# ADR-040: Quantum-Inspired Optimization Plugin

**Status:** Proposed
**Date:** 2026-01-24
**Category:** Exotic SOTA
**Author:** Plugin Architecture Team
**Version:** 1.0.0
**Deciders:** Plugin Architecture Team, Quantum Computing Advisors
**Supersedes:** None

## Context

Combinatorial optimization problems are ubiquitous in software development: dependency resolution, task scheduling, resource allocation, and test selection. Classical algorithms often struggle with NP-hard problems at scale. Quantum-inspired algorithms, running on classical hardware, can provide significant speedups for specific problem classes by leveraging quantum mechanical concepts like superposition and interference.

## Decision

Create a **Quantum-Inspired Optimization Plugin** that leverages RuVector's exotic WASM packages to provide quantum-inspired solvers for combinatorial optimization problems commonly encountered in software engineering.

## Plugin Name

`@claude-flow/plugin-quantum-optimizer`

## Description

An exotic optimization plugin implementing quantum-inspired algorithms including Quantum Annealing simulation, QAOA (Quantum Approximate Optimization Algorithm) emulation, and Grover-inspired search acceleration. The plugin provides dramatic speedups for dependency resolution, optimal scheduling, and constraint satisfaction while running entirely on classical WASM-accelerated hardware.

## Key WASM Packages

| Package | Purpose |
|---------|---------|
| `ruvector-exotic-wasm` | Quantum-inspired optimization algorithms |
| `ruvector-sparse-inference-wasm` | Efficient sparse matrix operations for quantum simulation |
| `micro-hnsw-wasm` | Amplitude-inspired search acceleration |
| `ruvector-dag-wasm` | Quantum circuit DAG representation |
| `ruvector-hyperbolic-hnsw-wasm` | Hyperbolic embeddings for quantum state spaces |

## MCP Tools

### 1. `quantum/annealing-solve`

Solve optimization problems using simulated quantum annealing.

```typescript
{
  name: 'quantum/annealing-solve',
  description: 'Solve combinatorial optimization using quantum annealing simulation',
  inputSchema: {
    type: 'object',
    properties: {
      problem: {
        type: 'object',
        properties: {
          type: {
            type: 'string',
            enum: ['qubo', 'ising', 'sat', 'max_cut', 'tsp', 'dependency']
          },
          variables: { type: 'number' },
          constraints: { type: 'array' },
          objective: { type: 'object' }
        }
      },
      parameters: {
        type: 'object',
        properties: {
          numReads: { type: 'number', default: 1000 },
          annealingTime: { type: 'number', default: 20 },
          chainStrength: { type: 'number', default: 1.0 },
          temperature: {
            type: 'object',
            properties: {
              initial: { type: 'number' },
              final: { type: 'number' }
            }
          }
        }
      },
      embedding: { type: 'string', enum: ['auto', 'minor', 'pegasus', 'chimera'] }
    },
    required: ['problem']
  }
}
```

### 2. `quantum/qaoa-optimize`

Approximate optimization using QAOA emulation.

```typescript
{
  name: 'quantum/qaoa-optimize',
  description: 'Optimize using Quantum Approximate Optimization Algorithm',
  inputSchema: {
    type: 'object',
    properties: {
      problem: {
        type: 'object',
        properties: {
          type: { type: 'string', enum: ['max_cut', 'portfolio', 'scheduling', 'routing'] },
          graph: { type: 'object', description: 'Problem graph representation' },
          weights: { type: 'object' }
        }
      },
      circuit: {
        type: 'object',
        properties: {
          depth: { type: 'number', default: 3, description: 'QAOA circuit depth (p)' },
          optimizer: { type: 'string', enum: ['cobyla', 'bfgs', 'adam'], default: 'cobyla' },
          initialParams: { type: 'string', enum: ['random', 'heuristic', 'transfer'] }
        }
      },
      shots: { type: 'number', default: 1024 }
    },
    required: ['problem']
  }
}
```

### 3. `quantum/grover-search`

Grover-inspired quadratic speedup for search.

```typescript
{
  name: 'quantum/grover-search',
  description: 'Grover-inspired search with quadratic speedup',
  inputSchema: {
    type: 'object',
    properties: {
      searchSpace: {
        type: 'object',
        properties: {
          size: { type: 'number', description: 'N elements in search space' },
          oracle: { type: 'string', description: 'Predicate function definition' },
          structure: { type: 'string', enum: ['unstructured', 'database', 'tree', 'graph'] }
        }
      },
      targets: { type: 'number', default: 1, description: 'Expected number of solutions' },
      iterations: { type: 'string', enum: ['optimal', 'fixed', 'adaptive'], default: 'optimal' },
      amplification: {
        type: 'object',
        properties: {
          method: { type: 'string', enum: ['standard', 'fixed_point', 'robust'] },
          boostFactor: { type: 'number' }
        }
      }
    },
    required: ['searchSpace']
  }
}
```

