content: in-document prose search via asText (763/763)

content/search-text + search-text-ids find every block whose (asText b)
contains a term — spanning all text-bearing fields by reusing the canonical
asText projection, so it can't drift from stats/find-replace. Section
wrappers excluded. +7 query tests.

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

lib/content/query.sx

@@ -1,10 +1,10 @@
 ;; content-on-sx — block query + table of contents.
 ;;
 ;; Collect blocks across the whole tree (descending into sections) by predicate
-;; or type, and derive a table of contents from headings. Tree detection is
-;; inline (class + st-iv-get) so this needs no section.sx.
+;; or type, search them by prose, and derive a table of contents from headings.
+;; Tree detection is inline (class + st-iv-get) so this needs no section.sx.
 ;;
-;; Requires (loaded by harness): block.sx, doc.sx.
+;; Requires (loaded by harness): block.sx, doc.sx, text.sx (asText for search).
 
 (define
   qry-section?
@@ -45,6 +45,30 @@
   content/select-ids
   (fn (doc pred) (map (fn (b) (blk-id b)) (content/select doc pred))))
 
+;; Blocks (tree-wide, excluding section containers) whose own prose contains
+;; `term`. "Prose" is (asText b), so search covers exactly what every block
+;; exposes as text — text/heading/code/quote/callout text, image alt, list
+;; items, table headers+cells — with no separate field list to drift from
+;; asText / find-replace / stats. Case-sensitive substring match.
+(define
+  content/search-text
+  (fn
+    (doc term)
+    (content/select
+      doc
+      (fn
+        (b)
+        (and
+          (not (qry-section? b))
+          (>= (index-of (asText b) term) 0))))))
+
+;; Same search, returning matching block ids in document order.
+(define
+  content/search-text-ids
+  (fn
+    (doc term)
+    (map (fn (b) (blk-id b)) (content/search-text doc term))))
+
 ;; table of contents: {:id :level :text} for every heading, in document order.
 (define
   content/headings