content: tree reparent — move-into section + promote (812/812)

insert/move were top-level only; a block could never move into/out of a
section. content/move-into (relocate to a section child at index, tree-wide)
+ content/promote (lift nested block to top level, subtree intact). Pure
tree transforms like the rest of move.sx; cycle-safe (rejects moving a block
into its own descendant). +13 tests.

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

lib/content/move.sx

@@ -1,8 +1,13 @@
-;; content-on-sx — relative block reorder.
+;; content-on-sx — block reorder + reparent.
 ;;
-;; Move a top-level block to just before / after another block by id — more
-;; ergonomic than the index-based doc-move. No-op if either id is missing.
-;; Immutable; composes the doc.sx list helpers.
+;; Relative reorder of top-level blocks (move-before/after/to-front/to-back by
+;; id) plus TREE reparenting: move a block into a section (content/move-into) or
+;; promote a nested block back out to the top level (content/promote). Reparent
+;; ops are tree-wide (the block may start anywhere) and cycle-safe — moving a
+;; block into its own descendant is rejected (no-op), so a section can never
+;; become its own ancestor. No-op if any id is missing. Immutable; composes the
+;; doc.sx list + tree helpers (doc-find-deep / ct-find-id / ct-remove-id /
+;; ct-replace-id / ct-insert-at).
 ;;
 ;; Requires (loaded by harness): doc.sx.
 
@@ -67,3 +72,57 @@
         (doc-with-blocks
           doc
           (append (ct-remove-id (doc-blocks doc) id) (list blk)))))))
+
+;; ── reparent (tree-wide) ──
+;; move block `id` (from anywhere in the tree) to be a child of section
+;; `section-id` at index `i`. No-op if either id is missing, if id = section-id,
+;; or if section-id sits inside id's own subtree (would create a cycle).
+(define
+  content/move-into
+  (fn
+    (doc id section-id i)
+    (let
+      ((blk (doc-find-deep doc id)))
+      (if
+        (= blk nil)
+        doc
+        (if
+          (= (doc-find-deep doc section-id) nil)
+          doc
+          (if
+            (= id section-id)
+            doc
+            (if
+              (= (ct-find-id (list blk) section-id) nil)
+              (let
+                ((without (ct-remove-id (doc-blocks doc) id)))
+                (doc-with-blocks
+                  doc
+                  (ct-replace-id
+                    without
+                    section-id
+                    (fn
+                      (sec)
+                      (let
+                        ((ch (st-iv-get sec "children")))
+                        (if
+                          (list? ch)
+                          (st-iv-set! sec "children" (ct-insert-at ch i blk))
+                          sec))))))
+              doc)))))))
+
+;; promote block `id` (wherever it sits) out to the end of the top level. If it
+;; is already top-level this is a move-to-back. No-op if missing. A section keeps
+;; its whole subtree.
+(define
+  content/promote
+  (fn
+    (doc id)
+    (let
+      ((blk (doc-find-deep doc id)))
+      (if
+        (= blk nil)
+        doc
+        (doc-with-blocks
+          doc
+          (append (ct-remove-id (doc-blocks doc) id) (list blk)))))))

lib/content/scoreboard.json

@@ -12,7 +12,7 @@
     "section": {"pass": 25, "fail": 0},
     "compose": {"pass": 17, "fail": 0},
     "tree-edit": {"pass": 17, "fail": 0},
-    "move": {"pass": 11, "fail": 0},
+    "move": {"pass": 24, "fail": 0},
     "clone": {"pass": 10, "fail": 0},
     "query": {"pass": 20, "fail": 0},
     "toc": {"pass": 8, "fail": 0},
@@ -43,7 +43,7 @@
     "md-doc": {"pass": 12, "fail": 0},
     "fed": {"pass": 20, "fail": 0}
   },
-  "total_pass": 799,
+  "total_pass": 812,
   "total_fail": 0,
-  "total": 799
+  "total": 812
 }

