content: Ghost/CMS sync via injected adapter + round-trip tests (210/210)

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

plans/content-on-sx.md

@@ -19,7 +19,7 @@ injected adapter, not core.
 
 ## Status (rolling)
 
-`bash lib/content/conformance.sh` → **196/196** (Phases 1–3 complete: blocks, doc, render, api, persist op log, CRDT merge)
+`bash lib/content/conformance.sh` → **210/210** (Phases 1–3 complete + Phase 4 Ghost adapter)
 
 ## Ground rules
 
@@ -71,12 +71,20 @@ lib/content/api.sx ── (content/edit) (content/render) (content/history) ─
 - [x] concurrent-edit tests (any order, double-apply → identical)
 
 ## Phase 4 — External sync + federation
-- [ ] Ghost/CMS sync via injected adapter (import/export)
+- [x] Ghost/CMS sync via injected adapter (import/export)
 - [ ] federated documents (peer-authored blocks) — trust-gated stub
-- [ ] tests: round-trip import/export, conflict on concurrent external edit
+- [~] tests: round-trip import/export (done), conflict on concurrent external edit (pending)
 
 ## Progress log
 
+- 2026-06-07 — Phase 4 `sync.sx` (cb1): external CMS sync via an injected
+  adapter. Core defines the shape — `{:import :export}` — and delegates;
+  `content/import` / `content/export` / `content/round-trip` know nothing about
+  Ghost. A Ghost-flavoured adapter confines all format translation (post
+  `:sections` ↔ content blocks, all 8 kinds). Swapping in a stub `raw-adapter`
+  works identically. Round-trip (export∘import and import∘export) preserves ids,
+  types, fields, order. 14 tests; suite 210/210. Next: trust-gated federation +
+  concurrent-external-edit conflict (via CRDT).
 - 2026-06-07 — Phase 3 `crdt.sx` (**Phase 3 complete**): collaborative merge as
   a state-based CvRDT. Merge is a join (lub) on a semilattice → commutative,
   associative, idempotent by construction. Ordering = unique dense Logoot