host: per-request IO kernel fix + fully-dynamic blog (no cache), 159/159

KERNEL (sx_server.ml): route http-listen handlers through cek_run_with_io
instead of bare Sx_runtime.sx_call, so handlers resolve per-request IO
(durable persist reads/writes) via the same IO-driving runner the REPL uses.
Verified: per-request read+write, 10 concurrent writes (15 on disk, no
corruption), handler errors don't crash the server, http contract 6/6.

BLOG: fully dynamic — host/blog-post reads the post from the durable store
(content/head) AND renders (content/html) per request, no in-memory view, no
cached output. Possible because of the IO fix. Honest ~2s due to interpreted
Smalltalk render.

Render speed is NOT solved here: the JIT (precompiler) isn't installed in the
serving mode and currently miscompiles the Smalltalk evaluator's nested ASTs
(enabling it breaks ~60% of tests). Fixing the JIT is a separate, high-payoff
effort. Documented in the plan.

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

lib/host/blog.sx

@@ -1,15 +1,16 @@
 ;; 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
+;; whose source of truth is the durable SX store (persist op-log on disk). Serving
+;; GET /<slug>/ is FULLY DYNAMIC: the handler reads the post from the store and
+;; renders it to HTML, per request — no in-memory view, no cached output. This is
+;; possible because http-listen handlers now resolve per-request IO (the
+;; cek_run_with_io kernel fix). The original strangler target (Quart blog
 ;; post_detail); published posts are world-visible, so this endpoint is ANONYMOUS.
 ;;
-;; 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.
+;; NOTE ON SPEED: content/html runs the interpreted Smalltalk-on-SX dispatch
+;; (~2s for a tiny doc) because the JIT is not installed in this serving mode AND
+;; currently miscompiles the Smalltalk evaluator's nested ASTs. Making the render
+;; fast is a JIT-compiler fix (or a Smalltalk-interpreter optimisation), tracked
+;; separately — it is NOT solved by caching the output.
 ;; Depends on lib/content/* (+ Smalltalk + persist preloads) + lib/dream/* +
 ;; lib/host/handler.sx.
 
@@ -17,20 +18,13 @@
 (define host/blog-bootstrap!
   (fn () (begin (st-bootstrap-classes!) (content/bootstrap!))))
 
-;; ── store (durable source of truth) + view (in-memory serving cache) ─
+;; ── store (durable source of truth, injectable) ─────────────────────
 (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 {}))))
+(define host/blog-use-store! (fn (b) (set! host/blog-store b)))
 
-;; 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 + lookup (per-request, against the store) ───────────────
 ;; 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.
+;; to the durable store. `at` is a caller-supplied logical timestamp.
 (define host/blog-publish!
   (fn (slug title body at)
     (let ((hid (str slug "-h")) (tid (str slug "-body")))
@@ -38,35 +32,21 @@
         (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))))))
+        at))))
 
-;; 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.
+;; Idempotent seed: publish only if the slug has no content yet (so a restart
+;; replaying serve.sh doesn't append duplicate blocks to a persisted post).
 (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))))))
+    (when (= (content/count (content/head host/blog-store slug)) 0)
+      (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)))
+;; Materialise the post from the store by replaying its op-log; nil if no content.
+;; Reads the durable store via per-request IO (works inside the handler thread).
+(define host/blog-lookup
+  (fn (slug)
+    (let ((doc (content/head host/blog-store slug)))
+      (if (> (content/count doc) 0) doc nil))))
 
 ;; ── handler: GET /<slug>/ -> rendered HTML (200) or 404 ─────────────
 (define host/blog-post