omni-viewer-core

Shared parsing and rendering core for Omni Viewer — a family of file viewers that run inside VS Code, Chrome extensions, Obsidian, and plain web pages from a single codebase.

The core is platform-agnostic: parsers take bytes and return typed document models, viewers mount into a DOM element, and everything host-specific (file access, printing, asset URLs) is injected through small interfaces.

Status: 0.x pre-release. APIs may change between minor versions.

Supported formats

• Documents — PDF, Word (DOCX and legacy DOC), HWP, PowerPoint (PPTX and legacy PPT), Markdown
• Data & spreadsheets — Excel, CSV/TSV, JSON, JSONL/NDJSON, YAML, TOML, Parquet, Avro, HDF5, MATLAB MAT, Protocol Buffers, ReqIF, SQLite
• Media & graphics — audio (waveform/spectrogram), video, images, Photoshop PSD
• Engineering & automotive — CAN DBC, AUTOSAR ARXML, ASAM A2L, Vector ASC/BLF logs, ASAM MDF 4 (MF4), PCAP/PCAPNG, ROS bag, STEP (STP)
• Diagrams & GIS — Mermaid, PlantUML, ESRI Shapefile
• Archives — ZIP-family listing and safe entry preview

Install

npm install omni-viewer-core

Heavy format libraries are optional peer dependencies: install only what the formats you use need (pdfjs-dist for PDF, jszip + docx-preview for Word, mermaid for Mermaid, and so on). Bundlers never have to resolve the ones you skip.

Note on xlsx (Excel / embedded workbooks)

The Excel paths require xlsx >= 0.20.2. The npm registry's xlsx package stops at 0.18.5, which has known vulnerabilities (prototype pollution, ReDoS); SheetJS distributes patched builds from its own CDN:

npm install https://cdn.sheetjs.com/xlsx-0.20.3/xlsx-0.20.3.tgz

Usage

Each format is a subpath export. Parsers are pure functions over bytes; libraries they need are injected, never imported at the top level:

import { parseExcel } from 'omni-viewer-core/parsers/excel';
import * as XLSX from 'xlsx'; // your app's copy, from the SheetJS CDN

const { result } = parseExcel(bytes, { xlsx: XLSX });
if (result.status !== 'failed') {
    console.log(result.document.sheetNames);
}

Viewers follow the same pattern — a mount*Viewer(input, container, ctx, deps) entry per format, plus self-loading variants that dynamically import their own dependencies for hosts that don't want to wire them manually.

PDF host integration

The PDF viewer asks ctx.assets.resolveAssetUrl for the exact key assets/pdfjs/pdf.worker.min.mjs. The published package also exposes that worker at omni-viewer-core/assets/pdfjs/pdf.worker.min.mjs; a host may return its own compatible pdfjs-dist worker URL instead, or pass workerSrc in the PDF mount options. isEvalSupported defaults to false for CSP-safe hosts.

PDF mount options are additive and optional. saveMode is hybrid by default (editable text/markup sidecar; signatures and deleted pages are permanent) and may be set to flattened for smaller output. toolbarActions adds host-owned buttons without exposing platform APIs to core. zoomLevels, maxMergeBytes, and onSaveAsComplete configure navigation and host save behavior.

Large save and merge work can be delegated through the optional PdfViewerDeps.processing service. VS Code extension-host and Web Worker adapters can implement buildPdf and/or mergePdfs; each receives an AbortSignal and progress callback. When the service is absent, the default auto mode preserves the browser pdf-lib fallback. host requires the service and browser forces the fallback. PdfViewerHandle.operation reports running, succeeded, failed, and cancelled states, and cancelOperation() requests cancellation.

FileSaveService.saveFile may continue resolving void for compatibility. New adapters should return { status: 'cancelled' } when a Save As picker is dismissed, or { status: 'saved', fileName?, uri? } after any host post-save work (for example opening the new file or showing a notification) completes.

Parsers never throw on malformed input; they return a ParseOutcome with a typed failure and diagnostics, and they enforce resource limits (input size, cell/row/entry counts, declared decompressed size for ZIP containers) that callers can tighten via ParseOptions.limits.

Security

This library is built to open untrusted files. See SECURITY.md for the threat model, the guarantees and their limits, and how to report a vulnerability.

License

MIT. Bundled third-party components are listed in THIRD_PARTY_NOTICES.md.