feat: support EncodedContent and transcript messages

proto/mls/message_contents/content.proto

@@ -0,0 +1,42 @@
+// Message content encoding structures
+// Copied from V2 code so that we can eventually retire all V2 message content
+syntax = "proto3";
+
+package xmtp.mls.message_contents;
+
+option go_package = "github.com/xmtp/proto/v3/go/mls/message_contents";
+option java_package = "org.xmtp.proto.mls.message.contents";
+
+// ContentTypeId is used to identify the type of content stored in a Message.
+message ContentTypeId {
+  string authority_id = 1; // authority governing this content type
+  string type_id = 2; // type identifier
+  uint32 version_major = 3; // major version of the type
+  uint32 version_minor = 4; // minor version of the type
+}
+
+// Recognized compression algorithms
+// protolint:disable ENUM_FIELD_NAMES_ZERO_VALUE_END_WITH
+enum Compression {
+  COMPRESSION_DEFLATE = 0;
+  COMPRESSION_GZIP = 1;
+}
+// protolint:enable ENUM_FIELD_NAMES_ZERO_VALUE_END_WITH
+
+// EncodedContent bundles the content with metadata identifying its type
+// and parameters required for correct decoding and presentation of the content.
+message EncodedContent {
+  // content type identifier used to match the payload with
+  // the correct decoding machinery
+  ContentTypeId type = 1;
+  // optional encoding parameters required to correctly decode the content
+  map<string, string> parameters = 2;
+  // optional fallback description of the content that can be used in case
+  // the client cannot decode or render the content
+  optional string fallback = 3;
+  // optional compression; the value indicates algorithm used to
+  // compress the encoded content bytes
+  optional Compression compression = 5;
+  // encoded content itself
+  bytes content = 4;
+}

proto/mls/message_contents/transcript_messages.proto

@@ -0,0 +1,21 @@
+// Message content encoding structures
+syntax = "proto3";
+
+package xmtp.mls.message_contents;
+
+option go_package = "github.com/xmtp/proto/v3/go/mls/message_contents";
+option java_package = "org.xmtp.proto.mls.message.contents";
+
+// A group member and affected installation IDs
+message Member {
+    repeated bytes installation_ids = 1;
+    string wallet_address = 2;
+}
+
+// The group membership change proto
+message GroupMembershipChange {
+    repeated Member members_added = 1;
+    repeated Member members_removed = 2;
+    repeated Member installations_added = 3;
+    repeated Member installations_removed = 4;
+}