description: Design comprehensive system architecture that serves as the technical blueprint for the entire project.

User input:

$ARGUMENTS

The text the user typed after /project-architecture in the triggering message. Parse any architecture focus areas or constraints.

Context Requirements

This command requires:

•Active project with project.md
•Required: /project-context (constraints that architecture must work within)
•Recommended: ux-strategy.md (for user experience alignment)
•Recommended: constitution.md (for technical principles)
•Recommended: Existing research reports (check project dir for -research-report-.md)
•Optional: project-landscape-overview.md (brownfield architecture extraction)
•Optional: project-import.md (brownfield non-code aspects)
•Optional: Recipe selection (if project.md has _active_recipe: metadata)

Position in Flow: Runs AFTER context/constitution, BEFORE planning (architecture decisions inform planning!)

Research Approach: Uses just-in-time research pattern (.cursor/skills/just-in-time-research/SKILL.md) for technology evaluation and architecture patterns

Subagent Parallelization

This command benefits from parallel subagent execution:

Research Phase - Spawn parallel speck-researcher:

code

├── [Parallel] speck-researcher: "Best database for [requirements]"
├── [Parallel] speck-researcher: "Architecture patterns for [scale]"
├── [Parallel] speck-researcher: "Deployment patterns for [cloud]"
├── [Parallel] speck-researcher: "Security patterns for [domain]"
├── [Parallel] speck-researcher: "Integration patterns for [services]"
└── [Wait] → Synthesize findings into decisions

Decision Phase (for complex trade-offs) - Spawn speck-architect:

code

├── [Parallel] speck-architect: "Database architecture decision"
├── [Parallel] speck-architect: "Auth architecture decision"
├── [Parallel] speck-architect: "API design decision"
└── [Wait] → Consolidate into coherent architecture

Drafting Phase - Spawn parallel speck-scribe:

code

├── [Parallel] speck-scribe: "System Architecture" section
├── [Parallel] speck-scribe: "Technology Strategy" section
├── [Parallel] speck-scribe: "Security Architecture" section
├── [Parallel] speck-scribe: "Data Architecture" section
├── [Parallel] speck-scribe: "Integration Architecture" section
├── [Parallel] speck-scribe: "Deployment Architecture" section
└── [Wait] → Assemble into architecture.md

Speedup: 5-10x compared to sequential execution.

Architecture Design Process

•
Load project context and detect mode:
- •Find active project directory
- •Load project.md for vision and scope
- •Load context.md for constraints and requirements (REQUIRED)
- •Load constitution.md if exists (for technical principles)
- •Check for existing research reports: -research-report-.md (for informed decisions)
- •Load project-landscape-overview.md if exists (brownfield extraction)
- •Load project-import.md if exists (brownfield non-code)
- •Check for existing architecture.md
Check for Active Recipe (greenfield only):
- •Look for _active_recipe: in project.md metadata
- •If found, load .speck/recipes/[recipe-name]/recipe.yaml
- •
  Recipe provides pre-made architecture decisions:
  - •stack: → Framework, language, database choices
  - •architecture: → Pattern, API style, rendering approach
  - •patterns: → Pre-configured implementation patterns
  - •external_services: → Recommended services (auth, payments, etc.)
- •Use recipe as starting point, customize based on project specifics
- •Skip questions about areas the recipe already addresses
Determine Architecture Mode:
- •
  BROWNFIELD MODE (if project-landscape-overview.md exists):
  - •Extract existing architecture from landscape overview
  - •Document current state ("as-is")
  - •Identify what to keep vs refactor
  - •Propose evolution path ("to-be")
- •
  GREENFIELD MODE (if no landscape overview):
  - •Design architecture from scratch
  - •If recipe active: Pre-fill from recipe, ask only for customizations
  - •If no recipe: Ask architecture questions interactively
  - •Make technology choices based on context constraints
  - •Use just-in-time research for technology evaluation
IMPORTANT:
- •Architecture must work within context.md constraints!
- •If landscape-overview exists, document existing architecture first!
- •Architecture decisions will feed into project-plan for realistic epic breakdown
•
Just-In-Time Research (BOTH modes - before architectural decisions):

Reference: Follow the just-in-time research pattern (.cursor/skills/just-in-time-research/SKILL.md)

