onenote-tools/docs/FORMAT_SUPPORT.md

Format support

Version 0.2.1 support matrix

Input or feature	Status	Tested evidence and boundary
Desktop revision-store .one	Supported subset	Real 34,904-byte Joplin golden; three pages and rich content
FSSHTTPB package-store .one	Supported subset	Licensed 17,197-byte Joplin golden; one page; unfragmented data elements
Unknown/legacy .one variants	Unsupported	File type and format GUIDs are validated before traversal
.onepkg, one CAB	Supported subset	Real Joplin LZX package; generated/pinned none, MSZIP, Quantum, and LZX codec fixtures
.onepkg, complete CAB set	Supported extraction	Licensed five-part libmspack set plus split-block, spanning-file, ordering, and malformed-set tests
Missing/inconsistent CAB parts	Rejected	Set ID, indexes, previous/next names, compression, split blocks, and spanning records must agree
CAB without compression	Supported extraction	Byte-for-byte rust-cab fixture
CAB MSZIP	Supported extraction	rust-cab single block plus generated two-block dictionary-chain fixture
CAB Quantum	Supported extraction	Pinned compcol payloads and generated CAB integration fixture
CAB LZX	Supported extraction	Real OneNote 0x1203 package and rust-cab 0x1303 fixture
.onetoc2 inside a package	Supported subset	Desktop golden/hierarchy tests; FSSHTTPB dispatch uses a mocked shared-store seam, not a real golden
Standalone .onetoc2 in the app	Not selectable	The picker accepts .one, or .onepkg together with .cab companions
Rich text and layout hints	Supported subset	Run formatting, paragraph properties, safe links, and bounded layout metadata
Tables	Supported subset	Rows, cells, nested blocks, column widths, locks, borders, and cell backgrounds
Images	Supported subset	Lazy, signature/header-validated PNG and JPEG resources; unsafe images stay downloadable only
Ink	Supported subset	Bounded delta decoding, strokes, colors, width/height, transparency, and SVG display/export
Embedded attachments	Supported subset	ATTACHMENT_DECLARATION/file-data resources remain inert until explicit download
Export	Supported subset	JSON, text, Markdown, inert HTML, and deterministic static notebook ZIP

“Supported subset” is intentionally narrower than “all files with this extension.” A successful open requires the tested desktop or FSSHTTPB OneStore structures and content graph nodes. Malformed offsets, counts, references, CAB checksums, paths, compressed data, and unsupported variants produce bounded diagnostics or a controlled failure.

OneStore and package boundaries

FSSHTTPB support covers the OneStore packaging envelope, Storage Index and Storage Manifest, header/data-root cells, bounded revision chains, Object Group partitions, resolved object/page-space references, and available Object Data BLOB references. Data Element Fragment records are recognized and bounded by the low-level parser, but fragmented-element reconstruction is not implemented; the store adapter rejects packages containing fragment records with a controlled UNSUPPORTED_FORMAT error. Excluded object data cannot be reconstructed from a standalone file and is likewise unsupported.

For a split package, the browser must receive the .onepkg and every linked .cab companion in one selection. The extractor validates a complete, uniquely indexed cabinet chain before decoding. It reassembles split CFDATA blocks, preserves codec state across cabinets, and reconciles the CAB continued from previous, continued to next, and continued both file records. Partial sets are not opened heuristically.

The default LZX limit accepts CAB window sizes through 8 MiB, but compatibility claims are fixture-backed only for window bits 18 (0x1203) and 19 (0x1303). MSZIP validates the CK prefix, limits each compressed block to 32 KiB + 12, decodes into a fixed-size output buffer, requires the declared output length, and carries at most 32 KiB of history between blocks in one logical folder. Quantum validates level/window metadata, bounds its window to 2 MiB by default, requires full 32 KiB intermediate frames, preserves its arithmetic models and LZ window across frames/cabinets, and injects exactly one 0xFF CAB block sentinel. Trailer, match, frame, output, operation, and cancellation bounds are enforced.

Trailing CAB data is ignored with a warning. Reserved CAB areas are bounded and skipped. CAB names are decoded as strict UTF-8; unmarked valid UTF-8 receives a warning, while invalid non-ASCII legacy-code-page names are rejected rather than guessed.

Notebook and page model

Supported .onetoc2 stores provide authored section order, nested section groups, display names, identities, and colors. Exact normalized paths take precedence; same-directory file identity is a guarded fallback. Recycle-bin entries are omitted, duplicate/cyclic references are diagnosed, and readable sections not reachable from a TOC are appended deterministically. Page levels are interpreted as a page/subpage tree.

The supported section path returns:

• section/page identities, names, timestamps, page levels, and diagnostics;
• outlines and recursively nested content blocks;
• rich-text runs with bold, italic, underline, strikeout, super/subscript, font, size, foreground/highlight color, paragraph alignment/spacing, and allow-listed http, https, and mailto links;
• tables, lazy PNG/JPEG images, embedded-file declarations, and decoded ink;
• bounded layout hints such as offsets, maximum dimensions, and alignment.

This is not a pixel-perfect OneNote renderer. Equations, audio/video, page versions/conflicts, and producer-specific structures outside the golden corpus are not represented. Encountered unsupported object kinds remain visible as diagnostics. Active notebook HTML/SVG is never injected.

Export

All exports are created inside the existing local parser worker. They include a versioned parser/support manifest, the readable page hierarchy, diagnostics, and unsupported-content summaries. The static ZIP contains inert semantic HTML plus JSON, text, Markdown, warnings, and bounded resources. Resource names are normalized, potentially active attachment suffixes are neutralized, and only validated image types may be embedded for automatic display.

Export is a representation of the parser-supported subset, not a round trip: it neither emits .one/.onepkg nor promises full OneNote visual fidelity.

Test fixtures

The exact hashes, source revisions, licences, expected content, and CAB structures are recorded in tests/fixtures/README.md. Tests use no private notebooks and do not treat a synthetic archive as proof of Microsoft OneNote export compatibility.