Add EmptyCommitFileSystemProvider for displaying empty commits

Co-authored-by: alexr00 <38270282+alexr00@users.noreply.github.com>

Author: Copilot

src/common/uri.ts

@@ -117,6 +117,14 @@ export function toGitHubCommitUri(fileName: string, params: GitHubCommitUriParam
 	});
 }
 
+export function toEmptyCommitUri(commitSha: string): vscode.Uri {
+	return vscode.Uri.from({
+		scheme: Schemes.EmptyCommit,
+		path: `/commit-${commitSha.substring(0, 7)}.txt`,
+		query: commitSha
+	});
+}
+
 const ImageMimetypes = ['image/png', 'image/gif', 'image/jpeg', 'image/webp', 'image/tiff', 'image/bmp'];
 // Known media types that VS Code can handle: https://github.com/microsoft/vscode/blob/a64e8e5673a44e5b9c2d493666bde684bd5a135c/src/vs/base/common/mime.ts#L33-L84
 export const KnownMediaExtensions = [
@@ -750,7 +758,8 @@ export enum Schemes {
 	Repo = 'repo', // New issue file for passing data
 	Git = 'git', // File content from the git extension
 	PRQuery = 'prquery', // PR query tree item
-	GitHubCommit = 'githubcommit' // file content from GitHub for a commit
+	GitHubCommit = 'githubcommit', // file content from GitHub for a commit
+	EmptyCommit = 'emptycommit' // Empty commit placeholder file
 }
 
 export function resolvePath(from: vscode.Uri, to: string) {

src/extension.ts

@@ -44,6 +44,7 @@ import { CommentDecorationProvider } from './view/commentDecorationProvider';
 import { CompareChanges } from './view/compareChangesTreeDataProvider';
 import { CreatePullRequestHelper } from './view/createPullRequestHelper';
 import { EmojiCompletionProvider } from './view/emojiCompletionProvider';
+import { EmptyCommitFileSystemProvider } from './view/emptyCommitFileSystemProvider';
 import { FileTypeDecorationProvider } from './view/fileTypeDecorationProvider';
 import { GitHubCommitFileSystemProvider } from './view/githubFileContentProvider';
 import { getInMemPRFileSystemProvider } from './view/inMemPRContentProvider';
@@ -500,6 +501,8 @@ async function deferredActivate(context: vscode.ExtensionContext, showPRControll
 	context.subscriptions.push(vscode.workspace.registerFileSystemProvider(Schemes.Pr, inMemPRFileSystemProvider, { isReadonly: readOnlyMessage }));
 	const githubFilesystemProvider = new GitHubCommitFileSystemProvider(reposManager, apiImpl, credentialStore);
 	context.subscriptions.push(vscode.workspace.registerFileSystemProvider(Schemes.GitHubCommit, githubFilesystemProvider, { isReadonly: new vscode.MarkdownString(vscode.l10n.t('GitHub commits cannot be edited')) }));
+	const emptyCommitFileSystemProvider = new EmptyCommitFileSystemProvider();
+	context.subscriptions.push(vscode.workspace.registerFileSystemProvider(Schemes.EmptyCommit, emptyCommitFileSystemProvider, { isReadonly: true }));
 
 	await init(context, apiImpl, credentialStore, repositories, prTree, liveshareApiPromise, showPRController, reposManager, createPrHelper, copilotRemoteAgentManager, themeWatcher, prsTreeModel);
 	return apiImpl;

src/github/pullRequestModel.ts

@@ -89,7 +89,7 @@ import { Remote } from '../common/remote';
 import { DEFAULT_MERGE_METHOD, PR_SETTINGS_NAMESPACE } from '../common/settingKeys';
 import { ITelemetry } from '../common/telemetry';
 import { ClosedEvent, EventType, ReviewEvent, TimelineEvent } from '../common/timelineEvent';
-import { resolvePath, Schemes, toGitHubCommitUri, toPRUri, toReviewUri } from '../common/uri';
+import { resolvePath, Schemes, toEmptyCommitUri, toGitHubCommitUri, toPRUri, toReviewUri } from '../common/uri';
 import { formatError, isDescendant } from '../common/utils';
 import { InMemFileChangeModel, RemoteFileChangeModel } from '../view/fileChangeModel';
 
@@ -1475,8 +1475,9 @@ export class PullRequestModel extends IssueModel<PullRequest> implements IPullRe
 
 			const changes = await githubRepository.compareCommits(parentCommit, commitSha);
 			if (!changes?.files || changes.files.length === 0) {
-				vscode.window.showInformationMessage(vscode.l10n.t('No changes found in commit {0}', commitSha.substring(0, 7)));
-				return;
+				// Open a file showing the empty commit message instead of showing a notification
+				const emptyCommitUri = toEmptyCommitUri(commitSha);
+				return vscode.window.showTextDocument(emptyCommitUri, { preview: false });
 			}
 
 			// Create URI pairs for the multi diff editor using review scheme

src/view/emptyCommitFileSystemProvider.ts

@@ -0,0 +1,18 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import * as vscode from 'vscode';
+import { ReadonlyFileSystemProvider } from './readonlyFileSystemProvider';
+
+/**
+ * File system provider for displaying empty commits.
+ * This provides a simple file that explains when a commit has no content.
+ */
+export class EmptyCommitFileSystemProvider extends ReadonlyFileSystemProvider {
+	async readFile(_uri: vscode.Uri): Promise<Uint8Array> {
+		const message = vscode.l10n.t('No changes to show.\nThis commit has no content.');
+		return new TextEncoder().encode(message);
+	}
+}