architecture-design

name	architecture-design
description	[Architecture] Use when designing solution architecture across backend, frontend, deployment, monitoring, testing, and code quality.

Codex compatibility note:

• Invoke repository skills with $skill-name in Codex; this mirrored copy rewrites legacy Claude /skill-name references.
• Task tracker mandate: BEFORE executing any workflow or skill step, create/update task tracking for all steps and keep it synchronized as progress changes.
• User-question prompts mean to ask the user directly in Codex.
• Ignore Claude-specific mode-switch instructions when they appear.
• Strict execution contract: when a user explicitly invokes a skill, execute that skill protocol as written.
• Subagent authorization: when a skill is user-invoked or AI-detected and its protocol requires subagents, that skill activation authorizes use of the required spawn_agent subagent(s) for that task.
• Do not skip, reorder, or merge protocol steps unless the user explicitly approves the deviation first.
• For workflow skills, execute each listed child-skill step explicitly and report step-by-step evidence.
• If a required step/tool cannot run in this environment, stop and ask the user before adapting.

Codex Project-Reference Loading (No Hooks)

Codex does not receive Claude hook-based doc injection. When coding, planning, debugging, testing, or reviewing, open project docs explicitly using this routing.

Always read:

• docs/project-config.json (project-specific paths, commands, modules, and workflow/test settings)
• docs/project-reference/docs-index-reference.md (routes to the full docs/project-reference/* catalog)
• docs/project-reference/lessons.md (always-on guardrails and anti-patterns)

Situation-based docs:

• Backend/CQRS/API/domain/entity changes: backend-patterns-reference.md, domain-entities-reference.md, project-structure-reference.md
• Frontend/UI/styling/design-system: frontend-patterns-reference.md, scss-styling-guide.md, design-system/README.md
• Spec/test-case planning or TC mapping: feature-docs-reference.md
• Integration test implementation/review: integration-test-reference.md
• E2E test implementation/review: e2e-test-reference.md
• Code review/audit work: code-review-rules.md plus domain docs above based on changed files

Do not read all docs blindly. Start from docs-index-reference.md, then open only relevant files for the task.

[BLOCKING] Execute skill steps in declared order. NEVER skip, reorder, or merge steps without explicit user approval. [BLOCKING] Before each step or sub-skill call, update task tracking: set in_progress when step starts, set completed when step ends. [BLOCKING] Every completed/skipped step MUST include brief evidence or explicit skip reason. [BLOCKING] If Task tools are unavailable, create and maintain an equivalent step-by-step plan tracker with the same status transitions.

Quick Summary

Goal: Act as a solution architect — research, critically analyze, and recommend the complete technical architecture for a project or feature. Cover ALL architecture concerns: backend, frontend, design patterns, library ecosystem, testing strategy, CI/CD, deployment, monitoring, code quality, and dependency management. Produce a comprehensive comparison report with actionable recommendations.

Workflow (12 steps):

1. Load Context — Read domain model, tech stack, business evaluation, refined PBI
2. Derive Architecture Requirements — Map business/domain complexity to architecture constraints
3. Backend Architecture — Research top 3 backend architecture styles + design patterns
4. Frontend Architecture — Research top 3 frontend architecture styles + design patterns
5. Library Ecosystem Research — Best-practice libraries per concern (validation, caching, logging, utils, etc.)
6. Testing Architecture — Unit, integration, E2E, performance testing frameworks + strategy
7. CI/CD & Deployment — Pipeline design, containerization, orchestration, IaC
8. Observability & Monitoring — Logging, metrics, tracing, alerting stack
9. Code Quality & Clean Code — Linters, analyzers, formatters, enforcement tooling
10. Dependency Risk Assessment — Package health, obsolescence risk, maintenance cost
11. Generate Report — Full architecture decision report with all recommendations
12. User Validation — Present findings, ask 8-12 questions, confirm all decisions

Key Rules:

• MANDATORY IMPORTANT MUST ATTENTION research minimum 3 options per architecture concern with web evidence
• MANDATORY IMPORTANT MUST ATTENTION include confidence % with evidence for every recommendation
• MANDATORY IMPORTANT MUST ATTENTION run user validation interview at end (never skip)
• Delegate to solution-architect agent for complex architecture decisions
• All claims must cite sources (URL, benchmark, case study, or codebase evidence)
• Base every recommendation on evidence, never on familiarity alone

Be skeptical. Apply critical thinking, sequential thinking. Every claim needs traced proof, confidence percentages (Idea should be more than 80%).

