fix(graph-ui): navigate Windows drive breadcrumbs to real paths

The index file picker built breadcrumb targets as '/' + segments, so on a Windows drive path (C:/Users/rap) clicking a crumb browsed to '/C:/...', which the backend rejected as 'not a directory'. Only the '.. (up)' button worked.

Build drive-aware crumb targets (C:/, C:/Users) and drop the bogus unified '/' root crumb on Windows drive paths; POSIX behavior is unchanged. Add a regression test for Windows breadcrumb navigation and cleanup() for test isolation.

Signed-off-by: Zadak <rarepops@protonmail.com>

graph-ui/src/components/StatsTab.test.tsx

@@ -1,6 +1,6 @@
 /* @vitest-environment jsdom */
 import "@testing-library/jest-dom/vitest";
-import { fireEvent, render, screen, waitFor, act } from "@testing-library/react";
+import { cleanup, fireEvent, render, screen, waitFor, act } from "@testing-library/react";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { StatsTab, IndexProgress } from "./StatsTab";
 import { messages } from "../lib/i18n";
@@ -43,6 +43,7 @@ function mockProjectsFetch(extra?: (url: string, init?: RequestInit) => Response
 
 describe("StatsTab index modal", () => {
   afterEach(() => {
+    cleanup();
     vi.unstubAllGlobals();
   });
 
@@ -93,6 +94,39 @@ describe("StatsTab index modal", () => {
     expect(screen.getByRole("button", { name: "Index beta" })).toBeInTheDocument();
     expect(screen.getByRole("button", { name: "Browse D:/" })).toBeInTheDocument();
   });
+
+  it("navigates Windows breadcrumb segments to real drive paths", async () => {
+    const fetchMock = mockProjectsFetch((url) => {
+      if (url.startsWith("/api/browse")) {
+        return new Response(JSON.stringify({
+          path: "C:/Users/rap",
+          parent: "C:/Users",
+          dirs: ["Documents", "Downloads"],
+          roots: ["C:/", "D:/"],
+        }), { status: 200, headers: { "Content-Type": "application/json" } });
+      }
+      return undefined;
+    });
+
+    render(<StatsTab onSelectProject={() => {}} />);
+    fireEvent.click(await screen.findByRole("button", { name: "Index your first repository" }));
+
+    /* No bogus unified "/" root crumb on a Windows drive path. */
+    await screen.findByRole("button", { name: "C:" });
+    expect(screen.queryByRole("button", { name: "/" })).not.toBeInTheDocument();
+
+    /* Clicking the drive crumb browses to "C:/", not "/C:". */
+    fireEvent.click(screen.getByRole("button", { name: "C:" }));
+    await waitFor(() => {
+      expect(fetchMock).toHaveBeenCalledWith("/api/browse?path=C%3A%2F");
+    });
+
+    /* Clicking a nested crumb browses to "C:/Users", not "/C:/Users". */
+    fireEvent.click(screen.getByRole("button", { name: "Users" }));
+    await waitFor(() => {
+      expect(fetchMock).toHaveBeenCalledWith("/api/browse?path=C%3A%2FUsers");
+    });
+  });
 });
 
 describe("IndexProgress", () => {

graph-ui/src/components/StatsTab.tsx

@@ -239,6 +239,16 @@ function CreateIndexModal({ onClose, onCreated }: { onClose: () => void; onCreat
   /* Breadcrumb segments */
   const displayPath = currentPath.replace(/\\/g, "/");
   const segments = displayPath.split("/").filter(Boolean);
+  /* A Windows drive path ("C:/Users/rap") has no unified "/" root — its first
+   * segment is the drive letter. Build crumb targets accordingly so clicking a
+   * segment navigates to a real directory instead of a bogus "/C:/..." path
+   * that the backend rejects as "not a directory". */
+  const isWinPath = /^[A-Za-z]:$/.test(segments[0] ?? "");
+  const crumbPath = (i: number): string => {
+    const parts = segments.slice(0, i + 1);
+    if (isWinPath) return parts.length === 1 ? `${parts[0]}/` : parts.join("/");
+    return "/" + parts.join("/");
+  };
 
   return (
     <div className="fixed inset-0 z-50 flex items-center justify-center" onClick={onClose}>
@@ -297,12 +307,14 @@ function CreateIndexModal({ onClose, onCreated }: { onClose: () => void; onCreat
 
         {/* Breadcrumb */}
         <div className="px-5 py-2 border-y border-border/20 flex items-center gap-0.5 overflow-x-auto text-[11px] shrink-0">
-          <button onClick={() => browse("/")} className="text-primary/60 hover:text-primary shrink-0 transition-colors">/</button>
+          {!isWinPath && (
+            <button onClick={() => browse("/")} className="text-primary/60 hover:text-primary shrink-0 transition-colors">/</button>
+          )}
           {segments.map((seg, i) => (
             <span key={i} className="flex items-center gap-0.5 shrink-0">
-              <span className="text-foreground/15">/</span>
+              {(i > 0 || !isWinPath) && <span className="text-foreground/15">/</span>}
               <button
-                onClick={() => browse("/" + segments.slice(0, i + 1).join("/"))}
+                onClick={() => browse(crumbPath(i))}
                 className={`transition-colors ${i === segments.length - 1 ? "text-foreground/70 font-medium" : "text-primary/50 hover:text-primary"}`}
               >
                 {seg}