The MCP Pattern: SQLite as the AI-Queryable Cache

I keep building the same thing. Not the same product — the products are different. One indexes a Hugo blog. One indexes AI conversations. One consolidates medical records from three hospitals. One catalogs a hundred git repositories. But underneath, they all have the same skeleton. After the fifth time, I think the skeleton deserves a name. The pattern Domain files (ground truth) ↓ index SQLite database (read-only cache, FTS5) ↓ expose MCP server (tools + resources → AI assistant) That's it. Three layers. The domain files are always canonical — the database is a disposable cache you can rebuild from them at any time. SQLite gives you structured queries, full-text search, and JSON extraction over data that was previously trapped in flat files. MCP exposes it to an AI assistant that can write SQL, retrieve content, and (in some cases) create new content. Here's the inventory: Project Domain Ground Truth What the MCP Exposes hugo-memex Blog content Markdown files with YAML front matter 95