Crate nika_engine 

Nika Engine — Embeddable workflow execution engine

Module Architecture

┌──────────────────────────────────────────────────────────────┐
│                        DOMAIN MODEL                          │
│  ast/       YAML → Rust types (Workflow, Task, TaskAction)   │
└──────────────────────────────────────────────────────────────┘
                             │
                             ▼
┌──────────────────────────────────────────────────────────────┐
│                      APPLICATION LAYER                       │
│  runtime/   DAG execution (Runner, TaskExecutor)             │
│  dag/       DAG structure (Dag, validate)                    │
│  binding/   Data binding (WithSpec, ResolvedBindings)        │
└──────────────────────────────────────────────────────────────┘
                             │
                             ▼
┌──────────────────────────────────────────────────────────────┐
│                    INFRASTRUCTURE LAYER                      │
│  store/     State management (RunContext, TaskResult)         │
│  event/     Event sourcing (EventLog, EventKind)             │
│  provider/  LLM abstraction (rig-core wrapper)               │
└──────────────────────────────────────────────────────────────┘

Re-exports

pub use error::NikaError;

pub use ast::AgentParams;

pub use ast::ExecParams;

pub use ast::FetchParams;

pub use ast::InferParams;

pub use ast::InvokeParams;

pub use ast::Task;

pub use ast::TaskAction;

pub use ast::Workflow;

pub use runtime::Runner;

pub use runtime::TaskExecutor;

pub use dag::validate_bindings;

pub use dag::Dag;

pub use dag::StableDag;

pub use binding::validate_task_id;

pub use binding::ResolvedBindings;

pub use store::RunContext;

pub use store::TaskResult;

pub use serde_saphyr as serde_yaml;

pub use nika_init as init;

Modules

ast

AST Module - Abstract Syntax Tree for YAML workflows

binding

Binding Module - Data binding between tasks.

config

Nika Configuration Module

core

Core types for Nika — zero-dependency provider, model, and MCP definitions.

dag

DAG Module - Directed Acyclic Graph structure

display

CLI display — header, event stream, summary renderers.

error

Nika Error Types with Error Codes

error_domains

Domain-specific error types for ARCH-3 incremental migration.

event

Event Module — re-exports from nika-event crate.

io

I/O utilities for Nika

mcp

MCP Integration Module — re-exports from nika-mcp crate.

media

Media pipeline — re-exports from nika-media crate.

new

nika new - Workflow scaffolding module

provider

Provider abstraction layer

registry

SuperNovae Package Registry

runtime

Runtime Module - Workflow execution

secrets

Secrets management – env vars + optional keyring.

source

Source span tracking — re-exported from nika-core.

store

Store Module - state management

tools

File Tools Module - Claude Code-like filesystem operations

util

Utilities Module - shared infrastructure

Structs

BindingEntry

Unified with entry - supports both string and extended object syntax

ByteOffset

A byte offset in a source file.

Event

Single event in the workflow execution log

EventLog

FileId

Unique identifier for a source file in the SourceRegistry.

McpClient

MCP Client for connecting to and interacting with MCP servers.

McpConfig

MCP server configuration.

SourceFile

A single source file with its content and path.

SourceRegistry

Registry of all source files in a compilation unit.

Span

A span in a source file (byte range + file ID).

Spanned

A value with an associated span.

Enums

EventKind

All possible event types (3 levels)

Functions

list_traces

List all trace files

prune_traces

Prune old trace files, enforcing both max_traces and retention_days.

Type Aliases

BindingSpec

Binding spec - map of alias to entry (YAML with: block)