content: Markdown frontmatter -> metadata + 9 tests (469/469)

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

lib/content/md-import.sx

@@ -1,14 +1,15 @@
 ;; content-on-sx — Markdown import adapter (markdown text -> block document).
 ;;
 ;; A line-based parser, the inverse of markdown.sx's asMarkdown. Confined to the
-;; adapter boundary: the core knows nothing about Markdown. Handles ATX headings
+;; adapter boundary: the core knows nothing about Markdown. Handles a leading
-;; (#..######), fenced code (```lang), blockquotes (> ), unordered (- / * ) and
+;; --- frontmatter block (key: value -> doc metadata), ATX headings (#..######),
-;; ordered (1. ) lists, thematic breaks (--- / ***), pipe tables (header row +
+;; fenced code (```lang), blockquotes (> ), unordered (- / * ) and ordered (1. )
-;; --- separator row + body rows), and paragraphs (consecutive plain lines joined
+;; lists, thematic breaks (--- / ***), pipe tables (header + --- separator +
-;; with a space). Block ids are assigned sequentially b0,b1…
+;; body), and paragraphs (consecutive plain lines joined with a space). Block ids
+;; are assigned sequentially b0,b1…
 ;;
-;; Requires (loaded by harness): block.sx, doc.sx, table.sx (mk-table); and
+;; Requires (loaded by harness): block.sx, doc.sx, table.sx (mk-table),
-;; markdown.sx for the adapter's export side.
+;; meta.sx (doc-with-meta); markdown.sx for the adapter's export side.
 
 (define md/-id (fn (i) (str "b" i)))
 (define md/-blank? (fn (s) (= s "")))
@@ -35,6 +36,18 @@
   md/-drop
   (fn (s prefix) (substring s (string-length prefix) (string-length s))))
 
+(define
+  md/-drop-n
+  (fn
+    (xs n)
+    (if
+      (= n 0)
+      xs
+      (if
+        (= (len xs) 0)
+        xs
+        (md/-drop-n (rest xs) (- n 1))))))
+
 (define
   md/-join-with
   (fn
@@ -365,7 +378,72 @@
   md/parse
   (fn (text) (md/-walk (split text (str "\n")) 0 (list))))
 
+;; ── frontmatter (leading --- key: value --- block) ──
+(define
+  md/-frontmatter?
+  (fn (lines) (and (> (len lines) 0) (= (first lines) "---"))))
+(define
+  md/-fm-end
+  (fn
+    (lines i)
+    (cond
+      ((>= i (len lines)) -1)
+      ((= (nth lines i) "---") i)
+      (else (md/-fm-end lines (+ i 1))))))
+(define
+  md/-fm-add
+  (fn
+    (acc line)
+    (let
+      ((parts (split line ":")))
+      (if
+        (< (len parts) 2)
+        acc
+        (let
+          ((key (trim (first parts)))
+            (val (trim (md/-join-with ":" (rest parts)))))
+          (cond
+            ((= key "title") (assoc acc :title val))
+            ((= key "slug") (assoc acc :slug val))
+            ((= key "tags")
+              (assoc acc :tags (map (fn (t) (trim t)) (split val ","))))
+            (else acc)))))))
+(define
+  md/-fm-pairs
+  (fn
+    (lines start end acc)
+    (if
+      (>= start end)
+      acc
+      (md/-fm-pairs
+        lines
+        (+ start 1)
+        end
+        (md/-fm-add acc (nth lines start))))))
+
 ;; ── adapter ──
-(define md/import (fn (text doc-id) (doc-new doc-id (md/parse text))))
+(define
+  md/import
+  (fn
+    (text doc-id)
+    (let
+      ((lines (split text (str "\n"))))
+      (if
+        (md/-frontmatter? lines)
+        (let
+          ((end (md/-fm-end lines 1)))
+          (if
+            (= end -1)
+            (doc-new doc-id (md/-walk lines 0 (list)))
+            (doc-with-meta
+              (doc-new
+                doc-id
+                (md/-walk
+                  (md/-drop-n lines (+ end 1))
+                  0
+                  (list)))
+              (md/-fm-pairs lines 1 end {}))))
+        (doc-new doc-id (md/-walk lines 0 (list)))))))
+
 (define content/from-markdown md/import)
 (define markdown-adapter {:export (fn (doc) (asMarkdown doc)) :import md/import})

lib/content/scoreboard.json

@@ -17,10 +17,10 @@
     "crdt": {"pass": 34, "fail": 0},
     "crdt-store": {"pass": 14, "fail": 0},
     "sync": {"pass": 14, "fail": 0},
-    "md-import": {"pass": 29, "fail": 0},
+    "md-import": {"pass": 38, "fail": 0},
     "fed": {"pass": 20, "fail": 0}
   },
-  "total_pass": 460,
+  "total_pass": 469,
   "total_fail": 0,
-  "total": 460
+  "total": 469
 }

