Add isExternal flag to RESET_BLOCKS and ignore panel state changes when a change is RTC-initiated

Author: alecgeatches

docs/reference-guides/data/data-core-block-editor.md

@@ -1587,6 +1587,8 @@ Action that resets blocks state to the specified array of blocks, taking precede
 _Parameters_
 
 -   _blocks_ `Array`: Array of blocks.
+-   _options_ `Object`: Optional options.
+-   _options.isExternal_ `boolean`: Whether this reset is from an external action (e.g. real-time collaboration).
 
 ### resetSelection
 

packages/block-editor/src/components/provider/use-block-sync.js

@@ -270,8 +270,12 @@ export default function useBlockSync( {
 			if ( subscribedRef.current ) {
 				pendingChangesRef.current.incoming = controlledBlocks;
 			}
+			// This reset is always from an external data source (real-time
+			// collaboration, undo/redo) pushing blocks into the editor,
+			// so mark it isExternal. The current user's edits are filtered out
+			// by the isOutgoing check above.
 			__unstableMarkNextChangeAsNotPersistent();
-			resetBlocks( controlledBlocks );
+			resetBlocks( controlledBlocks, { isExternal: true } );
 		}
 	};
 

packages/block-editor/src/store/actions.js

@@ -46,12 +46,15 @@ const castArray = ( maybeArray ) =>
  * Action that resets blocks state to the specified array of blocks, taking precedence
  * over any other content reflected as an edit in state.
  *
- * @param {Array} blocks Array of blocks.
+ * @param {Array}   blocks             Array of blocks.
+ * @param {Object}  options            Optional options.
+ * @param {boolean} options.isExternal Whether this reset is from an external
+ *                                     action (e.g. real-time collaboration).
  */
 export const resetBlocks =
-	( blocks ) =>
+	( blocks, { isExternal = false } = {} ) =>
 	( { dispatch } ) => {
-		dispatch( { type: 'RESET_BLOCKS', blocks } );
+		dispatch( { type: 'RESET_BLOCKS', blocks, isExternal } );
 		dispatch( validateBlocksToTemplate( blocks ) );
 	};
 

packages/block-editor/src/store/reducer.js

@@ -2254,7 +2254,7 @@ export function insertionPoint( state = null, action ) {
  *
  * @return {Object} Updated state.
  */
-function openedListViewPanels(
+export function openedListViewPanels(
 	state = { allOpen: false, panels: {} },
 	action
 ) {
@@ -2293,9 +2293,15 @@ function openedListViewPanels(
 			} );
 			return hasChanges ? { ...state, panels: newPanels } : state;
 		}
-		case 'RESET_BLOCKS':
-			// Clear all panel state when blocks are reset
+		case 'RESET_BLOCKS': {
+			// Ignore external resets (like from real-time collaboration) and
+			// keep the user's sidebar from collapsing due to remote changes.
+			if ( action.isExternal ) {
+				return state;
+			}
+
 			return { allOpen: false, panels: {} };
+		}
 	}
 	return state;
 }