From 295864786dad7dafef3a7b5d7b49f2ba5ef9237d Mon Sep 17 00:00:00 2001
From: giles <giles.bradshaw@rose-ash.com>
Date: Sun, 7 Jun 2026 01:33:50 +0000
Subject: [PATCH] content: Markdown import adapter (md-import) + 24 tests
 (318/318)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 lib/content/conformance.sh     |   3 +-
 lib/content/md-import.sx       | 270 +++++++++++++++++++++++++++++++++
 lib/content/scoreboard.json    |   5 +-
 lib/content/scoreboard.md      |   3 +-
 lib/content/tests/md-import.sx | 120 +++++++++++++++
 plans/content-on-sx.md         |  10 +-
 6 files changed, 406 insertions(+), 5 deletions(-)
 create mode 100644 lib/content/md-import.sx
 create mode 100644 lib/content/tests/md-import.sx

diff --git a/lib/content/conformance.sh b/lib/content/conformance.sh
index b74c3590..8084c116 100755
--- a/lib/content/conformance.sh
+++ b/lib/content/conformance.sh
@@ -15,7 +15,7 @@ if [ ! -x "$SX_SERVER" ]; then
   fi
 fi
 
-SUITES=(block doc render api markdown validate store crdt crdt-store sync fed)
+SUITES=(block doc render api markdown validate store crdt crdt-store sync md-import fed)
 
