sandbase-harness
Open-source CMA-compatible agent runtime for any model, with MCP tools, sandboxed sessions, audit, replay, and a local console. Includes a native DeepSeek Harness bundle over stdio MCP.
Install / Use
claude mcp add sandbaseai -- npx -y github:sandbaseai/sandbase-harnessIf the server publishes to npm under a different name, use that package instead — check the repo README.
MCP Server
Model Context Protocol server
Quality Score
Category
Development & EngineeringSupported Platforms
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Skill content
View source on GitHubmanaged-agents
A local-first runtime for AI agents. Sessions, sandboxed tools, memory, credentials, audit trails, and a built-in Console — all running on your machine or in your own infrastructure.
git clone --branch v0.3.0 --depth 1 https://github.com/sandbaseai/sandbase-harness.git
cd sandbase-harness
npm ci
npm run build
mkdir ../my-agents && cd ../my-agents
node ../sandbase-harness/dist/index.js init
node ../sandbase-harness/dist/index.js start
# open http://127.0.0.1:3000/dashboard
Why
Agent SDKs handle the model loop. Production agents need more: persistent
sessions, tool governance, sandbox boundaries, credential handling, memory,
auditability, and a UI for humans to inspect what happened. managed-agents
is that runtime layer — not a visual workflow builder and not another model SDK.
Features
- Claude Managed Agents-style
/v1API and local Console - SQLite-backed agents, sessions, environments, credential vaults, memory stores, files, skills, and API keys — SQLite metadata by default
- local file/skill bytes stored in the workspace state directory
- Resumable Server-Sent Events for session replay and debugging
- One active model provider boundary configured through Settings V2
- Sandbox backends: local process, Docker (per-session containers), Kubernetes (kubectl exec/cp), self-hosted worker queue
- Settings V2: one workspace model vendor, loop engine, storage, memory, sandbox — with validation, form/JSON modes, and restart flow
- MCP toolsets, permission policies, built-in tools, and skill packages
- DeepSeek Harness bridge over MCP stdio for agents, sessions, streamed turns, artifacts, and cancellation
- TypeScript SDK at
managed-agents/sdk - Release gate:
npm run release:check
Screenshots
| Console overview | Settings | API reference |
| --- | --- | --- |
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Requirements
- Node.js 22+
- npm 10+
- A model provider API key (OpenAI, Anthropic, or OpenAI-compatible endpoint)
- Docker (optional, for Docker-backed sandboxes)
DeepSeek Harness
Run this project as a DSH plugin instead of treating dsh-plugin as discovery
metadata only. Install the bundle into a DSH profile, start managed-agents,
then boot that profile:
export MANAGED_AGENTS_URL=http://127.0.0.1:3000
dsh plugin --profile web add managed-agents
dsh web
The patch starts managed-agents-mcp over stdio. DSH can then list agents,
create and run sessions, inspect results and artifacts, and stop work through
native mcp__sandbase__* tools. See
examples/deepseek-harness for the full
tool list and authenticated-runtime configuration.
Quick Start
git clone --branch v0.3.0 --depth 1 https://github.com/sandbaseai/sandbase-harness.git
cd sandbase-harness
npm ci
npm run build
mkdir ../my-agents && cd ../my-agents
node ../sandbase-harness/dist/index.js init
node ../sandbase-harness/dist/index.js start
Open http://127.0.0.1:3000/dashboard, go to Settings > Models, paste your
API key, and you're running.
The unscoped managed-agents name on npm is not this project. Until an
official scoped package is announced in this repository, install only from the
tagged GitHub source release shown above. Do not run npx managed-agents or
npm install managed-agents.
For development from the latest main branch:
git clone https://github.com/sandbaseai/sandbase-harness.git
cd sandbase-harness && npm ci && npm run build
cd .. && mkdir my-agents-dev && cd my-agents-dev
node ../sandbase-harness/dist/index.js init
node ../sandbase-harness/dist/index.js start
Workspace Layout
my-agents/
├── agents/ # Seed agent definitions (YAML)
│ └── assistant.yaml
├── skills/ # Seed skill packages
│ └── example-skill/
│ └── SKILL.md
└── .managed-agents/ # Runtime state (gitignored)
├── config.yaml # Workspace configuration
├── data.db # SQLite metadata
├── logs/runtime.log
├── files/ # Uploaded file bytes
├── skills/ # Uploaded skill packages
├── snapshots/ # Session workspace snapshots
└── sandbox/ # Local session sandboxes
Configuration
.managed-agents/config.yaml:
model:
provider: openai
api_key: ${OPENAI_API_KEY}
storage:
metadata: { provider: sqlite, options: {} }
artifacts: { provider: local, options: { base_path: files } }
Agents pick concrete model IDs (gpt-4o, claude-sonnet-4-20250514,
openai/gpt-5.5). The workspace config only says how to reach the model
service.
