plan: north star — the metamodel as a system-construction kit

Name the destination: the host becomes a self-describing metamodel where you define a
domain (types + relations with signatures/algebra) and a working system falls out — the
blog is one seeded configuration. Most instance UI is already generic (relation editors
iterate the relations, pickers come from declares-anchors, validation from :schema), so
'define the types' is mostly a metamodel editor + a generic instance form + a
clear-and-reseed. Frames Slices 6-7 as the schema language this is for.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

plans/relations-as-posts.md

@@ -11,6 +11,31 @@ itself in its own graph.
 
 Supersedes the hardcoded `:candidates "types"/"tags"/"all"` field of `host/blog-rel-kinds`.
 
+## North star — the metamodel as a system-construction kit
+
+The destination this is all heading toward: the host stops being "a blog" and becomes a
+**self-describing metamodel**. You *define a domain* — types (with schemas/refinements) and
+relations (with role signatures + algebra) — and a working system falls out. The blog content
+is one seeded configuration; clear it and define different types and you have a different system
+on the same engine. Framework, not application (cf. `[[feedback_runtime_control]]`,
+`[[project_zero_dependencies]]`).
+
+Most of the **instance UI is already generic** — the edit page's relation editors are generated
+by iterating the relations; each picker's candidates come from the relation's `declares`-anchor /
+role type; validation comes from the type's `:schema`. So once Slices 6–7 land, "define the
+types" through a UI is mostly two surfaces, plus a reset:
+
+1. **Metamodel editor** — create a type-post (give it a schema/refinement); create a relation-post
+   (give it a role signature + algebra). The thing that lets you *construct* a system.
+2. **Generic instance form** — create/edit any post of any type, driven entirely by the
+   definitions above (the relation editors + pickers + save-time validation we already have).
+3. **Clear-and-reseed** — wipe instance data, seed only the metamodel roots (`type`, `relation`,
+   the core relations); start from a bare kit and build a domain up from nothing.
+
+Sequence: finish the schema language (Slices 6–7) → the two UI surfaces + reset → clear the demo
+data and define a real domain through the UI. The slices below are the schema language; this is
+what it's *for*.
+
 ## Why (the wrinkle that started this)
 
 Candidates for `is-a`/`subtype-of` were `instances-of("type")` — the *instances* that are