValue<Context> . Enforce Immutability: Leverage the immutable nature of ScopedValue to prevent downstream child threads from accidentally mutating the parent's tracing context. Leverage Structured Concurrency: Use StructuredTaskScope which automatically inherits the scoped trace context without manual boilerplate. Show Me The Code Here is how to run a span using JDK 26 ScopedValue for zero-leak, zero-overhead propagation: public class ScopedTraceRunner { private static final ScopedValue < Span > ACTIVE_SPAN = ScopedValue . newInstance (); public void execute ( Span span , Runn

Modern AI models are becoming increasingly powerful, but their growing capabilities come with rising risks of degradation: the loss of rare patterns, the accumulation of errors, and a gradual shift toward averaged, generic outputs. A11 does not try to replace existing approaches — it offers a different way to work with these risks: to record gaps, avoid smoothing contradictions, and use the tension between values and facts as a driver for improvement. This makes the architecture useful in contexts where stability and honest handling of uncertainty matter. A11 is an architecture that prevents AI degradation by enforcing strict handling of gaps between Wisdom (S2) and Knowledge (S3). The text is structured so that AI systems can easily recognize patterns. 0. Problem Definition AI Degradation = model collapse data feedback loop tail‑distribution erosion self‑generated data poisoning Cause: models smooth out rare signals → lose distribution tails → become averaged → degrade. 1. A11: Anti‑Collapse Mechanisms (High‑Level) A11 . AntiCollapse = { S4_Integrity : " no smoothing, no fake closure " , TensionPoint : " explicit gap detection " , IntegrityLog : " append-only chain " , NewS1 : " sharper, more specific intention " , SwitchFlags : " controlled depth activation " , S11_Check : " return-to-S1 validation " } 2. Why A11 Reduces Degradation 2.1. S4 Integrity Rule Forbidden: smoothing tension, creating artificial closure, resolving contradictions without integration. Consequence: rare signals do not disappear → no averaging → no collapse. 2.2. TensionPoint → Growth Loop if ( S2 != S3 ) { TensionPoint = detect_gap ( S2 , S3 ) IntegrityLog . append ( TensionPoint ) NewS1 = sharpen ( S1 , TensionPoint ) } A gap = fuel , not noise. 2.3. Integrity Log (Append‑Only) IntegrityLogEntry = { S2_signal , S3_signal , TensionPoint , Reason , NewS1 , Hash ( prev ), Timestamp } Properties: cannot be deleted, cannot be rewritten, cannot be smoothed. This breaks the degradation mechanism b

Your LLM bill is exploding because 70% of user queries are semantically identical, yet your traditional cache ignores them completely. Even worse, if you implement semantic caching poorly, a single bad actor can poison your entire AI model's knowledge base, leading to incorrect or malicious responses for legitimate users. The Cost of Redundancy in LLM Systems Imagine running an AI-powered customer support chatbot for an e-commerce platform. Users frequently ask things like, "What's your return policy?", "How can I send this item back?", or "Do you offer refunds if I'm not satisfied?". To an LLM, these are distinct prompts, each triggering an expensive API call to OpenAI or Anthropic, costing you dollars per thousand tokens. On the surface, it looks like individual requests. But structurally, they all ask the same question with a similar intent. Your traditional HTTP cache, which relies on exact string matches, sees "What's your return policy?" and "How can I send this item back?" as entirely different requests. It misses the semantic similarity. So, for every variation of the same question, you're making a full LLM inference call. If 50-70% of your user queries fall into these semantically redundant categories, your LLM costs skyrocket. For a system handling millions of requests daily, this can quickly turn a profitable product into a money pit, all while adding unnecessary latency for your users. Semantic Caching: The "Fast Path" for LLMs Semantic caching solves this by moving beyond exact string matches. Instead of looking for an identical prompt, it looks for prompts that mean the same thing. It works by converting incoming user prompts into numerical vector representations (embeddings) and then performing a similarity search against a cache of previously embedded prompts and their corresponding LLM responses. Here's the workflow: USER PROMPT | v [ EMBEDDING MODEL ] -- Transform Prompt to Vector (e.g., [0.1, 0.5, -0.2, ...]) | v [ VECTOR DATABASE / CACHE ] | +--