### 4. `quantum/dependency-resolve`

Quantum-inspired dependency resolution.

```typescript
{
  name: 'quantum/dependency-resolve',
  description: 'Resolve complex dependency graphs using quantum optimization',
  inputSchema: {
    type: 'object',
    properties: {
      packages: {
        type: 'array',
        items: {
          type: 'object',
          properties: {
            name: { type: 'string' },
            version: { type: 'string' },
            dependencies: { type: 'object' },
            conflicts: { type: 'array' }
          }
        }
      },
      constraints: {
        type: 'object',
        properties: {
          minimize: { type: 'string', enum: ['versions', 'size', 'vulnerabilities'] },
          lockfile: { type: 'object' },
          peer: { type: 'boolean' }
        }
      },
      solver: { type: 'string', enum: ['quantum_annealing', 'qaoa', 'hybrid'], default: 'hybrid' }
    },
    required: ['packages']
  }
}
```

### 5. `quantum/schedule-optimize`

Quantum-optimized task scheduling.

```typescript
{
  name: 'quantum/schedule-optimize',
  description: 'Optimize task scheduling using quantum algorithms',
  inputSchema: {
    type: 'object',
    properties: {
      tasks: {
        type: 'array',
        items: {
          type: 'object',
          properties: {
            id: { type: 'string' },
            duration: { type: 'number' },
            dependencies: { type: 'array' },
            resources: { type: 'array' },
            deadline: { type: 'number' }
          }
        }
      },
      resources: {
        type: 'array',
        items: {
          type: 'object',
          properties: {
            id: { type: 'string' },
            capacity: { type: 'number' },
            cost: { type: 'number' }
          }
        }
      },
      objective: {
        type: 'string',
        enum: ['makespan', 'cost', 'utilization', 'weighted'],
        default: 'makespan'
      }
    },
    required: ['tasks', 'resources']
  }
}
```

## Use Cases

1. **Dependency Resolution**: Solve complex version conflicts in package managers
2. **Task Scheduling**: Optimal CI/CD pipeline scheduling
3. **Resource Allocation**: Distribute workloads across agents/machines
4. **Test Selection**: Find minimal test sets with maximum coverage
5. **Configuration Optimization**: Find optimal system configurations

## Architecture

```
+------------------+     +----------------------+     +------------------+
| Problem Input    |---->| Quantum Optimizer    |---->| Optimal Solution |
| (Constraints)    |     | (WASM Accelerated)   |     | (+ Certificate)  |
+------------------+     +----------------------+     +------------------+
                                   |
              +--------------------+--------------------+
              |                    |                    |
       +------+------+     +-------+-------+    +------+------+
       | Quantum     |     |    QAOA       |    | Grover      |
       | Annealing   |     | Variational   |    | Search      |
       +-------------+     +---------------+    +-------------+
                                   |
                           +-------+-------+
                           | Exotic WASM   |
                           | Primitives    |
                           +---------------+
```

## Quantum-Inspired Algorithms

| Algorithm | Speedup | Problem Class | Classical Equivalent |
|-----------|---------|---------------|---------------------|
| Quantum Annealing | Exponential (heuristic) | Combinatorial | Simulated Annealing |
| QAOA | Polynomial | Max-Cut, QUBO | Goemans-Williamson |
| Grover Search | Quadratic O(sqrt(N)) | Unstructured Search | Linear Search |
| Quantum Walk | Polynomial | Graph Problems | Random Walk |
| VQE | Variable | Eigenvalue | Power Iteration |

## Performance Targets

| Metric | Target | Baseline (Classical) | Improvement |
|--------|--------|----------------------|-------------|
| Annealing (100 vars) | <1s for 1000 reads | ~30s (brute force) | 30x |
| QAOA (50 qubits) | <10s for p=5 | ~5min (classical approx) | 30x |
| Grover (1M elements) | <100ms | ~1s (linear search) | 10x (sqrt speedup) |
| Dependency resolution | <5s for 1000 packages | ~2min (SAT solver) | 24x |
| Schedule optimization | <30s for 100 tasks | ~10min (ILP solver) | 20x |