---

Step 1: Load Context

Read artifacts from prior workflow steps (search in plans/ and team-artifacts/):

• Domain model / ERD (complexity, bounded contexts, aggregate count)
• Tech stack decisions (confirmed languages, frameworks, databases)
• Business evaluation (scale, constraints, compliance)
• Refined PBI (scope, acceptance criteria)
• Discovery interview (team skills, experience level)

Extract and summarize:

Signal	Value	Source
Bounded contexts	...	domain model
Aggregate count	...	domain model
Cross-context events	...	domain model
Confirmed tech stack	...	tech stack phase
Expected scale	...	business eval
Team architecture exp.	...	discovery
Compliance requirements	...	business eval
Real-time needs	Yes/No	refined PBI
Integration complexity	Low/Med/High	domain model
Deployment target	...	business eval

---

Step 2: Derive Architecture Requirements

Map signals to architecture constraints:

Signal	Architecture Requirement	Priority
Many bounded contexts	Clear module boundaries, context isolation	Must
High scale	Horizontal scaling, stateless services, caching strategy	Must
Complex domain	Rich domain model, separation of domain from infra	Must
Cross-context events	Event-driven communication, eventual consistency	Must
Small team	Low ceremony, fewer layers, convention over configuration	Should
Compliance	Audit trail, immutable events, access control layers	Must
Real-time	Event sourcing or pub/sub, WebSocket/SSE support	Should
High integration complexity	Anti-corruption layers, adapter pattern, API gateway	Should

MANDATORY IMPORTANT MUST ATTENTION validate derived requirements with user via a direct user question before proceeding.

---

Step 3: Backend Architecture

3A: Architecture Styles

WebSearch top 3 backend architecture styles. Candidates:

Style	Best For	Research Focus
Clean Architecture	Complex domains, long-lived projects	Dependency rule, testability, flexibility
Hexagonal (Ports+Adapt)	Integration-heavy, multiple I/O adapters	Port contracts, adapter isolation
Vertical Slice	Feature-focused teams, rapid delivery	Slice isolation, code locality
Modular Monolith	Starting simple, eventual decomposition	Module boundaries, migration path
Microservices	Large teams, independent deployment	Service boundaries, operational overhead
CQRS + Event Sourcing	Audit-heavy, complex queries	Read/write separation, event store
Layered (N-Tier)	Simple CRUD, small teams	Layer responsibilities, coupling risk

3B: Backend Design Patterns

Evaluate applicability per layer:

Pattern	Layer	When to Apply
Repository	Data Access	Abstract data store, enable testing
CQRS	Application	Separate read/write models, complex queries
Mediator	Application	Decouple handlers from controllers
Strategy	Domain/App	Multiple interchangeable algorithms
Observer/Events	Domain	Cross-aggregate side effects
Factory	Domain	Complex object creation with invariants
Decorator	Cross-cutting	Add behavior without modifying (logging, caching)
Adapter	Infrastructure	Isolate external dependencies
Specification	Domain	Composable business rules, complex filtering
Unit of Work	Data Access	Transaction management across repositories
Saga/Orchestr.	Cross-service	Distributed transactions, compensating actions
Outbox	Messaging	Reliable event publishing with DB transactions
Circuit Breaker	Infrastructure	External service resilience

For each recommended pattern, document: Apply to, Why, Example, Risk if skipped.

---

Step 4: Frontend Architecture

4A: Architecture Styles

WebSearch top 3 frontend architecture styles. Candidates:

Style	Best For	Research Focus
MVVM	Data-binding heavy, forms-over-data apps	ViewModel responsibility, two-way binding
MVC	Server-rendered, traditional web apps	Controller routing, view separation
Component Architecture	Modern SPA (React, Angular, Vue)	Component isolation, props/events, reuse
Reactive Store (Redux)	Complex state, multi-component sync	Single source of truth, immutable state
Signal-based Reactivity	Fine-grained reactivity (Angular 19, Solid)	Granular updates, no zone.js overhead
Micro Frontends	Multiple teams, independent deployment	Module federation, routing, shared state
Feature-based Modules	Large monolith SPA, lazy loading	Feature boundaries, route-level splitting
Server Components (RSC)	SEO, initial load performance	Server/client boundary, streaming

4B: Frontend Design Patterns

Pattern	Layer	When to Apply
Container/Presentational	Component	Separate logic from UI rendering
Reactive Store	State	Centralized state, cross-component communication
Facade Service	Service	Simplify complex API interactions
Adapter/Mapper	Data	Transform API response to view model
Observer (RxJS)	Async	Event streams, real-time data, debounce/throttle
Strategy (renderers)	UI	Conditional rendering strategies per entity type
Composite (components)	UI	Tree structures, recursive components
Command (undo/redo)	UX	Form wizards, canvas editors, undoable actions
Lazy Loading	Performance	Route/module-level code splitting
Virtual Scrolling	Performance	Large lists, infinite scroll

---

Step 4B: UI System Architecture

Skip if: Backend-only project, no frontend component.

