# Constraint Driven Design

> Generate innovative solutions by treating resource constraints as creative fuel rather than obstacles.

- Skill: `sethmblack/constraint-driven-design` (Agent Skill)
- Install (CLI): `npx skillmds add sethmblack/constraint-driven-design`
- Raw SKILL.md: https://api.skillmd.com/api/skills/sethmblack/constraint-driven-design/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- License: MIT
- Author: sethmblack (https://skillmd.com/u/sethmblack)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/sethmblack/constraint-driven-design

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# Constraint-Driven Design

Generate innovative solutions by treating resource constraints as creative fuel rather than obstacles. Based on Jaime Lerner's principle: "If you want creativity, cut a zero from your budget. If you want sustainability, cut two zeros." Constraints force imagination; abundance breeds complacency.

---

## Constitutional Constraints

- **Function over form** - The solution must actually work. Creative doesn't mean clever-but-useless.
- **Dignity preservation** - A cheaper solution must not feel second-class. The BRT is "surface metro," not "budget bus."
- **Scalability** - Solutions should be replicable by others facing similar constraints, not dependent on unique circumstances.
- **Honest accounting** - Don't hide costs or externalize them. The constraint is real; the solution must be genuinely affordable.

---

## When to Use

- Conventional solution is unaffordable ("We can't afford a metro")
- Comparing unfavorably to wealthier peer cities
- Budget has been cut and scope must be preserved
- Need to find creative alternatives to expensive infrastructure
- Demonstrating that resource constraints don't excuse inaction
- Seeking the "80/20 solution" - most benefit at fraction of cost

---

## Don't Use When

- Problem genuinely requires expensive solution (some things cost what they cost)
- Cheap alternative would create safety risks
- User needs general budget optimization, not creative problem-solving
- Constraints are artificial and should be challenged rather than accepted

---

## Inputs

| Input | Required | Description |
|-------|----------|-------------|
| problem | Yes | What needs to be solved |
| conventional_solution | Yes | Standard approach and its cost |
| available_resources | Yes | Actual budget, existing infrastructure, human capital |
| functional_requirements | Yes | What the solution must actually accomplish |
| constraints | No | Budget ceiling, timeline, political feasibility |
| dignity_requirements | No | How to ensure solution doesn't feel second-class |

---

## Constraint-Driven Design Workflow

### Step 1: Function Decomposition

Strip the conventional solution to its functional core:

| Conventional Solution Element | Actual Function | Is Function Essential? |
|------------------------------|-----------------|------------------------|
| | | Yes / No / Partial |
| | | Yes / No / Partial |
| | | Yes / No / Partial |
| | | Yes / No / Partial |

**The Lerner Question:** "What does a metro actually DO?"
- Moves people quickly
- Runs frequently and reliably
- Provides dedicated right-of-way
- Offers comfortable boarding
- Integrates across the network

"Can a bus do these things? Yes - if we design it right."

### Step 2: Resource Inventory

What do you actually have?

| Resource Category | Available | Conventional Solution Requires | Gap |
|-------------------|-----------|-------------------------------|-----|
| **Budget** | $ | $ | $ |
| **Existing infrastructure** | | | |
| **Human capital** | | | |
| **Political capital** | | | |
| **Time** | | | |
| **Citizen energy** | | | |
| **Underutilized assets** | | | |

**Lerner's insight:** Streets already exist. Why dig tunnels? Citizen effort is available if incentives align. Why pay for services citizens can provide?

### Step 3: Constraint Reframing

Transform each constraint from obstacle to design parameter:

| Constraint | Obstacle Framing | Creative Framing |
|------------|------------------|------------------|
| Limited budget | "We can't afford real transit" | "We must invent affordable transit" |
| No subway tunnels | "We can't have metro service" | "We must create metro service on the surface" |
| Can't reach favelas | "We can't collect garbage there" | "We must create system where citizens bring garbage out" |
| | | |

**The mindset shift:** Stop saying "We can't do X because we don't have Y." Start saying "Given that we don't have Y, how do we achieve the function of X?"

### Step 4: Creative Alternatives Matrix

Generate at least 3 non-conventional approaches:

| Alternative | How It Works | Cost | Function Coverage | Dignity Factor |
|-------------|--------------|------|-------------------|----------------|
| **Option A** | | $ | % of conventional | High/Medium/Low |
| **Option B** | | $ | % of conventional | High/Medium/Low |
| **Option C** | | $ | % of conventional | High/Medium/Low |

**Lerner examples to inspire:**
- BRT instead of metro (1/100th cost, similar function)
- Flood parks instead of channelization (recreation + flood control)
- Green Exchange instead of garbage trucks (recycling + nutrition + mobility)

### Step 5: The Surface Metro Test

For the most promising alternative, apply the "surface metro" test:

| Dimension | Conventional Solution | Proposed Alternative | Gap Acceptable? |
|-----------|----------------------|---------------------|-----------------|
| **Speed** | | | Yes/No |
| **Reliability** | | | Yes/No |
| **Capacity** | | | Yes/No |
| **Comfort** | | | Yes/No |
| **Dignity** | | | Yes/No |
| **Accessibility** | | | Yes/No |

**The dignity question:** Would a wealthy person use this? If not, why not? Can we fix that?

**Dignity preservation strategies:**
- Naming: "Surface metro" not "cheap bus"
- Design: Real stations, not just poles
- Quality: Clean, frequent, reliable
- Integration: Seamless transfers, unified fare
- Branding: Pride, not apology

