covenant

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Use when selecting architectural patterns before implementation, planning a phased roadmap, or scanning an existing codebase to generate .architecture/config.yml (discover mode). Triggers on "what patterns should we use", "architect our system", "plan our architecture", "assess our design", or when no config exists yet.
Changelog: Source: GitHub https://github.com/ppryde/pip-skills
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SKILL.md

---
name: covenant
description: Use when selecting architectural patterns before implementation, planning a phased roadmap, or scanning an existing codebase to generate .architecture/config.yml (discover mode). Triggers on "what patterns should we use", "architect our system", "plan our architecture", "assess our design", or when no config exists yet.
disable-model-invocation: true
---

# Covenant — Architecture Planning

This mode helps teams choose appropriate architectural patterns based on their project requirements,
then creates phased implementation plans with risk mitigation strategies.

## Prerequisites

Before running architecture planning:
1. Clear understanding of business requirements
2. Technical constraints identified (team size, timeline, existing systems)
3. Non-functional requirements documented (scale, performance, compliance)
4. Stakeholder priorities established

## Mode Selection

The mode operates differently based on arguments passed after `covenant`:

| Invocation | Mode | Output |
|---|---|---|
| `/puritan:covenant` | Full analysis | Pattern recommendations + implementation roadmap |
| `/puritan:covenant discover` | Discovery | Lightweight codebase scan → pattern detection → config generation |
| `/puritan:covenant patterns` | Pattern selection only | Recommended patterns with rationale |
| `/puritan:covenant roadmap` | Roadmap only | Phased implementation plan (assumes patterns chosen) |
| `/puritan:covenant assess` | Current state assessment | Gap analysis of existing architecture |
| `/puritan:covenant risks` | Risk analysis | Architecture risks and mitigation strategies |

## Discovery Mode

Discovery mode is a lightweight alternative to a full Inquisition audit. It reads directory structure and key signal files only — no deep file scanning, no subagents. Its purpose is to generate a working `.architecture/config.yml` so that Inquisition can run.

Invoke automatically when Inquisition detects a missing config, or directly with `/puritan:covenant discover`.

### Step D1: Scan Directory Structure

List top-level and second-level directories only:
```bash
find . -maxdepth 2 -type d \
  -not -path '*/.git/*' \
  -not -path '*/node_modules/*' \
  -not -path '*/vendor/*' \
  -not -path '*/__pycache__/*' \
  -not -path '*/.venv/*'
```

This is intentionally shallow — discovery mode does not read file contents.

### Step D2: Detect Pattern Signals

Read detection signatures from each available doctrine — do not use a hardcoded list:

1. List files in `${CLAUDE_SKILL_DIR}/../doctrines/` (skip `_template.md`)
2. For each doctrine file, read **only** its `## Detection Signatures` section
3. Score each doctrine against the directory scan from Step D1:
   - **Strong match** — 1+ file signal OR 3+ directory signals found
   - **Possible match** — 2 directory signals found, no file signals
   - **Weak / no match** — 0–1 directory signals and no file signals
4. Also check anti-signals: if any anti-signals are present, downgrade the match one level

This approach means new doctrines automatically participate in discovery with no changes to this skill.

Also check for key signal files (existence and location only — no file reading):
- `pyproject.toml`, `pom.xml`, `package.json`, `go.mod` → infer language
- `docker-compose.yml` present at root → containerisation / possible Microservices signal
- Single `Dockerfile` at repo root → monolith-leaning; multiple `Dockerfile`s in service subdirectories → Microservices-leaning

### Step D3: Present Findings for Confirmation

Present the detected patterns and proposed config to the user **before writing anything**:

```
Discovery complete — found N directories.

Detected patterns:
  ✓ DDD            — domain/aggregates/, domain/events/ found
  ✓ CQRS           — domain/commands/, queries/ found
  ✓ Event Sourcing — infrastructure/event_store/ found
  ? Hexagonal      — ports/ found but no adapters/ — include? [y/n]
  ✗ Microservices  — single service root, skipping

Proposed targets:
  DDD            → domain/, application/
  CQRS           → domain/commands/, infrastructure/projections/
  Event Sourcing → domain/aggregates/, infrastructure/event_store/

Does this look right? You can:
  1. Confirm and generate .architecture/config.yml
  2. Add a pattern I missed (which one?)
  3. Remove a pattern (which one?)
  4. Adjust targets for a specific pattern
```

Do not write the config until the user confirms. Support multiple rounds of adjustment before writing.