## Security Considerations

### Input Validation (CRITICAL)

All MCP tool inputs MUST be validated using Zod schemas:

```typescript
// quantum/annealing-solve input validation
const AnnealingSolveSchema = z.object({
  problem: z.object({
    type: z.enum(['qubo', 'ising', 'sat', 'max_cut', 'tsp', 'dependency']),
    variables: z.number().int().min(1).max(10000), // Max 10K variables
    constraints: z.array(z.unknown()).max(100000),
    objective: z.record(z.string(), z.number().finite())
  }),
  parameters: z.object({
    numReads: z.number().int().min(1).max(10000).default(1000),
    annealingTime: z.number().min(1).max(1000).default(20),
    chainStrength: z.number().min(0.1).max(100).default(1.0),
    temperature: z.object({
      initial: z.number().min(0.001).max(1000).optional(),
      final: z.number().min(0.0001).max(100).optional()
    }).optional()
  }).optional(),
  embedding: z.enum(['auto', 'minor', 'pegasus', 'chimera']).optional()
});

// quantum/qaoa-optimize input validation
const QAOAOptimizeSchema = z.object({
  problem: z.object({
    type: z.enum(['max_cut', 'portfolio', 'scheduling', 'routing']),
    graph: z.object({
      nodes: z.number().int().min(1).max(1000),
      edges: z.array(z.tuple([z.number(), z.number()])).max(100000)
    }),
    weights: z.record(z.string(), z.number().finite()).optional()
  }),
  circuit: z.object({
    depth: z.number().int().min(1).max(20).default(3),
    optimizer: z.enum(['cobyla', 'bfgs', 'adam']).default('cobyla'),
    initialParams: z.enum(['random', 'heuristic', 'transfer']).optional()
  }).optional(),
  shots: z.number().int().min(100).max(100000).default(1024)
});

// quantum/grover-search input validation
const GroverSearchSchema = z.object({
  searchSpace: z.object({
    size: z.number().int().min(1).max(1_000_000_000), // Max 1B elements
    oracle: z.string().max(10000), // Predicate definition
    structure: z.enum(['unstructured', 'database', 'tree', 'graph'])
  }),
  targets: z.number().int().min(1).max(1000).default(1),
  iterations: z.enum(['optimal', 'fixed', 'adaptive']).default('optimal'),
  amplification: z.object({
    method: z.enum(['standard', 'fixed_point', 'robust']).optional(),
    boostFactor: z.number().min(1).max(10).optional()
  }).optional()
});
```

### WASM Security Constraints (CRITICAL FOR EXOTIC ALGORITHMS)

| Constraint | Value | Rationale |
|------------|-------|-----------|
| Memory Limit | 4GB max | Quantum simulation is memory-intensive |
| CPU Time Limit | 600 seconds (10 min) | Allow long optimization runs |
| Iteration Limit | 1M iterations max | Prevent infinite loops |
| Variable Limit | 10K variables max | Bound computational complexity |
| No Parallelism Escape | WASM threads only | Prevent resource exhaustion |

### Computational Resource Limits (HIGH)

```typescript
// Quantum-inspired algorithms can be computationally expensive
// MUST enforce strict resource limits

interface QuantumResourceLimits {
  maxVariables: 10000;       // Problem size limit
  maxIterations: 1000000;    // Annealing/optimization steps
  maxMemoryBytes: 4294967296; // 4GB
  maxCpuTimeMs: 600000;      // 10 minutes
  maxCircuitDepth: 20;       // QAOA circuit depth
  maxQubits: 50;             // Simulated qubits

  // Progress checkpoints (cancel if no progress)
  progressCheckIntervalMs: 10000; // Check every 10 seconds
  minProgressThreshold: 0.001;    // Min improvement per checkpoint
}

// Enforce limits during execution
async function runWithLimits<T>(
  operation: () => Promise<T>,
  limits: QuantumResourceLimits
): Promise<T> {
  const startTime = Date.now();
  const memoryBefore = process.memoryUsage().heapUsed;

  // Set up timeout
  const timeout = setTimeout(() => {
    throw new ResourceLimitError('CPU_TIME_EXCEEDED');
  }, limits.maxCpuTimeMs);

  try {
    const result = await operation();
    return result;
  } finally {
    clearTimeout(timeout);
  }
}
```