 OUT_JSON="lib/content/scoreboard.json"
 OUT_MD="lib/content/scoreboard.md"
@@ -48,6 +48,7 @@ run_suite() {
 (load "lib/content/crdt.sx")
 (load "lib/content/crdt-store.sx")
 (load "lib/content/sync.sx")
+(load "lib/content/md-import.sx")
 (load "lib/content/fed.sx")
 (epoch 2)
 (eval "(define content-test-pass 0)")
diff --git a/lib/content/md-import.sx b/lib/content/md-import.sx
new file mode 100644
index 00000000..5abd885c
--- /dev/null
+++ b/lib/content/md-import.sx
@@ -0,0 +1,270 @@
+;; 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
+;; (#..######), fenced code (```lang), blockquotes (> ), unordered (- / * ) and
+;; ordered (1. ) lists, thematic breaks (--- / ***), and paragraphs (consecutive
+;; plain lines joined with a space). Block ids are assigned sequentially b0,b1…
+;;
+;; Requires (loaded by harness): block.sx, doc.sx (and markdown.sx for the
+;; adapter's export side).
+
+(define md/-id (fn (i) (str "b" i)))
+(define md/-blank? (fn (s) (= s "")))
+(define md/-hr? (fn (s) (if (= s "---") true (= s "***"))))
+
+(define
+  ct-in?
+  (fn
+    (x xs)
+    (cond
+      ((= (len xs) 0) false)
+      ((= (first xs) x) true)
+      (else (ct-in? x (rest xs))))))
+
+(define
+  ct-starts-with?
+  (fn
+    (s prefix)
+    (and
+      (>= (string-length s) (string-length prefix))
+      (= (substring s 0 (string-length prefix)) prefix))))
+
+(define
+  md/-drop
+  (fn (s prefix) (substring s (string-length prefix) (string-length s))))
+
+(define
+  md/-join-with
+  (fn
+    (sep parts)
+    (cond
+      ((= (len parts) 0) "")
+      ((= (len parts) 1) (first parts))
+      (else (str (first parts) sep (md/-join-with sep (rest parts)))))))
+(define md/-join-sp (fn (parts) (md/-join-with " " parts)))
+(define md/-join-nl (fn (parts) (md/-join-with (str "\n") parts)))
+
+;; ── heading detection (leading #s then a space) ──
+(define
+  md/-hashes
+  (fn
+    (s n)
+    (if
+      (and
+        (< n (string-length s))
+        (= (substring s n (+ n 1)) "#"))
+      (md/-hashes s (+ n 1))
+      n)))
+(define
+  md/-heading?
+  (fn
+    (line)
+    (let
+      ((n (md/-hashes line 0)))
+      (and
+        (> n 0)
+        (<= n 6)
+        (> (string-length line) n)
+        (= (substring line n (+ n 1)) " ")))))
+(define
+  md/-heading-block
+  (fn
+    (line i)
+    (let
+      ((n (md/-hashes line 0)))
+      (mk-heading
+        (md/-id i)
+        n
+        (substring line (+ n 1) (string-length line))))))
+
+;; ── list detection ──
+(define
+  ct-digit?
+  (fn (ch) (ct-in? ch (list "0" "1" "2" "3" "4" "5" "6" "7" "8" "9"))))
+(define
+  md/-digits
+  (fn
+    (s n)
+    (if
+      (and
+        (< n (string-length s))
+        (ct-digit? (substring s n (+ n 1))))
+      (md/-digits s (+ n 1))
+      n)))
+(define
+  md/-ol?
+  (fn
+    (line)
+    (let
+      ((n (md/-digits line 0)))
+      (and
+        (> n 0)
+        (>= (string-length line) (+ n 2))
+        (= (substring line n (+ n 2)) ". ")))))
+(define
+  md/-drop-ol
+  (fn
+    (line)
+    (let
+      ((n (md/-digits line 0)))
+      (substring line (+ n 2) (string-length line)))))
+(define
+  md/-ul?
+  (fn
+    (line)
+    (if (ct-starts-with? line "- ") true (ct-starts-with? line "* "))))
+(define
+  md/-drop-ul
+  (fn (line) (substring line 2 (string-length line))))
+
+(define
+  md/-plain?
+  (fn
+    (line)
+    (if
+      (md/-blank? line)
+      false
+      (if
+        (ct-starts-with? line "```")
+        false
+        (if
+          (md/-heading? line)
+          false
+          (if
+            (ct-starts-with? line "> ")
+            false
+            (if
+              (md/-hr? line)
+              false
+              (if (md/-ul? line) false (if (md/-ol? line) false true)))))))))
+
+;; ── multi-line collectors ──
+(define
+  md/-code
+  (fn
+    (lines i acc)
+    (md/-code-collect
+      (rest lines)
+      (md/-drop (first lines) "```")
+      (list)
+      i
+      acc)))
+(define
+  md/-code-collect
+  (fn
+    (lines lang body i acc)
+    (cond
+      ((= (len lines) 0)
+        (md/-walk
+          lines
+          (+ i 1)
+          (cons (mk-code (md/-id i) lang (md/-join-nl (reverse body))) acc)))
+      ((= (first lines) "```")
+        (md/-walk
+          (rest lines)
+          (+ i 1)
+          (cons (mk-code (md/-id i) lang (md/-join-nl (reverse body))) acc)))
+      (else
