host: blog persisted in durable SX store + materialised view, 158/158

Blog posts now live in the durable SX store (persist/durable-backend, on-disk
under $SX_PERSIST_DIR — already built: sx_persist_store.ml + lib/persist/
durable.sx). Publishing appends insert ops to the slug's content stream; posts
survive restarts (verified: seq/log stable across container restart, re-seed
idempotent).

Read path: http-listen handlers can't drive per-request perform/IO (sx_call
doesn't resolve the CEK IO suspension the way the main loop does), so posts are
materialised from the store into an in-memory view at boot (host/blog-load-all!
+ host/blog-seed!) and request handlers read the view — perform-free. Store is
source of truth; view is a boot-rebuilt cache.

Deploy: docker-compose.dev-sx-host.yml mounts /root/sx-host-persist (chowned to
appuser 10001) at /data/persist; SX_PERSIST_DIR set. blog.rose-ash.com/welcome/
live. Per-request-IO kernel fix tracked in the plan as the next task.

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

lib/host/blog.sx

@@ -1,34 +1,72 @@
-;; lib/host/blog.sx — Blog domain on the host. Serves published posts as HTML at
-;; GET /<slug>/ — the original strangler target (Quart: blog/bp/post/routes.py,
-;; handler post_detail). Published posts are world-visible, so this endpoint is
-;; ANONYMOUS — no auth, visibility is trivially "visible".
+;; lib/host/blog.sx — Blog domain on the host. Posts are content-on-sx documents
+;; whose SOURCE OF TRUTH is the durable SX store (persist op-log on disk): a post
+;; is published by appending insert ops to its stream. Serving GET /<slug>/ renders
+;; the post to HTML via content/html. The original strangler target (Quart blog
+;; post_detail); published posts are world-visible, so this endpoint is ANONYMOUS.
 ;;
-;; A post is a content-on-sx document (CtDoc) rendered to HTML via the content
-;; facade (content/html). Posts live in an in-memory registry keyed by slug: this
-;; is the "prove the machinery" step — swap host/blog-lookup for a persist-backed
-;; content stream later without touching the handler or the route.
-;; Depends on lib/content/* (+ the Smalltalk + persist preloads its classes need)
-;; + lib/dream/* + lib/host/handler.sx.
+;; READ PATH — materialised view, not per-request IO. The durable backend reads
+;; via `perform` (kernel IO suspension), which is serviceable on the main thread
+;; (boot) but NOT inside an http-listen request handler thread. So posts are
+;; materialised from the store into an in-memory view at boot (and on publish),
+;; and request handlers read that view — fast, perform-free. The store stays the
+;; source of truth; the view is a cache rebuilt from it on startup.
+;; Depends on lib/content/* (+ Smalltalk + persist preloads) + lib/dream/* +
+;; lib/host/handler.sx.
 
-;; Register the content class table + render methods (idempotent). Must run before
-;; any CtDoc is built/rendered; called at module load below.
+;; Register content classes + render methods (idempotent); called at load below.
 (define host/blog-bootstrap!
   (fn () (begin (st-bootstrap-classes!) (content/bootstrap!))))
 
-;; ── in-memory post registry (slug -> CtDoc) ─────────────────────────
-(define host/blog-posts {})
-(define host/blog-register!
-  (fn (slug doc) (set! host/blog-posts (assoc host/blog-posts slug doc))))
-(define host/blog-lookup (fn (slug) (get host/blog-posts slug)))
-(define host/blog-reset! (fn () (set! host/blog-posts {})))
+;; ── store (durable source of truth) + view (in-memory serving cache) ─
+(define host/blog-store (persist/open))
+(define host/blog-view {})
+(define host/blog-use-store!
+  (fn (b) (begin (set! host/blog-store b) (set! host/blog-view {}))))
 
-;; Build a simple post doc (title heading + body paragraph). Convenience for
-;; seeding and tests; real posts arrive from the content store.
-(define host/blog-make
-  (fn (slug title body)
-    (doc-append
-      (doc-append (doc-empty slug) (mk-heading (str slug "-h") 1 title))
-      (mk-text (str slug "-body") body))))
+;; content streams are keyed "content:<slug>"; recover the slug.
+(define host/blog--stream-slug
+  (fn (stream)
+    (if (starts-with? stream "content:") (substr stream 8) nil)))
+
+;; ── publish + lookup ────────────────────────────────────────────────
+;; Publish a simple post (title heading + body paragraph): append its insert ops
+;; to the durable store, then refresh the in-memory view. `at` is a logical ts.
+(define host/blog-publish!
+  (fn (slug title body at)
+    (let ((hid (str slug "-h")) (tid (str slug "-body")))
+      (content/commit-all! host/blog-store slug
+        (list
+          (op-insert (mk-heading hid 1 title) nil)
+          (op-insert (mk-text tid body) hid))
+        at)
+      (set! host/blog-view
+        (assoc host/blog-view slug (content/head host/blog-store slug))))))
+
+;; Materialise every persisted post from the store into the view. Run at boot on
+;; the main thread (content/head performs IO, fine here, not in a request).
+(define host/blog-load-all!
+  (fn ()
+    (for-each
+      (fn (stream)
+        (let ((slug (host/blog--stream-slug stream)))
+          (when slug
+            (let ((doc (content/head host/blog-store slug)))
+              (when (> (content/count doc) 0)
+                (set! host/blog-view (assoc host/blog-view slug doc)))))))
+      (persist/backend-streams host/blog-store))))
+
+;; Idempotent seed: if the slug isn't already materialised, recover it from the
+;; store (prior run) or publish it fresh. No duplicate ops on restart.
+(define host/blog-seed!
+  (fn (slug title body at)
+    (when (nil? (get host/blog-view slug))
+      (let ((existing (content/head host/blog-store slug)))
+        (if (> (content/count existing) 0)
+          (set! host/blog-view (assoc host/blog-view slug existing))
+          (host/blog-publish! slug title body at))))))
+
+;; Lookup is pure in-memory (no perform) — safe inside a request handler.
+(define host/blog-lookup (fn (slug) (get host/blog-view slug)))
 
