Why: The base must stay unmodified by downstream products, so the roadmap, compatibility window, and plugin contract need a written proposal before further forks.
Evidence: Three proposals under docs/proposals and a short pointer in the plugin development guide.
Impact: Downstream work follows extension-point requests and a published base version. Tag commands in the compat proposal are not executed.
Refs: .task/feature-base-extension-roadmap.md
Co-authored-by: Cursor <cursoragent@cursor.com>
