From 909a1067252f1adaa49f5ecf97cda63c641f361d Mon Sep 17 00:00:00 2001
From: Matt Bierner <12821956+mjbvz@users.noreply.github.com>
Date: Tue, 10 Mar 2026 19:26:48 -0700
Subject: [PATCH] Use case insentive file uri compare in md extension

For #265277
---
 .../markdown-language-features/src/preview/preview.ts      | 6 +++---
 .../markdown-language-features/src/util/resources.ts       | 7 +++++++
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/extensions/markdown-language-features/src/preview/preview.ts b/extensions/markdown-language-features/src/preview/preview.ts
index 19d1755e7eb..1053c305cac 100644
--- a/extensions/markdown-language-features/src/preview/preview.ts
+++ b/extensions/markdown-language-features/src/preview/preview.ts
@@ -10,7 +10,7 @@ import { MarkdownContributionProvider } from '../markdownExtensions';
 import { Disposable } from '../util/dispose';
 import { isMarkdownFile } from '../util/file';
 import { MdLinkOpener } from '../util/openDocumentLink';
-import { WebviewResourceProvider } from '../util/resources';
+import { areUrisEqual, WebviewResourceProvider } from '../util/resources';
 import { urlToUri } from '../util/url';
 import { ImageInfo, MdDocumentRenderer } from './documentRenderer';
 import { MarkdownPreviewConfigurationManager } from './previewConfig';
@@ -29,7 +29,7 @@ export class PreviewDocumentVersion {
 	}
 
 	public equals(other: PreviewDocumentVersion): boolean {
-		return this.resource.fsPath === other.resource.fsPath
+		return areUrisEqual(this.resource, other.resource)
 			&& this._version === other._version;
 	}
 }
@@ -204,7 +204,7 @@ class MarkdownPreview extends Disposable implements WebviewResourceProvider {
 
 
 	public isPreviewOf(resource: vscode.Uri): boolean {
-		return this._resource.fsPath === resource.fsPath;
+		return areUrisEqual(this._resource, resource);
 	}
 
 	public postMessage(msg: ToWebviewMessage.Type) {
diff --git a/extensions/markdown-language-features/src/util/resources.ts b/extensions/markdown-language-features/src/util/resources.ts
index f1f2d0886ab..a3248b954db 100644
--- a/extensions/markdown-language-features/src/util/resources.ts
+++ b/extensions/markdown-language-features/src/util/resources.ts
@@ -11,3 +11,10 @@ export interface WebviewResourceProvider {
 	readonly cspSource: string;
 }
 
+export function areUrisEqual(uri1: vscode.Uri, uri2: vscode.Uri): boolean {
+	if (uri1.scheme === 'file' && uri2.scheme === 'file') {
+		return uri1.fsPath.toLowerCase() === uri2.fsPath.toLowerCase();
+	}
+
+	return uri1.fsPath === uri2.fsPath;
+}