jamjet 0.3.1

JamJet Python SDK — agent-native workflow authoring and CLI

JamJet

The agent-native runtime — built for performance, designed for interoperability, reliable enough for production.

JamJet is a performance-first, agent-native runtime and framework for building reliable, interoperable AI agent systems. It is not another prompt wrapper or thin agent SDK — it is a production-grade orchestration substrate for agents that need to work, not just demo.

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Why JamJet?

Problem	JamJet's answer
Fragile agent runs that lose state on crash	Durable graph execution with event sourcing and crash recovery
No way to pause for human approval	Human-in-the-loop as a first-class workflow primitive
Agents siloed in their own framework	Native MCP + A2A — interoperate with any agent, any framework
Slow Python orchestration at scale	Rust core for scheduling, state, concurrency; Python for authoring
Weak observability, no replay	Full event timeline, replay from any checkpoint
No standard agent identity	Agent Cards — every agent is addressable, discoverable, composable
Inconsistent tool contracts	Typed schemas everywhere — Pydantic, TypedDict, JSON Schema

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How JamJet compares

As of March 2026. All frameworks evolve quickly — check their docs for the latest.

Capability	JamJet	LangChain	AutoGen	CrewAI	BeeAI
Default model	Agent-first + strategy	Chain / LCEL	Conversational agents	Role-based crew	Agent loop
Durable execution	✅ event-sourced; crash-safe resume	❌ ephemeral	❌ ephemeral	❌ ephemeral	❌ ephemeral
Human-in-the-loop	✅ first-class primitive	🟡 callback hooks	🟡 first-class for conversational flows	🟡 manual	❌
MCP support	✅ client + server	🟡 client only	🟡 client only	🟡 client only	🟡 client only
A2A protocol	✅ client + server	❌	❌	❌	❌
Pluggable reasoning strategies	✅ react, plan-and-execute, critic, reflection, consensus, debate	❌ manual wiring	🟡 user-built	🟡 role-based tasks	🟡 user-built
Enforced cost/iteration limits	✅ compile-time guards	❌	🟡 partial	🟡 partial	❌
Typed state schemas	✅ Pydantic / TypedDict / JSON Schema	🟡 optional	🟡 optional	🟡 partial	🟡 partial
Built-in observability	✅ OTel GenAI, full event timeline, replay	🟡 LangSmith (external)	❌	❌	❌
Agent identity + discovery	✅ Agent Cards, A2A discovery	❌	❌	❌	🟡 framework-level discovery
Runtime language	Rust core + Python authoring	Python	Python	Python	TypeScript
Scheduler / throughput	✅ Rust async scheduler; low-overhead worker pool	🟡 Python asyncio; GIL-bound	🟡 Python asyncio; message-passing overhead	🟡 Python; sequential by default	🟡 Node.js event loop
Deployment model	Long-running server (local or cloud)	Library (in-process)	Library (in-process)	Library (in-process)	Library (in-process)
Best for	Production multi-agent systems needing durability and interop	Rapid prototyping, LLM chains	Conversational multi-agent apps	Role-based collab agents	TypeScript agentic apps

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Key Features

Durable graph workflows — every step is checkpointed; crash the runtime and execution resumes exactly where it left off.

Native MCP + A2A — connect to any MCP server, expose your tools as an MCP server, delegate to or serve external agents via A2A.

Agent-native identity — every agent has a URI, an Agent Card describing its capabilities, and a managed lifecycle.

Human-in-the-loop — pause any workflow for human approval or input as a first-class primitive.

Configurable autonomy — from strict deterministic graph execution to bounded autonomous agents operating within defined budgets.

Typed schemas everywhere — Pydantic, TypedDict, JSON Schema. No stringly-typed state.

Distributed workers — horizontal scale with lease semantics, retry policies, and queue isolation by workload type.

Python-friendly authoring — define workflows with Python decorators or YAML; both compile to the same runtime graph.

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Quick Start

Requirements: Python 3.11+

# Install the CLI (runtime binary included)
pip install jamjet

# Option A — scaffold a new project
jamjet init my-agent-project
cd my-agent-project

# Option B — add JamJet to an existing project (works like git init)
cd my-existing-project
jamjet init

# Start local dev runtime (SQLite, embedded — no server setup needed)
jamjet dev

In another terminal:

# Run the example workflow
jamjet run examples/basic_tool_flow

Hello World — Python

from jamjet import Workflow, tool
from pydantic import BaseModel

class SearchResult(BaseModel):
    summary: str
    sources: list[str]

@tool
async def web_search(query: str) -> SearchResult:
    # your implementation here
    ...

workflow = Workflow("research")

@workflow.state
class ResearchState(BaseModel):
    question: str
    result: SearchResult | None = None

@workflow.step
async def search(state: ResearchState) -> ResearchState:
    result = await web_search(query=state.question)
    return state.model_copy(update={"result": result})

@workflow.step
async def summarize(state: ResearchState) -> ResearchState:
    # model call here
    ...

