diff --git a/corpus/README.md b/corpus/README.md
new file mode 100644
index 0000000..4122780
--- /dev/null
+++ b/corpus/README.md
@@ -0,0 +1,8 @@
+# The corpus
+
+`<name>.json` is an ADF document; `<name>.md` is the markdown `adfToMarkdown` must emit for it,
+byte for byte including the trailing newline, and that `markdownToAdf` must read back to that same
+document (AGENTS.md §2). Directories mirror `spec/flavour.md`'s sections.
+
+The JSON is editor-normal — empty `attrs`, `marks` and `content` as the absent key, adjacent
+identical-mark text nodes merged — two-space indent, keys sorted.
diff --git a/corpus/canonical-form/blockquote.json b/corpus/canonical-form/blockquote.json
new file mode 100644
index 0000000..145989c
--- /dev/null
+++ b/corpus/canonical-form/blockquote.json
@@ -0,0 +1,29 @@
+{
+  "content": [
+    {
+      "content": [
+        {
+          "content": [
+            {
+              "text": "Ship it.",
+              "type": "text"
+            }
+          ],
+          "type": "paragraph"
+        },
+        {
+          "content": [
+            {
+              "text": "Then tell them.",
+              "type": "text"
+            }
+          ],
+          "type": "paragraph"
+        }
+      ],
+      "type": "blockquote"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}
diff --git a/corpus/canonical-form/blockquote.md b/corpus/canonical-form/blockquote.md
new file mode 100644
index 0000000..f46663f
--- /dev/null
+++ b/corpus/canonical-form/blockquote.md
@@ -0,0 +1,3 @@
+> Ship it.
+>
+> Then tell them.
diff --git a/corpus/canonical-form/bullet-list.json b/corpus/canonical-form/bullet-list.json
new file mode 100644
index 0000000..17d1b65
--- /dev/null
+++ b/corpus/canonical-form/bullet-list.json
@@ -0,0 +1,72 @@
+{
+  "content": [
+    {
+      "content": [
+        {
+          "content": [
+            {
+              "content": [
+                {
+                  "text": "Bolt M8",
+                  "type": "text"
+                }
+              ],
+              "type": "paragraph"
+            }
+          ],
+          "type": "listItem"
+        },
+        {
+          "content": [
+            {
+              "content": [
+                {
+                  "text": "Nut M8",
+                  "type": "text"
+                }
+              ],
+              "type": "paragraph"
+            }
+          ],
+          "type": "listItem"
+        },
+        {
+          "content": [
+            {
+              "content": [
+                {
+                  "text": "Washer M8",
+                  "type": "text"
+                }
+              ],
+              "type": "paragraph"
+            },
+            {
+              "content": [
+                {
+                  "content": [
+                    {
+                      "content": [
+                        {
+                          "text": "Fibre",
+                          "type": "text"
+                        }
+                      ],
+                      "type": "paragraph"
+                    }
+                  ],
+                  "type": "listItem"
+                }
+              ],
+              "type": "bulletList"
+            }
+          ],
+          "type": "listItem"
+        }
+      ],
+      "type": "bulletList"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}
diff --git a/corpus/canonical-form/bullet-list.md b/corpus/canonical-form/bullet-list.md
new file mode 100644
index 0000000..51738d8
--- /dev/null
+++ b/corpus/canonical-form/bullet-list.md
@@ -0,0 +1,4 @@
+- Bolt M8
+- Nut M8
+- Washer M8
+  - Fibre
diff --git a/corpus/canonical-form/code-block-backtick-run.json b/corpus/canonical-form/code-block-backtick-run.json
new file mode 100644
index 0000000..012ffd4
--- /dev/null
+++ b/corpus/canonical-form/code-block-backtick-run.json
@@ -0,0 +1,15 @@
+{
+  "content": [
+    {
+      "content": [
+        {
+          "text": "```\ncode\n```",
+          "type": "text"
+        }
+      ],
+      "type": "codeBlock"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}
diff --git a/corpus/canonical-form/code-block-backtick-run.md b/corpus/canonical-form/code-block-backtick-run.md
new file mode 100644
index 0000000..436503d
--- /dev/null
+++ b/corpus/canonical-form/code-block-backtick-run.md
@@ -0,0 +1,5 @@
+````
+```
+code
+```
+````
diff --git a/corpus/canonical-form/code-block.json b/corpus/canonical-form/code-block.json
new file mode 100644
index 0000000..e22ce1e
--- /dev/null
