content: durable CRDT replication (crdt-store) + 14 tests (277/277)

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

lib/content/crdt-store.sx

@@ -0,0 +1,71 @@
+;; content-on-sx — durable collaborative replication: CRDT ops on persist.
+;;
+;; Each replica appends its CRDT ops to its own persist stream
+;; (crdt:<doc>:<replica>). Any node reconstructs the converged document by
+;; replaying every replica's log into a CvRDT state and merging them. Because
+;; the merge is a join and crdt-apply is order/duplicate-insensitive, the
+;; converged result is identical regardless of replica order or re-delivery —
+;; the durable log + CRDT give offline-capable, eventually-consistent editing.
+;;
+;; Requires (loaded by harness): crdt.sx (+ deps) and persist
+;; (event/backend/log/kv/api). Backend `b` injected via (persist/open).
+
+(define crdt/-stream (fn (doc-id replica) (str "crdt:" doc-id ":" replica)))
+
+;; ── commit ops to a replica's durable log ──
+(define
+  crdt/commit!
+  (fn
+    (b doc-id replica op at)
+    (persist/append b (crdt/-stream doc-id replica) (get op :op) at op)))
+
+(define
+  crdt/commit-all!
+  (fn
+    (b doc-id replica ops at)
+    (if
+      (= (len ops) 0)
+      nil
+      (begin
+        (crdt/commit! b doc-id replica (first ops) at)
+        (crdt/commit-all! b doc-id replica (rest ops) at)))))
+
+;; ── read a replica's log ──
+(define
+  crdt/log
+  (fn (b doc-id replica) (persist/read b (crdt/-stream doc-id replica))))
+
+(define
+  crdt/replica-ops
+  (fn
+    (b doc-id replica)
+    (map (fn (ev) (persist/event-data ev)) (crdt/log b doc-id replica))))
+
+(define
+  crdt/replica-version
+  (fn (b doc-id replica) (persist/last-seq b (crdt/-stream doc-id replica))))
+
+;; ── replay one replica's log into a CvRDT state ──
+(define
+  crdt/replay
+  (fn
+    (b doc-id replica)
+    (crdt-apply-all (crdt-empty) (crdt/replica-ops b doc-id replica))))
+
+;; ── converge: merge every replica's replayed state ──
+(define
+  crdt/converge
+  (fn
+    (b doc-id replicas)
+    (crdt-merge-all (map (fn (r) (crdt/replay b doc-id r)) replicas))))
+
+;; ── converged, materialised document ──
+(define
+  crdt/document
+  (fn
+    (b doc-id replicas)
+    (crdt-materialize doc-id (crdt/converge b doc-id replicas))))
+
+(define
+  crdt/order
+  (fn (b doc-id replicas) (crdt-order (crdt/converge b doc-id replicas))))