The cards-as-OBJECTS model (plans/composition-objects.md): an object's :body is a tiny UI
language over content-addressed object refs; the render-fold is its interpreter. Four
combinators — seq (sequence) / row,grid (layout/par) / alt+when (conditional/or) / each
(iteration/loop) — plus field/text/card leaves, ref (transclude), and tmpl (recursion).
The two fundamentals designed IN: (1) recursion via self-referential named templates
(tmpl) + each over (children) + a depth guard — renders trees (verified: a nested type
hierarchy -> [Types[Article][Card[Image][Callout]]]); (2) the context is an extensible
ENVIRONMENT — reads it, extends it (:item, :depth) — so behaviour (Slice 9)
and reactivity (signals) plug in via the context with no new combinators.
and/or/choice fall out of one axis ( on forks) x the container strategy (render-all
vs render-first), so Alt isn't a new node — it's 'first'. The unifying property, proven:
the object's CID is its DEFINITION (query/template/every when-variant); render is the
EXECUTION (which items/branch/context). One object renders two ways by context (anon ->
'Please log in', authed -> 'Members area'). Render-fold and the Slice-9 behaviour interpreter
are the same shape — interpreters over content-addressed objects.
lib/host/compose.sx is self-contained (no blog deps); verified via sx_eval (every combinator
+ a recursive tree + a full composed doc across two contexts). Roadmap: wire :body into
host/blog-render, each-source=graph-query, live context, Lexical->card-objects import, block
editor.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
