If you published /.well-known/ai-catalog.json for AI agents, the spec now asks you to publish /.well-known/ard.json instead. Version 0.91 of the Agentic Resource Discovery (ARD) specification defines one well-known path, and agents are no longer required to look at the old one.

What changed in ARD v0.91

The ARD spec repository published v0.91 on 2026-08-26, promoting the draft to the main spec file and, in the commit’s own words, setting a “single well-known path” (commit a305a52). The spec is still marked “Proposal” (ard.md at the 2026-10-11 head).

Section 5.1 now says:

  • Path: the manifest lives at https://{domain}/.well-known/ard.json, a JSON document with an entries array.
  • Link tag: the HTML link relation is rel="ard".
  • Consumers: they MUST fetch /.well-known/ard.json and MUST honour a rel="ard" link.
  • Old names: the predecessor path /.well-known/ai-catalog.json and the ai-catalog relation are optional for consumers. Reading them is “a courtesy”, not a conformance requirement.

What it means for a store that already shipped ai-catalog.json

The spec’s publishing note is direct: a resource that remains only at /.well-known/ai-catalog.json “may not be found”, and a publisher on the old path “SHOULD move to ard.json”. Serving both is not needed; one path is enough for every conformant consumer.

Our earlier guide, ai-catalog.json: make your store discoverable to AI agents, describes the original v0.9 path. Read it for what ARD is and who backs it; use the path below.

The checklist

  1. Publish your manifest at /.well-known/ard.json.
  2. Keep the content: an entries array of ARD entries (spec section 4).
  3. If you used <link rel="ai-catalog">, add <link rel="ard" href="...">.
  4. Optionally keep the old file in place. The spec says consumers may read it, but does not promise they will.
  5. Fetch the new URL from outside your network and confirm a 200 with a JSON body.

Other discovery routes are unchanged in kind: an Agentmap: directive in robots.txt, in-page JSON-LD, and DNS service-binding records are all listed in section 5.1.

An entry is now JSON-LD

v0.91 also restates entries as JSON-LD nodes. An entry can declare extra vocabularies through @context, and the spec says existing manifests “remain valid entries unchanged”. A working-group decision recorded on 2026-07-09 keeps ARD entries and ai-catalog entries only loosely coupled: an ARD entry is the ai-catalog core plus flat, namespaced extensions (ADR 0010).

What this does not tell you

The spec defines where agents may look. It does not say which agents or registries look today, or that a catalog earns a store any traffic. Pair it with the part that decides sales: whether an agent that finds you can actually check out.

FAQ

What is the new well-known path for ARD?

ARD v0.91 defines https://{domain}/.well-known/ard.json. The file is a JSON document with an entries array, and conformant consumers must fetch it.

Do I have to delete my ai-catalog.json?

The spec does not require deleting it. It says consumers may still read the old path as a courtesy, but a consumer that reads only ard.json is fully conformant, so a store on the old path alone may not be found.

Is ARD a finished standard?

No. The spec header reads “Version v0.91, Status: Proposal”. Paths and fields can still change, so treat the manifest as cheap to publish and cheap to update.

Sources

Discovery only matters if the transaction works after it, which is the part AgentReady audits.