Posts from 2026
Facing Is Not Position: Vectors, Dot and Cross Products and Coordinate Spaces in Games
How a game decides whether a target is ahead, which way to turn and how to slide along a wall: dot products, the 2D cross product and coordinate transforms, run in Python.
Mini Apps Inside Messaging Apps: WeChat, Telegram and How to Design the Host
Messaging apps can host third-party code because they already have the social graph, payments and sharing. Recent data on WeChat, Telegram and LINE, and how to design the host.
From Messaging to Community and Short Video: Storage, Recommendations, Mini Apps and Accounts
Public posts, video, ranking and mini apps put the server back in charge: storage after MinIO, a Qdrant recommender, mini app identity, and Taiwan and EU rules.
Building a Messaging App from the Device Out: Local-first, E2EE and On-Device Search
Once the device owns the chat history and the server only relays, identity keys, encryption, ordering, new-device history and search all change. Checked against Signal, WhatsApp and LINE.
Only 86 Million Ways to Shuffle: What Game RNG Certification Checks
Game RNG certification checks the seed, state recovery and mapping bias; statistical tests aren't enough. From a 1999 poker shuffle to Lineage M's odds dispute.
Counting the Cost of AI Code Review: Bugs Found, False Alarms and People's Time
AI code review's main cost is human triage time, not tokens. Whether it pays depends on the precision and severity of findings, as curl and an ICSE 2025 study show.
The Same Payment Sent Twice: Idempotency and Retries, by Way of Santander's Christmas
Safe payment retries need an idempotency key both sides agree on: when to create it, what goes in it, and what to do if payloads differ or a refund arrives first.