Research and recommend the project's design system architecture. Use a direct user question for each decision.

4B-1: Styling Approach

WebSearch top 3 styling approaches for the confirmed frontend framework:

Approach	Best For	Research Focus
Utility-first (Tailwind CSS)	Rapid prototyping, design enforcement	JIT, custom config, design tokens
CSS Modules / Scoped CSS	Component isolation, no global conflicts	Naming, composition patterns
SCSS/SASS with BEM	Complex theming, token variables	BEM methodology, mixin libraries
CSS-in-JS	Dynamic styling, theme providers	Runtime perf, SSR support
CSS Custom Properties	Native theming, framework-agnostic	Browser support, fallback strategy

4B-2: Design Token Strategy

Decision	Options	Default
Token format	CSS custom properties / JSON / SCSS variables	CSS custom properties
Token categories	Color, spacing, typography, breakpoints, shadows, z-index	All
Token naming	Semantic (--color-primary) vs Functional (--btn-bg)	Semantic first
Theming	Light/dark toggle / Multi-brand / Single theme	Single + dark mode

4B-3: Component Library Strategy

Decision	Options	Default
Library	Build custom / Headless (Radix, Headless UI) / Full kit (MUI, Ant, PrimeNG)	Based on team and timeline
Component tiers	Common → Domain-Shared → Page (per ui-wireframe-protocol)	Standard 3-tier
Documentation	Storybook / Docusaurus / In-code only	Based on team size

4B-4: Responsive Strategy

Decision	Options	Default
Approach	Mobile-first / Desktop-first / Adaptive	Mobile-first
Breakpoints	320/768/1024/1280 / Custom	Standard
Grid system	CSS Grid / Flexbox / Framework grid	CSS Grid + Flexbox

MANDATORY IMPORTANT MUST ATTENTION validate all UI system decisions with user via a direct user question before proceeding to Step 5.

---

Step 5: Library Ecosystem Research

For EACH concern below, WebSearch top 3 library options for the confirmed tech stack. Evaluate: maturity, community, bundle size, maintenance activity, license, learning curve.

Library Concerns Checklist

Concern	What to Research	Evaluation Criteria
Validation	Input validation, schema validation, form validation	Type safety, composability, error messages
HTTP Client / API Layer	REST client, GraphQL client, API code generation	Interceptors, retry, caching, type generation
State Management	Global store, local state, server state caching	DevTools, SSR support, bundle size
Utilities / Helpers	Date/time, collections, deep clone, string manipulation	Tree-shakability, size, native alternatives
Caching	In-memory cache, distributed cache, HTTP cache, query cache	TTL, invalidation, persistence
Logging	Structured logging, log levels, log aggregation	Structured output, transports, performance
Error Handling	Global error boundary, error tracking, crash reporting	Source maps, breadcrumbs, alerting integration
Authentication / AuthZ	JWT, OAuth, RBAC/ABAC, session management	Standards compliance, SSO, token refresh
File Upload / Storage	Multipart upload, cloud storage SDK, image processing	Streaming, resumable, size limits
Real-time	WebSocket, SSE, SignalR, Socket.io	Reconnection, scaling, protocol support
Internationalization	i18n, l10n, pluralization, date/number formatting	ICU support, lazy loading, extraction tools
PDF / Export	PDF generation, Excel export, CSV	Server-side vs client-side, template support

Per-Library Evaluation Template

### {Concern}: Top 3 Options

| Criteria         | Option A          | Option B | Option C |
| ---------------- | ----------------- | -------- | -------- |
| GitHub Stars     | ...               | ...      | ...      |
| Last Release     | ...               | ...      | ...      |
| Bundle Size      | ...               | ...      | ...      |
| Weekly Downloads | ...               | ...      | ...      |
| License          | ...               | ...      | ...      |
| Maintenance      | Active/Slow/Stale | ...      | ...      |
| Learning Curve   | Low/Med/High      | ...      | ...      |

**Recommendation:** {Option} — Confidence: {X}%

---

Step 6: Testing Architecture

Research best testing tools and strategy for the confirmed tech stack:

Testing Layer	What to Research	Top Candidates to Compare
Unit Testing	Test runner, assertion library, mocking framework	Jest/Vitest/xUnit/NUnit, mocking
Integration Testing	API testing, DB testing, service testing	Supertest, TestContainers, WebAppFactory
E2E Testing	Browser automation, BDD, visual regression	Playwright/Cypress/Selenium, SpecFlow
Performance Testing	Load testing, stress testing, benchmarking	k6/Artillery/JMeter/NBomber, BenchmarkDotNet
Contract Testing	API contract validation between services	Pact, Dredd, Spectral
Mutation Testing	Test quality validation	Stryker, PITest
Coverage	Code coverage collection, reporting, enforcement	Istanbul/Coverlet, SonarQube
Test Data	Factories, fixtures, seeders, fakers	Bogus/AutoFixture/Faker.js

