diff --git a/packages/app/src/assistant-file-links/link.tsx b/packages/app/src/assistant-file-links/link.tsx
index d209411ac..2630685e1 100644
--- a/packages/app/src/assistant-file-links/link.tsx
+++ b/packages/app/src/assistant-file-links/link.tsx
@@ -18,6 +18,7 @@ import { useStableEvent } from "@/hooks/use-stable-event";
 import { CODE_SURFACE_DATASET } from "@/styles/code-surface";
 import { useAssistantFileLinkResolverContext } from "./provider";
 import type { AssistantFileLinkSource } from "./resolver";
+import { formatFileLinkTooltipPath } from "./tooltip-path";
 import { useFileLink } from "./use-file-link";
 
 interface AssistantMarkdownLinkProps {
@@ -38,7 +39,7 @@ export function AssistantMarkdownLink({
   const { configRef } = useAssistantFileLinkResolverContext();
   const workspaceRoot = configRef.current.workspaceRoot;
   const tooltipPath = useMemo(
-    () => (target ? formatInlinePathTargetForTooltip(target, workspaceRoot) : null),
+    () => (target ? formatFileLinkTooltipPath({ target, workspaceRoot }) : null),
     [target, workspaceRoot],
   );
   const handleAnchorClickCapture = useStableEvent((event: MouseEvent<HTMLAnchorElement>) => {
@@ -147,38 +148,6 @@ export function AssistantMarkdownCodeLink({
   );
 }
 
-function formatInlinePathTargetForTooltip(
-  target: { path: string; lineStart?: number; lineEnd?: number },
-  workspaceRoot: string | undefined,
-): string {
-  let result = relativizePathToWorkspace(target.path, workspaceRoot);
-  if (target.lineStart) {
-    result += `:${target.lineStart}`;
-    if (target.lineEnd && target.lineEnd !== target.lineStart) {
-      result += `-${target.lineEnd}`;
-    }
-  }
-  return result;
-}
-
-function relativizePathToWorkspace(filePath: string, workspaceRoot: string | undefined): string {
-  if (!workspaceRoot) {
-    return filePath;
-  }
-  const root = workspaceRoot.replace(/\/+$/, "");
-  if (!root) {
-    return filePath;
-  }
-  if (filePath === root) {
-    return ".";
-  }
-  const prefix = `${root}/`;
-  if (filePath.startsWith(prefix)) {
-    return filePath.slice(prefix.length);
-  }
-  return filePath;
-}
-
 interface AssistantInlineCodePathLinkProps {
   content: string;
   inheritedStyles: TextStyle;
diff --git a/packages/app/src/assistant-file-links/tooltip-path.test.ts b/packages/app/src/assistant-file-links/tooltip-path.test.ts
new file mode 100644
index 000000000..dc07f5a0d
--- /dev/null
+++ b/packages/app/src/assistant-file-links/tooltip-path.test.ts
@@ -0,0 +1,17 @@
+import { describe, expect, it } from "vitest";
+import { formatFileLinkTooltipPath } from "./tooltip-path";
+
+describe("formatFileLinkTooltipPath", () => {
+  it("shows a Windows file path relative to its workspace regardless of separators", () => {
+    expect(
+      formatFileLinkTooltipPath({
+        target: {
+          path: "C:/Users/me/repo/src/app.ts",
+          lineStart: 12,
+          lineEnd: 20,
+        },
+        workspaceRoot: "C:\\Users\\me\\repo",
+      }),
+    ).toBe("src/app.ts:12-20");
+  });
+});
diff --git a/packages/app/src/assistant-file-links/tooltip-path.ts b/packages/app/src/assistant-file-links/tooltip-path.ts
new file mode 100644
index 000000000..16f98c7fe
--- /dev/null
+++ b/packages/app/src/assistant-file-links/tooltip-path.ts
@@ -0,0 +1,23 @@
+import { resolveWorkspaceFilePaths, type WorkspaceFileLocation } from "@/workspace/file-open";
+
+interface FormatFileLinkTooltipPathInput {
+  target: WorkspaceFileLocation;
+  workspaceRoot?: string;
+}
+
+export function formatFileLinkTooltipPath({
+  target,
+  workspaceRoot,
+}: FormatFileLinkTooltipPathInput): string {
+  const resolvedPaths = workspaceRoot
+    ? resolveWorkspaceFilePaths({ path: target.path, workspaceRoot })
+    : null;
+  let result = resolvedPaths?.relativePath ?? target.path;
+  if (target.lineStart) {
+    result += `:${target.lineStart}`;
+    if (target.lineEnd && target.lineEnd !== target.lineStart) {
+      result += `-${target.lineEnd}`;
+    }
+  }
+  return result;
+}