◇ Could this help me?
Yes, with one correction to the top of the ladder. The core design is sound and underused: a small index that points at larger memory files is the right shape, because it gives the assistant a cheap way to discover what it knows without loading all of it, and asking at the end of a session whether to commit it removes the main reason memory systems die, which is that nobody remembers to write anything down. The part to handle more carefully is the final promotion step into the always-loaded instructions file, because that file is re-read on every conversation and research on instruction counts shows accuracy falling as it grows, so promotion needs a matching demotion and consolidation pass or the ladder quietly becomes the problem it was built to solve. General practice.
Help me build a tiered memory system for working with you, and design it so it cannot grow without bound. I want three layers: a small index file that gets referenced before every interaction and only holds pointers, a set of larger memory files holding the actual detail, and the always-loaded project instructions file at the top. Propose the promotion rule for moving a lesson up a layer, and propose the demotion and consolidation rule for moving things back down or merging them, since the top layer costs me tokens on every conversation. Then add a step at the end of each working session where you ask me whether anything from it should be committed, and summarize what you would write before writing it.