Phase: Implementation (Implementing + Fixing)

Related source files: src/agentmux/workflow/handlers/implementing.py, src/agentmux/workflow/handlers/fixing.py, src/agentmux/workflow/phase_registry.py, src/agentmux/workflow/prompts.py, src/agentmux/integrations/mcp_server.py Directory: 06_implementation/ (shared by implementing and fixing phases) | Optional: no (implementing); yes (fixing)

Implementation executes the execution plan produced by planning. Coders receive numbered prompt files mapped to scheduled plan units. After a failed review, the fixing sub-phase runs in the same directory.

Conditions

Implementing: entered after planning (or designing) completes. Fixing: entered after a review_failed event, as long as the review loop cap has not been reached.

Role

coder agent — receives a per-plan prompt and implements or fixes the assigned sub-plan. One coder is spawned per active plan in a parallel group; serial groups spawn one at a time.

Artifacts

File	Writer	Reader	Format
coder_prompt_<N>.md	orchestrator	coder agent N	Markdown
done_<N>	coder agent N (via submit_done)	orchestrator	empty marker
done_1	coder agent (fixing phase)	orchestrator	empty marker

Scheduling metadata (in state.json)

Key	Type	Purpose
implementation_group_total	int	Total number of scheduled execution groups
implementation_group_index	int	Current 1-based active group index
implementation_group_mode	serial/parallel	Active group execution mode
implementation_active_plan_ids	string[]	Active plan_<N> IDs for the current group
implementation_completed_group_ids	string[]	Ordered list of completed group_id values

Execution scheduling

• execution_plan.yaml (materialized from plan.yaml) must exist before implementation starts.
• Groups execute in order; within a group, serial dispatches one plan at a time, parallel dispatches all simultaneously.
• Each coder receives only its assigned plan's plan_<N>.md and tasks_<N>.md.

Fixing

After a review_fail event (and below the review loop cap), the pipeline re-enters 06_implementation/ for a fixing pass. The fix prompt is injected based on 07_review/fix_request.md (see 07_review.md). Fixing completion is signaled by writing done_1.

Transitions

From	Event	To
planning or designing	plan_written / design_written	implementing
implementing	implementation_completed	reviewing
reviewing	review_failed (below loop cap)	fixing
fixing	implementation_completed	reviewing
reviewing	review_failed (loop cap reached)	completing

Notes

• implementing and fixing share the same directory (06_implementation/); they differ only in how the prompt is built (plan vs. fix-request).
• Each coder receives only its assigned plan_<N>.md and tasks_<N>.md; coders for different sub-plans never see each other's prompts.
• See Artifact: state.json for the implementation scheduling fields (implementation_group_*).