COSESAI

HTTP/3 QUIC handshake anatomy cover poster

Inside the HTTP/3 QUIC Handshake: 1-RTT, 0-RTT, and Reading a PCAP

By xiezixing 2026年7月7日

A byte-level walkthrough of the HTTP/3 over QUIC handshake: 1-RTT fresh, 0-RTT resumption, connection migration, and how to read a packet capture without going cross-eyed.

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API Latency Budget Planner: Why Most Budgets Are Fiction Until You Compare Them to a Trace

By xiezixing 2026年7月6日

A 300 ms P99 budget that ignores OpenTelemetry measurements is a guess with a flag on it. The three decisions every team makes — cold path, warm path, processing — are almost always the wrong ones until the waterfall meets the trace.

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Cron Expression Generator: The Five-Field Decision Nobody Reads on Monday

By xiezixing 2026年7月6日

Six to nine characters decide whether your cron job fires every minute, every workday, or never. Here's the syntax that drives every Unix scheduler, and why a generator matters more than typing speed.

One total four scores — DOTS Wilks 1994 IPF GL and Goodlift compared side by side for an 83 kg raw lifter hitting a 600 kg total

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One Total, Four Scores: DOTS, Wilks, IPF GL and Goodlift Compared

By xiezixing 2026年7月6日

An 83 kg raw lifter hitting 600 kg posts 405 DOTS, 400 Wilks 1994, 88 IPF GL and 88 Goodlift — three different tiers from one total. Here is why the four formulas disagree, what each polynomial actually does, and when to quote which score in programming, meet prep and gym-floor conversations.

Blue Hour Calculator — Plan the 20-minute twilight window for landscape photography

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Blue Hour Calculator: Why Photographers Live by a 20-Minute Window

By xiezixing 2026年7月6日

Predict the precise blue hour window for any location and date — solar elevation math, IANA time zone handling, and a confidence indicator for polar edge cases.

Central Limit Theorem Demonstrator cover — Watch the bell curve emerge from any source distribution

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Watch the Bell Curve Emerge from Anything: Inside the Central Limit Theorem Demonstrator

By xiezixing 2026年7月6日

An interactive visual proof that the distribution of sample means converges to a Normal bell curve regardless of source distribution, plus four controls and four source distributions you can dial in.

JSON-LD Generator from CSV cover showing schema.org JSON-LD output and three validator decisions

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Three Spreadsheet Decisions That Decide Whether JSON-LD Survives the Validator

By xiezixing 2026年7月6日

How the schema.org type, public page URL, and spreadsheet column names decide whether the output JSON-LD earns a Google rich result.

PKCE Code Verifier and Challenge Generator — Three modes that turn invalid_grant into a concrete check

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Three PKCE Modes That Turn invalid_grant Into a Concrete Check

By xiezixing 2026年7月5日

Generate, validate, and verify OAuth 2.0 PKCE code_verifier and code_challenge pairs against RFC 7636 — without round-tripping through the identity provider.

Cover for Physics Kinematics Problem Solver article showing SUVAT equations

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The Kinematics Toolkit Most Students Only Learn Half Of

By xiezixing 2026年7月5日

Walk through SUVAT equations and projectile motion end-to-end, then see how the Physics Kinematics Problem Solver walks the algebra step by step.

PDF to Markdown Converter — convert PDF documents to Markdown with structure preserved

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PDF to Markdown: How to Get Publish-Ready Markdown From Any PDF

By xiezixing 2026年7月5日

A free browser-based PDF to Markdown converter that runs entirely client-side — extract headings, lists, tables, and code blocks from any PDF without uploading a single byte to a server.

Inside the HTTP/3 QUIC Handshake: 1-RTT, 0-RTT, and Reading a PCAP

API Latency Budget Planner: Why Most Budgets Are Fiction Until You Compare Them to a Trace

Cron Expression Generator: The Five-Field Decision Nobody Reads on Monday

One Total, Four Scores: DOTS, Wilks, IPF GL and Goodlift Compared

Blue Hour Calculator: Why Photographers Live by a 20-Minute Window

Watch the Bell Curve Emerge from Anything: Inside the Central Limit Theorem Demonstrator

Three Spreadsheet Decisions That Decide Whether JSON-LD Survives the Validator

Three PKCE Modes That Turn invalid_grant Into a Concrete Check

The Kinematics Toolkit Most Students Only Learn Half Of

PDF to Markdown: How to Get Publish-Ready Markdown From Any PDF

RDB SSTable LevelDB RocksDB Memcached Binary KV-Store Encoding Lineage Field Guide: When Six Formats Share One Byte Stream

Boolean Algebra Simplifier Field Guide: When Four Literals Collapse to One Gate and a Karnaugh Map Proves It

Z85 and RFC 1924 Base85 Field Guide: When Four Bytes, Five Characters, and Two Alphabets Decide Whether Your Payload Survives the Wire

Image Steganography Field Guide: When Three LSBs and One Chi-Square Number Tell You Whether the Message Is There