@ia2-dev/hare-viewer

@ia2-dev/hare-viewer is an optional, dependency-free browser UI for HARE (HTML Agent Resource Envelope) documents whose manifests use HTML/RDF.

The package reads the canonical HTML/RDF manifest already carried by the document. It does not introduce JSON metadata, replace the manifest, or make runtime state authoritative.

The reader recognizes the HARE 0.1 conformance and artifact-profile IRIs, Dublin Core membership, identifiers, and media types, the W3C Credentials SRI digest, and HARE's representation, carrier, and byte-length properties.

Automatic enhancement

<script type="module" src="./hare-viewer.js"></script>

Importing the package mounts one <ia2-hare-viewer> automatically:

• A document with no visible authored body content gets a full-height file browser.
• A document with authored content gets a sticky Document / Files header. The Files tab opens the browser over the document.

Semantic HTML representations are read directly from inert <template> carriers and previewed in sandboxed frames. Exact-byte representations are base64-decoded and checked against their declared byte length and SHA-256 digest before they can be previewed or downloaded.

The envelope's hare:virtualBase is the virtual URL of the host document. Each template-backed representation receives its own virtual URL by resolving its logical path against that base. Relative links navigate between bundled representations, / returns to the host document, fragments scroll within the selected document, and external links require an explicit user navigation. Template scripts are removed from the derived preview document, network loads are denied by CSP, and the frame sandbox does not grant script execution.

The viewer also materializes passive resources in template-backed documents. Images, audio, video, tracks, SVG image/use references, srcset, stylesheets, inline CSS, url(), and recursive @import resolve through the envelope's virtual URL space. Each byte representation is verified once and exposed to the derived document through a temporary Blob URL. Missing, external, incompatible, cyclic, DOM-backed, and executable destinations remain inert and are reported in the viewer. The original template and manifest are never rewritten.

Markdown byte representations use the package's dependency-free safe renderer. It covers headings, emphasis, links, images, block quotes, ordered and unordered lists, task items, tables, thematic breaks, and fenced or indented code. Raw HTML is displayed as text rather than interpreted. Links route through the HARE virtual address space, and images appear only after the referenced bundled byte representation passes its media-type, length, and digest checks. This renderer does not claim CommonMark conformance.

An authored host document can opt into the same verified lookup without putting a non-retrievable virtual URL in a browser-fetching attribute:

<img
  data-hare-src="https://example.hare.invalid/assets/mark.svg"
  alt="Bundled mark"
>

The viewer resolves data-hare-src against hare:virtualBase, verifies the matching byte representation, and then supplies a temporary Blob URL as the element's src. The inert attribute remains as inspectable source. This avoids the failed network request that a literal src under .invalid would trigger before the viewer runs.

Manual API

import {
  mountHareViewer,
  materializeHareDomRepresentation,
  materializeHareHostSubresources,
  readHareEnvelope,
  renderSafeMarkdown,
  verifyHareRepresentation,
} from "@ia2-dev/hare-viewer";

window.__IA2_HARE_VIEWER_NO_AUTO__ = true;

const viewer = mountHareViewer({ mode: "tabs" });
const envelope = readHareEnvelope();
const representation = envelope.representations[0];
if (representation?.kind === "bytes") {
  const verified = await verifyHareRepresentation(representation);
}

renderSafeMarkdown() is also exported for consumer-owned views. Its optional link and image resolvers let the embedding consumer decide which destinations are navigable or materializable; unresolved images remain inert.

Supported modes are auto, full, and tabs. The custom element also accepts a mode attribute.

Single-file use

A conforming self-viewing HARE artifact embeds its runtime. Treat this package as build-time source and inline its bundled output into the HTML file. A CDN or external module URL is useful for development, but makes the resulting artifact network-dependent and therefore not self-contained.

Security boundary

The viewer renders text as text, creates byte previews only after verification, and places HTML representations in a sandboxed iframe without script permission. It grants same-origin access only so consumer-owned routing code can inspect link activations; it strips representation scripts and applies a deny-by-default CSP before loading the derived preview document.