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ePub Export

EPub joins the F5 export pipeline (PDF / DOCX / TXT). Two flavours:

Single-file: Mark It Down: Export to ePub — turns the active markdown file into a one-chapter .epub.
Bundle a category: Mark It Down: Export Category as ePub — pick a category (or any nested path) and bundle every note underneath as ordered chapters, sorted by updatedAt ascending. Useful for journals, reference manuals, and any "book-like" collection.

Output

A valid EPUB 3.0 archive with this layout:

text

Apple Books, Calibre, and Readium open the output directly. EPUBCheck passes the structural rules — there's no JS or scripted content, so the strict EPUB 3.2 ruleset is fine.

Frontmatter (the --- block from the slug-overrides feature) is stripped before each chapter renders, so it doesn't appear in the book body.

Settings

Setting	Purpose
`markItDown.epub.author`	Baked into `<dc:creator>`. Empty → "Mark It Down".
`markItDown.epub.publisher`	Baked into `<dc:publisher>`. Empty → "Mark It Down".
`markItDown.epub.coverImage`	Path (absolute or workspace-relative) to a PNG or JPEG used as the cover. Empty → no cover.

Implementation

EPub is just a ZIP with rules. We bundle our own minimal generator instead of pulling a third-party dep:

File	Role
`packages/core/src/epub/zip.ts`	~110-line ZIP writer (stored + deflate via Node's `zlib`); precomputed CRC32 table; emits valid local headers + central directory + EOCD
`packages/core/src/epub/builder.ts`	EPUB 3 templates (container.xml, content.opf, nav.xhtml, toc.ncx) + chapter HTML via `marked` + XHTML hardening (self-close `<br>`, `<hr>`, `<img>`)
`src/exporters/exportEpub.ts`	Bridge — reads cover bytes through `vscode.workspace.fs`, strips frontmatter, calls `buildEpub`
`src/extension.ts`	Two commands (`exportEpub`, `exportCategoryEpub`) + cover-path resolver

The category bundler reuses the nested-categories prefix-match: a path like Reference collects every note whose category equals Reference or starts with Reference/. So Reference bundles Reference/Postgres + Reference/Networking/CIDR + the bare-Reference notes into one ePub, in oldest-first order.

Limitations

No image embedding from notes — [note attachments](note-attachments.md) images are referenced by relative URL in the chapter HTML; they won't render inside the ePub. Embedding attachments is a natural follow-up (the zip writer + manifest emission already supports arbitrary files).
No paginated TOC depth limit — every chapter is a top-level entry. Sub-headings inside a chapter are NOT pulled into the nav doc.
No EPUB 2 fallback for ancient readers — we ship the toc.ncx for compatibility but the rest of the package is EPUB 3.
Cover image is not validated; if you point at a missing or non-image file the cover is silently dropped.

Testing

$ pnpm dlx vitest run tests/unit/epub

13 tests cover the zip writer (CRC32 known value + empty-input edge case, single stored entry, deflate round-trip, mimetype-first ordering, EOCD record structure) and the EPUB builder (mimetype first, all required structural files, one chapter file per chapter, chapter HTML contains title + rendered markdown, content.opf manifest entries + metadata, optional cover image embedding, XML escaping in titles).