Crate agent_chain_core 

Agent Chain Core - A Rust implementation of LangChain core library.

This crate provides:

• Message types for LLM conversations (human, AI, system, tool)
• Tool trait and #[tool] macro for function calling
• Chat model abstractions
• Callback system for tracking and monitoring operations
• Prompt templates for flexible prompt construction
• Support for multiple providers (Anthropic, OpenAI, etc.)

Architecture

The architecture follows LangChain’s pattern:

• Core layer (chat_models): Base ChatModel trait that all providers implement
• Message layer (messages): Message types for conversations
• Prompts layer (prompts): Prompt templates for constructing prompts
• Tools layer (tools): Tool definitions and the #[tool] macro
• Callbacks layer (callbacks): Callback handlers and managers for monitoring

Feature Flags

• default: Includes all providers
• specta: Specta derive support

Re-exports

pub use env::VERSION;

pub use env::get_runtime_environment;

pub use error::Error;

pub use error::Result;

pub use language_models::AIMessageChunkStream;

pub use language_models::BaseChatModel;

pub use language_models::BaseLLM;

pub use language_models::BaseLanguageModel;

pub use language_models::ChatChunk;

pub use language_models::ChatGenerationStream;

pub use language_models::ChatModelConfig;

pub use language_models::ChatStream;

pub use language_models::DisableStreaming;

pub use language_models::FakeListChatModel;

pub use language_models::FakeListChatModelError;

pub use language_models::FakeListLLM;

pub use language_models::FakeListLLMError;

pub use language_models::FakeMessagesListChatModel;

pub use language_models::FakeStreamingListLLM;

pub use language_models::GenericFakeChatModel;

pub use language_models::LLM;

pub use language_models::LLMConfig;

pub use language_models::LangSmithParams;

pub use language_models::LanguageModelConfig;

pub use language_models::LanguageModelInput;

pub use language_models::LanguageModelOutput;

pub use language_models::ModelProfile;

pub use language_models::ModelProfileRegistry;

pub use language_models::OpenAiDataBlockFilter;

pub use language_models::ParrotFakeChatModel;

pub use language_models::ParsedDataUri;

pub use language_models::SimpleChatModel;

pub use language_models::ToolChoice;

pub use language_models::UsageMetadata;

pub use language_models::agenerate_from_stream;

pub use language_models::collect_and_merge_stream;

pub use language_models::generate_from_stream;

pub use language_models::get_prompts_from_cache;

pub use language_models::is_openai_data_block;

pub use language_models::parse_data_uri;

pub use language_models::update_cache;

pub use messages::AIMessage;

pub use messages::AnyMessage;

pub use messages::BaseMessage;

pub use messages::ContentPart;

pub use messages::HasId;

pub use messages::HumanMessage;

pub use messages::ImageDetail;

pub use messages::ImageSource;

pub use messages::MessageContent;

pub use messages::SystemMessage;

pub use messages::ToolCall;

pub use messages::ToolMessage;

pub use tools::BaseTool;

pub use tools::Tool;

pub use tools::ToolDefinition;

pub use chat_history::AIMessageInput;

pub use chat_history::BaseChatMessageHistory;

pub use chat_history::HumanMessageInput;

pub use chat_history::InMemoryChatMessageHistory;

pub use chat_sessions::ChatSession;

pub use chat_loaders::BaseChatLoader;

pub use caches::BaseCache;

pub use caches::CacheReturnValue;

pub use caches::InMemoryCache;

pub use globals::get_debug;

pub use globals::get_llm_cache;

pub use globals::get_verbose;

pub use globals::set_debug;

pub use globals::set_llm_cache;

pub use globals::set_verbose;

pub use output_parsers::BaseCumulativeTransformOutputParser;

pub use output_parsers::BaseLLMOutputParser;

pub use output_parsers::BaseOutputParser;

pub use output_parsers::BaseTransformOutputParser;

pub use output_parsers::CommaSeparatedListOutputParser;

pub use output_parsers::JsonOutputParser;

pub use output_parsers::ListOutputParser;

pub use output_parsers::MarkdownListOutputParser;

