From ba661dcbb5dc94bd3e5a440617389d993099c728 Mon Sep 17 00:00:00 2001
From: L4XB <lukas.buck@e-mail.de>
Date: Wed, 16 Sep 2026 13:59:50 +0200
Subject: [PATCH] Don't open two browser tabs when clicking the pull request
 number

02ac4de1529 gave the pull request number links in the overview header and the
sticky header an onClick that calls preventDefault and opens the item on
GitHub, so that the link also works in the Agents window. The webview host
opens any anchor with an href as well, and its click handler does not check
defaultPrevented, so in a regular window the click is handled twice and the
browser gets two tabs for the same URL.

Stop the click from reaching the host, the way the code reference link handler
in webviews/editorWebview/app.tsx already does.

Fixes #8955
---
 webviews/components/header.tsx                |  3 ++
 webviews/components/stickyHeader.tsx          |  3 ++
 webviews/editorWebview/test/overview.test.tsx | 39 +++++++++++++++++++
 3 files changed, 45 insertions(+)

diff --git a/webviews/components/header.tsx b/webviews/components/header.tsx
index 9e04929ead..b532dd6bf4 100644
--- a/webviews/components/header.tsx
+++ b/webviews/components/header.tsx
@@ -136,7 +136,10 @@ function Title({ title, titleHTML, number, url, inEditMode, setEditMode, setCurr
 					title={url}
 					data-vscode-context={JSON.stringify(context)}
 					onClick={event => {
+						// The webview host opens any anchor with an href and ignores defaultPrevented,
+						// so the click must not reach it or a second browser tab is opened.
 						event.preventDefault();
+						event.stopPropagation();
 						void openOnGitHub();
 					}}
 				>
diff --git a/webviews/components/stickyHeader.tsx b/webviews/components/stickyHeader.tsx
index dc6500bdda..f9ea2c9fa6 100644
--- a/webviews/components/stickyHeader.tsx
+++ b/webviews/components/stickyHeader.tsx
@@ -65,7 +65,10 @@ export function StickyHeader({ pr, visible }: { pr: PullRequest; visible: boolea
 						'github:copyMenu': true,
 					})}
 					onClick={event => {
+						// The webview host opens any anchor with an href and ignores defaultPrevented,
+						// so the click must not reach it or a second browser tab is opened.
 						event.preventDefault();
+						event.stopPropagation();
 						void openOnGitHub();
 					}}
 				>
diff --git a/webviews/editorWebview/test/overview.test.tsx b/webviews/editorWebview/test/overview.test.tsx
index 6a23cae97d..fe8d9a9c22 100644
--- a/webviews/editorWebview/test/overview.test.tsx
+++ b/webviews/editorWebview/test/overview.test.tsx
@@ -59,6 +59,45 @@ describe('Overview', function () {
 		assert.strictEqual(openOnGitHub.callCount, 2);
 	});
 
+	it('opens a PR number link exactly once', function () {
+		const pr = new PullRequestBuilder().build();
+		const context = new PRContext(pr);
+		const openOnGitHub = sinon.stub(context, 'openOnGitHub');
+
+		// Stands in for the webview host, which opens any anchor with an href that a click
+		// reaches, and does not check defaultPrevented.
+		const hostOpenedLinks: string[] = [];
+		const hostLinkHandler = (event: Event) => {
+			const anchor = (event.target as HTMLElement).closest('a[href]');
+			if (anchor) {
+				hostOpenedLinks.push(anchor.getAttribute('href')!);
+			}
+		};
+		window.addEventListener('click', hostLinkHandler);
+
+		try {
+			const out = render(
+				<PullRequestContext.Provider value={context}>
+					<Overview {...pr} />
+				</PullRequestContext.Provider>,
+			);
+
+			const numberLinks = out.container.querySelectorAll('.overview-title a, .sticky-header-number');
+			assert.strictEqual(numberLinks.length, 2);
+			numberLinks.forEach(link => {
+				openOnGitHub.resetHistory();
+				hostOpenedLinks.length = 0;
+
+				fireEvent.click(link);
+
+				assert.strictEqual(openOnGitHub.callCount, 1);
+				assert.deepStrictEqual(hostOpenedLinks, []);
+			});
+		} finally {
+			window.removeEventListener('click', hostLinkHandler);
+		}
+	});
+
 	it('shows view changes in both headers', function () {
 		const pr = new PullRequestBuilder().isAgentSessionsWorkspace(true).build();
 		const context = new PRContext(pr);