lean-ctx makes spaced repetition its default context policy

Version 3.9.18 of lean-ctx made spaced repetition its default context policy, auto-migrating every user still running CognitiveMode::Basic, per the release notes on GitHub.

Two fixes in the same release matter to anyone writing MCP servers, per the notes. The server used to exit on an unknown JSON-RPC method instead of returning MethodNotFound as the spec requires. ctx_patch batches applied partially instead of atomically before this release. Now a batch either fully applies or not at all.

The release also promotes CognitiveMode::Full to default. It wires an FSRS scheduler and Wasserstein-optimal token allocation into the production read path. Graph expansion, verbosity learning and prefetch warming go in alongside it. ctx_cognitive joins as the 83rd tool in lean-ctx's MCP surface.

Spaced repetition was built to schedule human memory review, not to decide what a coding agent keeps in its context window. Using it here reads as an admission that bigger context windows never solved the actual problem: deciding what to forget. Watch whether other context-management tools start citing spaced-repetition research instead of just raising token limits.