DeepSeek Harness: Building and Extending AI Coding Agents Training Course

Overview of DeepSeek Harness

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

Setup and Initial Execution

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

Configuring Models

• Setting the DeepSeek API key
• Choosing and switching between models
• Integrating OpenAI-compatible endpoints

Managing Workspaces and Sessions

• Selecting and switching active workspaces
• Using the session composer and managing conversation flow
• Reading, modifying, and generating files

Executing Coding Tasks

• Summarizing repositories and exploring codebases
• Running commands and delegating tasks
• Maintaining a structured task plan

Permissions and Sandboxing

• Implementing approval and permission policies
• Restricting file and command access
• Managing local and remote sandbox environments

Native Tools and Integrations

• Using 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 external coding agents
• Delegating work across active sessions

The Cordis Plugin Framework

• Defining plugins as services, events, and effects
• Understanding the shared context and lifecycle
• The rationale behind a non-privileged core

Profiles, Bundles, and Settings

• Managing profiles and bundle layering
• Modifying configuration via cordis.patch.yml
• Reviewing the initialized component tree

Internal Subsystems

• The append-only session logging system
• Assembling system prompts and tool schemas
• Understanding the agent loop and turn processing

Events and Extension Capabilities

• Handling session, agent, and capability events
• Utilizing waterfall and interceptor events
• Aligning behaviors with specific extension points

Plugin Development

• Registering services using context keys
• Implementing 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
• Implementing CLI and headless automation