Before making architecture decisions (greenfield) or proposing evolution (brownfield), conduct research for:

Research Areas for Architecture

1. Technology Stack Evaluation (greenfield or when considering new tech):
- •Decision: What framework/platform should we use for [component]?
- •Web Search: Framework comparisons, benchmarks, compatibility
- •Deep Research (if needed): Technology proof-of-concept evaluation
2. Architecture Patterns (both modes):
- •Decision: What pattern best fits [requirements]?
- •Web Search: Pattern recommendations (monolith, microservices, etc.), case studies
- •Deep Research (if needed): Pattern evaluation for specific domains
3. Performance Benchmarks (both modes):
- •Decision: Can [technology] handle [scale requirements]?
- •Web Search: Scalability data, performance benchmarks
- •Deep Research (if needed): Detailed performance analysis
4. Integration Patterns (both modes):
- •Decision: How should [system A] integrate with [system B]?
- •Web Search: API design best practices, integration patterns
- •Deep Research (if needed): Complex integration scenarios
5. Migration Strategies (brownfield evolution):
- •Decision: How do we migrate from [old tech] to [new tech]?
- •Web Search: Migration patterns, compatibility layers
- •Deep Research (if needed): Complex migration strategies
Execute Research

For each area with knowledge gaps:
1. •Quick web search for standards and best practices
2. •Generate deep research prompt if web search insufficient
3. •Document findings in "Research Informing This Architecture" section of output
If deep research needed, PAUSE and instruct user:
code
```
⏸️ Deep Research Needed

Topic: [Research Area]
Prompt Generated: project-architecture-research-prompt-[topic].md

Please:
1. Review research prompt in project directory
2. Run in Perplexity/Claude/Gemini/Grok
3. Save results as: project-architecture-research-report-[topic].md
4. Re-run this command to continue
```
•
BROWNFIELD MODE - Extract from Landscape Overview:

If project-landscape-overview.md exists, use it to document existing architecture:

Extract from Landscape Overview:
- •System architecture pattern (from "Architecture Overview" section)
- •Component breakdown (from "Code Organization" section)
- •Technology stack (from "Tech Stack" section)
- •Data models (from "Data & State" section)
- •API patterns (from "Integration Points" section)
- •Deployment approach (from "Deployment" section)
- •Patterns in use (from scan findings)
Document Current State:
- •List all existing components and their roles
- •Document current technology choices with rationale
- •Identify integration patterns already in use
- •Note architecture strengths from scan
Identify Evolution Needs:
- •Review "Risks & Technical Debt" section from landscape overview
- •Note any anti-patterns discovered
- •Propose refactoring priorities aligned with context.md constraints
- •Define migration path if technology changes needed
Then proceed to step 4 to generate architecture document
•
GREENFIELD MODE - Interactive architecture decisions:

Core Architecture Questions:
- •"What's the primary architectural pattern? (monolithic/microservices/serverless/event-driven)"
- •"What are the main deployment targets? (cloud/on-premise/hybrid/edge)"
- •"What are the critical quality attributes? (performance/security/scalability/reliability)"
Technology Stack Questions:
- •"Frontend framework preference? (or 'none' for backend-only)"
- •"Backend language/framework preference?"
- •"Database requirements? (relational/document/graph/time-series)"
- •"Any specific integration requirements?"
Align with Context:
- •Verify choices work within context.md constraints
- •Ensure tech stack matches team skills (from context.md)
- •Confirm deployment approach matches infrastructure constraints
•
Generate architecture document:
- •Load template from .speck/templates/project/architecture-template.md
- •Fill in all sections based on mode:
For BROWNFIELD:
- •Existing architecture from landscape overview
- •Current technology stack (from scan)
- •Established patterns (keep what works)
- •Identified issues and evolution path
- •Project constraints from context.md
For GREENFIELD:
- •Project vision and goals from project.md
- •Architectural decisions made interactively
- •Best practices for chosen stack
- •Alignment with research findings (if exists)
- •Project constraints from context.md
•
Architecture components to address:
- •System-wide component design
- •Technology stack justification
- •Data architecture strategy
- •Security architecture
- •Performance architecture
- •Scalability planning
- •Integration architecture
- •Deployment architecture
- •Operational considerations
•
Cross-reference with epics:
- •Ensure architecture supports all epics
- •Identify shared components
- •Define integration points
- •Establish data flow between epics
•
Risk and trade-off analysis:
- •Identify architectural risks
- •Document trade-offs made
- •Propose mitigation strategies
- •Define evolution path
•
Save architecture.md with:
- •Clear diagrams (ASCII or Mermaid)
- •Technology decisions with rationale
- •Component responsibilities
- •Integration strategies
- •Deployment approach
- •Operational requirements

•

Output summary (mode-specific):

For BROWNFIELD:

code

✅ Project Architecture Documented!

