Renderer

Introduction

dynamo-renderer turns OpenAI-style chat requests into model-ready prompt strings. It is the encode side of inference serving: messages + tools + generation settings in, a fully-rendered prompt out. It is standalone and runtime-free, so an external OpenAI frontend can reuse Dynamo's prompt formatting without pulling in the Dynamo runtime.

It renders HuggingFace chat_template jinja2 (via minijinja + minijinja-contrib pycompat) and also ships native Rust formatters for DeepSeek families whose repos ship no usable template. The crate is a bridge between OpenAI request types ([dynamo-protocols]) and the template engine; it does not depend on tokenizer internals, though it re-exports [dynamo-tokenizers] for one-import convenience.

Features

• HF chat templates: faithful apply_chat_template rendering, including tool-use and generation-prompt handling.
• Native DeepSeek formatters: Rust formatters for V4 / V3.2 families (under [deepseek]).
• Bring-your-own request type: implement [OAIChatLikeRequest] for any request type, or use the ready-made impl for dynamo-protocols' OpenAI chat request.
• Runtime-free: no async runtime, no networking, no tokenizer dependency on the rendering path.

Quick Start

use dynamo_renderer::{ChatTemplate, ContextMixins, PromptFormatter};
use dynamo_protocols::types::CreateChatCompletionRequest;

// `config` is parsed from a model's `tokenizer_config.json`.
let config: ChatTemplate = serde_json::from_str(tokenizer_config_json)?;
let PromptFormatter::OAI(formatter) =
    PromptFormatter::from_parts(config, ContextMixins::default(), /* exclude_tools_when_tool_choice_none */ false)?
else {
    unreachable!("from_parts always builds an OAI formatter")
};

// Any type implementing `OAIChatLikeRequest` can be rendered; the standard
// OpenAI chat request works out of the box.
let request: CreateChatCompletionRequest = serde_json::from_str(request_json)?;
let prompt: String = formatter.render(&request)?;

Relationship to other crates

• [dynamo-protocols] — OpenAI/wire request types this crate renders from.
• [dynamo-tokenizers] — tokenization (the next step after rendering); re-exported here for convenience.
• [dynamo-parsers] — the decode side (parsing model output back into reasoning / tool calls).