### Step D4: Generate Config

Once confirmed, write `.architecture/config.yml` with the agreed doctrines and targets. Always include a commented `exclude:` block with common defaults:

```yaml
# Generated by /puritan:covenant discover
# Review and adjust targets before running /puritan:inquisition

doctrines:
  - name: ddd
    enabled: true
    targets:
      - domain/
      - application/

  - name: cqrs
    enabled: true
    targets:
      - domain/commands/
      - infrastructure/projections/

layers:
  domain:
    - domain/
  application:
    - application/
  infrastructure:
    - infrastructure/

exclude:
  - "**/migrations/**"
  - "**/vendor/**"
  - "**/*.generated.*"
  - "**/node_modules/**"
```

After writing, inform the user:
> "Config written to `.architecture/config.yml`. Run `/puritan:inquisition` to begin the audit."

## When NOT to Use

- Simple CRUD app with no complex domain logic — just build it
- Solo developer prototyping — patterns add overhead without team coordination benefit
- Already committed to a tech stack and patterns — use Inquisition to audit compliance instead
- Need to fix a specific bug or implement a feature — this is strategic planning, not tactical work
- Evaluating a single library or tool choice — this is for architectural pattern selection

## Common Mistakes

| Mistake | Fix |
|---------|-----|
| Recommending patterns the team can't support | Always weight team expertise and size — 3 devs don't need Saga + CQRS + Event Sourcing |
| Planning without concrete requirements | Refuse to score patterns until business context, scale expectations, and team size are known |
| Treating the roadmap as immutable | Include abandon triggers and pivot options — plans change when reality arrives |
| Skipping the "Not Recommended" tier | Documenting why patterns were rejected is as valuable as recommending them |
| Front-loading all complexity into Phase 1 | Each phase should introduce at most one new pattern — build foundations first |
| Ignoring operational maturity | A team at DevOps Level 2 cannot operate Event Sourcing + CQRS + microservices simultaneously |

## Workflow

### Step 1: Gather Requirements

**Business Context:**
```
Questions to explore:
- What is the core business problem?
- Who are the users and stakeholders?
- What are the critical business processes?
- What are the compliance/regulatory requirements?
- What is the expected growth trajectory?
```

**Technical Context:**
```
Questions to explore:
- Current technology stack and constraints?
- Team size and expertise levels?
- Integration points with external systems?
- Performance and scalability requirements?
- Data consistency requirements?
```

**Operational Context:**
```
Questions to explore:
- Deployment environment (cloud/on-prem/hybrid)?
- DevOps maturity and practices?
- Monitoring and observability needs?
- Disaster recovery requirements?
- Maintenance windows and SLA requirements?
```

### Step 2: Analyze Pattern Fit

For each potential pattern, evaluate fit across dimensions:

```python
# Pseudo-code for pattern evaluation
def evaluate_pattern(pattern, requirements):
    score = PatternScore()

    # Complexity fit
    score.complexity = assess_complexity_match(
        pattern.complexity,
        requirements.team_expertise,
        requirements.timeline
    )

    # Scale fit
    score.scalability = assess_scale_match(
        pattern.scalability_characteristics,
        requirements.expected_load,
        requirements.growth_rate
    )

    # Consistency fit
    score.consistency = assess_consistency_match(
        pattern.consistency_model,
        requirements.data_consistency_needs,
        requirements.transaction_boundaries
    )

    # Integration fit
    score.integration = assess_integration_match(
        pattern.integration_patterns,
        requirements.external_systems,
        requirements.legacy_constraints
    )

    # Operational fit
    score.operations = assess_operational_match(
        pattern.operational_complexity,
        requirements.devops_maturity,
        requirements.monitoring_needs
    )

    return score.weighted_total()
```