+++ b/corpus/canonical-form/code-block.json
@@ -0,0 +1,18 @@
+{
+  "content": [
+    {
+      "attrs": {
+        "language": "sql"
+      },
+      "content": [
+        {
+          "text": "SELECT id\nFROM part\nWHERE qty > 0;",
+          "type": "text"
+        }
+      ],
+      "type": "codeBlock"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}
diff --git a/corpus/canonical-form/code-block.md b/corpus/canonical-form/code-block.md
new file mode 100644
index 0000000..1b22ef2
--- /dev/null
+++ b/corpus/canonical-form/code-block.md
@@ -0,0 +1,5 @@
+```sql
+SELECT id
+FROM part
+WHERE qty > 0;
+```
diff --git a/corpus/canonical-form/code-span.json b/corpus/canonical-form/code-span.json
new file mode 100644
index 0000000..dfdda44
--- /dev/null
+++ b/corpus/canonical-form/code-span.json
@@ -0,0 +1,118 @@
+{
+  "content": [
+    {
+      "content": [
+        {
+          "text": "Run ",
+          "type": "text"
+        },
+        {
+          "marks": [
+            {
+              "type": "code"
+            }
+          ],
+          "text": "npm ci",
+          "type": "text"
+        },
+        {
+          "text": " first.",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "text": "Nested backticks: ",
+          "type": "text"
+        },
+        {
+          "marks": [
+            {
+              "type": "code"
+            }
+          ],
+          "text": "run `date` twice",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "text": "A span holding ",
+          "type": "text"
+        },
+        {
+          "marks": [
+            {
+              "type": "code"
+            }
+          ],
+          "text": "`code`",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "text": "Held: ",
+          "type": "text"
+        },
+        {
+          "marks": [
+            {
+              "type": "code"
+            }
+          ],
+          "text": " spaced ",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "text": "Three: ",
+          "type": "text"
+        },
+        {
+          "marks": [
+            {
+              "type": "code"
+            }
+          ],
+          "text": "   ",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "text": "Literal: ",
+          "type": "text"
+        },
+        {
+          "marks": [
+            {
+              "type": "code"
+            }
+          ],
+          "text": "~~not strike~~",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}
diff --git a/corpus/canonical-form/code-span.md b/corpus/canonical-form/code-span.md
new file mode 100644
index 0000000..274490e
--- /dev/null
+++ b/corpus/canonical-form/code-span.md
@@ -0,0 +1,11 @@
+Run `npm ci` first.
+
+Nested backticks: ``run `date` twice``
+
+A span holding `` `code` ``
+
+Held: `  spaced  `
+
+Three: `   `
+
+Literal: `~~not strike~~`
diff --git a/corpus/canonical-form/em-strong-strike.json b/corpus/canonical-form/em-strong-strike.json
new file mode 100644
index 0000000..a185740
--- /dev/null
+++ b/corpus/canonical-form/em-strong-strike.json
@@ -0,0 +1,76 @@
+{
+  "content": [
+    {
+      "content": [
+        {
+          "text": "Read the ",
+          "type": "text"
+        },
+        {
+          "marks": [
+            {
+              "type": "em"
+            }
+          ],
+          "text": "manual",
+          "type": "text"
+        },
+        {
+          "text": " before ",
+          "type": "text"
+        },
+        {
+          "marks": [
+            {
+              "type": "strong"
+            }
+          ],
+          "text": "wiring",
+          "type": "text"
+        },
+        {
+          "text": " the ",
+          "type": "text"
+        },
+        {
+          "marks": [
+            {
+              "type": "strike"
+            }
+          ],
+          "text": "relay",
+          "type": "text"
+        },
+        {
+          "text": ".",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "text": "An un",
+          "type": "text"
+        },
+        {
+          "marks": [
+            {
+              "type": "em"
+            }
+          ],
+          "text": "real",
+          "type": "text"
+        },
+        {
+          "text": "istic goal.",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}
diff --git a/corpus/canonical-form/em-strong-strike.md b/corpus/canonical-form/em-strong-strike.md
new file mode 100644
index 0000000..d14ffda
--- /dev/null
+++ b/corpus/canonical-form/em-strong-strike.md
@@ -0,0 +1,3 @@
+Read the _manual_ before **wiring** the ~~relay~~.