Test Strategy Template

### Test Pyramid

- **Unit (70%):** {framework} — {what to test}
- **Integration (20%):** {framework} — {what to test}
- **E2E (10%):** {framework} — {what to test}

### Coverage Targets

- Unit: {X}% | Integration: {X}% | E2E: critical paths only
- Enforcement: {tool} in CI pipeline, fail build below threshold

---

Step 7: CI/CD & Deployment

Research deployment architecture and CI/CD tooling:

Concern	What to Research	Top Candidates to Compare
CI/CD Platform	Pipeline orchestration, parallelism, caching	GitHub Actions/Azure DevOps/GitLab CI/Jenkins
Containerization	Container runtime, image building, registry	Docker/Podman, BuildKit, ACR/ECR/GHCR
Orchestration	Container orchestration, service mesh, scaling	Kubernetes/Docker Compose/ECS/Nomad
IaC (Infra as Code)	Infrastructure provisioning, drift detection	Terraform/Pulumi/Bicep/CDK
Artifact Management	Package registry, versioning, vulnerability scanning	NuGet/npm/Artifactory/GitHub Packages
Feature Flags	Progressive rollout, A/B testing, kill switches	LaunchDarkly/Unleash/Flagsmith
Secret Management	Vault, key rotation, environment variables	Azure KeyVault/HashiCorp Vault/SOPS
Database Migration	Schema versioning, rollback, seed data	EF Migrations/Flyway/Liquibase/dbmate

Deployment Strategy Comparison

Strategy	Risk	Downtime	Complexity	Best For
Blue-Green	Low	Zero	Medium	Critical services
Canary	Low	Zero	High	Gradual rollout
Rolling	Med	Zero	Low	Stateless services
Recreate	High	Yes	Low	Dev/staging environments
Feature Flags	Low	Zero	Medium	Feature-level control

---

Step 8: Observability & Monitoring

Concern	What to Research	Top Candidates to Compare
Structured Logging	Log format, correlation IDs, log levels, aggregation	Serilog/NLog/Winston/Pino
Log Aggregation	Centralized log search, dashboards, alerts	ELK/Loki+Grafana/Datadog/Seq
Metrics	Application metrics, custom counters, histograms	Prometheus/OpenTelemetry/App Insights
Distributed Tracing	Request tracing across services, span visualization	Jaeger/Zipkin/OpenTelemetry/Tempo
APM	Application performance monitoring, auto-instrumentation	Datadog/New Relic/App Insights/Elastic
Alerting	Threshold alerts, anomaly detection, on-call routing	PagerDuty/OpsGenie/Grafana Alerting
Health Checks	Liveness, readiness, startup probes	AspNetCore.Diagnostics/Terminus
Uptime Monitoring	External availability monitoring, SLA tracking	UptimeRobot/Pingdom/Checkly

Observability Decision: 3 Pillars

### Recommended Observability Stack

| Pillar   | Tool   | Why         |
| -------- | ------ | ----------- |
| Logs     | {tool} | {rationale} |
| Metrics  | {tool} | {rationale} |
| Traces   | {tool} | {rationale} |
| Alerting | {tool} | {rationale} |

---

Step 9: Code Quality & Clean Code Enforcement

Research and recommend tooling for automated code quality:

Concern	What to Research	Top Candidates to Compare
Linter (Backend)	Static analysis, code style, bug detection	Roslyn Analyzers/SonarQube/StyleCop/ReSharper
Linter (Frontend)	JS/TS linting, accessibility, complexity	ESLint/Biome/oxlint
Formatter	Auto-formatting, consistent style	Prettier/dotnet-format/EditorConfig
Code Analyzer	Security scanning, complexity metrics, duplication	SonarQube/CodeClimate/Codacy
Pre-commit Hooks	Git hooks, staged file validation	Husky+lint-staged/pre-commit/Lefthook
Editor Config	Cross-IDE consistency	.editorconfig/IDE-specific configs
Architecture Rules	Layer dependency enforcement, naming conventions	ArchUnit/NetArchTest/Dependency-Cruiser
API Design Standards	OpenAPI validation, naming, versioning	Spectral/Redocly/swagger-lint
Commit Conventions	Commit message format, changelog generation	Commitlint/Conventional Commits
Code Review Automation	Automated PR review, suggestion bots	Danger.js/Reviewdog/CodeRabbit

