Loom

Build stateful agents with a stable Agent + Runtime + Capability SDK.

Loom's 0.8.0 public contract is centered on the runtime kernel:

Agent
    + Runtime
    + Capability
    -> Run / Session
    -> RuntimeTask / RuntimeSignal

Application developers should start from Agent(...), select a Model, choose a Runtime profile, and declare tool/MCP/skill access through Capability.

Quick Start

import asyncio

from loom import Agent, Capability, Model, Runtime


async def main():
    agent = Agent(
        model=Model.anthropic("claude-sonnet-4"),
        instructions="You are a concise coding assistant.",
        capabilities=[
            Capability.files(read_only=True),
            Capability.web(),
        ],
        runtime=Runtime.sdk(),
    )

    result = await agent.run("Summarize this repository")
    print(result.output)


asyncio.run(main())

Public Shape

Agent(...)
    ├── run(prompt_or_task, context=RunContext(...))
    ├── stream(prompt_or_task, context=RunContext(...))
    ├── receive(event_or_signal, adapter=SignalAdapter(...))
    └── session(SessionConfig(...)) -> Session
                                      ├── start(...)
                                      ├── run(...)
                                      ├── stream(...)
                                      └── receive(...)

Main Imports

from loom import (
    Agent,
    Capability,
    Model,
    Runtime,
    RuntimeSignal,
    RuntimeTask,
    SessionConfig,
    SignalAdapter,
    RunContext,
    tool,
)

Use from loom.config import ... only for advanced configuration internals. AgentConfig, ModelRef, GenerationConfig, and create_agent() remain available through 0.8.x, but they are no longer the recommended starting point for new applications.

Runtime Concepts

Concept	Meaning
Agent	User-side intelligent agent specification
Runtime	Execution mechanism composition
Run / Session	Single execution / multi-run state boundary
RuntimeTask	Structured work request
RuntimeSignal	External input from gateways, cron, heartbeat, or apps
AttentionPolicy	Decides whether a signal is observed, queued, or interrupts
ContextProtocol	Context partitioning, rendering, compaction, renewal
ContinuityPolicy	Continuation after reset or compaction
Harness	Long-task execution strategy
QualityGate	Acceptance criteria and PASS/FAIL evaluation
DelegationPolicy	Subtask and sub-agent dispatch boundary
Capability	Tools, Toolsets, MCP, skills, and future ability sources
GovernancePolicy	Permission, veto, rate limit, read-only/destructive checks
FeedbackPolicy	Runtime feedback collection and evolution input

Navigation

I want to...	Start here
Get running quickly	Getting Started
Understand the public API	API Reference
Configure providers and env vars	Providers
Understand runtime internals	Runtime
Copy app-ready patterns	Cookbook
Understand architecture	Architecture
Compare against other frameworks	Comparison
Read historical design material	hernss-agent-framework.md

Version Policy

• 0.8.0 is the public API stabilization line for the SDK runtime kernel.
• 0.8.x keeps compatibility exports for existing applications.
• loom.compat.v0 is the explicit legacy compatibility namespace.
• 0.9.0 removes the legacy compatibility surface.

Historical Note

If you see AgentRuntime, SessionHandle, TaskHandle, RunHandle, or create_agent(AgentConfig(...)) presented as the main path, treat that page as older material. The supported 0.8.x application path is Agent + Model + Runtime/Capability + Session/RunContext.