DeepSeek Harness: Building and Extending AI Coding Agents Training Course

Introduction to DeepSeek Harness

• Defining DeepSeek Harness and its role in the ecosystem
• The design philosophy of “everything is a plugin”
• Overview of Web UI, CLI, and headless modes

Installation and Initial Setup

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

Model Configuration

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

Workspaces and Sessions

• Selecting and managing workspaces
• Utilizing the session composer and managing conversation flow
• Operations for reading, modifying, and generating files

Executing Coding Tasks

• Summarizing repositories and navigating codebases
• Running commands and assigning delegated tasks
• Managing and maintaining task plans

Permissions and Sandbox Environment

• Defining approval and permission policies
• Restricting file and command access
• Implementing 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
• Utilizing product providers for other coding agents
• Distributing workloads across sessions

The Cordis Plugin Model

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

Profiles, Bundles, and Configuration

• Layering profiles and bundles
• Modifying configurations via cordis.patch.yml
• Reviewing the initialized system 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 Points

• Handling session, agent, and capability events
• Managing waterfall and interceptor events
• Aligning behavior with specific extension points

Plugin Development

• Registering services on context keys
• Incorporating new tools and model adapters
• Distributing and discovering plugins

SDK, Headless Mode, and Automation

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