Fix checkout workspace opening for Windows drive roots

src/workspaces.test.ts

@@ -7,7 +7,7 @@ import assert from "node:assert/strict";
 import { loadConfig } from "./config.js";
 import { GitWorktreeError } from "./git-worktrees.js";
 import { SqliteWorkspaceStore } from "./workspace-store.js";
-import { WorkspaceRegistry } from "./workspaces.js";
+import { ensureCheckoutWorkspaceRoot, WorkspaceRegistry } from "./workspaces.js";
 
 const execFileAsync = promisify(execFile);
 const root = await mkdtemp(join(tmpdir(), "devspace-workspace-test-"));
@@ -47,6 +47,21 @@ try {
   assert.equal(missingWorkspace.workspace.mode, "checkout");
   assert.equal((await stat(missingWorkspaceRoot)).isDirectory(), true);
 
+  {
+    let mkdirCalls = 0;
+    const existingStats = await ensureCheckoutWorkspaceRoot(root, {
+      stat: async (path) => {
+        assert.equal(path, root);
+        return await stat(path);
+      },
+      mkdir: async () => {
+        mkdirCalls += 1;
+      },
+    });
+    assert.equal(existingStats.isDirectory(), true);
+    assert.equal(mkdirCalls, 0);
+  }
+
   await assert.rejects(
     () => registry.openWorkspace({ path: root, mode: "worktree" }),
     (error: unknown) =>

src/workspaces.ts

@@ -1,4 +1,5 @@
 import { randomUUID } from "node:crypto";
+import type { Stats } from "node:fs";
 import type { WorkspaceMode, WorkspaceStore } from "./workspace-store.js";
 import { mkdir, opendir, stat } from "node:fs/promises";
 import { dirname, join, relative, resolve, sep } from "node:path";
@@ -61,6 +62,12 @@ export interface OpenWorkspaceInput {
   baseRef?: string;
 }
 
+type PathStats = Stats;
+type DirectoryOps = {
+  stat: (path: string) => Promise<PathStats>;
+  mkdir: (path: string, options: { recursive: true }) => Promise<unknown>;
+};
+
 export class WorkspaceRegistry {
   private readonly workspaces = new Map<string, Workspace>();
 
@@ -162,9 +169,7 @@ export class WorkspaceRegistry {
 
   private async openCheckoutWorkspace(path: string): Promise<WorkspaceContext> {
     const root = assertAllowedPath(path, this.config.allowedRoots);
-    await mkdir(root, { recursive: true });
-
-    const rootStats = await stat(root);
+    const rootStats = await ensureCheckoutWorkspaceRoot(root);
     if (!rootStats.isDirectory()) {
       throw new Error(`Workspace root must be a directory: ${path}`);
     }
@@ -273,6 +278,22 @@ export class WorkspaceRegistry {
   }
 }
 
+export async function ensureCheckoutWorkspaceRoot(
+  path: string,
+  ops: DirectoryOps = { stat, mkdir },
+): Promise<PathStats> {
+  try {
+    return await ops.stat(path);
+  } catch (error) {
+    if (!isErrnoException(error) || error.code !== "ENOENT") {
+      throw error;
+    }
+  }
+
+  await ops.mkdir(path, { recursive: true });
+  return await ops.stat(path);
+}
+
 const CONTEXT_FILE_NAMES = new Set(["AGENTS.md", "AGENTS.MD", "CLAUDE.md", "CLAUDE.MD"]);
 const SKIPPED_CONTEXT_DIRS = new Set([
   ".git",
@@ -326,3 +347,7 @@ async function walkWorkspace(
     await visit(path, entry);
   }
 }
+
+function isErrnoException(error: unknown): error is NodeJS.ErrnoException {
+  return error instanceof Error && "code" in error;
+}