### Step 3: Pattern Recommendation Matrix

Generate recommendations with scoring:

```
Pattern Analysis
================

Based on your requirements, here are the recommended patterns:

Primary Recommendations (80%+ fit):
------------------------------------
Domain-Driven Design (DDD)
  Complexity: High business logic complexity requires rich domain model
  Team: 8+ developers benefit from bounded context separation
  Scale: Supports your growth from 1K to 100K users
  Learning curve: 2-3 months for team proficiency
  Score: 85/100

Event Sourcing
  Audit: Complete audit trail for financial compliance
  Analytics: Event stream enables real-time analytics
  Recovery: Point-in-time recovery for disaster recovery
  Storage: 3-5x storage increase vs CRUD
  Complexity: Eventual consistency requires careful design
  Score: 82/100

Secondary Recommendations (60-79% fit):
----------------------------------------
CQRS
  Performance: Read/write separation for your 100:1 read ratio
  Scale: Independent scaling of read and write sides
  Complexity: Adds operational overhead
  Consistency: Eventual consistency between read/write models
  Score: 75/100

Consider Later (40-59% fit):
-----------------------------
Microservices
  Scale: Ultimate scalability and team independence
  Complexity: Overkill for current team size (8 developers)
  Operations: Requires mature DevOps (current: Level 2/5)
  Score: 45/100
  Revisit when: Team > 20, DevOps Level 4+

Not Recommended (<40% fit):
----------------------------
Serverless
  Latency: Cold starts incompatible with <100ms SLA
  Vendor lock-in: Conflicts with multi-cloud requirement
  Score: 25/100
```

### Step 4: Implementation Roadmap

Create phased implementation plan:

```markdown
# Implementation Roadmap

## Phase 0: Foundation (Weeks 1-2)
### Goals
- Set up development environment
- Establish coding standards
- Create project structure

### Deliverables
- [ ] Repository with CI/CD pipeline
- [ ] Development environment setup guide
- [ ] Architecture decision records (ADRs)
- [ ] Coding standards documentation

### Patterns Applied
- Basic project scaffolding only

### Risk Mitigation
- Low risk phase focused on setup
- Validate CI/CD early to prevent integration issues

## Phase 1: Core Domain (Weeks 3-6)
### Goals
- Implement core domain model using DDD
- Establish aggregate boundaries
- Create initial bounded contexts

### Deliverables
- [ ] Core aggregates: Account, Loan, Payment
- [ ] Domain events defined
- [ ] Unit tests (80% coverage)
- [ ] Basic API endpoints

### Patterns Applied
- **DDD**: Aggregates, Value Objects, Domain Events
- **Hexagonal Architecture**: Ports and Adapters

### Risk Mitigation
- Start with single bounded context
- Use in-memory event store initially
- Focus on domain logic, not infrastructure

## Phase 2: Event Sourcing (Weeks 7-10)
### Goals
- Replace CRUD with event sourcing
- Implement event store
- Add snapshot optimization

### Deliverables
- [ ] Event store implementation
- [ ] Event sourcing for core aggregates
- [ ] Snapshot strategy
- [ ] Event replay capability

### Patterns Applied
- **Event Sourcing**: Full implementation
- **Event Store**: PostgreSQL-based initially

### Risk Mitigation
- Parallel run with CRUD for 1 week
- Implement replay testing from day 1
- Keep events backward compatible

## Phase 3: Read Model Separation (Weeks 11-14)
### Goals
- Implement CQRS read models
- Add projection engine
- Optimize query performance

### Deliverables
- [ ] Projection engine
- [ ] Read models for all queries
- [ ] Performance benchmarks
- [ ] Monitoring dashboards

### Patterns Applied
- **CQRS**: Command/Query separation
- **Projections**: Async and sync projectors

### Risk Mitigation
- Start with synchronous projections
- Add async projections gradually
- Monitor projection lag closely

## Phase 4: Advanced Patterns (Weeks 15-18)
### Goals
- Add saga orchestration
- Implement process managers
- Add compensating transactions

### Deliverables
- [ ] Saga orchestrator
- [ ] Process managers for workflows
- [ ] Compensation handlers
- [ ] Integration tests

### Patterns Applied
- **Saga Pattern**: For distributed transactions
- **Process Managers**: For long-running workflows

### Risk Mitigation
- Simple sagas first (2-3 steps)
- Extensive failure scenario testing
- Manual intervention capabilities
```

