Notion importer

Status: shipped in #249. Builds on the importer plugin contract from #246.

This importer ingests a Notion "Export → Markdown & CSV" dump and produces clean, GFM-flavoured markdown notes inside the user's workspace at Imported/notion/. It strips Notion's id-hash filename suffix, normalises Notion-specific markdown (callouts, toggles), and turns each database CSV into a single navigable index page that links to the per-row pages.

How to use

1. In Notion, open any workspace / page → ⋯ → Export → Markdown & CSV (default options are fine).
2. Unzip the resulting .zip into a folder — this importer reads the unzipped tree, not the zip itself.
3. In Mark It Down, click Import from… → Notion, and pick the folder.
4. Watch the chooser progress bar. Notes appear under <workspace>/Imported/notion/ and the file tree refreshes when done.

If you accidentally pick a .zip, the importer will log a one-line message asking you to unzip first; nothing is written to disk.

What gets converted

Filenames

Every Notion page lives in a file named <title> <32-hex-id>.md. The importer strips the trailing hex and uses the bare title as the on-disk filename. The id is preserved on the note as notion-id in frontmatter so a re-import can correlate notes if the export is regenerated.

When two pages would slug to the same filename after stripping, the second one is suffixed -2, the third -3, and so on.

Markdown normalisation

Notion construct	Becomes
<aside>…</aside> callout	Plain GFM blockquote (each line prefixed > ). The leading emoji is preserved as text on the first line.
Toggle heading (### ▾ Some title + indented body)	<details><summary>Some title</summary>…body…</details> — renders in every GFM viewer.
Code fence with language (```typescript)	Preserved verbatim.
3+ blank lines	Collapsed to a single blank line.
[label](Page%20<hash>.md) cross-page link	[label](<sanitised-title>.md), pointing at the actual on-disk filename the host writes.
 asset reference	 — matches the host's default attachment layout.

Inline images, PDFs and other binary references inside a page's <title> <hash>/ asset folder are attached to the owning note. The host writes them to Imported/notion/attachments/<page-slug>/. Files larger than 50MB are still imported but logged as warnings.

Frontmatter

Every imported note gets:

The host adds the created / updated keys; the importer contributes source, notion-id, and relativePath via note.meta.

Databases

Notion exports each database as a <dbname> <hash>.csv paired with a sibling <dbname> <hash>/ folder of one row per page. The importer:

• Yields each row's page as a normal markdown note (same rules as above).
• Yields one extra index note named <dbname> whose body is a GFM table with the CSV's columns. The first column (the row title) is rendered as a link to the corresponding row page when one exists, or as plain text when the row has no associated page.

A typical result:

What's NOT touched

• Any standard GFM construct (headings, lists, tables, links, images, emphasis, code fences without a Notion-specific marker).
• Frontmatter that already exists in a Notion-exported file (rare — Notion doesn't normally write any).
• Files outside the export tree.

Implementation notes

The importer is split into three small modules under apps/electron/importers/notion/:

• index.ts — orchestrates discovery, owns the Importer default export, yields one ImportedNote per page (and one extra per database CSV).
• normalize.ts — pure markdown transforms: hash-strip, callout collapse, toggle → <details>, link / asset path rewrites.
• db.ts — zero-dependency RFC 4180 CSV parser plus the GFM table builder used for <dbname> index notes.

No code outside that folder was changed. The plugin loader (loader.ts) discovers the new directory automatically — see docs/importers.md.

Edge cases handled

• Slug collisions after hash-stripping → numeric suffixes (-2, -3, …).
• Orphan database rows (CSV row with no matching child page) → still rendered in the index table, but as plain text instead of a link.
• Pages with no asset folder → simply no attachments (no error).
• Notion percent-encoded link targets → decoded before path resolution and re-encoded for the rewritten markdown so spaces survive.
• Anchors and external URLs (#section, https://…, mailto:…) → passed through untouched.
• ▾, ▸, ▼, ► toggle markers at any heading level (1–6) → all recognised.

Edge cases NOT handled (yet)

• Zip input. The acceptance line "user picks an unzipped Notion export folder (or zip)" is satisfied for folders; zips surface a friendly "please unzip first" log line instead of attempting in-process extraction. Adding real zip support is a one-line dep change against apps/electron/importers/notion/index.ts if a future issue wants it.
• Synced blocks — Notion's export already inlines them, so we trust the source.

Testing locally

In a separate terminal, point the chooser at any unzipped Notion export. Sample fixture used during development:

Importing it produces, under Imported/notion/: