diff --git a/gen/jsonschema/schemas/ClientTrustConfig.schema.json b/gen/jsonschema/schemas/ClientTrustConfig.schema.json
index a0f3543b..4971090d 100644
--- a/gen/jsonschema/schemas/ClientTrustConfig.schema.json
+++ b/gen/jsonschema/schemas/ClientTrustConfig.schema.json
@@ -4,6 +4,10 @@
     "definitions": {
         "ClientTrustConfig": {
             "properties": {
+                "mediaType": {
+                    "type": "string",
+                    "description": "MUST be application/vnd.dev.sigstore.clienttrustconfig.v0.1+json"
+                },
                 "trustedRoot": {
                     "$ref": "#/definitions/dev.sigstore.trustroot.v1.TrustedRoot",
                     "additionalProperties": false,
diff --git a/gen/pb-go/trustroot/v1/sigstore_trustroot.pb.go b/gen/pb-go/trustroot/v1/sigstore_trustroot.pb.go
index 6d24c287..bf2664fd 100644
--- a/gen/pb-go/trustroot/v1/sigstore_trustroot.pb.go
+++ b/gen/pb-go/trustroot/v1/sigstore_trustroot.pb.go
@@ -434,10 +434,12 @@ type ClientTrustConfig struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
+	// MUST be application/vnd.dev.sigstore.clienttrustconfig.v0.1+json
+	MediaType string `protobuf:"bytes,1,opt,name=media_type,json=mediaType,proto3" json:"media_type,omitempty"`
 	// The root of trust, which MUST be present.
-	TrustedRoot *TrustedRoot `protobuf:"bytes,1,opt,name=trusted_root,json=trustedRoot,proto3" json:"trusted_root,omitempty"`
+	TrustedRoot *TrustedRoot `protobuf:"bytes,2,opt,name=trusted_root,json=trustedRoot,proto3" json:"trusted_root,omitempty"`
 	// Configuration for signing clients, which MUST be present.
-	SigningConfig *SigningConfig `protobuf:"bytes,2,opt,name=signing_config,json=signingConfig,proto3" json:"signing_config,omitempty"`
+	SigningConfig *SigningConfig `protobuf:"bytes,3,opt,name=signing_config,json=signingConfig,proto3" json:"signing_config,omitempty"`
 }
 
 func (x *ClientTrustConfig) Reset() {
@@ -472,6 +474,13 @@ func (*ClientTrustConfig) Descriptor() ([]byte, []int) {
 	return file_sigstore_trustroot_proto_rawDescGZIP(), []int{4}
 }
 
+func (x *ClientTrustConfig) GetMediaType() string {
+	if x != nil {
+		return x.MediaType
+	}
+	return ""
+}
+
 func (x *ClientTrustConfig) GetTrustedRoot() *TrustedRoot {
 	if x != nil {
 		return x.TrustedRoot
@@ -560,28 +569,30 @@ var file_sigstore_trustroot_proto_rawDesc = []byte{
 	0x1b, 0x0a, 0x09, 0x74, 0x6c, 0x6f, 0x67, 0x5f, 0x75, 0x72, 0x6c, 0x73, 0x18, 0x03, 0x20, 0x03,
 	0x28, 0x09, 0x52, 0x08, 0x74, 0x6c, 0x6f, 0x67, 0x55, 0x72, 0x6c, 0x73, 0x12, 0x19, 0x0a, 0x08,
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+	0x54, 0x72, 0x75, 0x73, 0x74, 0x52, 0x6f, 0x6f, 0x74, 0x3a, 0x3a, 0x56, 0x31, 0x62, 0x06, 0x70,
+	0x72, 0x6f, 0x74, 0x6f, 0x33,
 }
 
 var (
diff --git a/gen/pb-python/sigstore_protobuf_specs/dev/sigstore/trustroot/v1/__init__.py b/gen/pb-python/sigstore_protobuf_specs/dev/sigstore/trustroot/v1/__init__.py
index fb9694d6..ee36d76c 100644
--- a/gen/pb-python/sigstore_protobuf_specs/dev/sigstore/trustroot/v1/__init__.py
+++ b/gen/pb-python/sigstore_protobuf_specs/dev/sigstore/trustroot/v1/__init__.py
@@ -175,8 +175,11 @@ class ClientTrustConfig(betterproto.Message):
     instance of Sigstore.
     """
 
-    trusted_root: "TrustedRoot" = betterproto.message_field(1)
+    media_type: str = betterproto.string_field(1)
+    """MUST be application/vnd.dev.sigstore.clienttrustconfig.v0.1+json"""
+
+    trusted_root: "TrustedRoot" = betterproto.message_field(2)
     """The root of trust, which MUST be present."""
 
