Phase: Design

Related source files: src/agentmux/workflow/handlers/designing.py, src/agentmux/workflow/phase_registry.py, src/agentmux/workflow/prompts.py Directory: 05_design/ | Optional: yes (activated when needs_design: true in plan.yaml)

The designer produces a detailed design document before implementation begins, used when the plan flags a need for a separate design handoff step.

Conditions

Activated when the planner sets needs_design: true in plan.yaml. Skipped otherwise; the pipeline moves directly from planning to implementing.

Role

designer agent — reads architecture, plan, and requirements, then produces design.md.

Artifacts

File	Writer	Reader	Format
designer_prompt.md	orchestrator	designer agent	Markdown prompt
design.md	designer agent	coder agents (via prompt injection)	Markdown

Transitions

From	Event	To
planning	plan_written with needs_design: true	designing
designing	design_written (on design.md submitted)	implementing

Notes

• The monitor shows this phase only when it is active (optional phase).
• The need for a design phase is typically flagged by the product-manager or architect during their respective phases. The planner then captures this signal as needs_design: true in plan.yaml, which drives the planning → designing transition.