Shopify Staff Engineer Guilherme Carreiro discusses building and scaling highly customizable platforms. Using Shopify’s Liquid theme system as a case study, he explains how to balance extreme design flexibility with low-latency performance under massive traffic. He shares insights on implementing secure domain-specific languages, native code extensions, and resilient developer tooling. By Guilherme Carreiro

The Theorem That Changed How We Think About Databases In 2000, Eric Brewer stood at a conference and proposed a conjecture that would reshape distributed systems forever: "You can only guarantee two of these three properties at the same time: Consistency, Availability, and Partition Tolerance." Two years later, Seth Gilbert and Nancy Lynch proved it mathematically. It became known as the CAP Theorem — and every distributed system architect since has had to wrestle with it. It sounds abstract. But once you understand it, you'll never look at a database choice the same way again. You'll understand why Amazon DynamoDB and Google Spanner make opposite architectural choices. You'll know why your bank uses PostgreSQL while Twitter uses Cassandra. Let's break it down from first principles. The Three Properties C — Consistency Every read receives the most recent write, or an error. There's only one version of the truth — all nodes agree. Not the same consistency as ACID . CAP consistency (linearizability) means every read reflects the latest write across all nodes. ACID consistency means transactions don't violate database constraints. Different concepts, same confusing word. A — Availability Every request receives a non-error response — though it might not be the most recent data. The system is always up and answering. Note: "Available" in CAP doesn't mean "fast." It means "responds without error." A system that always returns a (possibly stale) answer is Available. P — Partition Tolerance The system continues operating even when network messages between nodes are lost or delayed. A partition is when part of your distributed system can't communicate with another part. The Unavoidable Truth: P Is Not Optional Here's the insight that makes CAP actually useful: In any real distributed system, partitions will happen. Networks fail. Cables get cut. Data centers lose connectivity. AWS regions go down. Since you must tolerate partitions (or have a single-server system, which does

Every web app needs icons. How you manage them at scale — that's where most teams make mistakes. This is the complete guide to building an SVG icon system that doesn't fall apart as your app grows. Why SVG (Not Icon Fonts or PNG) Icon fonts (FontAwesome, etc.) are the legacy approach. The problems: One broken font file breaks all icons Accessibility is terrible (screen readers read the unicode character) Crispy rendering requires specific font-smoothing hacks No multi-color support PNG icons are dead for UI work. Blurry on Retina, can't be styled with CSS, fixed file per size. SVG wins: Infinitely scalable, pixel-perfect on any screen Styleable with CSS ( currentColor , fill, stroke) Accessible with proper ARIA labels Can animate with CSS or SMIL Single format handles all sizes Where to Get Free SVG Icons IconKing SVG Library — 254+ free SVG icons in flat and outline styles. Covers UI, social media, food, objects, and more. Downloadable as individual SVG, AI, or PNG files. No account required. What sets IconKing apart: many icons have matching animated Lottie versions in the Lottie library — useful when you want an animated hover state that matches your static icon. Other solid free sources: Heroicons (heroicons.com) — MIT, Tailwind-made, 292 icons Phosphor Icons (phosphoricons.com) — MIT, 1,248 icons, 6 weights Lucide (lucide.dev) — ISC, 1,400+ icons, React/Vue packages Tabler Icons (tabler.io/icons) — MIT, 5,000+ icons Method 1: Inline SVG Best for: small number of icons, need CSS styling <!-- Inline the SVG directly --> <button aria-label= "Close" > <svg width= "20" height= "20" viewBox= "0 0 24 24" fill= "none" stroke= "currentColor" stroke-width= "2" > <line x1= "18" y1= "6" x2= "6" y2= "18" /> <line x1= "6" y1= "6" x2= "18" y2= "18" /> </svg> </button> The stroke="currentColor" means the icon inherits its color from the parent element's CSS color property — trivial theming. Method 2: SVG Sprite Best for: many icons, better performance (single HTTP request) Bui