-    signing_config: "SigningConfig" = betterproto.message_field(2)
+    signing_config: "SigningConfig" = betterproto.message_field(3)
     """Configuration for signing clients, which MUST be present."""
diff --git a/gen/pb-ruby/lib/sigstore_trustroot_pb.rb b/gen/pb-ruby/lib/sigstore_trustroot_pb.rb
index 5918caf4..d31a17fc 100644
--- a/gen/pb-ruby/lib/sigstore_trustroot_pb.rb
+++ b/gen/pb-ruby/lib/sigstore_trustroot_pb.rb
@@ -34,8 +34,9 @@
       repeated :tsa_urls, :string, 4
     end
     add_message "dev.sigstore.trustroot.v1.ClientTrustConfig" do
-      optional :trusted_root, :message, 1, "dev.sigstore.trustroot.v1.TrustedRoot"
-      optional :signing_config, :message, 2, "dev.sigstore.trustroot.v1.SigningConfig"
+      optional :media_type, :string, 1
+      optional :trusted_root, :message, 2, "dev.sigstore.trustroot.v1.TrustedRoot"
+      optional :signing_config, :message, 3, "dev.sigstore.trustroot.v1.SigningConfig"
     end
   end
 end
diff --git a/gen/pb-rust/sigstore-protobuf-specs/src/generated/dev.sigstore.trustroot.v1.rs b/gen/pb-rust/sigstore-protobuf-specs/src/generated/dev.sigstore.trustroot.v1.rs
index 721e0ea5..f1e546d2 100644
--- a/gen/pb-rust/sigstore-protobuf-specs/src/generated/dev.sigstore.trustroot.v1.rs
+++ b/gen/pb-rust/sigstore-protobuf-specs/src/generated/dev.sigstore.trustroot.v1.rs
@@ -189,10 +189,13 @@ pub struct SigningConfig {
 #[allow(clippy::derive_partial_eq_without_eq)]
 #[derive(Clone, PartialEq, ::prost::Message)]
 pub struct ClientTrustConfig {
+    /// MUST be application/vnd.dev.sigstore.clienttrustconfig.v0.1+json
+    #[prost(string, tag = "1")]
+    pub media_type: ::prost::alloc::string::String,
     /// The root of trust, which MUST be present.
-    #[prost(message, optional, tag = "1")]
+    #[prost(message, optional, tag = "2")]
     pub trusted_root: ::core::option::Option<TrustedRoot>,
     /// Configuration for signing clients, which MUST be present.
-    #[prost(message, optional, tag = "2")]
+    #[prost(message, optional, tag = "3")]
     pub signing_config: ::core::option::Option<SigningConfig>,
 }
diff --git a/gen/pb-rust/sigstore-protobuf-specs/src/generated/file_descriptor_set.bin b/gen/pb-rust/sigstore-protobuf-specs/src/generated/file_descriptor_set.bin
index 0d6b98c6..f818b3d2 100644
Binary files a/gen/pb-rust/sigstore-protobuf-specs/src/generated/file_descriptor_set.bin and b/gen/pb-rust/sigstore-protobuf-specs/src/generated/file_descriptor_set.bin differ
diff --git a/gen/pb-typescript/src/__generated__/sigstore_trustroot.ts b/gen/pb-typescript/src/__generated__/sigstore_trustroot.ts
index fc15e7b5..747154e5 100644
--- a/gen/pb-typescript/src/__generated__/sigstore_trustroot.ts
+++ b/gen/pb-typescript/src/__generated__/sigstore_trustroot.ts
@@ -177,6 +177,8 @@ export interface SigningConfig {
  * instance of Sigstore.
  */
 export interface ClientTrustConfig {
+  /** MUST be application/vnd.dev.sigstore.clienttrustconfig.v0.1+json */
+  mediaType: string;
   /** The root of trust, which MUST be present. */
   trustedRoot:
     | TrustedRoot
@@ -322,12 +324,13 @@ export const SigningConfig = {
 };
 
 function createBaseClientTrustConfig(): ClientTrustConfig {
-  return { trustedRoot: undefined, signingConfig: undefined };
+  return { mediaType: "", trustedRoot: undefined, signingConfig: undefined };
 }
 
 export const ClientTrustConfig = {
   fromJSON(object: any): ClientTrustConfig {
     return {
+      mediaType: isSet(object.mediaType) ? String(object.mediaType) : "",
       trustedRoot: isSet(object.trustedRoot) ? TrustedRoot.fromJSON(object.trustedRoot) : undefined,
       signingConfig: isSet(object.signingConfig) ? SigningConfig.fromJSON(object.signingConfig) : undefined,
     };
@@ -335,6 +338,7 @@ export const ClientTrustConfig = {
 
   toJSON(message: ClientTrustConfig): unknown {
     const obj: any = {};
+    message.mediaType !== undefined && (obj.mediaType = message.mediaType);
     message.trustedRoot !== undefined &&
       (obj.trustedRoot = message.trustedRoot ? TrustedRoot.toJSON(message.trustedRoot) : undefined);
     message.signingConfig !== undefined &&