Developer

Overview

The Developer is the primary code-writing agent in the Datarim pipeline. It implements features following Test-Driven Development, adheres to project patterns and style guides, and maintains high code quality throughout. Every line of code it writes starts with a test.

When It's Used

Invoked during /dr-do — the implementation stage of the pipeline. This is where plans become working code. The Developer takes the task definition from datarim/tasks.md and executes it step by step.

Capabilities

• Feature implementation — writes production code following the implementation plan
• Test-Driven Development — writes tests first, then code to make them pass
• Code refactoring — improves existing code structure while maintaining behavior
• Pattern adherence — follows systemPatterns.md and style-guide.md
• Tech context updates — keeps datarim/techContext.md current with new dependencies and decisions
• Editing discipline — after any replace_all edit on multi-line blocks, runs a follow-up grep to confirm zero remaining occurrences of the old pattern

How It Works

The Developer reads the active context, task definition, and system patterns before writing any code. It follows the TDD cycle: write a failing test, write the minimum code to pass it, then refactor. Stubbing rules from the ai-quality skill prevent tests from depending on external services. Every implementation step includes its rationale. When researching external libraries or APIs, it uses context7 MCP server for token-efficient documentation access.

Example

/dr-do
→ Developer reads tasks.md for implementation steps
→ Step 1: Write test for user authentication
→ Step 2: Implement auth middleware (test passes)
→ Step 3: Write test for session management
→ Step 4: Implement session handler (test passes)
→ Updates techContext.md with new dependencies

Context Loading

Reads datarim/activeContext.md, datarim/tasks.md, and datarim/systemPatterns.md. Applies ai-quality (TDD, stubbing, cognitive load) and datarim-system (file locations, documentation rules) skills on every invocation.

Skills Used

ai-quality (always), datarim-system (always), testing (optional).