pub use output_parsers::NumberedListOutputParser;

pub use output_parsers::OutputParserError;

pub use output_parsers::SimpleJsonOutputParser;

pub use output_parsers::StrOutputParser;

pub use output_parsers::XMLOutputParser;

pub use outputs::ChatGeneration;

pub use outputs::ChatGenerationChunk;

pub use outputs::ChatResult;

pub use outputs::Generation;

pub use outputs::GenerationChunk;

pub use outputs::GenerationType;

pub use outputs::LLMResult;

pub use outputs::RunInfo;

pub use outputs::merge_chat_generation_chunks;

pub use callbacks::AsyncCallbackHandler;

pub use callbacks::AsyncCallbackManager;

pub use callbacks::AsyncCallbackManagerForChainRun;

pub use callbacks::AsyncCallbackManagerForLLMRun;

pub use callbacks::BaseCallbackHandler;

pub use callbacks::BaseCallbackManager;

pub use callbacks::CallbackManager;

pub use callbacks::CallbackManagerForChainRun;

pub use callbacks::CallbackManagerForLLMRun;

pub use callbacks::Callbacks;

pub use callbacks::StdOutCallbackHandler;

pub use callbacks::StreamingStdOutCallbackHandler;

pub use callbacks::UsageMetadataCallbackHandler;

pub use callbacks::add_usage;

pub use prompts::AIMessagePromptTemplate;

pub use prompts::BaseChatPromptTemplate;

pub use prompts::BaseMessagePromptTemplate;

pub use prompts::BasePromptTemplate;

pub use prompts::ChatMessagePromptTemplate;

pub use prompts::ChatPromptTemplate;

pub use prompts::DictPromptTemplate;

pub use prompts::FewShotChatMessagePromptTemplate;

pub use prompts::FewShotPromptTemplate;

pub use prompts::FewShotPromptWithTemplates;

pub use prompts::HumanMessagePromptTemplate;

pub use prompts::ImagePromptTemplate;

pub use prompts::MessagesPlaceholder;

pub use prompts::PromptTemplate;

pub use prompts::PromptTemplateFormat;

pub use prompts::StringPromptTemplate;

pub use prompts::SystemMessagePromptTemplate;

pub use prompts::load_prompt;

pub use load::ConstructorInfo;

pub use load::RevivedValue;

pub use load::Reviver;

pub use load::ReviverConfig;

pub use load::Serializable;

pub use load::Serialized;

pub use load::SerializedConstructor;

pub use load::SerializedNotImplemented;

pub use load::SerializedSecret;

pub use load::dumpd;

pub use load::dumps;

pub use load::load as load_json;

pub use load::loads;

pub use prompt_values::ChatPromptValue;

pub use prompt_values::ChatPromptValueConcrete;

pub use prompt_values::ImageDetailLevel;

pub use prompt_values::ImagePromptValue;

pub use prompt_values::ImageURL;

pub use prompt_values::PromptValue;

pub use prompt_values::StringPromptValue;

pub use tracers::AsyncBaseTracer;

pub use tracers::AsyncListener;

pub use tracers::AsyncRootListenersTracer;

pub use tracers::BaseTracer;

pub use tracers::ConsoleCallbackHandler;

pub use tracers::FunctionCallbackHandler;

pub use tracers::Listener;

pub use tracers::PassthroughStreamingHandler;

pub use tracers::RootListenersTracer;

pub use tracers::Run;

pub use tracers::RunCollectorCallbackHandler;

pub use tracers::RunEvent;

pub use tracers::RunType;

pub use tracers::SchemaFormat;

pub use tracers::StreamingCallbackHandler;

pub use tracers::TracerCore;

pub use tracers::TracerCoreConfig;

pub use tracers::TracerError;

pub use rate_limiters::BaseRateLimiter;

pub use rate_limiters::InMemoryRateLimiter;

pub use rate_limiters::InMemoryRateLimiterConfig;

pub use documents::BaseDocumentCompressor;

pub use documents::BaseDocumentTransformer;

pub use documents::BaseMedia;

pub use documents::Blob;

pub use documents::BlobBuilder;

pub use documents::BlobData;

