Assembly LineBuild durable agents on the stack you choose.
Assembly Line makes the agent-as-a-folder model open and extensible across your models, state, storage, sandboxes, channels, connections, and deployment target.
Built on Pi, the world’s most efficient agent harness, Assembly Line helps agents keep working through pauses, failures, and restarts.
The run resumes after pauses and restarts.
A request arrives through Slack. Assembly Line records it, starts the agent, and streams progress back to the client. The agent opens a sandbox, calls tools, and saves checkpoints as it works.
A tool needs approval, so the run pauses. The user approves it hours later. Assembly Line resumes the model loop once, runs the approved action, and returns the result to the same conversation.
- 01Request accepted
- 02Progress persisted
- 03Approval requested
- 04Run resumed
- 05Result delivered
Start with a folder.
The scaffold creates instructions, an agent definition, gateway settings, and an example tool. Add capabilities only when the product needs them.
npx assemblyline-agents init my-agent
npx assemblyline-agents validate my-agent
npx assemblyline-agents run my-agent --message "hello"Change the infrastructure without rebuilding the agent.
Models, hosts, sandboxes, databases, and providers will change. Assembly Line keeps the agent in portable files and makes each infrastructure layer replaceable.
The runtime handles durable runs, approvals, channels, and recovery, so the agent stays small and readable.
Understand the whole agent at a glance.
An Assembly Line agent uses ordinary TypeScript, Markdown, and configuration files. A minimal agent needs only instructions.md and agent.ts. Add other files as the product grows.
agent/
instructions.md
agent.ts
context.ts
gateway.ts
tools/
skills/
channels/
automations/
connections/
sandbox/
subagents/
evals/Keep work through disconnects and restarts.
Assembly Line saves run events, checkpoints, tool calls, approvals, questions, and delivery state. Streams reconnect from the event log, and the record preserves failed work after the process ends.
- ↳Persisted run events and checkpoints
- ↳Reattachable event streams
- ↳Durable tool steps and replay
- ↳Human approval and question pauses
- ↳Cancellation, suspension, and resume controls
- ↳Recovery workers for interrupted runs
Change providers without changing the agent.
Provider registries keep state, blobs, sandboxes, deployment targets, channels, and connections independent of the hosting platform.
- ↳Portable Node.js runtime bundle
- ↳Local, Railway, and generic VPS deployment
- ↳Postgres state and S3-compatible artifact storage
- ↳Daytona, E2B, Modal, Docker, and other sandbox adapters
- ↳Extensible provider and plugin contracts
The parts agents need in production.
Define typed tools, classify effects, require approvals, connect channels, run scheduled work, delegate bounded tasks, evaluate changes, and inspect cost — without hiding those capabilities outside the project.
- ↳Tools and approvals
- ↳Channels and connections
- ↳Automations
- ↳Sandboxes and subagents
- ↳Evaluations
- ↳Operations and cost
What to know before you start.
01Is Assembly Line a framework or a runtime?＋
Both. The framework defines the folder and build contracts. The runtime provides durable execution, streaming, tools, approvals, channels, connections, scheduling, and operator controls.
02Does it require a particular model provider?＋
No. Its harness contract keeps stored state independent of provider-specific engine state.
03Do I need every file in the agent folder?＋
No. A minimal agent needs instructions.md and agent.ts. Add other directories only when needed.
04Where can I deploy it?＋
Assembly Line runs locally and deploys to Railway or a generic VPS. Additional deployment adapters can be added without changing the agent.