fix: create new blocks in their own group instead of sharing a single one

Author: saltenasl

src/notebooks/deepnote/blocks.md

@@ -45,7 +45,7 @@ project:
           type: 'code'
           content: "df = pd.DataFrame({'a': [1, 2, 3]})\ndf"
           sortingKey: '001'
-          blockGroup: 'default-group'
+          blockGroup: 'uuid-v4'
           executionCount: 1
           metadata:
             table_state_spec: '{"pageSize": 25, "pageIndex": 0}'
@@ -150,7 +150,7 @@ Example of a cell after pocket conversion:
         __deepnotePocket: {
             type: 'code',
             sortingKey: '001',
-            blockGroup: 'default-group',
+            blockGroup: 'uuid-v4',
             executionCount: 1
         }
     },
@@ -472,7 +472,7 @@ blocks:
     type: 'big-number'
     content: ''
     sortingKey: '001'
-    blockGroup: 'default-group'
+    blockGroup: 'uuid-v4'
     metadata:
       deepnote_big_number_title: 'Customers'
       deepnote_big_number_value: 'customers'
@@ -517,7 +517,7 @@ When opened in VS Code, the block becomes a cell with JSON content showing the c
         __deepnotePocket: {
             type: 'big-number',
             sortingKey: '001',
-            blockGroup: 'default-group'
+            blockGroup: 'uuid-v4'
         }
     }
 }

src/notebooks/deepnote/deepnoteDataConverter.ts

@@ -27,6 +27,7 @@ import {
     ButtonBlockConverter
 } from './converters/inputConverters';
 import { CHART_BIG_NUMBER_MIME_TYPE } from '../../platform/deepnote/deepnoteConstants';
+import { generateUuid } from '../../platform/common/uuid';
 
 /**
  * Utility class for converting between Deepnote block structures and VS Code notebook cells.
@@ -168,7 +169,7 @@ export class DeepnoteDataConverter {
 
     private createFallbackBlock(cell: NotebookCellData, index: number): DeepnoteBlock {
         return {
-            blockGroup: 'default-group',
+            blockGroup: generateUuid(),
             id: generateBlockId(),
             sortingKey: generateSortingKey(index),
             type: cell.kind === NotebookCellKind.Code ? 'code' : 'markdown',

src/platform/deepnote/pocket.ts

@@ -2,6 +2,7 @@ import type { NotebookCellData } from 'vscode';
 
 import type { DeepnoteBlock } from './deepnoteTypes';
 import { generateBlockId, generateSortingKey } from '../../notebooks/deepnote/dataConversionUtils';
+import { generateUuid } from '../common/uuid';
 
 // Note: 'id' is intentionally excluded from this list so it remains at the top level of cell.metadata
 // The id field is needed at runtime for cell identification during execution
@@ -64,7 +65,7 @@ export function createBlockFromPocket(cell: NotebookCellData, index: number): De
     }
 
     const block: DeepnoteBlock = {
-        blockGroup: pocket?.blockGroup || 'default-group',
+        blockGroup: pocket?.blockGroup || generateUuid(),
         content: cell.value,
         id: cellId || generateBlockId(),
         metadata,