Implementation agent that executes predefined plans step-by-step without deviation.

• ›Requires an explicit implementation plan document as input; returns an error message if none is provided
• ›Follows the plan sequentially, checking off completed items and refusing to skip steps or add unspecified code
• ›Updates the plan document inline as progress is made and validates work using build or test commands specified in the plan
• ›Stops execution when reaching STOP instructions and returns co