Answer in brief
Understand DeepSeek Harness's Plugin-first design through replaceable capabilities, event extension points, and configuration layers.
Many products treat Plugins as peripheral add-ons while the core workflow remains irreplaceable. The official architecture of DeepSeek Harness instead places model adaptation, Tool registration, Session logging, and the Agent Loop into the same Cordis Plugin tree.
Replaceable Capabilities
When the file system, Shell, Sandbox, or model Provider are all registered through clean seams, swapping a Provider no longer requires replicating the entire product. This makes experimentation faster and pushes design responsibility out to the capability boundaries.
Events and Persistent Facts
Session Events record facts that must survive reloads; Agent Events handle the task currently in progress; Capability Events extend Tools or policies without depending directly on the Loop. Choosing the right extension point matters more than deciding “where to insert a piece of code.”
The Cost of an Ecosystem
Everything-is-a-plugin also means the supply chain and compatibility become core concerns. A Plugin may hold file, Shell, network, and credential permissions. A mature ecosystem cannot just count numbers; it must also document provenance, compatible versions, the permission surface, and the uninstall path.