Ensure cell Id is the only part of internal metadata used in diffing (microsoft#242382)

* Ensure cell Id is the only part of internal metadata used in diffing

* misc

* misc

* Add comments

* wip

* Misc

Author: DonJayamanne

src/vs/workbench/contrib/notebook/common/model/notebookCellTextModel.ts

@@ -209,9 +209,6 @@ export class NotebookCellTextModel extends Disposable implements ICell {
 		this._outputs = outputs.map(op => new NotebookCellOutputTextModel(op));
 		this._metadata = metadata ?? {};
 		this._internalMetadata = internalMetadata ?? {};
-		this._internalMetadata.cellId = this._internalMetadata.cellId ??
-			this._metadata.id as string ??
-			uri.fragment;
 	}
 
 	enableAutoLanguageDetection() {

src/vs/workbench/contrib/notebook/common/notebookCommon.ts

@@ -121,6 +121,11 @@ export interface NotebookCellMetadata {
 }
 
 export interface NotebookCellInternalMetadata {
+	/**
+	 * Used only for diffing of Notebooks.
+	 * This is not persisted and generally useful only when diffing two notebooks.
+	 * Useful only after we've manually matched a few cells together so we know which cells are matching.
+	 */
 	cellId?: string;
 	executionId?: string;
 	executionOrder?: number;

src/vs/workbench/contrib/notebook/common/services/notebookSimpleWorker.ts

@@ -56,7 +56,8 @@ class MirrorCell {
 		hashValue = doHash(this.language, hashValue);
 		hashValue = doHash(this.getValue(), hashValue);
 		hashValue = doHash(this.metadata, hashValue);
-		hashValue = doHash({ ...this.internalMetadata, 'cellId': '' }, hashValue);
+		// For purpose of diffing only cellId matters, rest do not
+		hashValue = doHash(this.internalMetadata?.cellId || '', hashValue);
 		for (const op of this.outputs) {
 			hashValue = doHash(op.metadata, hashValue);
 			for (const output of op.outputs) {