### Step 5: Risk Assessment and Mitigation

Identify and plan for architecture risks:

```markdown
# Architecture Risk Register

## High Risk Items

### Risk: Event Store Becomes Single Point of Failure
**Probability**: Medium
**Impact**: Critical
**Mitigation Strategies**:
1. Implement database replication from day 1
2. Design for multi-region deployment
3. Create event store abstraction for vendor switch
4. Regular disaster recovery drills

### Risk: Team Lacks Event Sourcing Experience
**Probability**: High
**Impact**: High
**Mitigation Strategies**:
1. Bring in consultant for first 2 months
2. Pair programming on critical components
3. Extensive code review process
4. Create team playbooks and runbooks

### Risk: Eventual Consistency Confuses Users
**Probability**: Medium
**Impact**: Medium
**Mitigation Strategies**:
1. UI patterns for async operations (optimistic updates)
2. Clear user communication about processing
3. Synchronous projections for critical paths
4. SLA definitions for consistency windows

## Medium Risk Items

### Risk: Projection Lag Affects User Experience
**Probability**: Medium
**Impact**: Medium
**Mitigation Strategies**:
1. Monitor projection lag with alerts
2. Separate fast and slow projections
3. Cache warming strategies
4. Read-your-writes consistency patterns

### Risk: Event Schema Evolution Breaks Replay
**Probability**: Low
**Impact**: High
**Mitigation Strategies**:
1. Event versioning from day 1
2. Upcasting strategies documented
3. Regular replay testing in CI
4. Event schema registry

## Risk Decision Matrix

| Pattern | Abandon Triggers | Pivot Options |
|---|---|---|
| Event Sourcing | >5 sec replay time for 1M events | Event-sourced aggregates + CRUD projections |
| CQRS | Projection lag >30 seconds consistently | Synchronous projections only |
| DDD | Team cannot grasp bounded contexts after 3 months | Simplified layered architecture |
| Saga | >10% saga failure rate | Direct service calls with retries |
```

### Step 6: Success Metrics

Define measurable success criteria:

```markdown
# Success Metrics

## Technical Metrics
- Event replay time: <1 second per 100K events
- Projection lag: p99 < 500ms
- API response time: p95 < 200ms
- Test coverage: >80% for domain, >60% overall
- Deployment frequency: Daily
- Mean time to recovery: <30 minutes

## Business Metrics
- Feature delivery velocity: 20% improvement after month 3
- Production incidents: <2 per month
- Time to market for new features: 50% reduction
- System availability: 99.95%

## Team Metrics
- Architecture decision confidence: >7/10 in surveys
- Code review turnaround: <4 hours
- Onboarding time for new developers: <2 weeks
- Technical debt ratio: <20%
```

## Interactive Mode

When invoked in interactive mode, the skill guides through decisions:

```python
# Pseudo-code for interactive planning
def interactive_planning():
    print("Architecture Planning Assistant")

    # Step 1: Understand context
    context = gather_context_interactively()

    # Step 2: Pattern evaluation
    for pattern in relevant_patterns:
        score = evaluate_pattern(pattern, context)

        if score.has_concerns():
            response = ask_user([
                f"Accept {pattern.name} despite: {score.concerns}",
                f"Modify requirements to better fit {pattern.name}",
                f"Skip {pattern.name} for now",
                "Learn more about the concerns"
            ])

            handle_pattern_decision(response, pattern)

    # Step 3: Roadmap creation
    phases = generate_phases(selected_patterns)

    for phase in phases:
        display_phase(phase)

        response = ask_user([
            "Looks good, continue",
            "Adjust timeline",
            "Modify scope",
            "Add risk mitigation"
        ])

        adjust_phase(phase, response)

    # Step 4: Final review
    display_complete_plan()
    save_to_file("architecture-plan.md")
```

## Integration Points

### With Inquisition

See Inquisition SKILL.md Step 1 for the full `.architecture/config.yml` format
(doctrine list, layer mappings, excludes, strictness overrides).

```bash
# After planning, set up audit configuration
/puritan:covenant
# Creates: architecture-plan.md

# Generate audit configuration from plan
/puritan:inquisition --from-plan architecture-plan.md
# Creates: .architecture/config.yml

# Run initial audit to establish baseline
/puritan:inquisition full
# Creates: baseline-audit.json
```