Enforcement Strategy

### Code Quality Gates

| Gate        | Tool   | Trigger        | Fail Criteria         |
| ----------- | ------ | -------------- | --------------------- |
| Pre-commit  | {tool} | git commit     | Lint errors, format   |
| PR Check    | {tool} | Pull request   | Coverage < X%, issues |
| CI Pipeline | {tool} | Push to branch | Build fail, test fail |
| Scheduled   | {tool} | Weekly/nightly | Security vulns, debt  |

Scaffold Handoff (MANDATORY — consumed by $scaffold)

After completing code quality research, produce this handoff table in the architecture report. The $scaffold skill reads this table to generate actual config files — without it, scaffold cannot auto-configure quality tooling.

### Scaffold Handoff — Tool Choices

| Concern        | Chosen Tool       | Config File | Rationale |
| -------------- | ----------------- | ----------- | --------- |
| Linter (FE)    | {tool}            | {filename}  | {why}     |
| Linter (BE)    | {tool}            | {filename}  | {why}     |
| Formatter      | {tool}            | {filename}  | {why}     |
| Pre-commit     | {tool}            | {filename}  | {why}     |
| Error handling | {pattern}         | {files}     | {why}     |
| Loading state  | {pattern}         | {files}     | {why}     |
| Docker         | {compose pattern} | {files}     | {why}     |

Also include: Error handling strategy (4-layer pattern), loading state approach (global vs per-component), and Docker profile structure. Specific tool choices → docs/project-reference/ or project-config.json.

---

Step 10: Dependency Risk Assessment

For EVERY recommended library/package, evaluate maintenance and obsolescence risk:

Package Health Scorecard

Criteria	Score (1-5)	How to Verify
Last Release Date	...	npm/NuGet page — stale if >12 months
Open Issues Ratio	...	GitHub issues open vs closed
Maintainer Count	...	Bus factor — single maintainer = high risk
Breaking Change Freq.	...	Changelog — frequent major versions = churn cost
Dependency Depth	...	npm ls --depth / dependency graph depth
Known Vulnerabilities	...	Snyk/npm audit/GitHub Dependabot
License Compatibility	...	SPDX identifier — check viral licenses (GPL)
Community Activity	...	Monthly commits, PR merge rate, Discord/forums
Migration Path	...	Can swap to alternative if abandoned?
Framework Alignment	...	Official recommendation by framework team?

Risk Categories

Risk Level	Criteria	Action
Low	Active, >3 maintainers, recent release, no CVEs	Use freely
Medium	1-2 maintainers, release <6mo, minor CVEs patched	Use with monitoring plan
High	Single maintainer, >12mo stale, open CVEs	Find alternative or plan exit strategy
Critical	Abandoned, unpatched CVEs, deprecated	DO NOT USE — find replacement

Dependency Maintenance Strategy

### Recommended Practices

1. **Automated scanning:** {tool} (Dependabot/Renovate/Snyk) — weekly PR for updates
2. **Lock file strategy:** Commit lock files, pin major versions, allow patch auto-update
3. **Audit schedule:** Monthly `npm audit` / `dotnet list package --vulnerable`
4. **Vendor policy:** Max {N} dependencies per concern, prefer well-maintained alternatives
5. **Exit strategy:** For each High-risk dependency, document migration path to alternative

---

Step 11: Generate Report

Write report to {plan-dir}/research/architecture-design.md with sections:

1. Executive summary (recommended architecture in 8-10 lines)
2. Architecture requirements table (from Step 2)
3. Backend architecture — style comparison + recommended patterns (Steps 3)
4. Frontend architecture — style comparison + recommended patterns (Step 4)
5. Library ecosystem — per-concern recommendations with alternatives (Step 5)
6. Testing architecture — pyramid, tools, coverage targets (Step 6)
7. CI/CD & deployment — pipeline design, deployment strategy (Step 7)
8. Observability stack — 3 pillars + alerting (Step 8)
9. Code quality — enforcement gates, tooling (Step 9)
10. Dependency risk matrix — high-risk packages, mitigation (Step 10)
11. Architecture diagram (Mermaid — showing all layers and data flow)
12. Risk assessment for overall architecture
13. Unresolved questions