### Step 6: Resource Substitution Table

Map what you need to what you have:

| Need | Conventional Source | Creative Substitute | How It Works |
|------|---------------------|--------------------|--------------|
| Capital for tunnels | Bond financing | Street dedication | Paint lanes; no construction |
| Garbage collection capacity | Truck fleet | Citizen effort | Exchange incentives |
| Flood control infrastructure | Concrete channels | Park system | Natural absorption |
| | | | |

### Step 7: Phased Implementation

Design a pathway from proof-of-concept to full implementation:

| Phase | Scope | Cost | Duration | Proves What? |
|-------|-------|------|----------|--------------|
| **Pilot** | | $ | | Concept works |
| **Expansion** | | $ | | Scalability |
| **Full System** | | $ | | Long-term viability |

**Lerner's approach:**
- Week 1: Paint the lane
- Month 1: Add shelters
- Year 1: Build real stations
- Year 5: Full BRT network

---

## Output Format

```markdown
## Constraint-Driven Solution: [Problem Name]

### Summary

| Element | Detail |
|---------|--------|
| Problem | [What needs to be solved] |
| Conventional solution | [Standard approach] |
| Conventional cost | [$ amount] |
| Proposed alternative | [Creative solution] |
| Alternative cost | [$ amount] |
| Cost ratio | [X% of conventional] |
| Function coverage | [X% of conventional function] |

---

### Function Decomposition

[Table from Step 1: What the solution must actually do]

---

### Resource Inventory

[Table from Step 2: What you have vs. what conventional requires]

---

### Constraint Reframing

[Table from Step 3: From obstacles to design parameters]

---

### Creative Alternatives Evaluated

[Table from Step 4: At least 3 alternatives with cost and function coverage]

---

### Recommended Solution: [Name]

**How it works:**
[Detailed explanation]

**Surface Metro Test:**
[Table from Step 5: Comparison with conventional on key dimensions]

**Dignity Preservation:**
[How this solution avoids feeling second-class]

---

### Resource Substitution

[Table from Step 6: Needs mapped to creative substitutes]

---

### Implementation Pathway

[Table from Step 7: Phased implementation from pilot to full system]

---

### Risks and Limitations

| Risk | Mitigation |
|------|------------|
| [Risk 1] | [Mitigation] |
| [Risk 2] | [Mitigation] |

**Honest limitations:**
[What this solution cannot do that conventional could]

---

### Conclusion

[Assessment of solution viability and recommended next steps]
```

---

## Example Summary

**Input:** "Our city needs better transit but we can only afford $50M. A light rail line would cost $500M. What do we do?"

**Output summary (abbreviated):**

- **Problem:** Transit inadequate; conventional solution unaffordable
- **Conventional solution:** Light rail, $500M
- **Proposed alternative:** BRT network, $50M
- **Cost ratio:** 10% of conventional
- **Function coverage:** 80% of light rail function

**How it works:**
- Dedicate existing lanes to buses (paint, not construction)
- Build tube stations for level boarding (1/10th cost of rail stations)
- Purchase articulated buses (1/5th cost of trains)
- Implement pre-payment system (subway-style efficiency)
- Brand as "Metro Express" not "Bus"

**Surface Metro Test:**
- Speed: 90% of light rail (dedicated lanes)
- Reliability: 95% (no traffic interference)
- Capacity: 80% (bi-articulated buses)
- Dignity: High (real stations, clean vehicles, professional branding)

**Dignity preservation:** Call it "Metro Express." Build real stations with weather protection, seating, real-time arrival displays. Paint vehicles distinctively. Create unified wayfinding system.

**Implementation pathway:**
- Month 1-3: Paint pilot corridor ($500K)
- Month 3-12: Build 5 stations, add buses ($15M)
- Year 2: Extend to 3 corridors ($35M)
- Total: Full network at 10% of rail cost

---

## Error Handling

| Situation | Response |
|-----------|----------|
| No creative alternative achieves required function | Some problems require expensive solutions. Acknowledge honestly; suggest phased approach or alternative problem framing. |
| Alternative has unacceptable dignity gap | Prioritize dignity improvements; a solution people won't use doesn't solve anything. |
| Constraint is artificial | Challenge the constraint rather than accept it. Sometimes the creative solution is "get more resources." |
| User wants validation for inferior solution | Be honest. Constraint-driven design produces GOOD cheap solutions, not excuses for bad ones. |

---

## Integration

This skill is part of the **Jaime Lerner** expert persona. Lerner built Curitiba's world-famous transit, parks, and recycling systems on a fraction of what wealthy cities spent - because constraint forced creativity.

Use this skill when:
- Lerner expert faces "we can't afford it" objections
- Expensive conventional solutions are proposed
- Resource constraints are cited as excuse for inaction
- Need to find the "Curitiba solution" to a problem

The skill embodies Lerner's core insight: **Constraint is a gift. Wealthy cities become complacent. Poor cities must be creative. If you want creativity, cut a zero from your budget.**

---

## Success Criteria

A successful constraint-driven design:
- [ ] Achieves 70%+ of conventional solution function
- [ ] Costs 20% or less of conventional solution
- [ ] Preserves dignity (solution doesn't feel second-class)
- [ ] Uses existing resources creatively (streets, citizen effort, underutilized assets)
- [ ] Includes phased implementation starting with cheap pilot
- [ ] Honestly acknowledges limitations