Coder Agent

The Coder agent role, CodeDiff generation, and hunk-based editing.

The Coder Agent (⟠)

The Coder receives the TaskSpec produced by the Planner and generates precise code modifications.

What the Coder Does

1. Focused Implementation: Implements only the files and modifications specified in the TaskSpec. It is instructed not to introduce unsolicited refactors or unrelated changes.
2. Unified Diff Generation: Emits structured search/replace hunks (CodeDiff) with exact indentation and context lines.
3. Spec Adherence Check: Explains how each change satisfies the specific acceptance criteria defined by the Planner.
4. Handling Feedback: When the Reviewer rejects a draft or requests changes, the Coder receives the ReviewFeedback artifact and writes a targeted revision without starting from scratch.

Recommended Configuration

[agents.coder]
provider    = "anthropic"
model       = "claude-sonnet-4-20250514"
max_tokens  = 8192
temperature = 0.2