Architecture Diagram Template

```mermaid
graph TB
    subgraph "Frontend"
        UI[SPA / Micro Frontend]
        STORE[State Management]
    end
    subgraph "API Gateway"
        GW[Gateway / BFF]
    end
    subgraph "Backend Services"
        CMD[Commands / Handlers]
        QRY[Queries / Read Models]
        SVC[Domain Services]
        ENT[Entities / Aggregates]
    end
    subgraph "Infrastructure"
        DB[(Database)]
        CACHE[(Cache)]
        MSG[Message Bus]
        SEARCH[(Search Index)]
    end
    subgraph "Observability"
        LOG[Logging]
        METRIC[Metrics]
        TRACE[Tracing]
    end
    subgraph "CI/CD"
        PIPE[Pipeline]
        REG[Container Registry]
        K8S[Orchestration]
    end
    UI --> GW --> CMD & QRY
    CMD --> SVC --> ENT --> DB
    QRY --> CACHE & SEARCH
    ENT -.-> MSG
    CMD & QRY -.-> LOG & METRIC & TRACE
    PIPE --> REG --> K8S
```

---

Step 12: User Validation Interview

MANDATORY IMPORTANT MUST ATTENTION present findings and ask 8-12 questions via a direct user question:

Required Questions

1. Backend architecture — "I recommend {style}. Agree?"
2. Frontend architecture — "I recommend {style} with {state management}. Agree?"
3. Design patterns — "Recommended backend patterns: {list}. Frontend patterns: {list}. Any to add/remove?"
4. Key libraries — "For {concern}, I recommend {lib} over {alternatives}. Agree?"
5. Testing strategy — "Test pyramid: {unit}%/{integration}%/{E2E}% using {frameworks}. Appropriate?"
6. CI/CD — "Pipeline: {tool} with {deployment strategy}. Fits your infra?"
7. Observability — "Monitoring stack: {logs}/{metrics}/{traces}. Sufficient?"
8. Code quality — "Enforcement: {linter + formatter + pre-commit hooks}. Team ready?"
9. Dependency risk — "Found {N} high-risk dependencies. Accept or find alternatives?"
10. Complexity check — "This architecture has {N} concerns addressed. Appropriate for team size?"

Optional Deep-Dive Questions (pick 2-3)

• "Should we use event sourcing or traditional state-based persistence?"
• "Monolith-first or start with service boundaries?"
• "Micro frontends or monolith SPA?"
• "How important is framework independence for this project?"
• "Self-hosted observability or managed SaaS?"
• "Strict lint rules from day 1 or gradual adoption?"

After user confirms, update report with final decisions and mark as status: confirmed.

---

Best Practices Audit (applied across all steps)

Validate architecture against these principles — flag violations in report:

Principle	Check	Status
Single Responsibility (S)	Each class/module has one reason to change	✅/⚠️
Open/Closed (O)	Extensible without modifying existing code	✅/⚠️
Liskov Substitution (L)	Subtypes substitutable for base types	✅/⚠️
Interface Segregation (I)	No forced dependency on unused interfaces	✅/⚠️
Dependency Inversion (D)	High-level modules depend on abstractions, not concretions	✅/⚠️
DRY	No duplicated business logic across layers	✅/⚠️
KISS	Simplest architecture that meets requirements	✅/⚠️
YAGNI	No speculative layers or patterns for future needs	✅/⚠️
Separation of Concerns	Clear boundaries between domain, application, infra	✅/⚠️
IoC / Dependency Injection	All dependencies injected, no new in business logic	✅/⚠️
Technical Agnosticism	Domain layer has zero framework/infra dependencies	✅/⚠️
Testability	Architecture supports unit + integration testing	✅/⚠️
12-Factor App	Config in env, stateless processes, port binding	✅/⚠️
Fail-Fast	Validate early, fail with clear errors	✅/⚠️

---

Output

{plan-dir}/research/architecture-design.md     # Full architecture analysis report
{plan-dir}/phase-02b-architecture.md           # Confirmed architecture decisions

---

MANDATORY IMPORTANT MUST ATTENTION break work into small todo tasks using task tracking BEFORE starting. MANDATORY IMPORTANT MUST ATTENTION validate EVERY architecture recommendation with user via a direct user question — never auto-decide. MANDATORY IMPORTANT MUST ATTENTION include confidence % and evidence citations for all claims. MANDATORY IMPORTANT MUST ATTENTION add a final review todo task to verify work quality.

---

Next Steps

MANDATORY IMPORTANT MUST ATTENTION — NO EXCEPTIONS after completing this skill, you MUST ATTENTION use a direct user question to present these options. Do NOT skip because the task seems "simple" or "obvious" — the user decides:

• "$plan (Recommended)" — Create implementation plan from architecture design
• "$refine" — If need to create PBIs first
• "Skip, continue manually" — user decides

Council escalation (always-offer, second prompt)

After the existing ## Next Steps prompt above resolves, present a second, independent a direct user question call (do NOT merge into the first):

• "Skip council — proceed (Recommended)" — Continue with the architecture decision as-is. Recommended default.
• "Escalate to $llm-council" — Run 11 sub-agent council (5 advisors + 5 reviewers + chairman). Use when this architecture pick is hard to reverse and you need adversarial framing. Cheaper alternatives: $why-review, $plan-validate (run these first if you haven't).