+
+An un*real*istic goal.
diff --git a/corpus/canonical-form/hard-break.json b/corpus/canonical-form/hard-break.json
new file mode 100644
index 0000000..85f8cf6
--- /dev/null
+++ b/corpus/canonical-form/hard-break.json
@@ -0,0 +1,53 @@
+{
+  "content": [
+    {
+      "content": [
+        {
+          "text": "Line one",
+          "type": "text"
+        },
+        {
+          "type": "hardBreak"
+        },
+        {
+          "text": "Line two",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "text": "Trailing",
+          "type": "text"
+        },
+        {
+          "type": "hardBreak"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "attrs": {
+        "level": 2
+      },
+      "content": [
+        {
+          "text": "Two",
+          "type": "text"
+        },
+        {
+          "type": "hardBreak"
+        },
+        {
+          "text": "lines",
+          "type": "text"
+        }
+      ],
+      "type": "heading"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}
diff --git a/corpus/canonical-form/hard-break.md b/corpus/canonical-form/hard-break.md
new file mode 100644
index 0000000..ebede47
--- /dev/null
+++ b/corpus/canonical-form/hard-break.md
@@ -0,0 +1,6 @@
+Line one\
+Line two
+
+Trailing:hardBreak{}
+
+## Two:hardBreak{}lines
diff --git a/corpus/canonical-form/heading.json b/corpus/canonical-form/heading.json
new file mode 100644
index 0000000..589c4b3
--- /dev/null
+++ b/corpus/canonical-form/heading.json
@@ -0,0 +1,78 @@
+{
+  "content": [
+    {
+      "attrs": {
+        "level": 1
+      },
+      "content": [
+        {
+          "text": "Assembly",
+          "type": "text"
+        }
+      ],
+      "type": "heading"
+    },
+    {
+      "attrs": {
+        "level": 2
+      },
+      "content": [
+        {
+          "text": "Parts",
+          "type": "text"
+        }
+      ],
+      "type": "heading"
+    },
+    {
+      "attrs": {
+        "level": 3
+      },
+      "content": [
+        {
+          "text": "Fasteners",
+          "type": "text"
+        }
+      ],
+      "type": "heading"
+    },
+    {
+      "attrs": {
+        "level": 4
+      },
+      "content": [
+        {
+          "text": "Bolts",
+          "type": "text"
+        }
+      ],
+      "type": "heading"
+    },
+    {
+      "attrs": {
+        "level": 5
+      },
+      "content": [
+        {
+          "text": "Sizes",
+          "type": "text"
+        }
+      ],
+      "type": "heading"
+    },
+    {
+      "attrs": {
+        "level": 6
+      },
+      "content": [
+        {
+          "text": "M8",
+          "type": "text"
+        }
+      ],
+      "type": "heading"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}
diff --git a/corpus/canonical-form/heading.md b/corpus/canonical-form/heading.md
new file mode 100644
index 0000000..976188c
--- /dev/null
+++ b/corpus/canonical-form/heading.md
@@ -0,0 +1,11 @@
+# Assembly
+
+## Parts
+
+### Fasteners
+
+#### Bolts
+
+##### Sizes
+
+###### M8
diff --git a/corpus/canonical-form/link.json b/corpus/canonical-form/link.json
new file mode 100644
index 0000000..d50684b
--- /dev/null
+++ b/corpus/canonical-form/link.json
@@ -0,0 +1,116 @@
+{
+  "content": [
+    {
+      "content": [
+        {
+          "text": "See ",
+          "type": "text"
+        },
+        {
+          "marks": [
+            {
+              "attrs": {
+                "href": "https://example.com/changelog"
+              },
+              "type": "link"
+            }
+          ],
+          "text": "the changelog",
+          "type": "text"
+        },
+        {
+          "text": ".",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "marks": [
+            {
+              "attrs": {
+                "href": "https://example.com/"
+              },
+              "type": "link"
+            }
+          ],
+          "text": "https://example.com/",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "text": "Read ",
+          "type": "text"
+        },
+        {
+          "marks": [
+            {
+              "attrs": {
+                "href": "https://example.com/guide",
+                "title": "Setup guide"
+              },
+              "type": "link"
+            }
+          ],
+          "text": "the guide",
+          "type": "text"
+        },
+        {
+          "text": ".",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "text": "Open ",
+          "type": "text"
+        },
+        {
+          "marks": [
+            {
+              "attrs": {
+                "href": "https://example.com/the plan.pdf"
+              },
+              "type": "link"
+            }
+          ],
+          "text": "the plan",
+          "type": "text"
+        },
+        {
+          "text": ".",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "marks": [
+            {
+              "attrs": {
+                "href": "/parts/m8"
+              },
+              "type": "link"
+            }
+          ],
+          "text": "/parts/m8",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}
diff --git a/corpus/canonical-form/link.md b/corpus/canonical-form/link.md
new file mode 100644
index 0000000..ab5d9b1
--- /dev/null
+++ b/corpus/canonical-form/link.md
@@ -0,0 +1,9 @@
+See [the changelog](https://example.com/changelog).