+        (md/-code-collect (rest lines) lang (cons (first lines) body) i acc)))))
+
+(define
+  md/-list-collect
+  (fn
+    (lines items i acc ordered)
+    (if
+      (= (len lines) 0)
+      (md/-walk
+        lines
+        (+ i 1)
+        (cons (mk-list (md/-id i) ordered (reverse items)) acc))
+      (let
+        ((line (first lines)))
+        (cond
+          (ordered
+            (if
+              (md/-ol? line)
+              (md/-list-collect
+                (rest lines)
+                (cons (md/-drop-ol line) items)
+                i
+                acc
+                ordered)
+              (md/-walk
+                lines
+                (+ i 1)
+                (cons (mk-list (md/-id i) ordered (reverse items)) acc))))
+          (else
+            (if
+              (md/-ul? line)
+              (md/-list-collect
+                (rest lines)
+                (cons (md/-drop-ul line) items)
+                i
+                acc
+                ordered)
+              (md/-walk
+                lines
+                (+ i 1)
+                (cons (mk-list (md/-id i) ordered (reverse items)) acc)))))))))
+
+(define
+  md/-para-collect
+  (fn
+    (lines parts i acc)
+    (if
+      (= (len lines) 0)
+      (md/-walk
+        lines
+        (+ i 1)
+        (cons (mk-text (md/-id i) (md/-join-sp (reverse parts))) acc))
+      (let
+        ((line (first lines)))
+        (if
+          (md/-plain? line)
+          (md/-para-collect (rest lines) (cons line parts) i acc)
+          (md/-walk
+            lines
+            (+ i 1)
+            (cons (mk-text (md/-id i) (md/-join-sp (reverse parts))) acc)))))))
+
+;; ── main walk ──
+(define
+  md/-walk
+  (fn
+    (lines i acc)
+    (if
+      (= (len lines) 0)
+      (reverse acc)
+      (let
+        ((line (first lines)))
+        (cond
+          ((md/-blank? line) (md/-walk (rest lines) i acc))
+          ((ct-starts-with? line "```") (md/-code lines i acc))
+          ((md/-heading? line)
+            (md/-walk
+              (rest lines)
+              (+ i 1)
+              (cons (md/-heading-block line i) acc)))
+          ((ct-starts-with? line "> ")
+            (md/-walk
+              (rest lines)
+              (+ i 1)
+              (cons (mk-quote (md/-id i) "" (md/-drop line "> ")) acc)))
+          ((md/-hr? line)
+            (md/-walk
+              (rest lines)
+              (+ i 1)
+              (cons (mk-divider (md/-id i)) acc)))
+          ((md/-ul? line) (md/-list-collect lines (list) i acc false))
+          ((md/-ol? line) (md/-list-collect lines (list) i acc true))
+          (else (md/-para-collect lines (list) i acc)))))))
+
+(define
+  md/parse
+  (fn (text) (md/-walk (split text (str "\n")) 0 (list))))
+
+;; ── adapter ──
+(define md/import (fn (text doc-id) (doc-new doc-id (md/parse text))))
+(define content/from-markdown md/import)
+(define markdown-adapter {:export (fn (doc) (asMarkdown doc)) :import md/import})
diff --git a/lib/content/scoreboard.json b/lib/content/scoreboard.json
index 6fce4919..27c95023 100644
--- a/lib/content/scoreboard.json
+++ b/lib/content/scoreboard.json
@@ -10,9 +10,10 @@
     "crdt": {"pass": 34, "fail": 0},
     "crdt-store": {"pass": 14, "fail": 0},
     "sync": {"pass": 14, "fail": 0},
+    "md-import": {"pass": 24, "fail": 0},
     "fed": {"pass": 20, "fail": 0}
   },
-  "total_pass": 294,
+  "total_pass": 318,
   "total_fail": 0,
-  "total": 294
+  "total": 318
 }
diff --git a/lib/content/scoreboard.md b/lib/content/scoreboard.md
index 2a3fcb5c..cdc9f735 100644
--- a/lib/content/scoreboard.md
+++ b/lib/content/scoreboard.md
@@ -14,5 +14,6 @@ _Generated by `lib/content/conformance.sh`_
 | crdt | 34 | 0 | 34 |
 | crdt-store | 14 | 0 | 14 |
 | sync | 14 | 0 | 14 |
+| md-import | 24 | 0 | 24 |
 | fed | 20 | 0 | 20 |
-| **Total** | **294** | **0** | **294** |
+| **Total** | **318** | **0** | **318** |
diff --git a/lib/content/tests/md-import.sx b/lib/content/tests/md-import.sx
new file mode 100644
index 00000000..24572d65
--- /dev/null
+++ b/lib/content/tests/md-import.sx
@@ -0,0 +1,120 @@
+;; Extension — Markdown import adapter (markdown text -> blocks), inverse of
+;; asMarkdown. Round-trips canonical Markdown.
+
+(st-bootstrap-classes!)
+(content/bootstrap!)
+(content-bootstrap-markdown!)
+
+(define nl (str "\n"))
+
+;; ── headings ──
+(define dh (md/import "# Title" "d"))
