Answer architecture round 1: the node table says a hard break takes no marks, and a link text of hard breaks alone reads as its destination

corpus/normalization/hard-break-in-mark.json

@@ -0,0 +1,64 @@
+{
+  "content": [
+    {
+      "content": [
+        {
+          "marks": [
+            {
+              "type": "em"
+            }
+          ],
+          "text": "One",
+          "type": "text"
+        },
+        {
+          "type": "hardBreak"
+        },
+        {
+          "marks": [
+            {
+              "type": "em"
+            }
+          ],
+          "text": "Two",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    },
+    {
+      "content": [
+        {
+          "marks": [
+            {
+              "attrs": {
+                "href": "/u"
+              },
+              "type": "link"
+            }
+          ],
+          "text": "Three",
+          "type": "text"
+        },
+        {
+          "type": "hardBreak"
+        },
+        {
+          "marks": [
+            {
+              "attrs": {
+                "href": "/u"
+              },
+              "type": "link"
+            }
+          ],
+          "text": "Four",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}

corpus/normalization/hard-break-in-mark.md

@@ -0,0 +1,5 @@
+*One\
+Two*
+
+[Three  
+Four](/u)

corpus/round-trip/inline-nodes/hard-break-marks.json

@@ -0,0 +1,37 @@
+{
+  "content": [
+    {
+      "content": [
+        {
+          "marks": [
+            {
+              "type": "em"
+            }
+          ],
+          "text": "One",
+          "type": "text"
+        },
+        {
+          "marks": [
+            {
+              "type": "em"
+            }
+          ],
+          "type": "hardBreak"
+        },
+        {
+          "marks": [
+            {
+              "type": "em"
+            }
+          ],
+          "text": "Two",
+          "type": "text"
+        }
+      ],
+      "type": "paragraph"
+    }
+  ],
+  "type": "doc",
+  "version": 1
+}

corpus/round-trip/inline-nodes/hard-break-marks.md

@@ -0,0 +1 @@
+_One_!adf:carry{json="{\"marks\":[{\"type\":\"em\"}],\"type\":\"hardBreak\"}"}_Two_