DeepSeek Harness: Building and Extending AI Coding Agents Training Course

Introduction to DeepSeek Harness

• Defining DeepSeek Harness and its role in the ecosystem
• The "everything is a plugin" design philosophy
• Web UI, CLI, and headless operating modes

Setup and Initial Launch

• Node.js prerequisites and package installation
• Starting the Web UI using npx
• Compiling and running from source code

Model Configuration

• Configuring the DeepSeek API key
• Choosing and toggling between different models
• Integrating OpenAI-compatible endpoints

Workspaces and Session Management

• Selecting and navigating between workspaces
• Understanding the session composer and conversation flow
• Reading, modifying, and creating files

Executing Coding Tasks

• Summarizing repositories and traversing codebases
• Executing commands and offloading tasks
• Maintaining an organized task plan

Permissions and Sandboxing

• Defining approval and permission policies
• Restricting access to files and commands
• Utilizing local and remote sandbox backends

Native Tools and Integrations

• Filesystem, terminal, and shell utilities
• Support for the Model Context Protocol
• Integration with the Language Server Protocol

Subagents and Task Delegation

• Creating and forking subagents
• Product providers for alternative coding agents
• Distributing workloads across sessions

The Cordis Plugin Model

• Viewing plugins as services, events, and effects
• Shared context and lifecycle management
• The absence of a privileged core system

Profiles, Bundles, and Settings

• Layering profiles and bundles
• Modifying configuration via cordis.patch.yml
• Reviewing the initialized component tree

Core Subsystems

• The append-only session logging system
• Assembly of system prompts and tool schemas
• Agent loop mechanics and turn progression

Events and Extension Hooks

• Session, agent, and capability-related events
• Waterfall and interceptor event patterns
• Aligning behaviors with specific extension points

Plugin Development

• Registering services under context keys
• Implementing new tools and model adapters
• Publishing and discovering available plugins

SDK, Headless Mode, and Automation

• Controlling the harness from external processes
• Using the TypeScript and Python SDKs
• Automating workflows via CLI and headless mode