fix(sync): tolerate existing WebDAV dirs after MKCOL auth errors

packages/core/src/sync/webdav-client.test.ts

@@ -110,6 +110,51 @@ describe("WebDavClient PROPFIND parsing", () => {
     ]);
   });
 
+  it("treats MKCOL auth failure as success when the parent listing shows the directory", async () => {
+    const calls: { method: string; url: string }[] = [];
+    installFetchStub((url, options) => {
+      const method = String(options?.method ?? "GET");
+      calls.push({ method, url });
+
+      if (method === "PROPFIND" && url.endsWith("/readany/")) {
+        return new Response("", { status: 404 });
+      }
+      if (method === "MKCOL") {
+        return new Response("", { status: 401 });
+      }
+      return new Response(
+        `<?xml version="1.0" encoding="utf-8"?>
+        <d:multistatus xmlns:d="DAV:">
+          <d:response>
+            <d:href>/dav/</d:href>
+            <d:propstat><d:prop><d:resourcetype><d:collection /></d:resourcetype></d:prop></d:propstat>
+          </d:response>
+          <d:response>
+            <d:href>/dav/readany/</d:href>
+            <d:propstat><d:prop><d:resourcetype><d:collection /></d:resourcetype></d:prop></d:propstat>
+          </d:response>
+        </d:multistatus>`,
+        { status: 207 },
+      );
+    });
+
+    const warnSpy = vi.spyOn(console, "warn").mockImplementation(() => {});
+    try {
+      const client = new WebDavClient("https://dav.example.com/dav", "alice", "secret");
+      await client.ensureDirectory("/readany");
+    } finally {
+      warnSpy.mockRestore();
+    }
+
+    expect(calls.map((call) => call.method)).toEqual(["PROPFIND", "MKCOL", "PROPFIND", "PROPFIND"]);
+    expect(calls.map((call) => call.url)).toEqual([
+      "https://dav.example.com/dav/readany/",
+      "https://dav.example.com/dav/readany/",
+      "https://dav.example.com/dav/readany/",
+      "https://dav.example.com/dav/",
+    ]);
+  });
+
   it("uses a collection path when safely reading a directory", async () => {
     const calls: { method: string; url: string }[] = [];
     installFetchStub((url, options) => {

packages/core/src/sync/webdav-client.ts

@@ -93,6 +93,17 @@ function toCollectionPath(path: string): string {
   return path.endsWith("/") ? path : `${path}/`;
 }
 
+function getParentCollectionPath(path: string): { parent: string; name: string } | null {
+  const collectionPath = toCollectionPath(path);
+  if (collectionPath === "/") return null;
+
+  const trimmed = collectionPath.replace(/\/+$/g, "");
+  const lastSlash = trimmed.lastIndexOf("/");
+  const name = trimmed.slice(lastSlash + 1);
+  const parent = lastSlash <= 0 ? "/" : trimmed.slice(0, lastSlash);
+  return { parent: toCollectionPath(parent), name };
+}
+
 function createHttpWebDavError(
   status: number,
   statusText: string | undefined,
@@ -407,7 +418,7 @@ export class WebDavClient {
     try {
       resp = await this.request("MKCOL", collectionPath);
     } catch (e) {
-      if (await this.propfindExists(collectionPath, { timeoutMs: DIRECTORY_PROBE_TIMEOUT_MS })) {
+      if (await this.collectionExists(collectionPath)) {
         console.warn(`[WebDAV] MKCOL ${path} failed but directory exists; continuing`);
         return;
       }
@@ -420,6 +431,10 @@ export class WebDavClient {
     if (status === 405 || status === 409) {
       return;
     }
+    if ((status === 401 || status === 403) && (await this.collectionExists(collectionPath))) {
+      console.warn(`[WebDAV] MKCOL ${path} returned ${status} but directory exists; continuing`);
+      return;
+    }
     throw new Error(`WebDAV MKCOL failed for ${path}: ${status} ${resp.statusText || ""}`);
   }
 
@@ -661,6 +676,27 @@ export class WebDavClient {
     }
   }
 
+  private async parentListingContainsCollection(path: string): Promise<boolean> {
+    const parentInfo = getParentCollectionPath(path);
+    if (!parentInfo) return true;
+
+    try {
+      const resources = await this.propfind(parentInfo.parent);
+      return resources.some(
+        (resource) => resource.isCollection && resource.name === parentInfo.name,
+      );
+    } catch {
+      return false;
+    }
+  }
+
+  private async collectionExists(path: string): Promise<boolean> {
+    if (await this.propfindExists(path, { timeoutMs: DIRECTORY_PROBE_TIMEOUT_MS })) {
+      return true;
+    }
+    return this.parentListingContainsCollection(path);
+  }
+
   /** List directory contents (PROPFIND Depth 1) */
   async propfind(path: string): Promise<DavResource[]> {
     const resp = await this.request("PROPFIND", path, {