Why: completion claims require tool-written evidence (AGENTS.md).
Evidence: SELF receipt appended by make evidence; full suite green incl. ui 103 tests and agent-command.
Impact: task metadata only.
Refs: .task/feature-ext-5-host-parse.md
Why: Downstream products need a published extension surface, contract checks, and a sample plugin that does not modify the base.
Evidence: scripts/lint-boundaries.sh printed boundaries ok. examples/downstream-rdm go test passed. Submodule pointers record the core, documents, backend, ui, and frontend commits for this roadmap.
Impact: make test runs the boundary lint first. make plugin-new scaffolds a declaration plugin. Version tags and remote downstream repositories are not created.
Refs: .task/feature-base-extension-roadmap.md
Co-authored-by: Cursor <cursoragent@cursor.com>