diff --git a/lib/content/block.sx b/lib/content/block.sx
index d4aabf06..4aec68ef 100644
--- a/lib/content/block.sx
+++ b/lib/content/block.sx
@@ -15,6 +15,10 @@
 ;;     CtEmbed (url provider)
 ;;     CtDivider
 ;;     CtList (ordered items)
+;; Plus self-contained blocks registered by their own files: CtSection,
+;; CtTable, CtCallout, CtMedia. ct-class-for-type maps every tag (so mk-block,
+;; content/from-data and CRDT materialise build them uniformly); the classes
+;; themselves are registered by content-bootstrap-section!/table!/callout!/media!.
 
 (define
   ct-def-method!
@@ -87,6 +91,10 @@
       ((= tag "embed") "CtEmbed")
       ((= tag "divider") "CtDivider")
       ((= tag "list") "CtList")
+      ((= tag "section") "CtSection")
+      ((= tag "table") "CtTable")
+      ((= tag "callout") "CtCallout")
+      ((= tag "media") "CtMedia")
       (else (error (str "unknown block type: " tag))))))
 
 ;; Generic constructor — wire tag + id + (name value) field pairs.
diff --git a/lib/content/scoreboard.json b/lib/content/scoreboard.json
index 648f3581..bd3c1bc1 100644
--- a/lib/content/scoreboard.json
+++ b/lib/content/scoreboard.json
@@ -28,7 +28,7 @@
     "table": {"pass": 15, "fail": 0},
     "callout": {"pass": 12, "fail": 0},
     "media": {"pass": 15, "fail": 0},
-    "data": {"pass": 21, "fail": 0},
+    "data": {"pass": 25, "fail": 0},
     "wire": {"pass": 11, "fail": 0},
     "validate": {"pass": 23, "fail": 0},
     "store": {"pass": 29, "fail": 0},
@@ -41,7 +41,7 @@
     "md-doc": {"pass": 12, "fail": 0},
     "fed": {"pass": 20, "fail": 0}
   },
-  "total_pass": 727,
+  "total_pass": 731,
   "total_fail": 0,
-  "total": 727
+  "total": 731
 }
diff --git a/lib/content/scoreboard.md b/lib/content/scoreboard.md
index 885ba020..65aeabd4 100644
--- a/lib/content/scoreboard.md
+++ b/lib/content/scoreboard.md
@@ -32,7 +32,7 @@ _Generated by `lib/content/conformance.sh`_
 | table | 15 | 0 | 15 |
 | callout | 12 | 0 | 12 |
 | media | 15 | 0 | 15 |
-| data | 21 | 0 | 21 |
+| data | 25 | 0 | 25 |
 | wire | 11 | 0 | 11 |
 | validate | 23 | 0 | 23 |
 | store | 29 | 0 | 29 |
@@ -44,4 +44,4 @@ _Generated by `lib/content/conformance.sh`_
 | md-import | 38 | 0 | 38 |
 | md-doc | 12 | 0 | 12 |
 | fed | 20 | 0 | 20 |
-| **Total** | **727** | **0** | **727** |
+| **Total** | **731** | **0** | **731** |
diff --git a/lib/content/tests/data.sx b/lib/content/tests/data.sx
index 33eca9e5..9459758b 100644
--- a/lib/content/tests/data.sx
+++ b/lib/content/tests/data.sx
@@ -6,6 +6,8 @@
 (content-bootstrap-markdown!)
 (content-bootstrap-section!)
 (content-bootstrap-table!)
+(content-bootstrap-callout!)
+(content-bootstrap-media!)
 
 ;; ── block->data shape ──
 (define h (mk-heading "h" 2 "Hi"))
@@ -73,6 +75,27 @@
   (table-headers (doc-find rtt "t"))
   (list "A" "B"))
 
+;; ── callout + media round-trip (regression: ct-class-for-type must know them) ──
+(define
+  dcm
+  (doc-append
+    (doc-append (doc-empty "d") (mk-callout "co" "warning" "careful"))
+    (mk-video "vid" "/clip.mp4")))
+(define rtcm (content/from-data (content/to-data dcm)))
+(content-test "rt callout+media render" (asHTML rtcm) (asHTML dcm))
+(content-test
+  "rt callout kind"
+  (str (blk-send (doc-find rtcm "co") "kind"))
+  "warning")
+(content-test
+  "rt media kind"
+  (str (blk-send (doc-find rtcm "vid") "kind"))
+  "video")
+(content-test
+  "rt callout+media types"
+  (doc-types rtcm)
+  (list "callout" "media"))
+
 ;; ── data is plain (no st-instance markers at top level) ──
 (define dat (content/to-data d))
 (content-test "data id field" (get dat :id) "post")
diff --git a/plans/content-on-sx.md b/plans/content-on-sx.md
index 588a3a24..d30126bc 100644
--- a/plans/content-on-sx.md
+++ b/plans/content-on-sx.md
@@ -19,7 +19,7 @@ injected adapter, not core.
 
 ## Status (rolling)
 
-`bash lib/content/conformance.sh` → **727/727** (Phases 1–4 COMPLETE + ~34 extensions: HTML/SX escaping, Markdown render + import/export incl. tables & frontmatter (full round-trip), CvRDT flat + nested-tree + durable replication, tree-aware validation, snapshot cache, doc metadata, plain-text render, nested block trees + deep editing + flatten + relative reorder, doc stats + summary + multi-doc index, table + callout + media blocks, HTML page wrapper + SEO page, doc composition + id-remap, portable data + wire serialization, block query + transforms + find/replace, TOC + anchored headings + outline, normalization)
+`bash lib/content/conformance.sh` → **731/731** (Phases 1–4 COMPLETE + ~34 extensions: HTML/SX escaping, Markdown render + import/export incl. tables & frontmatter (full round-trip), CvRDT flat + nested-tree + durable replication, tree-aware validation, snapshot cache, doc metadata, plain-text render, nested block trees + deep editing + flatten + relative reorder, doc stats + summary + multi-doc index, table + callout + media blocks, HTML page wrapper + SEO page, doc composition + id-remap, portable data + wire serialization, block query + transforms + find/replace, TOC + anchored headings + outline, normalization)
 
 ## Ground rules
 
@@ -113,6 +113,13 @@ lib/content/api.sx ── (content/edit) (content/render) (content/history) ─
 
 ## Progress log
 
+- 2026-06-07 — Hardening: fixed `ct-class-for-type` (block.sx) to map all block
+  tags (added section/table/callout/media). Latent bug: `content/from-data` and
+  CRDT materialise of callout/media blocks failed with "unknown block type" (they
+  fell through to `mk-block`, which only knew the original 8 types). Now all block
+  types build uniformly via mk-block; data/wire/CRDT round-trips of callout/media
+  work. +4 data regression tests; full no-regression gate over the foundational
+  block.sx change: suite 731/731.
 - 2026-06-07 — Extension: nested-tree CvRDT (`crdt-tree.sx`). Extends the flat
   CvRDT to a TREE: each element carries a `parent` (containing section id, "" =
   root) beside its Logoot pos; merge reuses crdt.sx's pos/register/field joins +