Add new getClientCapabilities method

index.bs

@@ -2802,6 +2802,26 @@ Note: Invoking this method from a [=browsing context=] where the [=Web Authentic
 
 </div>
 
+### Get Client Capabilities - PublicKeyCredential's `getClientCapabilities()` Method ### {#sctn-getClientCapabilities}
+
+<div link-for-hint="WebAuthentication/getClientCapabilities">
+
+[=[WRPS]=] use this method to determine the availability of a limited set of [=WebAuthn Client|client=] capabilities to offer certain workflows and experiences to users. For example, an RP may offer a sign in button on clients where only {{AuthenticatorTransport/hybrid}} transport is available (instead of showing a username field), or offer security key enrollment on [=WebAuthn Client|clients=] that support client PIN entry.
+
+Upon invocation, the [=client=] employs a [=client platform=]-specific procedure to discover availablity of these capabilities.
+
+This method has no arguments and returns a set of strings.
+
+<xmp class="idl">
+    partial interface PublicKeyCredential {
+        static Promise<sequence<DOMString>> getClientCapabilities();
+    };
+</xmp>
+
+Note: Invoking this method from a [=browsing context=] where the [=Web Authentication API=] is "disabled" according to the [=allowed to use=] algorithm&mdash;i.e., by a [=permissions policy=]&mdash;will result in the promise being rejected with a {{DOMException}} whose name is "{{NotAllowedError}}". See also [[#sctn-permissions-policy]].
+
+</div>
+
 ### Deserialize Registration ceremony options - PublicKeyCredential's `parseCreationOptionsFromJSON()` Method ### {#sctn-parseCreationOptionsFromJSON}
 
 <div link-for-hint="WebAuthentication/parseCreationOptionsFromJSON">
@@ -3967,6 +3987,26 @@ Note: The {{UserVerificationRequirement}} enumeration is deliberately not refere
         interest of minimizing disruption to the user interaction flow).
 </div>
 
+### Client Capability Enumeration (enum <dfn enum>ClientCapability</dfn>) ### {#enum-clientCapability}
+
+<xmp class="idl">
+    enum ClientCapability {
+        "hybrid-transport",
+        "client-pin-entry"
+    };
+</xmp>
+
+This enumeration defines a limited set of client capabilities which a [=[WRP]=] may evaluate to offer certain workflows and experiences to users.
+
+Note: The {{ClientCapability}} enumeration is deliberately not referenced, see [[#sct-domstring-backwards-compatibility]].
+
+<div dfn-type="enum-value" dfn-for="ClientCapability">
+    :   <dfn>hybrid-transport</dfn>
+    ::  The [=WebAuthn Client=] supports the {{AuthenticatorTransport/hybrid}} transport.
+
+    :   <dfn>client-pin-entry</dfn>
+    ::  The [=WebAuthn Client=] supports PIN entry for [=user verification=] or other [=authenticator=] operations.
+</div>
 
 ## Permissions Policy integration ## {#sctn-permissions-policy}