pub use documents::Document;

pub use documents::FilterTransformer;

pub use documents::FunctionTransformer;

pub use retrievers::BaseRetriever;

pub use retrievers::DynRetriever;

pub use retrievers::FilterRetriever;

pub use retrievers::LangSmithRetrieverParams;

pub use retrievers::RetrieverInput;

pub use retrievers::RetrieverOutput;

pub use retrievers::SimpleRetriever;

pub use stores::BaseStore;

pub use stores::InMemoryBaseStore;

pub use stores::InMemoryByteStore;

pub use stores::InMemoryStore;

pub use stores::InvalidKeyException;

pub use runnables::AddableDict;

pub use runnables::BaseStreamEvent;

pub use runnables::CUSTOM_EVENT_TYPE;

pub use runnables::ConfigOrList;

pub use runnables::CustomStreamEvent;

pub use runnables::DynRouterRunnable;

pub use runnables::DynRunnable;

pub use runnables::EventData;

pub use runnables::PickKeys;

pub use runnables::RouterInput;

pub use runnables::RouterRunnable;

pub use runnables::Runnable;

pub use runnables::RunnableAssign;

pub use runnables::RunnableAssignBuilder;

pub use runnables::RunnableBinding;

pub use runnables::RunnableConfig;

pub use runnables::RunnableEach;

pub use runnables::RunnableLambda;

pub use runnables::RunnableParallel;

pub use runnables::RunnablePassthrough;

pub use runnables::RunnablePick;

pub use runnables::RunnableRetry;

pub use runnables::RunnableSequence;

pub use runnables::RunnableSerializable;

pub use runnables::StandardStreamEvent;

pub use runnables::StreamEvent;

pub use runnables::coerce_to_runnable;

pub use runnables::ensure_config;

pub use runnables::get_config_list;

pub use runnables::graph_passthrough;

pub use runnables::merge_configs;

pub use runnables::patch_config;

pub use runnables::pipe;

pub use runnables::runnable_lambda;

pub use runnables::to_dyn;

pub use structured_query::Comparator;

pub use structured_query::Comparison;

pub use structured_query::Expr;

pub use structured_query::FilterDirective;

pub use structured_query::FilterDirectiveEnum;

pub use structured_query::Operation;

pub use structured_query::Operator;

pub use structured_query::OperatorOrComparator;

pub use structured_query::StructuredQuery;

pub use structured_query::Visitor;

pub use sys_info::PackageInfo;

pub use sys_info::SystemInfo;

pub use sys_info::get_sys_info;

pub use sys_info::get_sys_info_map;

pub use sys_info::print_sys_info;

Modules

api

Helper functions for managing the Agent Chain API.

caches

Optional caching layer for language models.

callbacks

Callbacks module for LangChain.

chat_history

Chat message history stores a history of the message interactions in a chat.

chat_loaders

Chat loaders are used to load chat sessions from various sources.

chat_models

Re-export of language_models types for backward compatibility.

chat_sessions

Chat Sessions are a collection of messages and function calls.

documents

Documents module for data retrieval and processing workflows.

env

Utilities for getting information about the runtime environment.

error

Error types for agent-chain.

globals

Global values and configuration that apply to all of LangChain.

language_models

Core language model abstractions.

load

Load module helps with serialization and deserialization.

messages

Message types for LLM interactions.

output_parsers

Output parser classes.

outputs

Output classes.

prompt_values

Prompt values for language model prompts.

prompts

Prompt templates for LLM interactions.

rate_limiters

retrievers

Retriever trait returns Documents given a text query.

runnables

Runnables module for agent-chain-core.

stores

Store implements the key-value stores and storage helpers.

structured_query

Internal representation of a structured query language.

sys_info

Print information about the system and agent-chain packages for debugging purposes.

tools

Tools are classes that an Agent uses to interact with the world.

tracers

Tracers are classes for tracing runs.

utils

Utility functions for LangChain.

Macros

beta

Macro to mark a function or method as beta.

deprecated

Macro to emit a deprecation warning.

renamed_parameter

Macro for handling renamed parameters with deprecation warnings.

Attribute Macros

async_trait