Claude Code Deep Dive Part 4: Why It Uses Markdown Files Instead of Vector DBs

This is Part 4 of our Claude Code Architecture Deep Dive series. Part 1: 5 Hidden Features | Part 2: The 1,421-Line While Loop | Part 3: Context Engineering — 5-Level Compression Pipeline This article replaces and deepens our earlier analysis, Claude Code's Memory Is Simpler Than You Think . The original focused on limitations. This one focuses on **why * — the first-principles tradeoffs behind every design choice.* The Core Principle: Only Record What Cannot Be Derived This single constraint governs every decision in Claude Code's memory system: Don't save code patterns — read the current code. Don't save git history — run git log . Don't save file paths — glob the project. Don't save past bug fixes — they're in commits. This isn't about saving storage. It's about preventing memory drift . If a memory says "auth module lives in src/auth/ ", one refactor makes that memory a lie. But the model doesn't know it's a lie — it trusts specific references by default. A stale memory is worse th