For DeepSeek V4 Pro/Flash configuration, including maximum reasoning effort, see DeepSeek V4.
CLI
managed-agents init
managed-agents start [--host 127.0.0.1] [--port 3000]
managed-agents list
managed-agents reload
managed-agents chat <agent-id> --message "hello"
managed-agents template list | install <name> | create <name>
API Examples
Create an agent:
curl -X POST http://127.0.0.1:3000/v1/agents \
-H "Content-Type: application/json" \
-d '{
"name": "Incident commander",
"model": "gpt-4o",
"system": "You are an on-call incident commander.",
"tools": [{ "type": "agent_toolset_20260401" }]
}'
Create an environment (local sandbox):
curl -X POST http://127.0.0.1:3000/v1/environments \
-H "Content-Type: application/json" \
-d '{
"name": "Default local",
"config": { "hosting_type": "local", "sandbox_provider": "local" }
}'
Create a Docker-isolated environment:
curl -X POST http://127.0.0.1:3000/v1/environments \
-H "Content-Type: application/json" \
-d '{
"name": "Docker sandbox",
"config": {
"sandbox_provider": "docker",
"image": "node:22-slim",
"resources": { "memory": "1g", "cpu": 1 }
}
}'
Start a session:
curl -X POST http://127.0.0.1:3000/v1/sessions \
-H "Content-Type: application/json" \
-d '{
"agent": "agent_...",
"environment_id": "env_...",
"title": "Triage SENTRY-123"
}'
Send a message:
curl -X POST http://127.0.0.1:3000/v1/sessions/SESSION_ID/messages \
-H "Content-Type: application/json" \
-d '{ "content": "Investigate the alert." }'
Resume the event stream:
curl -N http://127.0.0.1:3000/v1/sessions/SESSION_ID/events/stream \
-H "Last-Event-ID: 42"
SDK
import { ManagedAgentsClient } from 'managed-agents/sdk';
const client = new ManagedAgentsClient({
baseUrl: 'http://127.0.0.1:3000',
});
const session = await client.sessions.create({
agent: 'agent_...',
environment_id: 'env_...',
});
for await (const event of client.sessions.chat(session.id, 'Hello')) {
if (event.type === 'agent.message_chunk') {
process.stdout.write(event.delta ?? '');
}
}
The /v1 API follows Claude Managed Agents resource shapes, so you can also
point the Anthropic SDK at the local runtime:
import Anthropic from '@anthropic-ai/sdk';
const client = new Anthropic({
apiKey: process.env.MANAGED_AGENTS_API_KEY ?? 'local-dev-key',
baseURL: 'http://127.0.0.1:3000',
});
const session = await client.beta.sessions.create({
agent: 'agent_...',
environment_id: 'env_...',
});
Authentication
Open by default. Authentication activates when at least one API key exists:
# Static key via environment
export MANAGED_AGENTS_API_KEY=sk-local-example
# Or create a managed key
curl -X POST http://127.0.0.1:3000/v1/api-keys \
-H "Content-Type: application/json" \
-d '{ "name": "Local Console" }'
Clients send Authorization: Bearer <key>.
Agent Definition
Agents are YAML files in agents/:
name: Incident commander
description: Triages alerts and coordinates response.
model: gpt-4o
system: |-
You are an on-call incident commander.
mcp_servers:
- name: sentry
type: url
url: https://mcp.sentry.dev/mcp
tools:
- type: agent_toolset_20260401
default_config:
permission_policy: { type: always_ask }
configs:
- name: bash
permission_policy: { type: always_ask }
- type: mcp_toolset
mcp_server_name: sentry
skills:
- type: custom
skill_id: skill_...
metadata:
template: incident-commander
Development
npm ci
npm run typecheck # src + tests
npm test # vitest
npm run build # runtime + console + SDK
npm run release:check # full local release gate
release:check runs typecheck, tests, both builds, npm pack --dry-run, CLI
init smoke, and examples/basic startup smoke.
Documentation
License
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