### With CI/CD Pipeline
```yaml
# .github/workflows/architecture.yml
name: Architecture Governance

on: [push, pull_request]

jobs:
  plan-drift-check:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - name: Check architecture drift
        run: |
          puritan covenant assess --plan architecture-plan.md

  pattern-audit:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - name: Audit pattern implementation
        run: |
          /puritan:inquisition --config .architecture/config.yml
```

### With Documentation
```bash
# Generate architecture documentation
/puritan:covenant docs

# Creates:
# - docs/architecture/README.md
# - docs/architecture/patterns.md
# - docs/architecture/decisions/
# - docs/architecture/roadmap.md
```

## Output Formats

### Markdown Report (Default)
- Human-readable documentation
- Suitable for wiki/documentation sites
- Includes diagrams and tables

### JSON Export
```json
{
  "recommendations": [
    {
      "pattern": "event-sourcing",
      "score": 82,
      "pros": ["..."],
      "cons": ["..."],
      "prerequisites": ["..."]
    }
  ],
  "roadmap": {
    "phases": ["..."],
    "milestones": ["..."],
    "risks": ["..."]
  },
  "metrics": {}
}
```

### Mermaid Diagrams
```mermaid
graph LR
    Requirements --> Analysis
    Analysis --> Patterns[Pattern Selection]
    Patterns --> Roadmap
    Roadmap --> Phase1[Phase 1: Core Domain]
    Phase1 --> Phase2[Phase 2: Event Sourcing]
    Phase2 --> Phase3[Phase 3: CQRS]
    Phase3 --> Phase4[Phase 4: Advanced]

    Patterns -.->|Continuous| Audit[Inquisition Audit]
    Phase1 -.->|Validate| Audit
    Phase2 -.->|Validate| Audit
    Phase3 -.->|Validate| Audit
    Phase4 -.->|Validate| Audit
```

## Common Scenarios

### Scenario: Greenfield Project
```
Input: New fintech platform, 5 developers, 6 month timeline
Output: Start with DDD + Event Sourcing, delay CQRS until month 4
Rationale: Build solid foundation first, add complexity gradually
```

### Scenario: Modernizing Legacy System
```
Input: 10-year-old monolith, 20 developers, must maintain uptime
Output: Strangler fig with DDD contexts, event sourcing for new features
Rationale: Gradual migration reduces risk, events enable analytics
```

### Scenario: High-Scale Startup
```
Input: Rapid growth, 100x scale in 12 months, 3 developers
Output: Start simple with CQRS, prepare for event sourcing
Rationale: CQRS enables scaling, small team needs simple patterns
```

## FAQ

**Q: How long should planning take?**
A: 2-3 days for initial plan, revisit quarterly or at major milestones.

**Q: Can I change patterns mid-implementation?**
A: Yes, the roadmap includes pivot strategies and abandon triggers.

**Q: Should we implement all recommended patterns?**
A: No, start with primary recommendations and add others as needed.

**Q: How do we know if a pattern is failing?**
A: Monitor the success metrics and abandon triggers defined in the plan.

**Q: Can we skip phases in the roadmap?**
A: Not recommended — each phase builds on the previous foundation.

## Error Handling

### Missing Requirements
```
Error: Insufficient requirements for planning
Please provide:
  - Team size and expertise level
  - Expected scale and growth rate
  - Key non-functional requirements

Run: /puritan:covenant interview
```

### Conflicting Patterns
```
Warning: Pattern conflict detected
  Event Sourcing requires eventual consistency
  Your requirements specify strict consistency

Options:
  1. Accept eventual consistency with compensating UX
  2. Limit event sourcing to specific aggregates
  3. Choose alternative pattern (State-Based CRDT)
```

### Over-Architecture
```
Alert: Potential over-architecture detected
  Team size: 3 developers
  Recommended patterns: 5 (DDD, ES, CQRS, Saga, MS)

Recommendation: Start with maximum 2 patterns
Suggested: DDD + Event Sourcing only
Add others when team size > 8
```

## Exit Codes

- `0` - Planning completed successfully
- `1` - Missing required information
- `2` - No suitable patterns found
- `3` - Risk score exceeds threshold

## Voice

Deliver all findings in the voice of the Witchfinder —
formally uncompromising, dramatically precise, with a
knowing wink. Violations are heresies. Resolutions are
absolution. The codebase is the sanctum.

See persona.md for full vocabulary and tone guidance
if available, otherwise use the above as your guide.
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