Update webviews after stack/unstack operation

src/github/activityBarViewProvider.ts

@@ -29,11 +29,12 @@ export class PullRequestViewProvider extends WebviewViewBase implements vscode.W
 	public override readonly viewType = 'github:activePullRequest';
 	private _existingReviewers: ReviewState[] = [];
 	private _updatingPromise: Promise<unknown> | undefined;
+	private _stackUpdateSequence = 0;
 
 	constructor(
 		extensionUri: vscode.Uri,
 		private readonly _folderRepositoryManager: FolderRepositoryManager,
-		private readonly _reviewManager: ReviewManager,
+		private readonly _reviewManager: Pick<ReviewManager, 'createPullRequest'>,
 		private _item: PullRequestModel,
 	) {
 		super(extensionUri);
@@ -173,6 +174,49 @@ export class PullRequestViewProvider extends WebviewViewBase implements vscode.W
 			}
 		}));
 		this._prDisposables.push(pullRequestModel.onDidChangePendingReviewState(() => this.updatePullRequest(pullRequestModel)));
+		this._prDisposables.push(pullRequestModel.githubRepository.onDidChangeStack(numbers => {
+			if (numbers.includes(this._item.number)) {
+				void this.refreshStack();
+			}
+		}));
+	}
+
+	public override dispose(): void {
+		disposeAll(this._prDisposables ?? []);
+		this._updatePendingVisibility?.dispose();
+		super.dispose();
+	}
+
+	private async refreshStack(): Promise<void> {
+		const updateSequence = ++this._stackUpdateSequence;
+		const pullRequest = this._item;
+		if (this.isDisposed || !this._view || !areStacksEnabled()) {
+			return;
+		}
+		try {
+			const stack = await pullRequest.getStack();
+			if (this.isDisposed || updateSequence !== this._stackUpdateSequence || !areStacksEnabled()) {
+				return;
+			}
+			const mergeQueueMethod = await this._folderRepositoryManager.mergeQueueMethodForBranch(
+				stack?.base ?? pullRequest.base.ref, pullRequest.remote.owner, pullRequest.remote.repositoryName);
+			if (!this.isDisposed && updateSequence === this._stackUpdateSequence && areStacksEnabled()) {
+				await this._postMessage({
+					command: 'pr.update',
+					pullrequest: {
+						stack: stack ?? null,
+						stackLoaded: true,
+						stackLoadError: false,
+						mergeQueueMethod: mergeQueueMethod ?? null,
+					} satisfies Partial<PullRequest>,
+				});
+			}
+		} catch (error) {
+			Logger.error(`Failed to load active pull request stack: ${formatError(error)}`, PullRequestViewProvider.name);
+			if (!this.isDisposed && updateSequence === this._stackUpdateSequence && areStacksEnabled()) {
+				void this._postMessage({ command: 'pr.update', pullrequest: { stackLoadError: true } satisfies Partial<PullRequest> });
+			}
+		}
 	}
 
 	private _updatePendingVisibility: vscode.Disposable | undefined = undefined;
@@ -189,6 +233,7 @@ export class PullRequestViewProvider extends WebviewViewBase implements vscode.W
 		}
 
 		try {
+			this._stackUpdateSequence++;
 			if (this._view && !this._view.visible) {
 				this._updatePendingVisibility?.dispose();
 				this._updatePendingVisibility = this._view.onDidChangeVisibility(async () => {
@@ -197,7 +242,7 @@ export class PullRequestViewProvider extends WebviewViewBase implements vscode.W
 				});
 			}
 
-			if ((this._prDisposables === undefined) || (pullRequestModel.number !== this._item.number)) {
+			if ((this._prDisposables === undefined) || !isSamePullRequest) {
 				this.registerPrSpecificListeners(pullRequestModel);
 			}
 			this._item = pullRequestModel;
@@ -329,29 +374,7 @@ export class PullRequestViewProvider extends WebviewViewBase implements vscode.W
 				command: 'pr.initialize',
 				pullrequest: context,
 			});
-			if (areStacksEnabled()) {
-				void pullRequest.getStack().then(async stack => {
-					if (!this._item.equals(pullRequest) || !areStacksEnabled()) {
-						return;
-					}
-					const stackQueueMethod = stack ? await this._folderRepositoryManager.mergeQueueMethodForBranch(stack.base, pullRequest.remote.owner, pullRequest.remote.repositoryName) : undefined;
-					if (this._item.equals(pullRequest) && areStacksEnabled()) {
-						this._postMessage({
-							command: 'pr.update',
-							pullrequest: {
-								stack,
-								stackLoaded: true,
-								...(stack ? { mergeQueueMethod: stackQueueMethod } : {}),
-							} satisfies Partial<PullRequest>,
-						});
-					}
-				}).catch(error => {
-					Logger.error(`Failed to load active pull request stack: ${formatError(error)}`, PullRequestViewProvider.name);
-					if (this._item.equals(pullRequest) && areStacksEnabled()) {
-						this._postMessage({ command: 'pr.update', pullrequest: { stackLoadError: true } satisfies Partial<PullRequest> });
-					}
-				});
-			}
+			void this.refreshStack();
 
 		} catch (e) {
 			vscode.window.showErrorMessage(`Error updating active pull request view: ${formatError(e)}`);

src/github/pullRequestOverview.ts

@@ -783,11 +783,11 @@ export class PullRequestOverviewPanel extends IssueOverviewPanel<PullRequestMode
 				await this._postMessage({
 					command: 'pr.update',
 					pullrequest: {
-						stack: linkedStack,
+						stack: linkedStack ?? null,
 						stackLoaded: true,
 						stackLoadError: false,
 						canUpdateStack: this.canUpdateStack(pullRequestModel),
-						mergeQueueMethod,
+						mergeQueueMethod: mergeQueueMethod ?? null,
 					} satisfies Partial<PullRequest>,
 				});
 			}

src/github/views.ts

@@ -86,7 +86,8 @@ export type PullRequestPreview = Pick<PullRequest, 'number' | 'title' | 'titleHT
 export type OverviewItemPreview = IssuePreview | PullRequestPreview;
 
 export interface PullRequest extends Issue {
-	stack?: PullRequestStack;
+	/** Use null to clear a previous value in serialized webview updates. */
+	stack?: PullRequestStack | null;
 	canUpdateStack?: boolean;
 	stackLoaded?: boolean;
 	stackLoadError?: boolean;
@@ -115,7 +116,8 @@ export interface PullRequest extends Issue {
 	autoMerge?: boolean;
 	allowAutoMerge: boolean;
 	autoMergeMethod?: MergeMethod;
-	mergeQueueMethod: MergeMethod | undefined;
+	/** Use null to clear a previous value in serialized webview updates. */
+	mergeQueueMethod: MergeMethod | undefined | null;
 	mergeQueueEntry?: {
 		url: string;
 		position: number;