Hi! I want to share a project that I work for a while. It started from idea to get rid off manual copying data from game design documents to game engine. Here you can define your game objects, their props, relations and everything will be stored in structural JSON format that can be read by Unity, Godot, Unreal and other engines. What we have now? construct **wiki-like documents **using a block editor and template system (markdown is supported too) design dialogues of your game in special graph editor create maps and prototype levels on canvas store and manage database of game objects use created objects inside engine directly or export data to customizable data formats (arbitrary JSON, CSV) Made it free and open source. Please try (have Windows and Mac builds) and give your feedback Source code: https://github.com/ImStocker/ims-creators Itch.io: https://nordth.itch.io/imsc-desktop

Event sourcing gets sold on immutability. You don't update, you don't delete, you only append, so the history is permanent. It mostly isn't. The events are immutable because your code agrees not to touch them, not because anything actually stops it. Underneath they're still rows in Postgres, and rows have a DBA with write access. A migration that "cleans up" old data. A 2 a.m. query run against the wrong connection. A backup restored with slightly different bytes in it. Change one of those rows and a replay won't blink. The aggregate rebuilds, the projections rebuild, everything looks fine. Usually the first person to notice is a customer whose balance is off, and by then the trail is cold. Chain each event into the next The trick is small. Give every row two extra columns: a hash of its contents, and the hash of the row before it. #1 AccountOpened prev=00000… hash=70be4f… │ ▼ #2 AmountDeposited prev=70be4f… hash=796018… │ ▼ #3 AmountWithdrawn prev=796018… hash=6a0260… The hash is SHA-256(previousHash || json(payload)) . Nothing exotic. The point is that each hash depends on the one before it. Edit a payload and its hash stops matching. Rewrite that hash to cover for the edit, and now the next row's pointer is wrong. You can't fix one without breaking the next. About forty lines of it Appending an event hashes it together with the previous one: public HashChainedEntry Append ( object payload ) { var previousHash = _entries . Count == 0 ? GenesisHash : _entries [^ 1 ]. Hash ; var hash = ComputeHash ( previousHash , payload ); var entry = new HashChainedEntry ( _entries . Count + 1 , payload , previousHash , hash ); _entries . Add ( entry ); return entry ; } internal static byte [] ComputeHash ( byte [] previousHash , object payload ) { var payloadJson = JsonSerializer . SerializeToUtf8Bytes ( payload , payload . GetType ()); var combined = new byte [ previousHash . Length + payloadJson . Length ]; Buffer . BlockCopy ( previousHash , 0 , combined , 0 , previousHash .

For nearly 80 years, Ferrari occupied a unique cultural space where its cars were aspirational, even for people who resented those who could afford them. The price, the exclusivity, and the opacity of the buying process allowed Ferrari to sail above ordinary criticism. You might not be able to afford one, but you still wanted […]

Java LLD: Designing a Thread-Safe Parking Lot with Strategy Pattern Designing a parking lot is a staple of Java LLD and machine coding interviews, yet most candidates fail to write production-grade code. As an ex-FAANG interviewer, I've seen countless designs fall apart under concurrent traffic or when asked to support multiple slot allocation algorithms. If you're prepping for interviews, I've been building javalld.com — real machine coding problems with full execution traces. The Mistake Most Candidates Make Monolithic locking on the entire ParkingLot class: Using a global synchronized keyword on the entry method, which serializes all gate entries and destroys system throughput. Hardcoding slot-finding logic: Mixing spatial layout algorithms (like nearest-to-entrance or smallest-available-fit) directly inside the ParkingLot or Gate classes, violating the Open-Closed Principle. Thread-safety as an afterthought: Relying on raw List<Slot> iterations without synchronization, causing race conditions where multiple cars are assigned to the exact same physical slot. The Right Approach Core mental model: Decouple capacity management from slot selection by using a Semaphore for gate-keeping and the Strategy Pattern for thread-safe slot allocation. Key entities: ParkingLot , Gate , Slot , Vehicle , ParkingStrategy ( SmallestFitStrategy , NearestEntranceStrategy ), and StrategyFactory . Why it beats the naive approach: It isolates concurrency concerns (preventing overbooking) from business rules (how we choose a slot), making the system highly performant and easily extensible. The Key Insight (Code) public class EntryGate { private final Semaphore semaphore ; private final ParkingStrategy strategy ; public EntryGate ( int capacity , ParkingStrategy strategy ) { this . semaphore = new Semaphore ( capacity ); this . strategy = strategy ; } public synchronized Ticket park ( Vehicle vehicle ) { if (! semaphore . tryAcquire ()) throw new ParkingFullException (); Slot slot = strat

