Technical Writings

Technical notes, engineering case studies, and practical reflections arising from work with software, Linux servers, WordPress, web infrastructure, automation, artificial intelligence, and human–AI development workflows. These writings document not only finished solutions but also failures, debugging processes, design decisions, rejected alternatives, validation methods, and lessons learned from real systems. Alongside implementation details, they examine the broader principles behind reliable technical work: observability, recoverability, security, resource constraints, careful experimentation, and the relationship between human judgment and increasingly autonomous tools.

La pericolosa invisibilità della malattia di Addison (morbo di Addison)

~ YIN Renlong

Nota medica: Questo articolo ha finalità esclusivamente informative, di sensibilizzazione sulla disabilità e di comprensione da parte delle istituzioni. Non fornisce consulenza medica, diagnosi, istruzioni di emergenza né raccomandazioni terapeutiche personalizzate. La malattia di Addison e la crisi surrenalica devono essere gestite secondo il piano clinico individuale del paziente e sotto la guida di professionisti sanitari. La crisi surrenalica è un’emergenza medica e richiede un trattamento immediato e un’assistenza medica urgente (NICE, 2024).

Uno dei fraintendimenti più pericolosi…
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The Dangerous Invisibility of Addison’s Disease

~ YIN Renlong

Medical note: This article is intended for general education, disability awareness and institutional understanding. It does not provide medical advice, diagnosis, emergency instructions or individualized treatment recommendations. Addison’s disease and adrenal crisis require management according to the individual patient’s clinical plan and professional medical guidance. Adrenal crisis is a medical emergency and requires immediate treatment and urgent medical care (NICE, 2024).

One of the most dangerous misunderstandings about Addison’s disease begins with something apparently reassuring: a person may…
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What an Addisonian/Adrenal Crisis Taught Me About Computer Failure, and When a System Can No Longer Compensate…

~ YIN Renlong

Medical note: This essay uses Addison’s disease and adrenal crisis as a systems-level analogy for thinking about computer failure. It is intended only as conceptual and educational discussion. It is not medical advice, diagnosis, or a treatment guide. Adrenal crisis is a potentially life-threatening medical emergency; suspected adrenal crisis requires urgent medical assessment and treatment according to established emergency guidance and the individual patient’s clinical plan (National Institute for Health and Care Excellence [NICE], 2024; Bornstein et al.,…
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How a VPS Turned a Network Failure Into a Full-System Outage (Tracing a Cloudflare WARP Failure from DNS Errors to Disk Exhaustion)

~ YIN Renlong

I was not looking for an interesting systems failure. I was expecting a boring one.

On August 16, 2026, I received an UptimeRobot notification saying that one of my WordPress sites had gone down. This was running on a very small Scaleway VPS, and my first thought was almost automatic: the disk was probably full again. I had seen that kind of problem before. UpdraftPlus could leave backup archives on a small root filesystem, free space would disappear, WordPress would…
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Deletion Is a Claim, Not a Command: Can “Deleted” Ever Be a Promise?

~ YIN Renlong

After finishing a long investigation into Git deletion, I thought the difficult part was over. The repository had been the experiment; the broader lesson seemed to be that deletion has several observable states. Then a more uncomfortable question appeared. If a system says that something is deleted, what exactly is it claiming, who defines the scope of that claim, and who gets to decide when the process is truly finished?

I documented the original technical investigation in Deleting in Git…
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Deleting in Git and Rethinking (Philosophically) Deletion as a System Design Question

~ YIN Renlong

Yesterday I removed a file that no longer belonged in one of my Git repositories. It had already been committed and pushed several times, so rather than simply deleting the current copy, I decided to clean up the corresponding history as well.

What looked like a straightforward maintenance task became more complicated once I started verifying the result. The file disappeared from the current branch, then from reachable history, but some of the old commit IDs could still be resolved…
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I’ve Almost Completely Forgotten the Code I Wrote a Week Ago…

~ YIN Renlong

Not only can I no longer find the directory where I stored it, but I’ve even forgotten the command I used to run it (Not only can I no longer find the directory where I stored it, but I’ve even forgotten the command I used to run it. I eventually found the solution in my ChatGPT history, but the experience made me reflect on the nature and fragility of memory. I remember doing it. I even wrote a blog post…
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Turning a Theme-Bound Generative Art System into a Maintainable WordPress Plugin

~ YIN Renlong

I began this migration for a practical reason: a background feature that had started as a theme customization had grown into a modular browser-based geometry engine. It still worked, but the theme now owned administration, persistence, mosaics, twelve generators, rendering, and a public badge. I wanted a cleaner boundary without losing the behaviour already proven on the live site.

The result was a site-specific standalone WordPress plugin, a deliberately minimal theme fallback, and a workflow in which the current VPS…
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Deploying a Modular Generative Geometry Generator (Browser-Based)

~ YIN Renlong

After completing the mosaic and scattered-collage stages of my WordPress Background Studio, I began asking a different question: could the system choose a mathematical composition method as well as choosing media? That question changed the project’s category. What began as background randomization became a modular browser-based generative-art engine with twelve algorithms, deterministic seeds, record-aware identity and a deployment process designed for a live, resource-constrained server.

I described the earlier evolution from a repeating background to mosaics and random collage in…
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