first stab at new approach for getClientCapabilities

index.bs

@@ -2779,6 +2779,36 @@ Note: Invoking this method from a [=browsing context=] where the [=Web Authentic
 
 </div>
 
+### Availability of [=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 or where {{CredentialMediationRequirement/conditional}} mediation is unavailable (instead of showing a username field).
+
+Upon invocation, the [=client=] employs a [=client platform=]-specific procedure to discover availablity of these capabilities.
+
+This method has no arguments and returns a map of capability keys to boolean values. 
+
+<xmp class="idl">
+    partial interface PublicKeyCredential {
+        static Promise<GetClientCapabilitiesResult> getClientCapabilities();
+    };
+
+    interface GetClientCapabilitiesResult {
+        readonly maplike<DOMString, boolean>;
+    };
+</xmp>
+
+Keys in {{GetClientCapabilitiesResult}} SHOULD be members of {{ClientCapability}}.
+
+When the value for a given capability is [TRUE], the feature is known to be currently supported by the client.
+When the value for a given capability is [FALSE], the feature is known to be not currently supported by the client.
+When a given capability is `undefined`, the availibility of the client feature is not known.
+
+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">
@@ -3944,32 +3974,33 @@ Note: The {{UserVerificationRequirement}} enumeration is deliberately not refere
         interest of minimizing disruption to the user interaction flow).
 </div>
 
-### Client Capabilities Set (dictionary <dfn dictionary>ClientCapabilities</dfn>) ### {#dictionary-client-capabilities}
+### Client Capability Enumeration (enum <dfn enum>ClientCapability</dfn>) ### {#enum-clientCapability}
 
 <xmp class="idl">
-    dictionary ClientCapabilities {
-        boolean userVerifyingPlatformAuthenticator;
-        boolean hybridTransport;
-        boolean passkeyPlatformAuthenticator;
-        boolean conditionalMediation;
+    enum ClientCapability {
+        "user-verifying-platform-authenticator",
+        "hybrid-transport,
+        "passkey-platform-authenticator",
+        "conditional-mediation"
     };
 </xmp>
 
-This dictionary defines a limited set of client capabilities which a [=[WRP]=] may evaluate to offer certain workflows and experiences to users.
+This enumeration defines a limited set of client capabilities which a [=[WRP]=] may evaluate to offer certain workflows and experiences to users.
 
-<div dfn-type="dict-member" dfn-for="ClientCapabilities">
-    :   <dfn>userVerifyingPlatformAuthenticator</dfn>
+Note: The {{ClientCapability}} enumeration is deliberately not referenced, see [[#sct-domstring-backwards-compatibility]].
+
+<div dfn-type="enum-value" dfn-for="ClientCapability">
+    :   <dfn>user-verifying-platform-authenticator</dfn>
     ::  The [=WebAuthn Client=] supports usage of a [=user-verifying platform authenticator=].
 
-    :   <dfn>hybridTransport</dfn>
+    :   <dfn>hybrid-transport</dfn>
     ::  The [=WebAuthn Client=] supports usage of the {{AuthenticatorTransport/hybrid}} transport.
 
-    :   <dfn>passkeyPlatformAuthenticator</dfn>
+    :   <dfn>passkey-platform-authenticator</dfn>
     ::  The [=WebAuthn Client=] supports usage of a [=passkey platform authenticator=], locally and/or via {{AuthenticatorTransport/hybrid}} transport.
 
-    :   <dfn>conditionalMediation</dfn>
+    :   <dfn>conditional-mediation</dfn>
     ::  The [=WebAuthn Client=] is capable of {{CredentialMediationRequirement/conditional}} mediation.
-
 </div>
 
 ## Permissions Policy integration ## {#sctn-permissions-policy}