 ;; ── handler: GET /<slug>/ -> rendered HTML (200) or 404 ─────────────
 (define host/blog-post

lib/host/conformance.sh

@@ -70,6 +70,8 @@ MODULES=(
   "lib/content/doc.sx"
   "lib/content/render.sx"
   "lib/content/api.sx"
+  "lib/content/store.sx"
+  "lib/persist/durable.sx"
   "lib/dream/types.sx"
   "lib/dream/json.sx"
   "lib/dream/auth.sx"

lib/host/serve.sh

@@ -75,6 +75,8 @@ MODULES=(
   "lib/content/doc.sx"
   "lib/content/render.sx"
   "lib/content/api.sx"
+  "lib/content/store.sx"
+  "lib/persist/durable.sx"
   "lib/dream/types.sx"
   "lib/dream/json.sx"
   "lib/dream/auth.sx"
@@ -95,10 +97,20 @@ EPOCH=1
   for M in "${MODULES[@]}"; do
     echo "(epoch $EPOCH)"; echo "(load \"$M\")"; EPOCH=$((EPOCH+1))
   done
-  # Seed a welcome post so blog.rose-ash.com/welcome/ renders live (until posts
-  # arrive from a persist-backed content store).
+  # Point the blog at the DURABLE file backend (persists under $SX_PERSIST_DIR),
+  # then idempotently seed a welcome post — re-seeding is a no-op if it already
+  # exists on disk, so restarts don't duplicate blocks.
   echo "(epoch $EPOCH)"
-  echo "(eval \"(host/blog-register! \\\"welcome\\\" (host/blog-make \\\"welcome\\\" \\\"Welcome to the SX host\\\" \\\"This page is rendered by lib/host on the SX runtime — no Quart.\\\"))\")"
+  echo "(eval \"(host/blog-use-store! (persist/durable-backend))\")"
+  EPOCH=$((EPOCH+1))
+  echo "(epoch $EPOCH)"
+  # Materialise any persisted posts into the in-memory view, then ensure the
+  # welcome post exists (idempotent). Both run on the main thread (IO is fine
+  # here; request handlers only read the view).
+  echo "(eval \"(host/blog-load-all!)\")"
+  EPOCH=$((EPOCH+1))
+  echo "(epoch $EPOCH)"
+  echo "(eval \"(host/blog-seed! \\\"welcome\\\" \\\"Welcome to the SX host\\\" \\\"This page is rendered by lib/host on the SX runtime, persisted in the SX store — no Quart.\\\" 1)\")"
   EPOCH=$((EPOCH+1))
   echo "(epoch $EPOCH)"
   # Anonymous read endpoints: feed timeline + relations container reads + blog

lib/host/tests/blog.sx

@@ -22,9 +22,9 @@
 (define host-bl-app
   (host/make-app (list host/feed-routes host/blog-routes)))
 
-;; ── render a registered post ────────────────────────────────────────
-(host/blog-reset!)
-(host/blog-register! "welcome" (host/blog-make "welcome" "Hello SX" "Served by lib/host."))
+;; ── publish a post to a fresh in-memory store (hermetic) ────────────
+(host/blog-use-store! (persist/open))
+(host/blog-publish! "welcome" "Hello SX" "Served by lib/host." 1)
 
 (host-bl-test
   "post 200"
@@ -48,11 +48,17 @@
   (dream-status (host-bl-app (host-bl-req "/welcome")))
   200)
 
-;; golden: endpoint body == content facade render of the same doc
+;; golden: endpoint body == the exact rendered HTML of the published post
 (host-bl-test
-  "golden = content/html"
+  "golden render"
   (dream-resp-body (host-bl-app (host-bl-req "/welcome/")))
-  (content/html (host/blog-make "welcome" "Hello SX" "Served by lib/host.")))
+  "<h1>Hello SX</h1><p>Served by lib/host.</p>")
+
+;; persistence: a post materialises from the op-log (replay), and re-seeding is
+;; idempotent (no duplicate blocks appended).
+(host-bl-test "lookup materialises 2 blocks" (content/count (host/blog-lookup "welcome")) 2)
+(host/blog-seed! "welcome" "Hello SX" "Served by lib/host." 2)
+(host-bl-test "re-seed is idempotent" (content/count (host/blog-lookup "welcome")) 2)
 
 ;; ── unknown slug -> 404 ─────────────────────────────────────────────
 (host-bl-test