Remove mention of extensions for now

Author: benbrandt

docs/rfds/acp-agent-registry.mdx

@@ -21,7 +21,7 @@ Every editor builds bespoke manifests or scrapes GitHub, leading to duplication
 
 ## Agent manifest format (core proposal)
 
-Each agent or extension advertises itself via a manifest stored under `<id>/` in the registry repo. Agents use `agent.json`; extensions use `extension.json`. A directory must contain one or the other, but not both. Both file types share the same schema.
+Each agent advertises itself via a manifest stored as `<id>/agent.json` in the registry repo.
 
 Fields marked with **\*** are required:
 
@@ -155,11 +155,10 @@ Using `currentColor` lets icons adapt automatically to the client's light or dar
 
 The aggregated `registry.json` file conforms to the registry schema and contains:
 
-| Field        | Description                                                                                               |
-| ------------ | --------------------------------------------------------------------------------------------------------- |
-| `version`    | Registry schema version (semver, e.g. `1.0.0`).                                                           |
-| `agents`     | Array of agent entries (each following the agent manifest schema above, sourced from `agent.json` files). |
-| `extensions` | Array of extension entries (same schema as agents, sourced from `extension.json` files).                  |
+| Field     | Description                                                                                               |
+| --------- | --------------------------------------------------------------------------------------------------------- |
+| `version` | Registry schema version (semver, e.g. `1.0.0`).                                                           |
+| `agents`  | Array of agent entries (each following the agent manifest schema above, sourced from `agent.json` files). |
 
 ## Authentication requirements
 
@@ -174,11 +173,11 @@ CI verifies this by checking that the agent returns an `authMethods` array in it
 
 1. **Manifest spec** (above) becomes normative; we publish the JSON Schema and validator script so maintainers can lint locally.
 2. **Registry repository** `github.com/agentclientprotocol/registry`:
-   - Structure: `<id>/agent.json` (or `extension.json`), optional `icon.svg`, optional `README.md`.
+   - Structure: `<id>/agent.json`, optional `icon.svg`, optional `README.md`.
    - CI validates manifests on every PR: schema compliance, slug uniqueness, icon format (16×16 SVG, monochrome `currentColor`), URL accessibility for all distribution URLs, authentication support via ACP handshake, and binary OS coverage.
    - Push to `main` triggers a build that aggregates all entries into `registry.json` and publishes versioned + `latest` GitHub releases.
 3. **Aggregated outputs**:
-   - `registry.json`: deterministic list of all agents and extensions with icons copied to `dist/<id>.svg`.
+   - `registry.json`: deterministic list of all agents with icons copied to `dist/<id>.svg`.
 4. **Distribution & search**:
    - Clients fetch `registry.json` from `https://cdn.agentclientprotocol.com/registry/v1/latest/registry.json`.
    - Static site offers filters for deployment model, license, and distribution type.
@@ -205,4 +204,4 @@ CI verifies this by checking that the agent returns an `authMethods` array in it
 
 - 2025-11-28: Initial draft.
 - 2025-12-16: Minors.
-- 2026-02-04: Updated to match latest schema — removed `schema_version`, `homepage`, `capabilities`, and `auth` fields; added `icon` field; restructured `distribution` into `binary`, `npx`, and `uvx` types; added `extensions` to registry schema.
+- 2026-02-04: Updated to match latest schema — removed `schema_version`, `homepage`, `capabilities`, and `auth` fields; added `icon` field; restructured `distribution` into `binary`, `npx`, and `uvx` types.