+
+<https://example.com/>
+
+Read [the guide](https://example.com/guide "Setup guide").
+
+Open [the plan](<https://example.com/the plan.pdf>).
+
+[/parts/m8](/parts/m8)
diff --git a/corpus/canonical-form/ordered-list-order.json b/corpus/canonical-form/ordered-list-order.json
new file mode 100644
index 0000000..c7d1fbe
--- /dev/null
+++ b/corpus/canonical-form/ordered-list-order.json
@@ -0,0 +1,65 @@
+{
+  "content": [
+    {
+      "attrs": {
+        "order": 9
+      },
+      "content": [
+        {
+          "content": [
+            {
+              "content": [
+                {
+                  "text": "Bolt M8",
+                  "type": "text"
+                }
+              ],
+              "type": "paragraph"
+            }
+          ],
+          "type": "listItem"
+        },
+        {
+          "content": [
+            {
+              "content": [
+                {
+                  "text": "Nut M8",
+                  "type": "text"
+                }
+              ],
+              "type": "paragraph"
+            },
+            {
+              "content": [
+                {
+                  "text": "Zinc-plated.",
+                  "type": "text"
+                }
+              ],
+              "type": "paragraph"
+            }
+          ],
+          "type": "listItem"
+        },
+        {
+          "content": [
+            {
+              "content": [
+                {
+                  "text": "Washer M8",
+                  "type": "text"
+                }
+              ],
+              "type": "paragraph"
+            }
+          ],
+          "type": "listItem"
+        }
+      ],
+      "type": "orderedList"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}
diff --git a/corpus/canonical-form/ordered-list-order.md b/corpus/canonical-form/ordered-list-order.md
new file mode 100644
index 0000000..163e5a2
--- /dev/null
+++ b/corpus/canonical-form/ordered-list-order.md
@@ -0,0 +1,5 @@
+9. Bolt M8
+10. Nut M8
+
+    Zinc-plated.
+11. Washer M8
diff --git a/corpus/canonical-form/ordered-list.json b/corpus/canonical-form/ordered-list.json
new file mode 100644
index 0000000..a39528a
--- /dev/null
+++ b/corpus/canonical-form/ordered-list.json
@@ -0,0 +1,53 @@
+{
+  "content": [
+    {
+      "content": [
+        {
+          "content": [
+            {
+              "content": [
+                {
+                  "text": "Bolt M8",
+                  "type": "text"
+                }
+              ],
+              "type": "paragraph"
+            }
+          ],
+          "type": "listItem"
+        },
+        {
+          "content": [
+            {
+              "content": [
+                {
+                  "text": "Nut M8",
+                  "type": "text"
+                }
+              ],
+              "type": "paragraph"
+            }
+          ],
+          "type": "listItem"
+        },
+        {
+          "content": [
+            {
+              "content": [
+                {
+                  "text": "Washer M8",
+                  "type": "text"
+                }
+              ],
+              "type": "paragraph"
+            }
+          ],
+          "type": "listItem"
+        }
+      ],
+      "type": "orderedList"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}
diff --git a/corpus/canonical-form/ordered-list.md b/corpus/canonical-form/ordered-list.md
new file mode 100644
index 0000000..3e512e7
--- /dev/null
+++ b/corpus/canonical-form/ordered-list.md
@@ -0,0 +1,3 @@
+1. Bolt M8
+2. Nut M8
+3. Washer M8
diff --git a/corpus/canonical-form/paragraph-empty.json b/corpus/canonical-form/paragraph-empty.json
new file mode 100644
index 0000000..f7ebf4b
--- /dev/null
+++ b/corpus/canonical-form/paragraph-empty.json
@@ -0,0 +1,27 @@
+{
+  "content": [
+    {
+      "content": [
+        {
+          "text": "First.",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "text": "Second.",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}
diff --git a/corpus/canonical-form/paragraph-empty.md b/corpus/canonical-form/paragraph-empty.md
new file mode 100644
index 0000000..9255212
--- /dev/null
+++ b/corpus/canonical-form/paragraph-empty.md
@@ -0,0 +1,5 @@
+First.