lib/content/scoreboard.md

@@ -16,7 +16,7 @@ _Generated by `lib/content/conformance.sh`_
 | section | 25 | 0 | 25 |
 | compose | 17 | 0 | 17 |
 | tree-edit | 17 | 0 | 17 |
-| move | 11 | 0 | 11 |
+| move | 24 | 0 | 24 |
 | clone | 10 | 0 | 10 |
 | query | 20 | 0 | 20 |
 | toc | 8 | 0 | 8 |
@@ -46,4 +46,4 @@ _Generated by `lib/content/conformance.sh`_
 | md-import | 38 | 0 | 38 |
 | md-doc | 12 | 0 | 12 |
 | fed | 20 | 0 | 20 |
-| **Total** | **799** | **0** | **799** |
+| **Total** | **812** | **0** | **812** |

lib/content/tests/move.sx

@@ -1,7 +1,8 @@
-;; Extension — relative block reorder.
+;; Extension — relative block reorder + tree reparent.
 
 (st-bootstrap-classes!)
 (content/bootstrap!)
+(content-bootstrap-section!)
 
 (define
   d
@@ -61,3 +62,84 @@
   "render after move"
   (asHTML (content/move-after d "a" "c"))
   "<p>B</p><p>C</p><p>A</p>")
+
+;; ── reparent: move a top-level block INTO a section ──
+(define
+  nd
+  (doc-append
+    (doc-append (doc-empty "d") (mk-text "p" "P"))
+    (mk-section "s" (list (mk-text "x" "X")))))
+(content-test
+  "move-into: block leaves top level"
+  (doc-ids (content/move-into nd "p" "s" 1))
+  (list "s"))
+(content-test
+  "move-into: block lands in section at index"
+  (doc-tree-ids (content/move-into nd "p" "s" 1))
+  (list "s" "x" "p"))
+(content-test
+  "move-into at front of section"
+  (doc-tree-ids (content/move-into nd "p" "s" 0))
+  (list "s" "p" "x"))
+(content-test "move-into immutable" (doc-tree-ids nd) (list "p" "s" "x"))
+
+;; ── reparent: move a NESTED block to a different section ──
+(define
+  two
+  (doc-append
+    (doc-append (doc-empty "d") (mk-section "s1" (list (mk-text "n" "N"))))
+    (mk-section "s2" (list (mk-text "y" "Y")))))
+(content-test
+  "move-into across sections"
+  (doc-tree-ids (content/move-into two "n" "s2" 1))
+  (list "s1" "s2" "y" "n"))
+
+;; ── promote: nested block out to top level (appended last) ──
+(content-test
+  "promote nested to top level"
+  (doc-tree-ids (content/promote two "n"))
+  (list "s1" "s2" "y" "n"))
+(content-test
+  "promote leaves section empty shell"
+  (doc-ids (content/promote two "n"))
+  (list "s1" "s2" "n"))
+(content-test
+  "promote a whole section keeps its subtree"
+  (doc-tree-ids
+    (content/promote
+      (doc-append
+        (doc-empty "d")
+        (mk-section "o" (list (mk-section "i" (list (mk-text "z" "Z"))))))
+      "i"))
+  (list "o" "i" "z"))
+
+;; ── cycle guard: cannot move a section into its own descendant ──
+(define
+  nest
+  (doc-append
+    (doc-empty "d")
+    (mk-section
+      "outer"
+      (list (mk-section "inner" (list (mk-text "t" "T")))))))
+(content-test
+  "move section into its own child is a no-op"
+  (doc-tree-ids (content/move-into nest "outer" "inner" 0))
+  (list "outer" "inner" "t"))
+(content-test
+  "move block into itself is a no-op"
+  (doc-tree-ids (content/move-into nest "inner" "inner" 0))
+  (list "outer" "inner" "t"))
+
+;; ── reparent no-ops on missing ids ──
+(content-test
+  "move-into missing block no-op"
+  (doc-tree-ids (content/move-into nd "zzz" "s" 0))
+  (list "p" "s" "x"))
+(content-test
+  "move-into missing section no-op"
+  (doc-tree-ids (content/move-into nd "p" "zzz" 0))
+  (list "p" "s" "x"))
+(content-test
+  "promote missing no-op"
+  (doc-tree-ids (content/promote nd "zzz"))
+  (list "p" "s" "x"))