Import does not restore the folder tree, and pages cannot be moved into folders

Version: 0.27.4 (self-hosted Docker, ghcr.io/toeverything/affine:stable), import performed in the web app (Chrome), same result in the desktop app.

What happened

I imported an Obsidian vault (939 pages: 849 markdown notes + 84 canvas conversions) using Markdown with media files (.zip) in several batches. Import reports Import completed and all pages exist — doc_search/read_document find them, and they are all listed under All docs.

But the sidebar tree does not match the source:

• folders are created from the zip paths and appear with the right names (techniques, troubleshooting, tools, sources, research, references);
• the documents are not placed inside them — e.g. research/videos shows "Empty folder" although all 69 pages from that folder exist in the workspace;
• two sibling folders with the same name appear (sources twice) after importing the same source folder in two archives.

Expected: pages from research/videos/*.md appear under research/videos in the sidebar.

Actual: pages land at the root of All docs; folders are empty shells.

There is also no way to fix it from the UI:

• row menu (doc-list-operation-button) contains only Add to favourites, View Info, Open in new tab, Duplicate, Move to trash — no "Move to folder";
• selecting all documents (740 selected) shows only Clear selection — no bulk action.

So the imported structure can only be rebuilt by hand, one drag at a time.

Reproduction

1. Create a vault with research/videos/a.md, research/videos/b.md.
2. Pack it as a zip and import it via Import → Markdown with media files (.zip).
3. Open the sidebar: research/videos is present and empty; a and b are in All docs.

Environment

• self-hosted Docker, image ghcr.io/toeverything/affine:stable, Postgres 16 + Redis + Manticore
• import from the web app on http://localhost:3010, Chrome 141
• workspace_pages after import: 939 rows; the pages exist, only their parent is wrong.

Related code (for reference)

• blocksuite/affine/widgets/linked-doc/src/transformers/obsidian.ts:863-868 — importer reads file.webkitRelativePath || file.name and creates docs; the parent assignment is not derived from that path.