+(content-test "heading import type" (doc-types dh) (list "heading"))
+(content-test
+  "heading level"
+  (blk-send (doc-find dh "b0") "level")
+  1)
+(content-test
+  "heading text"
+  (str (blk-send (doc-find dh "b0") "text"))
+  "Title")
+(content-test
+  "h3 import"
+  (blk-send (doc-find (md/import "### Deep" "d") "b0") "level")
+  3)
+
+;; ── paragraph (consecutive lines join with space) ──
+(content-test
+  "paragraph join"
+  (str
+    (blk-send
+      (doc-find (md/import (str "hello" nl "world") "d") "b0")
+      "text"))
+  "hello world")
+
+;; ── blockquote, divider ──
+(content-test
+  "blockquote"
+  (str (blk-send (doc-find (md/import "> quoted" "d") "b0") "text"))
+  "quoted")
+(content-test "divider" (doc-types (md/import "---" "d")) (list "divider"))
+
+;; ── unordered + ordered lists ──
+(define dul (md/import (str "- a" nl "- b" nl "- c") "d"))
+(content-test "ul type" (doc-types dul) (list "list"))
+(content-test
+  "ul not ordered"
+  (blk-send (doc-find dul "b0") "ordered")
+  false)
+(content-test
+  "ul items"
+  (blk-send (doc-find dul "b0") "items")
+  (list "a" "b" "c"))
+(define dol (md/import (str "1. x" nl "2. y") "d"))
+(content-test "ol ordered" (blk-send (doc-find dol "b0") "ordered") true)
+(content-test
+  "ol items"
+  (blk-send (doc-find dol "b0") "items")
+  (list "x" "y"))
+
+;; ── fenced code ──
+(define dc (md/import (str "```sx" nl "(+ 1 2)" nl "(* 3 4)" nl "```") "d"))
+(content-test "code type" (doc-types dc) (list "code"))
+(content-test
+  "code language"
+  (str (blk-send (doc-find dc "b0") "language"))
+  "sx")
+(content-test
+  "code body"
+  (str (blk-send (doc-find dc "b0") "text"))
+  (str "(+ 1 2)" nl "(* 3 4)"))
+
+;; ── multiple blocks separated by blank lines ──
+(define dm (md/import (str "# H" nl nl "para" nl nl "- a" nl "- b") "d"))
+(content-test "multi types" (doc-types dm) (list "heading" "text" "list"))
+(content-test "multi ids" (doc-ids dm) (list "b0" "b1" "b2"))
+
+;; ── empty / blank input ──
+(content-test "empty input" (doc-ids (md/import "" "d")) (list))
+(content-test
+  "blank lines only"
+  (doc-ids (md/import (str nl nl) "d"))
+  (list))
+
+;; ── round-trip: import . export == identity (canonical markdown) ──
+(define
+  src
+  (str
+    "# Title"
+    nl
+    nl
+    "hello world"
+    nl
+    nl
+    "> quoted"
+    nl
+    nl
+    "- a"
+    nl
+    "- b"
+    nl
+    nl
+    "---"))
+(content-test "round-trip markdown" (asMarkdown (md/import src "d")) src)
+(content-test
+  "round-trip code"
+  (asMarkdown (md/import (str "```js" nl "x = 1" nl "```") "d"))
+  (str "```js" nl "x = 1" nl "```"))
+
+;; ── adapter form ──
+(content-test
+  "adapter import"
+  (doc-types (content/import markdown-adapter "# Hi" "d"))
+  (list "heading"))
+(content-test
+  "adapter export round-trip"
+  (content/export markdown-adapter (content/import markdown-adapter src "d"))
+  src)
+
+;; ── imported doc validates ──
+(content-test "imported doc valid" (content/valid? (md/import src "d")) true)
diff --git a/plans/content-on-sx.md b/plans/content-on-sx.md
index bc103f1f..c9ba47d7 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` → **294/294** (Phases 1–4 COMPLETE + extensions: HTML/SX escaping, Markdown, durable CRDT replication, validation)
+`bash lib/content/conformance.sh` → **318/318** (Phases 1–4 COMPLETE + extensions: HTML/SX escaping, Markdown render+import, durable CRDT replication, validation)
 
 ## Ground rules
 
@@ -81,9 +81,17 @@ 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)
+- [x] Markdown import adapter (`md-import.sx`: text → blocks, round-trips export)
 
 ## Progress log
 
+- 2026-06-07 — Extension: Markdown import adapter (`md-import.sx`), inverse of
+  asMarkdown. Line-based parser: ATX headings, fenced code (```lang), blockquotes,
+  unordered/ordered lists (grouping consecutive items), thematic breaks,
+  paragraphs (consecutive plain lines joined with a space). Sequential ids
+  b0,b1…. `md/import` / `content/from-markdown` / `markdown-adapter` (import +
+  asMarkdown export). Round-trips canonical Markdown (import∘export == identity);
+  imported docs pass validation. 24 tests; suite 318/318.
 - 2026-06-07 — Extension: document validation (`validate.sx`). `content/validate`
   returns issue dicts `{:id :kind :detail}` (empty = valid); `content/valid?`
   and `content/issue-kinds` convenience. Checks block id (non-empty string),