feat: moveBlocks behaviour when leaving empty columns (BLO-1109)

packages/core/src/api/blockManipulation/commands/moveBlocks/moveBlocks.ts

@@ -11,6 +11,8 @@ import type { BlockNoteEditor } from "../../../../editor/BlockNoteEditor";
 import { BlockIdentifier } from "../../../../schema/index.js";
 import { getNearestBlockPos } from "../../../getBlockInfoFromPos.js";
 import { getNodeById } from "../../../nodeUtil.js";
+import { insertBlocks } from "../insertBlocks/insertBlocks.js";
+import { removeAndInsertBlocks } from "../replaceBlocks/replaceBlocks.js";
 
 type BlockSelectionData = (
   | {
@@ -148,24 +150,26 @@ export function moveBlocks(
   referenceBlock: BlockIdentifier,
   placement: "before" | "after",
 ) {
-  editor.transact(() => {
-    // A `columnList` reference can be dissolved by `fixColumnList` when its
-    // `column`s are removed, leaving its ID invalid for re-insertion. Anchor
-    // to an adjacent block instead, which is unaffected by the removal.
-    const refBlock = editor.getBlock(referenceBlock);
-    if (refBlock?.type === "columnList") {
-      const adjacent =
-        placement === "after"
-          ? editor.getNextBlock(refBlock)
-          : editor.getPrevBlock(refBlock);
-      if (adjacent) {
-        referenceBlock = adjacent;
-        placement = placement === "after" ? "before" : "after";
-      }
-    }
-
-    editor.removeBlocks(blocks);
-    editor.insertBlocks(flattenColumns(blocks), referenceBlock, placement);
+  editor.transact((tr) => {
+    // Don't fix columns/columnLists in the removal step. Since a move is a
+    // rearrangement rather than a deletion, columns that it empties out are
+    // deliberately left as-is instead of being collapsed - this keeps moves
+    // free of side effects (and reversible by moving back), and matches
+    // dragging a block out of a column, which doesn't collapse it either.
+    // Fixing them mid-move also broke the following case:
+    // <column>
+    //  <paragraph></paragraph>
+    //  <paragraph>Paragraph</paragraph>
+    // </column>
+    // When the non-empty block is moved up, the column is seen as empty and
+    // collapsed in the removal step, so the following insertion fails.
+    removeAndInsertBlocks(tr, blocks, [], { fixColumns: false });
+    insertBlocks<any, any, any>(
+      tr,
+      flattenColumns(blocks),
+      referenceBlock,
+      placement,
+    );
   });
 }
 

packages/core/src/api/blockManipulation/commands/replaceBlocks/replaceBlocks.ts

@@ -20,6 +20,9 @@ export function removeAndInsertBlocks<
   tr: Transaction,
   blocksToRemove: BlockIdentifier[],
   blocksToInsert: PartialBlock<BSchema, I, S>[],
+  options: {
+    fixColumns?: boolean;
+  } = {},
 ): {
   insertedBlocks: Block<BSchema, I, S>[];
   removedBlocks: Block<BSchema, I, S>[];
@@ -112,7 +115,12 @@ export function removeAndInsertBlocks<
     );
   }
 
-  columnListPositions.forEach((pos) => fixColumnList(tr, pos));
+  // Collapses empty columns/columnLists. Callers where the removal isn't a
+  // deletion can opt out - e.g. `moveBlocks` re-inserts the blocks elsewhere
+  // and deliberately leaves emptied columns as-is.
+  if (options.fixColumns !== false) {
+    columnListPositions.forEach((pos) => fixColumnList(tr, pos));
+  }
 
   // Converts the nodes created from `blocksToInsert` into full `Block`s.
   const insertedBlocks = nodesToInsert.map((node) =>