+
+::paragraph
+
+Second.
diff --git a/corpus/canonical-form/paragraph.json b/corpus/canonical-form/paragraph.json
new file mode 100644
index 0000000..dd8141f
--- /dev/null
+++ b/corpus/canonical-form/paragraph.json
@@ -0,0 +1,24 @@
+{
+  "content": [
+    {
+      "content": [
+        {
+          "text": "The converter emits every paragraph on a single line, however long it runs, because a soft line break in input carries no meaning ADF can hold.",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "text": "Blocks are separated by exactly one blank line.",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}
diff --git a/corpus/canonical-form/paragraph.md b/corpus/canonical-form/paragraph.md
new file mode 100644
index 0000000..3dd7081
--- /dev/null
+++ b/corpus/canonical-form/paragraph.md
@@ -0,0 +1,3 @@
+The converter emits every paragraph on a single line, however long it runs, because a soft line break in input carries no meaning ADF can hold.
+
+Blocks are separated by exactly one blank line.
diff --git a/corpus/canonical-form/rule.json b/corpus/canonical-form/rule.json
new file mode 100644
index 0000000..8caf8ab
--- /dev/null
+++ b/corpus/canonical-form/rule.json
@@ -0,0 +1,27 @@
+{
+  "content": [
+    {
+      "content": [
+        {
+          "text": "Before.",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "type": "rule"
+    },
+    {
+      "content": [
+        {
+          "text": "After.",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}
diff --git a/corpus/canonical-form/rule.md b/corpus/canonical-form/rule.md
new file mode 100644
index 0000000..8c2fd78
--- /dev/null
+++ b/corpus/canonical-form/rule.md
@@ -0,0 +1,5 @@
+Before.
+
+---
+
+After.
diff --git a/corpus/canonical-form/text-escaping.json b/corpus/canonical-form/text-escaping.json
new file mode 100644
index 0000000..1465d19
--- /dev/null
+++ b/corpus/canonical-form/text-escaping.json
@@ -0,0 +1,42 @@
+{
+  "content": [
+    {
+      "content": [
+        {
+          "text": "# Not a heading",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "text": "- not a bullet",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "text": "2 * 3 * 4 = 24",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "text": "snake_case_name",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}
diff --git a/corpus/canonical-form/text-escaping.md b/corpus/canonical-form/text-escaping.md
new file mode 100644
index 0000000..de71c9c
--- /dev/null
+++ b/corpus/canonical-form/text-escaping.md
@@ -0,0 +1,7 @@
+\# Not a heading
+
+\- not a bullet
+
+2 * 3 * 4 = 24
+
+snake_case_name
diff --git a/todo.md b/todo.md
index 88c719b..1e57210 100644
--- a/todo.md
+++ b/todo.md
@@ -21,7 +21,25 @@ detail is settled at its own milestone.
       payloads for external-URL support — if it exists, revisit the media section's
       mid-text-image error and its "no slot" ground.
 - [ ] **1d — Corpus start** (§10): checked-in ADF ↔ canonical-markdown fixture pairs per spec'd
-      node.
+      node, in `corpus/`, one directory per `spec/flavour.md` section.
+  - [ ] **1d1 — Canonical form**: the plain-CommonMark subset — blockquote, bulletList,
+        codeBlock, heading, orderedList, paragraph, rule, listItem, hardBreak, text, code spans,
+        and the `code`, `em`, `link`, `strike` and `strong` marks.
+  - [ ] **1d2 — Block nodes**: panel, expand/nestedExpand, the media family and the CommonMark
+        image shape, both table forms, task and decision lists, layout, extensions, syncBlock —
+        with the reserved `marks` attribute and the fence lengths nesting forces.
+  - [ ] **1d3 — Inline nodes and marks**: date, emoji, inlineCard, mediaInline, mention, status;
+        border, subsup, textColor, underline; the content slot's `text` attribute and the
+        `:text{text="…"}` whitespace spelling.
+  - [ ] **1d4 — Opaque carry** (§3): an unknown node in both positions, the reserved `adf` info
+        string, and the `codeBlock` whose language is `adf`.
+  - [ ] **1d5 — Carve-outs and combinations**: the three carve-outs and their escapes, mark
+        nesting order and the runs a carry breaks, attribute canonicalization, and documents
+        combining nodes rather than isolating one.
+  - [ ] **1d6 — Input normalization**: one-way markdown→ADF fixtures, not pairs — setext
+        headings, indented code, loose lists, `*`/`+` bullets, entity references, soft wraps.
+  - [ ] **1d7 — Error input**: also one-way, a markdown input per named error. Waits on milestone
+        3 naming them; 1d's pairs are valid documents only.
 - [ ] **2 — `adfToMarkdown`.** First real code — decide here where §10's coverage check lives.
 - [ ] **3 — `markdownToAdf`.** The CommonMark parser is the largest single component. The raw-HTML
       element mapping is empty until milestone 6, so at `0.1.0` every raw-HTML construct in input