cognis-core

cognis-core is the smallest, most stable crate. Everything else depends on it; it depends on nothing internally. If you’re building a primitive that the rest of the workspace should be able to compose, this is where the trait goes.

Crate metadata

Field	Value
Latest version	`0.3`
docs.rs	docs.rs/cognis-core
Repo path	`crates/cognis-core`
Default features	none

Modules at a glance

Module	What
`runnable`	`Runnable<I, O>` trait, `RunnableConfig`.
`runnable_ext`	`RunnableExt` — `pipe`, `with_max_retries`, `with_timeout`, `with_fallback`, `with_memory_cache`, `each`.
`compose`	`Branch`, `Parallel`, `Each`, `Lambda`, `Passthrough`, `Pipe`. Plus the `lambda` and `pipe` helpers.
`wrappers`	`Retry`, `RetryPolicy`, `Timeout`, `Fallback`, `Cache`, `MemoryCache`, `CacheBackend`, `Bind`, `Configurable`, `Assign`.
`message`	`Message`, `HumanMessage`, `AiMessage`, `SystemMessage`, `ToolMessage`, `ToolCall`.
`content`	`ContentPart`, `ImageSource`, `AudioSource`.
`prompts`	`ChatPromptTemplate`, `PromptTemplate`, `FewShotTemplate`, `Role`.
`output_parsers`	`OutputParser`, `StructuredOutputParser`, `OutputFixingParser`, `RetryParser`, `JsonParser`, `JsonExtractor`, `XmlParser`, `BooleanParser`, `NumberedListParser`, `CommaListParser`, `StringParser`.
`callbacks`	`CallbackHandler`, `CallbackManager`, `HandlerObserver`, `BuiltHandler`, `HandlerBuilder`.
`stream`	`Event`, `EventStream`, `Observer`, `RunnableStream`.
`tools`	`BaseTool` (re-export of `Tool`). The trait shape lives in `cognis-llm`.
`tokenizer`	`Tokenizer`, `CharTokenizer`, `FnTokenizer`.
`loaders`	`Loader` trait — used by `cognis-rag`.
`error`	`CognisError`, `Result`.

Key types

Runnable

#[async_trait]
pub trait Runnable<I, O>: Send + Sync
where I: Send + 'static, O: Send + 'static
{
    async fn invoke(&self, input: I, config: RunnableConfig) -> Result<O>;
    async fn batch(&self, inputs: Vec<I>, config: RunnableConfig) -> Result<Vec<O>> { /* default */ }
    async fn stream(&self, input: I, config: RunnableConfig) -> Result<RunnableStream<O>> { /* default */ }
    async fn stream_events(&self, input: I, config: RunnableConfig) -> Result<EventStream> { /* default */ }
    fn name(&self) -> &str { /* type_name */ }
    fn input_schema(&self) -> Option<serde_json::Value> { None }
    fn output_schema(&self) -> Option<serde_json::Value> { None }
}

RunnableConfig

pub struct RunnableConfig {
    pub recursion_limit: u32,
    pub max_concurrency: usize,
    pub tags: Vec<String>,
    pub metadata: serde_json::Value,
    pub observers: Vec<Arc<dyn Observer>>,
    pub run_id: Uuid,
    pub cancel_token: Option<tokio_util::sync::CancellationToken>,
    pub deadline: Option<Instant>,
    pub extras: Extensions,
    pub parent_run_id: Option<Uuid>,
}

Builder methods: new, with_recursion_limit, with_max_concurrency, with_observer, with_tag, with_cancel_token, with_parent_run_id. Plus is_cancelled and emit.

Event

pub enum Event {
    OnStart { runnable, run_id, input },
    OnNodeStart { node, step, run_id },
    OnNodeEnd { node, step, output, run_id },
    OnLlmToken { token, run_id },
    OnToolStart { tool, args, run_id },
    OnToolEnd { tool, result, run_id },
    OnError { error, run_id },
    OnEnd { runnable, run_id, output },
    OnCheckpoint { step, run_id },
    Custom { kind, payload, run_id },
}

Message

pub enum Message {
    Human(HumanMessage),
    Ai(AiMessage),
    System(SystemMessage),
    Tool(ToolMessage),
}

Constructors: Message::human, Message::ai, Message::system, Message::tool, plus *_with_parts variants.

CognisError

pub enum CognisError {
    ProviderError { provider, message, status },
    RateLimited { retry_after_ms },
    Tool { name, reason },
    ToolValidationError(String),
    OutputParse { raw, error },
    GraphInterrupted { kind, step, .. },
    RecursionLimit,
    Cancelled,
    DeadlineExceeded,
    Other(String),
    // …
}

Result<T> = std::result::Result<T, CognisError>. Cross-crate errors wrap via From.

docs.rs

Browse the full API at docs.rs/cognis-core. Every public type, trait, and function has rustdoc.

Runnables

The conceptual page on the trait.

Messages

What flows through chat-shaped Runnables.

Structured output

StructuredOutputParser, OutputFixingParser, RetryParser.

API per crate

Reference

Crate metadata

Modules at a glance

Key types

Runnable

RunnableConfig

Event

Message

CognisError

docs.rs

See also

Runnables

Messages

Structured output

​Crate metadata

​Modules at a glance

​Key types

​Runnable

​RunnableConfig

​Event

​Message

​CognisError

​docs.rs

​See also

Runnables

Messages

Structured output

Crate metadata

Modules at a glance

Key types

Runnable

RunnableConfig

Event

Message

CognisError

docs.rs

See also