diff --git a/packages/lsp/tool-lsp/src/render.ts b/packages/lsp/tool-lsp/src/render.ts
index 3f49d1edfd..4613312c87 100644
--- a/packages/lsp/tool-lsp/src/render.ts
+++ b/packages/lsp/tool-lsp/src/render.ts
@@ -148,7 +148,7 @@ export function renderUri(uri: string, workspaceUri: string): string {
   const workspaceSegments = decodeFileSegments(workspace)
   if (targetSegments === undefined || workspaceSegments === undefined) return uri
   const sameAuthority = target.hostname === workspace.hostname
-  const windowsWorld = /^[A-Za-z]:$/.test(workspaceSegments[0] ?? '')
+  const windowsWorld = isWindowsFileWorld(workspace, workspaceSegments)
   const inside = sameAuthority
     && targetSegments.length >= workspaceSegments.length
     && workspaceSegments.every((segment, index) => samePathSegment(segment, targetSegments[index] as string, windowsWorld))
@@ -159,6 +159,11 @@ export function renderUri(uri: string, workspaceUri: string): string {
   return absoluteUriPath(target, targetSegments, workspaceSegments)
 }
 
+/** Whether a canonical file URI names a drive path or UNC path in a Windows execution world. */
+function isWindowsFileWorld(url: URL, segments: readonly string[]): boolean {
+  return url.hostname.length > 0 || /^[A-Za-z]:$/.test(segments[0] ?? '')
+}
+
 /** Decode URI path segments while rejecting encoded separators that would change path structure. */
 function decodeFileSegments(url: URL): string[] | undefined {
   try {
diff --git a/packages/lsp/tool-lsp/tests/render.spec.ts b/packages/lsp/tool-lsp/tests/render.spec.ts
index 9f87d663fb..d76600ea6f 100644
--- a/packages/lsp/tool-lsp/tests/render.spec.ts
+++ b/packages/lsp/tool-lsp/tests/render.spec.ts
@@ -75,8 +75,10 @@ describe('renderUri', () => {
 
   it('renders remote file authorities without host path conversion', () => {
     expect(renderUri('file://server/share/workspace/a.ts', 'file://server/share/workspace')).toBe('a.ts')
+    expect(renderUri('file://SERVER/share/workspace/src/A.ts', 'file://server/Share/Workspace')).toBe('src/A.ts')
     expect(renderUri('file://other/share/b.ts', 'file://server/share/workspace')).toBe('//other/share/b.ts')
     expect(renderUri('file:///a.ts', 'file://server/')).toBe('/a.ts')
+    expect(renderUri('file:///a.ts', 'file:///')).toBe('a.ts')
   })
 
   it('keeps malformed or mismatched URI coordinates verbatim', () => {