# Build a coding assistant

> Build a useful coding assistant from one model call to a durable, tool-using Harness session with a workspace, sandboxed processes, and your choice of interface.

- Path: `Getting Started > Build a coding assistant`
- Human: https://looprig.com/docs/start/choose-a-path
- Machine index: https://looprig.com/llms.txt

This tutorial builds a coding assistant that can answer a question, inspect files through declared tools, keep a resumable session, work inside a session-owned directory, and confine process tools. The final runtime is independent of its presentation, so you can keep the CLI or attach the TUI, Web UI, ACP, or MCP later.

## What you will build

```mermaid
%%{init: {"theme":"dark"}}%%
flowchart LR
  U[CLI input] --> S[Harness Session]
  S --> L[Loop]
  L --> I[Inference Client]
  L --> T[Read-only Tools]
  S --> J[Session Store]
  S --> W[Workspace]
  T --> X[Sandboxed Process]
  S --> E[Events]
  E --> U
```

The tutorial uses one project named `looprig-coding-assistant`. Each page adds one boundary without changing the responsibilities added earlier.

## How the pieces fit

| Module | Responsibility in the assistant | Added when |
| --- | --- | --- |
| Core and Inference | Messages, model identity, requests, responses, and streaming | First model call |
| LLM | OpenAI, Anthropic, Ollama, and other provider clients | Model configuration |
| Harness | Loop, Rig, Session, commands, events, tools, and shutdown | Agent runtime |
| Tools | Read, search, edit, process, interaction, and delegation definitions | Tool registration |
| Fsstore and Storage | Durable session history and workspace snapshots | Persistence |
| Sandbox | Native confinement for child processes | Process execution |
| TUI or Client | Terminal and framework-neutral browser presentation | Interface selection |

You do not need to adopt the full stack at once. Inference is useful by itself. Harness becomes useful when you need a live agent runtime. Storage, Sandbox, protocols, workflows, and interfaces remain optional composition boundaries.

## Tutorial path

1. [Create the Go project](/docs/start/installation.md).
2. [Connect a model with Inference](/docs/start/model-call.md).
3. [Run the agent with Harness](/docs/start/first-run.md).
4. [Add read-only tools and gates](/docs/start/tools-and-gates.md).
5. [Persist and restore sessions](/docs/start/sessions.md).
6. [Add a session workspace](/docs/start/workspaces.md).
7. [Sandbox process tools](/docs/start/sandbox-and-interfaces.md).
8. [Run the coding assistant CLI](/docs/start/run-cli.md).
9. [Choose an interface and extend the agent](/docs/start/next-steps.md).

Start with the project directory. You will have a working model call before introducing Harness.