Claude Code is the interactive experience. The Claude Agent SDK is the programmable interface to the same agent loop, tools, and context management.
That distinction changes what we can build. Instead of opening a terminal and guiding one task by hand, we can place the agent inside a product, internal service, CI job, or document pipeline. Our application defines the goal and operational boundary. Claude decides which permitted actions to take, observes the results, and continues until the task is complete.
This is Part 2 of my Agentic Coding with Claude Code series. We will move from the concepts in Part 1 to the SDK primitives that make an agent work: query(), message streams, sessions, tools, and permissions.