runtime/proto/token.proto

// Copyright 2025 The ODML Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.


syntax = "proto3";

package litert.lm.proto;

// A union of token ids and token strings, representing single semantic meaning.
//
// Single semantic meaning might be represented by single token id or multiple
// token ids, depending on the tokenizer. For example, in Gemma3N
// <start_of_turn> represent the start of turn, and can be represented by a
// single token id 105. And some models use multiple token ids to represent
// the end of sentence, signaling to terminate the model decoding.
//
// Note some models do not have valid string representation
// for all tokens, e.g. Gemma3, Gemma3N. Where the <bos> token id is 2, but the
// "<bos>" string would not map to the same token id. In such case, we use
// token_ids to represent the token instead of token_str.
message TokenUnion {
  oneof token_union {
    TokenIds token_ids = 1;
    string token_str = 2;
  }
}

// A list of token ids.
message TokenIds {
  repeated int32 ids = 1;
}