DeepSeek Harness “Everything Is a Plugin”: choose the right Cordis extension seam

DeepSeek Harness “Everything Is a Plugin”: choose the right Cordis extension seam

Quick answer

DeepSeek Harness does not treat plugins as optional add-ons around a privileged core. At the source snapshot checked for this guide—default branch master, commit 141eb6fef83422698aef7a981029e843e8161534—the model adapter, tool registry, session log, and agent loop are all Cordis plugins. A plugin contributes services, typed events, and reversible effects to a shared context; profiles and bundles compose those plugins into a runnable product.

The practical rule is:

use a service for a capability another plugin calls directly;