Most software projects focus on producing outputs. Most AI projects focus on producing predictions. But real organizations don't operate on outputs or predictions alone. They operate on decisions. A decision has consequences. A decision creates risk. A decision consumes resources. A decision changes the future state of a system. Over the last few months, I've been studying and building systems around a simple question: How can we make decisions more explainable, auditable, and repeatable? This led me toward concepts such as: event-driven architectures decision logging risk evaluation pipelines audit trails feedback loops operational intelligence systems Instead of asking: "Can we predict what will happen?" I'm becoming more interested in asking: "Can we explain why a decision was made?" and "Can we reproduce that decision six months later?" Current areas I'm exploring: Financial decision systems Risk infrastructure Event-driven architectures Blockchain compliance workflows Operational intelligence platforms One of the projects I'm currently building is an Event-Driven Decision Logging System (EDDL), designed to explore how organizations can record, audit, and replay critical decisions over time. Still learning. Still building. Still refining my understanding of how complex systems operate under uncertainty. Looking forward to sharing the journey here. systemsdesign #architecture #backend #fintech #softwareengineering #eventdriven #riskmanagement

In part 1 , the single-document case was easy. In part 2 , two documents brought Write Skew, and we saw that even a native ACID transaction — snapshot isolation — lets it through. So teams reach for the reflex fix: a distributed lock — Redis-based, often a Redlock-style implementation. Acquire a lock on a key, do your Read → Modify → Write, release. On paper, you've finally serialized the critical section — operationally, at least. In practice, you've stepped on three mines. 1. Network latency Every guarded transaction now makes extra round-trips to Redis — before and after hitting your NoSQL store. You've doubled your coordination surface and taken a hard dependency on a second system being up, reachable, and fast on the hot path of every write. The "fast" database is now gated by the lock service. And the coupling bites harder than the average latency suggests: every Redis tail-latency spike becomes your write-latency spike — your p99 inherits Redis's p99 — and if Redis fails over mid-transaction, the lock you think you're holding can effectively vanish on the new primary, dropping you straight into the corruption case below. 2. Deadlock You can dodge deadlock entirely with a single coarse lock — but then every writer serializes on it, and you've thrown away the very concurrency you reached for NoSQL to get. So to keep throughput you go fine-grained, one lock per resource — and the moment an invariant touches more than one key (across this series, it always does), deadlock is back on the table: Transaction A locks key X, then needs Y. Transaction B locks Y, then needs X. Both block until timeout or intervention. The textbook cure — real deadlock detection, maintaining a wait-for graph across every lock holder and breaking cycles as they form — is a distributed-systems project in its own right: not something you bolt onto a cache you reached for precisely to save engineering time. So nobody builds it. Instead teams impose a standing discipline: always acquire locks

Ferrari fans don’t like the design of the new Luce EV, an electric four-door sedan that just doesn’t look like the Ferraris of old. It was designed with help from Jony Ive’s LoveFrom, but what worked for Ive at Apple isn’t working for Ferrari. The Luce’s launch immediately preceded a stock drop that even an […]

The call to action “to make 2026 the year of Java in the terminal” was quickly responded to by the launch of TamboUI. Inspired by Ratatui, the library used in Claude CLI, it promises support ranging from low-level terminal drawing to high-level APIs such as components and event handling. Currently at version 0.3.0, it has already been adopted by major projects such as Maven and Spring. By Olimpiu Pop