add hard breaks

app/lish/[did]/[publication]/[rkey]/BaseTextBlock.tsx

···
       ${isStrikethrough ? "line-through decoration-tertiary" : ""}
       ${isHighlighted ? "highlight bg-highlight-1" : ""}`.replaceAll("\n", " ");
 
+    // Split text by newlines and insert <br> tags
+    const textParts = segment.text.split('\n');
+    const renderedText = textParts.flatMap((part, i) =>
+      i < textParts.length - 1 ? [part, <br key={`br-${counter}-${i}`} />] : [part]
+    );
+
     if (isCode) {
       children.push(
         <code key={counter} className={className} id={id?.id}>
-          {segment.text}
+          {renderedText}
         </code>,
       );
     } else if (link) {
···
           className={`text-accent-contrast hover:underline ${className}`}
           target="_blank"
         >
-          {segment.text}
+          {renderedText}
         </a>,
       );
     } else {
       children.push(
         <span key={counter} className={className} id={id?.id}>
-          {segment.text}
+          {renderedText}
         </span>,
       );
     }

components/Blocks/TextBlock/RenderYJSFragment.tsx

···
                   );
                 }
 
+                if (node.constructor === XmlElement && node.nodeName === "hard_break") {
+                  return <br key={index} />;
+                }
+
                 return null;
               })
             )}
···
   node: XmlElement | XmlText | XmlHook,
 ): string {
   if (node.constructor === XmlElement) {
+    // Handle hard_break nodes specially
+    if (node.nodeName === "hard_break") {
+      return "\n";
+    }
     return node
       .toArray()
       .map((f) => YJSFragmentToString(f))

components/Blocks/TextBlock/keymap.ts

···
       );
     },
     "Shift-Enter": (state, dispatch, view) => {
-      if (multiLine) {
-        return baseKeymap.Enter(state, dispatch, view);
+      // Insert a hard break
+      let hardBreak = schema.nodes.hard_break.create();
+      if (dispatch) {
+        dispatch(state.tr.replaceSelectionWith(hardBreak).scrollIntoView());
       }
-      return um.withUndoGroup(() =>
-        enter(propsRef, repRef)(state, dispatch, view),
-      );
+      return true;
     },
     "Ctrl-Enter": CtrlEnter(propsRef, repRef),
     "Meta-Enter": CtrlEnter(propsRef, repRef),

components/Blocks/TextBlock/schema.ts

···
     text: {
       group: "inline",
     },
+    hard_break: {
+      group: "inline",
+      inline: true,
+      selectable: false,
+      parseDOM: [{ tag: "br" }],
+      toDOM: () => ["br"] as const,
+    },
   },
 };
 export const schema = new Schema(baseSchema);