Create Implementation Plan

Generate a detailed implementation plan with architecture overview and task breakdown.

Full workflow guide: docs/development/spec-driven-workflow.md

Prerequisites

• Feature spec exists at specs/NNN-feature-name/spec.yaml
• Research completed at specs/NNN-feature-name/research.yaml
• On the feature branch feat/NNN-feature-name

GATE CHECK (Mandatory)

Before starting planning, verify:

1. Read research.yaml and check the openQuestions field
2. If any items have resolved: false: STOP and inform user:

   Cannot proceed with planning. Open questions in research.yaml must be resolved first. Please complete research or mark questions as resolved.

3. Only proceed when all open questions have resolved: true or the openQuestions array is empty

Workflow

1. Review Spec & Research

Read both YAML source files to understand:

• Requirements and success criteria (spec.yaml)
• Technical decisions and constraints (research.yaml)
• Affected areas and dependencies

2. Design Architecture

Create high-level architecture:

• Component diagram (ASCII or Mermaid)
• Data flow between components
• Integration points with existing code

3. Define Implementation Phases (MANDATORY TDD STRUCTURE)

CRITICAL: Plans MUST follow Test-Driven Development (TDD) with RED-GREEN-REFACTOR cycles.

Break implementation into phases following TDD:

• Foundational phases (no tests): Build pipeline, TypeSpec models, configuration
• TDD Cycle phases: For each layer (Domain, Application, Infrastructure):
  • RED: Write failing tests first
  • GREEN: Write minimal code to pass tests
  • REFACTOR: Clean up while keeping tests green
• Each phase should be independently testable
• Order by dependencies (foundational first)
• Identify parallelizable work

4. Identify Files to Create/Modify

For each phase, list:

• New files: Path and purpose
• Modified files: Path and changes needed

5. Define Testing Strategy (TDD: Tests FIRST)

MANDATORY: Define what tests to write FIRST in each TDD cycle.

For each layer, specify tests to write BEFORE implementation:

• Unit tests (RED first): Domain logic, use cases with mocks
• Integration tests (RED first): Repositories, migrations, database operations
• E2E tests (RED first): User-facing features, CLI commands

Each TDD phase MUST follow:

1. RED: Write failing test
2. GREEN: Write minimal code to pass
3. REFACTOR: Improve code while keeping tests green

6. Document Risks & Rollback

• Identify potential risks
• Define mitigation strategies
• Document rollback plan if needed

7. Create Task Breakdown

Convert phases into actionable tasks:

• Each task should be completable in one session
• Mark parallelizable tasks with [P]
• Include acceptance checklist

8. Write plan.yaml and tasks.yaml

Write structured YAML source files (the source of truth):

• specs/NNN-feature-name/plan.yaml - Architecture and strategy
• specs/NNN-feature-name/tasks.yaml - Detailed task list

NO DUPLICATION between files:

• plan.yaml content: Architecture overview, implementation strategy walkthrough, file tables, testing strategy, risks. NO task-by-task listing (that's in tasks.yaml).
• tasks.yaml content: Brief summary (scope + counts) and acceptance checklist ONLY. Individual task details live exclusively in the tasks[] structured array.
• tasks.yaml tasks[]: The single source of truth for all task details (title, description, TDD cycles, acceptance criteria, dependencies, effort).

9. Update Status Fields & feature.yaml

CRITICAL: Update status in YAML source files AND feature.yaml:

Update the status field in each YAML source file:

• spec.yaml → set status.phase: planning (was research)
• research.yaml → set status.phase: planning (was research)
• plan.yaml → set status.phase: planning, status.updatedAt: <today's date>
• tasks.yaml → set status.phase: implementation, status.updatedAt: <today's date>

Update feature.yaml:

# specs/NNN-feature-name/feature.yaml
feature:
  lifecycle: 'implementation' # Update from "planning"

status:
  phase: 'ready-to-implement' # Update from "planning"
  progress:
    total: <count from tasks.yaml> # Count tasks[].id entries
  lastUpdated: '<timestamp>'
  lastUpdatedBy: 'shep-kit:plan'

checkpoints:
  # Add new checkpoint:
  - phase: 'plan-complete'
    completedAt: '<timestamp>'
    completedBy: 'shep-kit:plan'

Count tasks from the YAML array (not markdown grep):

# Count entries in tasks.yaml tasks[] array
yq '.tasks | length' specs/NNN-feature-name/tasks.yaml

Reference: docs/development/feature-yaml-protocol.md

10. Update data-model.md (if needed)

If feature requires entity changes:

• Define new entities with TypeSpec structure
• Document modifications to existing entities
• List new enums or value objects

11. Commit

git add specs/NNN-feature-name/
git commit -m "feat(specs): add NNN-feature-name implementation plan"

12. Next Steps

Inform the user:

Plan complete for NNN-feature-name! Ready to implement. Use tasks.yaml to track progress.

⚠️ MANDATORY TDD: Each phase follows RED-GREEN-REFACTOR:

1. RED: Write failing test FIRST
2. GREEN: Write minimal code to pass
3. REFACTOR: Improve while keeping tests green

MANDATORY Phase Completion Workflow:

After EACH phase:

1. Update tasks.yaml status fields FREQUENTLY (as you complete items, not at the end!)
2. Commit and push: git add . && git commit -m "feat: complete phase N" && git push
3. Watch CI: gh run watch --exit-status
4. If CI fails: Fix → Commit → Push → Watch again (LOOP until green)
5. Only proceed to next phase after CI passes

IMPORTANT: After implementation, update all spec file statuses to "Complete"

Key Principles

• Gate enforcement: Never skip the open questions check
• TDD MANDATORY: Plans MUST follow RED-GREEN-REFACTOR cycles for all implementation phases
• Tests FIRST: Every TDD phase starts with failing tests, never implementation first
• Incremental: Each phase produces working, tested code
• Parallel-aware: Mark independent tasks for concurrent execution
• Reversible: Always have a rollback plan
• Status tracking: Always update Phase fields before committing

Template Locations

• Plan: .claude/skills/shep-kit-new-feature/templates/plan.yaml
• Tasks: .claude/skills/shep-kit-new-feature/templates/tasks.yaml
• Data Model: .claude/skills/shep-kit-new-feature/templates/data-model.md

Example

See: .claude/skills/shep-kit-plan/examples/sample-plan.md