lib/content/scoreboard.md

@@ -21,6 +21,6 @@ _Generated by `lib/content/conformance.sh`_
 | crdt | 34 | 0 | 34 |
 | crdt-store | 14 | 0 | 14 |
 | sync | 14 | 0 | 14 |
-| md-import | 29 | 0 | 29 |
+| md-import | 38 | 0 | 38 |
 | fed | 20 | 0 | 20 |
-| **Total** | **460** | **0** | **460** |
+| **Total** | **469** | **0** | **469** |

lib/content/tests/md-import.sx

@@ -1,5 +1,5 @@
 ;; Extension — Markdown import adapter (markdown text -> blocks), inverse of
-;; asMarkdown. Round-trips canonical Markdown.
+;; asMarkdown. Round-trips canonical Markdown; parses frontmatter + tables.
 
 (st-bootstrap-classes!)
 (content/bootstrap!)
@@ -130,6 +130,43 @@
   (doc-types dmix)
   (list "heading" "table" "text"))
 
+;; ── frontmatter ──
+(define
+  dfm
+  (md/import
+    (str
+      "---"
+      nl
+      "title: My Post"
+      nl
+      "slug: my-post"
+      nl
+      "tags: a, b, c"
+      nl
+      "---"
+      nl
+      "# Hi"
+      nl
+      nl
+      "body")
+    "d"))
+(content-test "fm title" (doc-title dfm) "My Post")
+(content-test "fm slug" (doc-slug dfm) "my-post")
+(content-test "fm tags" (doc-tags dfm) (list "a" "b" "c"))
+(content-test "fm body types" (doc-types dfm) (list "heading" "text"))
+(content-test
+  "fm body content"
+  (str (blk-send (doc-find dfm "b0") "text"))
+  "Hi")
+(content-test "no fm title nil" (doc-title (md/import "# Hi" "d")) nil)
+(content-test
+  "hr not frontmatter"
+  (doc-types (md/import (str "text" nl nl "---") "d"))
+  (list "text" "divider"))
+(define dfmo (md/import (str "---" nl "title: T" nl "---") "d"))
+(content-test "fm only title" (doc-title dfmo) "T")
+(content-test "fm only empty body" (doc-ids dfmo) (list))
+
 ;; ── round-trip: import . export == identity (canonical markdown) ──
 (define
   src

plans/content-on-sx.md

@@ -19,7 +19,7 @@ injected adapter, not core.
 
 ## Status (rolling)
 
-`bash lib/content/conformance.sh` → **460/460** (Phases 1–4 COMPLETE + 13 extensions: HTML/SX escaping, Markdown render + import incl. tables, CRDT replication, tree-aware validation, snapshot cache, doc metadata, plain-text render, nested block trees, doc stats, table block, HTML page wrapper)
+`bash lib/content/conformance.sh` → **469/469** (Phases 1–4 COMPLETE + 13 extensions: HTML/SX escaping, Markdown render + import incl. tables & frontmatter, CRDT replication, tree-aware validation, snapshot cache, doc metadata, plain-text render, nested block trees, doc stats, table block, HTML page wrapper)
 
 ## Ground rules
 
@@ -81,7 +81,7 @@ lib/content/api.sx ── (content/edit) (content/render) (content/history) ─
 - [x] Markdown render mode (`asMarkdown:` / `content/render doc "md"`)
 - [x] durable CRDT replication (`crdt-store.sx`: ops on persist, replay + converge)
 - [x] document validation (`validate.sx`: ids, per-type fields, duplicate ids; tree-aware — descends into sections, tree-wide dup ids, section field check)
-- [x] Markdown import adapter (`md-import.sx`: text → blocks, round-trips export; incl. pipe tables)
+- [x] Markdown import adapter (`md-import.sx`: text → blocks, round-trips export; incl. pipe tables + frontmatter → metadata)
 - [x] snapshot cache over replay (`snapshot.sx`: cache-not-primary, transparent)
 - [x] document metadata (`meta.sx`: title/slug/tags + Ghost title plumbing)
 - [x] plain-text render + excerpt (`text.sx`: asText, content/excerpt)
@@ -92,6 +92,11 @@ lib/content/api.sx ── (content/edit) (content/render) (content/history) ─
 
 ## Progress log
 
+- 2026-06-07 — Extension: Markdown frontmatter. `md/import` parses a leading
+  `---` / `key: value` / `---` block into document metadata (title, slug,
+  comma-separated tags via `doc-with-meta`) before parsing the body; a `---`
+  elsewhere stays a divider. Ties the Markdown importer to the metadata layer the
+  way real blog posts work. +9 tests; suite 469/469.
 - 2026-06-07 — Extension: Markdown table import. `md-import.sx` now recognizes a
   `| … |` header row followed by a `| --- |` separator and parses a `CtTable`
   (cells trimmed, mixed with other blocks via blank-line separation), completing