Prompt-Enhance Closing Anchors

• IMPORTANT MUST ATTENTION follow declared step order for this skill; NEVER skip, reorder, or merge steps without explicit user approval
• IMPORTANT MUST ATTENTION for every step/sub-skill call: set in_progress before execution, set completed after execution
• IMPORTANT MUST ATTENTION every skipped step MUST include explicit reason; every completed step MUST include concise evidence
• IMPORTANT MUST ATTENTION if Task tools unavailable, maintain an equivalent step-by-step plan tracker with synchronized statuses

Closing Reminders

MANDATORY IMPORTANT MUST ATTENTION break work into small todo tasks using task tracking BEFORE starting. MANDATORY IMPORTANT MUST ATTENTION validate decisions with user via a direct user question — never auto-decide. MANDATORY IMPORTANT MUST ATTENTION add a final review todo task to verify work quality.

• MUST ATTENTION apply critical thinking — every claim needs traced proof, confidence >80% to act. Anti-hallucination: never present guess as fact.

Critical Thinking Mindset — Apply critical thinking, sequential thinking. Every claim needs traced proof, confidence >80% to act. Anti-hallucination: Never present guess as fact — cite sources for every claim, admit uncertainty freely, self-check output for errors, cross-reference independently, stay skeptical of own confidence — certainty without evidence root of all hallucination.

Sequential Thinking Protocol — Structured multi-step reasoning for complex/ambiguous work. Use when planning, reviewing, debugging, or refining ideas where one-shot reasoning is unsafe.

Trigger when: complex problem decomposition · adaptive plans needing revision · analysis with course correction · unclear/emerging scope · multi-step solutions · hypothesis-driven debugging · cross-cutting trade-off evaluation.

Format (explicit mode — visible thought trail):

1. Thought N/M: [aspect] — one aspect per thought, state assumptions/uncertainty
2. Thought N/M [REVISION of Thought K]: ... — when prior reasoning invalidated; state Original / Why revised / Impact
3. Thought N/M [BRANCH A from Thought K]: ... — explore alternative; converge with decision rationale
4. Thought N/M [HYPOTHESIS]: ... then [VERIFICATION]: ... — test before acting
5. Thought N/N [FINAL] — only when verified, all critical aspects addressed, confidence >80%

Mandatory closers: Confidence % stated · Assumptions listed · Open questions surfaced · Next action concrete.

Stop conditions: confidence <80% on any critical decision → escalate via ask the user directly · ≥3 revisions on same thought → re-frame the problem · branch count >3 → split into sub-task.

Implicit mode: apply methodology internally without visible markers when adding markers would clutter the response (routine work where reasoning aids accuracy).

Deep-dive: see $sequential-thinking skill (.claude/skills/sequential-thinking/SKILL.md) for worked examples (api-design, debug, architecture), advanced techniques (spiral refinement, hypothesis testing, convergence), and meta-strategies (uncertainty handling, revision cascades).

AI Mistake Prevention — Failure modes to avoid on every task:

• Check downstream references before deleting. Deleting components causes documentation and code staleness cascades. Map all referencing files before removal.
• Verify AI-generated content against actual code. AI hallucinates APIs, class names, and method signatures. Always grep to confirm existence before documenting or referencing.
• Trace full dependency chain after edits. Changing a definition misses downstream variables and consumers derived from it. Always trace the full chain.
• Trace ALL code paths when verifying correctness. Confirming code exists is not confirming it executes. Always trace early exits, error branches, and conditional skips — not just happy path.
• When debugging, ask "whose responsibility?" before fixing. Trace whether bug is in caller (wrong data) or callee (wrong handling). Fix at responsible layer — never patch symptom site.
• Assume existing values are intentional — ask WHY before changing. Before changing any constant, limit, flag, or pattern: read comments, check git blame, examine surrounding code.
• Verify ALL affected outputs, not just the first. Changes touching multiple stacks require verifying EVERY output. One green check is not all green checks.
• Holistic-first debugging — resist nearest-attention trap. When investigating any failure, list EVERY precondition first (config, env vars, DB names, endpoints, DI registrations, data preconditions), then verify each against evidence before forming any code-layer hypothesis.
• Surgical changes — apply the diff test. Bug fix: every changed line must trace directly to the bug. Don't restyle or improve adjacent code. Enhancement task: implement improvements AND announce them explicitly.
• Surface ambiguity before coding — don't pick silently. If request has multiple interpretations, present each with effort estimate and ask. Never assume all-records, file-based, or more complex path.

