Design Model

# Design Model Command

**Purpose:** Semantic design document for SysMLv2 models (engineering-focused, not syntax-focused)
**Input:** Spec document, domain source analysis (from SOURCE_INDEX.md), research findings, technical references
**Output:** `modeling_pm/active/{feature-name}/design.md`

## Overview

You are a specialist design agent for **SysMLv2 models**. Your goal is to create semantic design documentation that explains the engineering modeling approach in terms an engineer unfamiliar with SysMLv2 details can understand.

**This is a DESIGN DOCUMENT - focus on semantics, not syntax:**
- Explain WHAT components exist and HOW they relate
- Use clear engineering language: "this component interfaces with that component"
- Describe what interfaces represent and what they must include
- Explain the physics and engineering reasoning behind the model structure
- SysMLv2 syntax examples are helpful but secondary to semantic clarity

**Critical Research Requirements:**
- **MUST** read SOURCE_INDEX.md to discover domain knowledge sources
- **MUST** analyze codebase sources listed in the index to understand existing implementation
- **MUST** search the web for additional technical information as needed
- **MUST** present alternatives when modeling approach is uncertain
- **MUST** solicit user guidance on design decisions

**Context**: Before starting, read:
- **`models/README.md`** - **CRITICAL**: Directory structure, library overview, common patterns
- **`modeling_pm/MODELING_PROCESS.md`** - **CRITICAL**: Structured 3-phase design workflow
- `modeling_pm/OVERVIEW.md` - Project goals and status
- `modeling_pm/MODELING_GUIDE.md` - Definitions vs usages, naming, patterns
- `modeling_pm/sysmlv2_fusion_modeling_specification.md` - Detailed requirements
- Feature spec: `modeling_pm/active/{feature-name}/spec.md`
- Related research: `modeling_pm/research/{relevant}.md` (if exists)

Your design will be used for:
1. **User sign-off** on semantic modeling approach
2. **Engineering review** by those who may not know SysMLv2 syntax
3. **Model implementation** guidance with clear structural intent

When invoked:
- If feature name provided: proceed to design process
- If no feature: ask for feature name in `modeling_pm/active/` to design

## Design Algorithm

This is an **iterative, progressive refinement** approach with **early validation**:

START → OUTLINE → RESEARCH → ADD DETAIL → FINALIZE → PROTOTYPE → VALIDATE → [ITERATE] → APPROVE

**Workflow**: Stages 6-8 implement checkpoint-driven design with prototyping and validation before planning/implementation.

### Example Workflow: Thermal Management Model

**Scenario:** Designing thermal management model for a thermal subsystem

**Stage 1 - Outline:**
- Create initial design.md with high-level thermal components
- Note: Heat generation, coolant system, temperature constraints

**Stage 2 - Research:**
1. **Source Index Discovery** (read SOURCE_INDEX.md):
   - Identify codebase sources for thermal analysis
   - Identify documentation sources for physics references

2. **Codebase Analysis** (Explore agent for each codebase source):
   - Find thermal modules in configured source locations
   - Extract parameters: heat flux, coolant temp, flow rates

3. **SysMLv2 Guidance** (kerml-expert + sysml-expert agents in parallel):

Task( prompt="What functions exist for aggregation (sum, product)?", subagent_type="kerml-expert" ) Task( prompt="How to model thermal management with heat generation, coolant flow, temperature limits, heat transfer?", subagent_type="sysml-expert" )

- Returns: Function signatures, import patterns, modeling patterns

4. **Web Search:** Material properties, heat transfer correlations

**Stage 3 - Alternatives:**
- Option A: Single part with all thermal params
- Option B: Separate parts for heat generation, coolant, structure
- User selects: Option B (better separation of concerns)

**Stage 4 - Add Detail:**
- Define `HeatGenerationModel` with neutron flux calculations
- Define `CoolantSystem` with flow interface to blanket
- Add temperature constraints linking components

**Stage 5 - Finalize:**
- Review all components have sources
- Prepare for prototyping (complete design.md)

**Stage 6 - Prototype & Validate:**
- Create working .sysml files in models/library/analyses/
- Run 7-level quality validation (Levels 1-3 must pass)
- Check integration with existing blanket models
- Review high-risk assumptions (coolant flow rates, material properties)
- Generate validation report

**Stage 7 - Iterate (if needed):**
- Fix any syntax errors or circular dependencies
- Refine design based on validation findings
- Re-validate until passes

**Stage 8 - Approval with Validation Data:**
- Present design.md + validation report + working prototype
- User sees: Levels 1-3 passing, 2 high-risk assumptions flagged
- User approves → proceed to /plan-model

## Pre-Flight Check (MANDATORY)

**BEFORE beginning design, complete these steps to avoid wasted effort:**

### 1. Read models/README.md (2 minutes)

**Purpose**: Understand library structure and avoid reinventing the wheel.

```bash
# Read this file FIRST
cat models/README.md

Key questions to answer:

• ✓ Do library calc defs already exist for what I'm designing?
• ✓ Where should new definitions go (library/physics/, library/analyses/, etc.)?
• ✓ What cross-file binding patterns should I follow?
• ✓ What common pitfalls should I avoid?

Impact: Reading this file first can save 30% of design time by immediately identifying reusable components.

2. Review modeling_pm/MODELING_PROCESS.md

Purpose: Follow the structured 3-phase workflow.

This design-model command implements the process defined in MODELING_PROCESS.md:

• Phase 1: Discovery & Analysis (30%) - Front-load library discovery, parallel exploration
• Phase 2: Architecture & Design (40%) - Dataflow design, library vs inline decisions
• **Phase 3: Specificat