PortalJS is a framework for building data portals that present searchable datasets through a home page, catalog, and dataset showcase. It is for teams that want to choose a data backend, scaffold a Next.js portal, load CSV or JSON data, connect services such as CKAN, and deploy the result. The catalogue entries are agent commands, skills, instructions, and a plugin that guide portal creation and data loading.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
git clone --depth 1 https://github.com/datopian/portaljsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/commands/datopian/portaljs/portaljs-add-dcat)<a href="https://agentmods.dev/commands/datopian/portaljs/portaljs-add-dcat"><img src="https://agentmods.dev/badge/commands/datopian/portaljs/portaljs-add-dcat/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/commands/datopian/portaljs/portaljs-add-dcat"><img src="https://agentmods.dev/badge/commands/datopian/portaljs/portaljs-add-dcat.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00069 | $0.04472 |
| Opus 5 | $0.00034 | $0.02236 |
| Sonnet 5 | $0.00014 | $0.00894 |
| Haiku 4.5 | $0.00007 | $0.00447 |
Grade A, and why
portaljs-add-dcat scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
curl -s https://www.itb.ec.europa.eu/shacl/dcat-ap/api/validate \ How it starts
The opening of the file, as written. The whole thing — 276 lines — stays where its author put it; the contents beside it link to each section on GitHub.
/portaljs-add-dcat
Turn an existing PortalJS (portaljs-catalog) portal into a harvestable data
catalog: emit standards-compliant DCAT metadata feeds so external catalogs and
government data portals (data.europa.eu, data.gov, national portals) can harvest its
datasets automatically.
PortalJS is Frictionless-native (a dataset is a Data Package — see
/portaljs-define-schema); DCAT is the serialization + harvest layer on top
(lib/metadata/dcat.ts + lib/metadata/dcat-profiles.ts). This skill selects one or
more DCAT application profiles, maps every dataset's metadata to them, and writes
static feed files at build so they harvest on any host (static Cloudflare Pages, a
CDN, a Worker) — no runtime.
What it produces
Wired into predev/prebuild via scripts/generate-dcat.ts, so the feeds are always
fresh:
| File | What |
|---|---|
public/catalog.jsonld · catalog.ttl · catalog.rdf |
Canonical feed (first profile) in JSON-LD, Turtle, RDF/XML — the stable autodiscovery targets |
public/catalog.<profile>.{jsonld,ttl,rdf} |
One feed per configured profile × serialization (e.g. catalog.dcat-ap.ttl) |
public/catalog-feeds.json |
Machine-readable index of every emitted feed |
<link rel="alternate" type="application/ld+json" href="/catalog.jsonld"> in _document.tsx |
Autodiscovery — how harvesters find the feed |
Config lives in dcat.config.json at the portal root (created/updated by this
skill). All feeds regenerate from datasets.json + this config.
Supported profiles
Profiles are a pluggable registry (lib/metadata/dcat-profiles.ts) — national
profiles are config/data, not hardcoded, and multiple can be emitted at once.
| id | Profile | Notes |
|---|---|---|
dcat-3 |
DCAT 3 (W3C) | Default. conformsTo DCAT-3. |
dcat-2 |
DCAT 2 (W3C) | Same core subset stamped as DCAT-2. |
dcat-ap |
DCAT-AP (data.europa.eu) | EU profile: adds foaf/vcard, publisher, contactPoint, dcat:theme (EU data-theme vocab). |
dcat-us |
DCAT-US 3.0 (data.gov) | US federal / Project Open Data: adds publisher, contactPoint, dct:accessLevel. |
geodcat-ap |
GeoDCAT-AP (spatial / INSPIRE) | DCAT-AP + spatial coverage: dct:spatial (bbox/geometry as gsp:wktLiteral) + dcat:spatialResolutionInMeters from each dataset's dcat.spatial (or the catalog-wide spatial config). |
croissant |
Croissant (MLCommons / schema.org) | ML-dataset metadata: a schema.org DataCatalog of Croissant Datasets with cr:FileObject distributions + cr:RecordSet/cr:Field mapped from the Frictionless Table Schema. JSON-LD only. |
dcat-ap-se · dcat-ap-ch · dcat-ap-de |
National (Sweden / Switzerland / Germany) | DCAT-AP + national conformsTo; examples of the plug mechanism. |
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 9d ago First seen · 276 lines · 69 tokens per session scan A 4fb9e47c0cee
portaljs-add-dcat is a command published in the GitHub repository datopian/portaljs (2,349 stars, last pushed yesterday), licensed MIT. It adds 69 tokens to every session and 4,472 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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