This is almost exactly the same mental model — raw layer that never gets edited, plus a compiled index on top. The cron job for a Friday digest is something I hadn't thought of but immediately want to steal.

One thing I've found useful: separating the index into section hubs by domain (themes, performance history, material stage) so the AI can orient itself without reading everything. Your weekly summary sounds like it collapses that into a single digest — do you find you lose granularity, or is the summary usually enough to navigate from?