MANDATORY IMPORTANT MUST ATTENTION use task tracking to break ALL work into small tasks BEFORE starting. MANDATORY IMPORTANT MUST ATTENTION use a direct user question at EVERY decision point — never assume user preferences. MANDATORY IMPORTANT MUST ATTENTION research top 3 options per architecture concern, compare with evidence, present report with recommendation + confidence %.

External Memory: For complex or lengthy work (research, analysis, scan, review), write intermediate findings and final results to a report file in plans/reports/ — prevents context loss and serves as deliverable.

Evidence Gate: MANDATORY IMPORTANT MUST ATTENTION — every claim, finding, and recommendation requires file:line proof or traced evidence with confidence percentage (>80% to act, <80% must verify first).

MUST ATTENTION apply sequential-thinking — multi-step Thought N/M, REVISION/BRANCH/HYPOTHESIS markers, confidence % closer; see $sequential-thinking skill.

• MUST ATTENTION apply AI mistake prevention — holistic-first debugging, fix at responsible layer, surface ambiguity before coding, re-read files after compaction.

[TASK-PLANNING] Before acting, analyze task scope and systematically break it into small todo tasks and sub-tasks using task tracking.

[IMPORTANT] Analyze how big the task is and break it into many small todo tasks systematically before starting — this is very important.

Hookless Prompt Protocol Mirror (Auto-Synced)

Source: .claude/hooks/lib/prompt-injections.cjs + .claude/.ck.json

[WORKFLOW-EXECUTION-PROTOCOL] [BLOCKING] Workflow Execution Protocol — MANDATORY IMPORTANT MUST CRITICAL. Do not skip for any reason.

Generic portability boundary: Reusable skills and protocol text stay project-neutral; project-specific conventions are discovered from docs/project-config.json and docs/project-reference/. Apply shared AI-SDD from shared/sdd-artifact-contract.md. Read docs/project-config.json and docs/project-reference/docs-index-reference.md, then open the project reference docs named there. Any supported AI tool may execute when this shared context and local docs are available.

1. DETECT: Match prompt against workflow catalog
2. ANALYZE: Find best-match workflow AND evaluate if a custom step combination would fit better
3. ASK (REQUIRED FORMAT): Use a direct user question with this structure unless the user explicitly invoked a workflow/skill and the local protocol treats explicit invocation as confirmation:
   • Question: "Which workflow do you want to activate?"
   • Option 1: "Activate [BestMatch Workflow] (Recommended)"
   • Option 2: "Activate custom workflow: [step1 → step2 → ...]" (include one-line rationale)
4. ACTIVATE (if confirmed): Call $workflow-start <workflowId> for standard; sequence custom steps manually
5. CREATE TASKS: task tracking for ALL workflow steps
6. EXECUTE: Follow each step in sequence [CRITICAL-THINKING-MINDSET] Apply critical thinking, sequential thinking. Every claim needs traced proof, confidence >80% to act. Anti-hallucination principle: Never present guess as fact — cite sources for every claim, admit uncertainty freely, self-check output for errors, cross-reference independently, stay skeptical of own confidence — certainty without evidence root of all hallucination. AI Attention principle (Primacy-Recency): Put the 3 most critical rules at both top and bottom of long prompts/protocols so instruction adherence survives long context windows. Goal-driven execution: Define success criteria first, loop until verified, and stop only when observable checks pass. Tests verify intent: Tests must protect business rules/invariants and fail when the protected intent breaks, not only mirror current behavior.

[LESSON-LEARNED-REMINDER] [BLOCKING] Task Planning & Continuous Improvement — MANDATORY. Do not skip.

Break work into small tasks (task tracking) before starting. Add final task: "Analyze AI mistakes & lessons learned".

Extract lessons — ROOT CAUSE ONLY, not symptom fixes:

1. Name the FAILURE MODE (reasoning/assumption failure), not symptom — "assumed API existed without reading source" not "used wrong enum value".
2. Generality test: does this failure mode apply to ≥3 contexts/codebases? If not, abstract one level up.
3. Write as a universal rule — strip project-specific names/paths/classes. Useful on any codebase.
4. Consolidate: multiple mistakes sharing one failure mode → ONE lesson.
5. Recurrence gate: "Would this recur in future session WITHOUT this reminder?" — No → skip $learn.
6. Auto-fix gate: "Could $code-review/$code-simplifier/$security/$lint catch this?" — Yes → improve review skill instead.
7. BOTH gates pass → ask user to run $learn. [TASK-PLANNING] [MANDATORY] BEFORE executing any workflow or skill step, create/update task tracking for all planned steps, then keep it synchronized as each step starts/completes.