feat(Breaks): replace double breaks with new paragraph

src/extensions/markdown/Breaks/index.ts

@@ -1,9 +1,12 @@
-import type {NodeType} from 'prosemirror-model';
+import type {Node, NodeType} from 'prosemirror-model';
+import {TextSelection} from 'prosemirror-state';
 import {chainCommands, exitCode} from 'prosemirror-commands';
 import {logger} from '../../../logger';
 import type {ExtensionAuto, Keymap} from '../../../core';
 import {isMac} from '../../../utils/platform';
+import {isTextSelection} from '../../../utils/selection';
 import {BreaksSpecs, BreaksSpecsOptions, hbType, sbType} from './BreaksSpecs';
+import {pType} from '../../base/BaseSchema/BaseSchemaSpecs';
 
 export {BreaksSpecs, BreakNodeName, hbType, sbType} from './BreaksSpecs';
 
@@ -45,6 +48,38 @@ export const Breaks: ExtensionAuto<BreaksOptions> = (builder, opts) => {
 
 const addBr = (br: NodeType) =>
     chainCommands(exitCode, (state, dispatch) => {
+        const {selection: sel, schema} = state;
+        if (
+            !isTextSelection(sel) ||
+            !sel.empty ||
+            // breaks can only be in the paragraph
+            sel.$cursor?.parent.type !== pType(schema)
+        )
+            return false;
+
+        if (isBreakNode(sel.$cursor.nodeBefore)) {
+            if (dispatch) {
+                const {
+                    $cursor,
+                    $cursor: {pos},
+                } = sel;
+                const from = isBreakNode($cursor.nodeAfter) ? pos + 1 : pos;
+                const posEnd = $cursor.end();
+                const posAfter = $cursor.after();
+
+                const contentAfter = state.doc.slice(from, posEnd, false).content;
+
+                let tr = state.tr.insert(posAfter, pType(schema).create(null, contentAfter));
+                tr = tr
+                    .setSelection(TextSelection.create(tr.doc, posAfter + 1))
+                    .scrollIntoView()
+                    .delete(pos, posEnd) // remove content after current pos (it's moved to next para)
+                    .delete(pos - 1, pos); // remove break before current pos ($cursor.nodeBefore)
+                dispatch(tr);
+            }
+            return true;
+        }
+
         dispatch?.(state.tr.replaceSelectionWith(br.create()).scrollIntoView());
         return true;
     });
@@ -59,3 +94,7 @@ declare global {
         }
     }
 }
+
+function isBreakNode(node?: Node | null | undefined): boolean {
+    return Boolean(node?.type.spec.isBreak);
+}