Hello World — YAML

# workflow.yaml
workflow:
  id: research
  version: 0.1.0
  state_schema: schemas.ResearchState
  start: search

nodes:
  search:
    type: tool
    tool_ref: tools.web_search
    input:
      query: "{{ state.question }}"
    output_schema: schemas.SearchResult
    next: summarize

  summarize:
    type: model
    model: default_chat
    prompt: prompts/summarize.md
    output_schema: schemas.Summary
    next: end

jamjet validate workflow.yaml
jamjet run workflow.yaml --input '{"question": "What is JamJet?"}'

Connecting to an MCP Server

# agents.yaml
agents:
  researcher:
    model: default_chat
    mcp:
      servers:
        github:
          transport: http_sse
          url: https://mcp.github.com/v1
          auth:
            type: bearer
            token_env: GITHUB_TOKEN

# workflow.yaml (node using MCP tool)
nodes:
  search_github:
    type: mcp_tool
    server: github
    tool: search_code
    input:
      query: "{{ state.search_query }}"
    output_schema: schemas.SearchResults
    retry_policy: io_default

Delegating to an External Agent via A2A

nodes:
  code_review:
    type: a2a_task
    remote_agent: partner_reviewer   # defined in agents.yaml
    skill: security_review
    input:
      code: "{{ state.generated_code }}"
    stream: true
    timeout: 300s
    on_input_required: human_review

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Architecture

┌──────────────────────────────────────────────────────────┐
│                     Authoring Layer                       │
│              Python SDK  |  YAML  |  CLI                  │
├──────────────────────────────────────────────────────────┤
│                 Compilation / Validation                   │
│         Graph IR  |  Schema  |  Policy lint               │
├────────────────────────────┬─────────────────────────────┤
│      Rust Runtime Core     │      Protocol Layer          │
│  Scheduler  |  State SM    │  MCP Client  |  MCP Server   │
│  Event log  |  Snapshots   │  A2A Client  |  A2A Server   │
│  Workers    |  Timers      │  Protocol Adapter Framework  │
├────────────────────────────┴─────────────────────────────┤
│                      Runtime Services                      │
│  Model Adapters  |  Tool Execution  |  Memory/Retrieval   │
│  Policy Engine   |  Observability   |  Secret Management  │
├──────────────────────────────────────────────────────────┤
│                    Control Plane / APIs                    │
│        REST / gRPC  |  Agent Registry  |  Admin           │
├──────────────────────────────────────────────────────────┤
│                         Storage                           │
│           Postgres (production)  |  SQLite (local)        │
└──────────────────────────────────────────────────────────┘

Read more: Architecture Overview

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Documentation

Start here

Guide	Description
Quickstart	Get a workflow running in 10 minutes
Core Concepts	Agents, workflows, nodes, state, durability
Workflow Authoring	YAML and Python authoring guide
Python SDK	Full SDK reference
YAML Reference	Complete YAML spec

Connect to other systems

Guide	Description
MCP Integration	Connect to MCP servers, expose tools
A2A Integration	Delegate to and serve external agents
Agent Model	Agent Cards, lifecycle, autonomy levels
Human-in-the-Loop	Approval nodes, state editing, audit
Observability	Traces, replay, cost attribution, OTel GenAI
Deployment	Production deployment guide

Advanced & enterprise

Guide	Description
Security	Auth, secrets, RBAC, OAuth delegated agent auth
WASI Sandboxing	Sandboxed tool execution via Wasmtime
Eval Node	Evaluation as a workflow primitive
ANP Discovery	Decentralized agent discovery via DID

Architecture deep-dives

Document	Description
Architecture Overview	Full system architecture
Execution Model	State machine, node types, IR
State & Durability	Event sourcing, snapshotting, recovery
Agent Model	Agent-native runtime design
MCP Architecture	MCP client/server internals
A2A Architecture	A2A protocol internals
Protocol Adapters	Extensible protocol layer

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Roadmap

Phase	Status	Goal
0 — Architecture & RFCs	In progress	Design docs, RFCs, scaffolding
1 — Minimal Viable Runtime	Planned	Local durable execution, MCP client, agent cards
2 — Production Core	Planned	Distributed workers, MCP server, full A2A
3 — Developer Delight	Planned	Templates, eval harness, trace debugging
4 — Enterprise	Planned	Policy engine, tenant isolation, federation security
5 — Scale & Ecosystem	Planned	Go SDK, TypeScript SDK, hosted plane, agent marketplace

Track milestone progress in GitHub Issues and the project board.

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Contributing

We welcome contributions of all kinds — bug reports, feature requests, documentation, and code.

• Read CONTRIBUTING.md to get started
• Check open issues for good first issue tags
• RFCs for major changes: see docs/rfcs/
• Architecture decisions: see docs/adr/

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Community

• GitHub Discussions: github.com/jamjet-labs/jamjet/discussions

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License

Apache 2.0 — see LICENSE.