feat: multiline in checklist

src/core/markdown/MarkdownSerializer.js

@@ -315,6 +315,28 @@ export class MarkdownSerializerState {
         this.inTightList = prevTight;
     }
 
+    renderCheckbox(node){
+        let canSetBreak = false
+        node.forEach((child, _, i) => {
+
+            if(child.type.name === "soft_break" || (child.type.name === 'text' && child.text === String.fromCharCode(160))){
+                if(canSetBreak){
+                    const delim = i === 0 ? '' : '     '
+                    this.flushClose(1);
+                    this.wrapBlock(delim, null, node, () => {});
+                    return
+                }
+                canSetBreak = true
+                return 
+            }
+
+            canSetBreak = false
+            const delim = i === 0 ? '' : '    '
+            this.flushClose(1);
+            this.wrapBlock(delim, null, node, () => this.render(child, node, i));
+        });
+    }
+
     // :: (string, ?bool) → string
     // Escape the given string so that it can safely appear in Markdown
     // content. If `startOfLine` is true, also escape characters that

src/extensions/markdown/Breaks/index.ts

@@ -7,6 +7,7 @@ import {logger} from '../../../logger';
 import {isMac} from '../../../utils/platform';
 import {isTextSelection} from '../../../utils/selection';
 import {pType} from '../../base/BaseSchema/BaseSchemaSpecs';
+import {checkboxLabelType} from '../../yfm/Checkbox/CheckboxSpecs/const';
 
 import {BreaksSpecs, BreaksSpecsOptions, hbType, sbType} from './BreaksSpecs';
 
@@ -55,7 +56,8 @@ const addBr = (br: NodeType) =>
             !isTextSelection(sel) ||
             !sel.empty ||
             // breaks can only be in the paragraph
-            sel.$cursor?.parent.type !== pType(schema)
+            (sel.$cursor?.parent.type !== pType(schema) &&
+                sel.$cursor?.parent.type !== checkboxLabelType(schema))
         )
             return false;
 

src/extensions/yfm/Checkbox/CheckboxSpecs/serializer.ts

@@ -24,6 +24,6 @@ export const serializerTokens: Record<CheckboxNode, SerializerNodeToken> = {
             state.write('[ ] ');
         }
 
-        state.renderInline(node);
+        state.renderCheckbox(node);
     },
 };

src/extensions/yfm/Checkbox/index.scss

@@ -1,6 +1,6 @@
 .g-md-checkbox {
     display: flex;
-    align-items: center;
+    align-items: start;
 
     &__label {
         display: inline-block;

src/extensions/yfm/Checkbox/plugin.ts

@@ -94,5 +94,4 @@ export const keymapPlugin = () =>
     keymap({
         Enter: splitCheckbox(),
         Backspace: removeCheckbox,
-        'Shift-Enter': splitCheckbox(true),
     });