content: content/* API facade + 26 tests (Phase 1 complete, 133/133)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/content/api.sx

@@ -0,0 +1,63 @@
+;; content-on-sx — public API facade.
+;;
+;; The stable surface other code calls. Composes block + doc + render. Document
+;; values are immutable; every edit returns a new document, so callers hold
+;; explicit versions (the persist op log in Phase 2 becomes the source of truth).
+;;
+;; Requires (loaded by the harness): block.sx, doc.sx, render.sx and a base
+;; Smalltalk class table (st-bootstrap-classes!).
+
+;; Register the content class hierarchy + render methods. Caller bootstraps the
+;; base Smalltalk classes first; this only adds content classes (idempotent).
+(define
+  content/bootstrap!
+  (fn
+    ()
+    (begin
+      (content-bootstrap-blocks!)
+      (content-bootstrap-doc!)
+      (content-bootstrap-render!)
+      true)))
+
+;; ── documents ──
+(define content/new doc-new)
+(define content/empty doc-empty)
+(define content/append doc-append)
+(define content/blocks doc-blocks)
+(define content/count doc-count)
+(define content/find doc-find)
+(define content/has? doc-has?)
+(define content/ids doc-ids)
+(define content/types doc-types)
+
+;; ── blocks ──
+(define content/block mk-block)
+
+;; ── edit ops (data payload) ──
+(define content/insert op-insert)
+(define content/update op-update)
+(define content/move op-move)
+(define content/delete op-delete)
+
+(define content/op? (fn (x) (and (dict? x) (has-key? x :op))))
+
+;; edit — apply one op or a stream of ops; returns a new document.
+(define
+  content/edit
+  (fn
+    (doc ops)
+    (if (content/op? ops) (doc-apply doc ops) (doc-apply-all doc ops))))
+
+;; ── render boundary ──
+;; fmt is "html"/"sx" (or :html/:sx — keywords evaluate to their name).
+(define
+  content/render
+  (fn
+    (doc fmt)
+    (cond
+      ((= fmt "html") (asHTML doc))
+      ((= fmt "sx") (asSx doc))
+      (else (error (str "unknown render format: " fmt))))))
+
+(define content/html asHTML)
+(define content/sx asSx)