[Side B] Should a Binary-Only FS Support Text Mode? Redrawing the Architecture Boundary

From the Author: D-MemFS was featured in Python Weekly Issue #737 (March 19, 2026) under Interesting Projects, Tools and Libraries . Being picked up by one of the most widely-read Python newsletters confirmed that in-memory I/O bottlenecks and memory management are truly universal challenges for developers everywhere. This series is my response to that interest. 🧭 About this Series: The Two Sides of Development In Japan, I publish this series across two distinct platforms to serve different developer needs. To provide the complete picture here on Dev.to, I've brought them together as two "Sides": Side A (Practical / originally on Qiita): Focuses on the "How" . Implementation details, benchmarks, and concrete solutions for practical use cases. Side B (Philosophy / originally on Zenn): Focuses on the "Why" . The development war stories, design decisions, and how I collaborated with AI through Specification-Driven Development (SDD). What the Design Document Said D-MemFS's design principle