Hold the lazy-continuation fence, and fault a colon run that closes nothing

corpus/README.md

@@ -4,7 +4,7 @@ One directory per contract kind, each landing with its milestone:
 
 - `round-trip/` — `<name>.json` + `<name>.md`: the markdown `adfToMarkdown` must emit for that
   document, byte for byte, and that `markdownToAdf` must read back to it (AGENTS.md §2). Grouped
-  by node family, `combinations/` holding what crosses them.
+  by what the fixture exercises.
 - `normalization/` — `<name>.md` + `<name>.json`: markdown input, and the document
   `markdownToAdf` must build from it. One-way; the markdown is not canonical.
 - `errors/` — `<name>.md`: markdown input that must not convert. A `<name>.error` beside it

corpus/round-trip/combinations/closing-fence-line.json

@@ -5,33 +5,6 @@
         "panelType": "info"
       },
       "content": [
-        {
-          "content": [
-            {
-              "text": ":::",
-              "type": "text"
-            }
-          ],
-          "type": "paragraph"
-        },
-        {
-          "content": [
-            {
-              "text": "::: x",
-              "type": "text"
-            }
-          ],
-          "type": "paragraph"
-        },
-        {
-          "content": [
-            {
-              "text": "::",
-              "type": "text"
-            }
-          ],
-          "type": "paragraph"
-        },
         {
           "content": [
             {
@@ -64,6 +37,33 @@
             }
           ],
           "type": "blockquote"
+        },
+        {
+          "content": [
+            {
+              "text": ":::",
+              "type": "text"
+            }
+          ],
+          "type": "paragraph"
+        },
+        {
+          "content": [
+            {
+              "text": "::: x",
+              "type": "text"
+            }
+          ],
+          "type": "paragraph"
+        },
+        {
+          "content": [
+            {
+              "text": "::",
+              "type": "text"
+            }
+          ],
+          "type": "paragraph"
         }
       ],
       "type": "panel"

corpus/round-trip/combinations/closing-fence-line.md

@@ -1,13 +1,13 @@
 :::panel info
+- \:::
+
+> \:::
+
 \:::
 
 \::: x
 
 \::
-
-- \:::
-
-> \:::
 :::
 
 \:::

src/corpus.test.ts

@@ -86,7 +86,8 @@ function fenceNestingFault(markdown: string): string | undefined {
     const run = colons[1]?.length ?? 0
     const enclosing = open[open.length - 1]
     if (colons[2] === '') {
-      if (enclosing !== undefined && run < enclosing) return `${JSON.stringify(line)} is shorter than the ${enclosing} colons it would close`
+      if (enclosing === undefined) return `${JSON.stringify(line)} closes no open container`
+      if (run < enclosing) return `${JSON.stringify(line)} is shorter than the ${enclosing} colons it would close`
       open.pop()
       continue
     }
@@ -101,6 +102,7 @@ test('the fence nesting check catches a fence a container cannot hold', () => {
   assert.equal(fenceNestingFault(':::panel info\n- - :::panel warning\n    B\n    :::\n:::'), '"- - :::panel warning" sits in a container fenced with 3 colons')
   assert.equal(fenceNestingFault(':::panel info\n10. :::panel warning\n    B\n    :::\n:::'), '"10. :::panel warning" sits in a container fenced with 3 colons')
   assert.equal(fenceNestingFault('::::panel info\n:::\n::::'), '":::" is shorter than the 4 colons it would close')
+  assert.equal(fenceNestingFault('Text\n:::\n'), '":::" closes no open container')
   assert.equal(fenceNestingFault('::::panel info\n- - :::panel warning\n    B\n    :::\n::::'), undefined)
   assert.equal(fenceNestingFault(':::tableCell\n```text\n:::::::panel warning\n:::\n```\n:::'), undefined)
 })

todo.md

@@ -84,8 +84,8 @@ detail is settled at its own milestone.
         attribute fallback 2e owes, since the reservation leaves that node no other spelling
         whatever 1d decides for its `localId`.
   - [ ] **2e — Carve-outs and combinations.** Fixtures and emitter together, into
-        `corpus/round-trip/combinations/` — the documents that cross what 2a–2d isolated.
+        `corpus/round-trip/combinations/`.
-    - [ ] **2e1 — The carve-outs and the claimed line.** The directory opens: the three carve-outs
+    - [ ] **2e1 — The carve-outs and the claimed line.** The three carve-outs
           and their escapes, and a paragraph line inside a container body shaped like a closing
           fence (`:::`, `::: x`). Guard `fenceNestingFault`'s bare-run pop here too — a run shorter
           than the open fence is a fault, not a close — which today's emitter cannot reach.
@@ -117,7 +117,8 @@ detail is settled at its own milestone.
           and it is provable without one. It also settles the emitter's one known approximation:
           delimiter flanking is exact, but CommonMark's *matching* — the multiple-of-3 rule and the
           way a run splits across several openers — is not modelled. No reachable violation has been
-          found by hand; the property test is what decides it.
+          found by hand; the property test is what decides it, and 2e1's `carve-out-strike` pins a
+          second backslash only flanking-without-matching emits.
   - [ ] **2f — The attributes CommonMark cannot hold.** 1d's settled answer: the block nodes
         CommonMark spells — `blockquote`, `bulletList`, `codeBlock`, `heading`, `listItem`,
         `orderedList`, `paragraph`, `rule` — get directive sections in `spec/flavour.md` carrying
@@ -140,7 +141,10 @@ detail is settled at its own milestone.
       assumes — CommonMark flanking, as for `*` — which `spec/flavour.md` does not yet pin, and
       the precedence between a directive and the constructs a raw attribute value opens inside it —
       a code span, an entity, raw HTML — which one directive alone already reaches until 2e's
-      escape lands.
+      escape lands. Whether a claimed line interrupts a paragraph is pinned for the plain case and
+      unstated for the lazy one: a closing fence on the line after a blockquote's open paragraph is
+      lazy continuation in CommonMark, which would swallow the fence and leave the container
+      unclosed. 2e1's `closing-fence-line` orders its blockquote away from that edge meanwhile.
       `src/` gets its hierarchy at the same split — `adf/`,
       `markdown/`, `html/`, the grammar module shared inside `markdown/` — while the rename is
       still mechanical. Three files do not move whole: `block-directives.ts` and