Mode: BROWNFIELD (extracted from codebase scan)
Architecture Pattern: [Pattern from scan]
Primary Stack: [Technologies from scan]

Current State:
- [Components documented]
- [Patterns identified]
- [Integration points mapped]

Technical Debt:
- [Issue 1 from scan]
- [Issue 2 from scan]

Evolution Path:
- [Refactoring priority 1]
- [Refactoring priority 2]

Next Steps:
- Review architecture document
- Validate against current implementation
- Plan refactoring epics if needed
- Continue with /project-validate

For GREENFIELD:

code

✅ Project Architecture Designed!

Mode: GREENFIELD (designed from requirements)
Architecture Pattern: [Pattern chosen]
Primary Stack: [Technologies chosen]

Key Decisions:
- [Decision 1 with rationale]
- [Decision 2 with rationale]
- [Decision 3 with rationale]

Risk Factors:
- [Risk 1 with mitigation]
- [Risk 2 with mitigation]

Next Steps:
- Recommended: /project-roadmap (epic timeline and resource allocation)
- Then: /project-validate (architecture and plan review)
- If approved: Begin epic development
- For each epic: /epic-specify → /epic-architecture → /epic-plan

Architecture Validation

Ensure the architecture:

•✓ Supports all functional requirements
•✓ Meets non-functional requirements
•✓ Aligns with team capabilities
•✓ Fits within constraints (time, budget, resources)
•✓ Provides clear epic boundaries
•✓ Enables independent epic development
•✓ Includes operational requirements
•✓ Addresses security concerns
•✓ Plans for scale

Integration with Existing Flow

This command fits in Phase 3 (Technical Design) BEFORE planning:

code

Phase 2: Foundation
/project-ux → /project-context → /project-constitution

Phase 3: Technical Design (BEFORE planning!)
/project-architecture → /project-design-system

Phase 4: Planning
/project-plan (creates PRD using foundation + architecture inputs)

Phase 5: Validation
/project-validate

The architecture informs:

•Epic technical specifications
•Technology choices in stories
•Integration approaches
•Deployment strategies
•Operational requirements

Example Workflows

Brownfield Example (Existing App)

code

1. Run /project-scan → Generates project-landscape-overview.md
2. Run /project-architecture:
   - Detects scan exists → BROWNFIELD MODE
   - Extracts: "Modular monolithic, FastAPI + React, 14 models"
   - Documents: Current component boundaries, WebSocket handlers
   - Identifies: Claude AI placeholder, Capacitor missing
   - Proposes: Migration to Capacitor, Claude integration
3. Output: architecture.md with as-is + to-be sections

Greenfield Example

code

1. Run /project-context (and optionally /project-constitution) → No existing code
2. Run /project-architecture:
   - No scan found → GREENFIELD MODE
   - Asks: Architecture pattern, deployment targets, tech stack
   - Designs: Component structure, integration approach
   - Documents: Technology choices with rationale
3. Run /project-plan:
   - Uses architecture.md + context.md as inputs
   - Produces PRD.md + epics.md + epics/
4. Output: architecture.md with design from scratch

Notes

•For small projects (Level 0-1): Architecture might be minimal or skipped
•For large projects (Level 3-4): Architecture is critical for success
•For brownfield: Always run /project-scan first to extract existing architecture
•For greenfield: Use research and planning to inform architecture decisions
•Architecture should be living document, updated as project evolves
•Consider re-running /project-architecture later (or updating architecture.md) as the project evolves

description: Design comprehensive system architecture that serves as the technical blueprint for the entire project.

Context Requirements

Subagent Parallelization

Architecture Design Process

Research Areas for Architecture

Execute Research

Architecture Validation

Integration with Existing Flow

Example Workflows

Brownfield Example (Existing App)

Greenfield Example

Notes