### Denial of Service Prevention (HIGH)

```typescript
// Quantum problems can be crafted to cause exponential blowup
// Validate problem structure before processing

function validateQuantumProblem(problem: QuantumProblem): ValidationResult {
  // Check for pathological cases
  if (problem.variables > 10000) {
    return { valid: false, error: 'Too many variables' };
  }

  // Detect highly connected graphs (exponential complexity)
  const avgDegree = problem.constraints.length / problem.variables;
  if (avgDegree > problem.variables / 10) {
    return { valid: false, error: 'Graph too densely connected' };
  }

  // Check coefficient magnitudes (numerical stability)
  for (const coeff of Object.values(problem.objective)) {
    if (!Number.isFinite(coeff) || Math.abs(coeff) > 1e15) {
      return { valid: false, error: 'Invalid coefficient magnitude' };
    }
  }

  return { valid: true };
}
```

### Identified Security Risks

| Risk ID | Severity | Description | Mitigation |
|---------|----------|-------------|------------|
| QUANT-SEC-001 | **HIGH** | DoS via exponentially complex problems | Problem validation, complexity bounds |
| QUANT-SEC-002 | **HIGH** | Resource exhaustion via large simulations | Memory/CPU limits, progress monitoring |
| QUANT-SEC-003 | **MEDIUM** | Numerical overflow in quantum operations | Coefficient validation, numerical guards |
| QUANT-SEC-004 | **MEDIUM** | Oracle injection (arbitrary predicate) | Predicate sandboxing, no eval() |
| QUANT-SEC-005 | **LOW** | Timing side-channels revealing problem structure | Constant-time operations where feasible |

### Oracle Security (Grover Search)

```typescript
// The oracle predicate MUST be sandboxed
// NEVER use eval() or Function() constructor

// BAD - arbitrary code execution
const oracle = new Function('x', userProvidedPredicate);

// GOOD - parsed and interpreted safely
const oracleAST = parseOraclePredicate(userProvidedPredicate);
const oracle = compileOracleToSafeFunction(oracleAST);

// Allowed predicate operations:
// - Comparison: ==, !=, <, >, <=, >=
// - Logical: &&, ||, !
// - Arithmetic: +, -, *, /, %
// - Property access: x.field
// NOT allowed:
// - Function calls
// - Object construction
// - Property assignment
```

### Rate Limiting

```typescript
const QuantumRateLimits = {
  'quantum/annealing-solve': { requestsPerMinute: 5, maxConcurrent: 1 },
  'quantum/qaoa-optimize': { requestsPerMinute: 5, maxConcurrent: 1 },
  'quantum/grover-search': { requestsPerMinute: 10, maxConcurrent: 2 },
  'quantum/dependency-resolve': { requestsPerMinute: 10, maxConcurrent: 2 },
  'quantum/schedule-optimize': { requestsPerMinute: 5, maxConcurrent: 1 }
};
```

## Risk Assessment

| Risk | Likelihood | Impact | Mitigation |
|------|------------|--------|------------|
| Suboptimal solutions | High | Medium | Solution quality bounds, hybrid fallback |
| Problem encoding errors | Medium | High | Validation framework, encoding templates |
| Compute requirements | Medium | Medium | Efficient WASM, progressive refinement |
| Overpromising quantum advantage | Medium | Low | Clear documentation of "inspired" vs "actual" |

## Problem Encoding

```
Classical Problem --> QUBO/Ising --> Quantum Circuit --> Solution
       |                  |                |               |
       v                  v                v               v
[constraints]      [energy function]  [parameterized]  [measured]
[objective]        [coupling matrix]  [variational]    [decoded]
```

## Implementation Notes

### Phase 1: Core Solvers
- QUBO/Ising formulation
- Simulated quantum annealing
- Basic Grover emulation

### Phase 2: Advanced Algorithms
- QAOA variational optimizer
- Quantum walk search
- Hybrid classical-quantum solvers

### Phase 3: Domain Applications
- Dependency resolver
- Task scheduler
- Test selector

## Dependencies

```json
{
  "dependencies": {
    "ruvector-exotic-wasm": "^0.1.0",
    "ruvector-sparse-inference-wasm": "^0.1.0",
    "micro-hnsw-wasm": "^0.2.0",
    "ruvector-dag-wasm": "^0.1.0",
    "ruvector-hyperbolic-hnsw-wasm": "^0.1.0"
  }
}
```

## Theoretical Background

### Quantum Annealing
Exploits quantum tunneling to escape local minima during optimization. Simulated via Path Integral Monte Carlo.

### QAOA
Variational algorithm alternating between problem Hamiltonian and mixer. Emulated via tensor network contraction.

### Grover's Algorithm
Amplitude amplification for unstructured search. Classical implementation uses interference-inspired importance sampling.

## Consequences

### Positive
- Significant speedups for NP-hard optimization problems
- No quantum hardware required - runs on WASM
- Applicable to many software engineering problems

### Negative
- Approximation algorithms - not guaranteed optimal
- Problem encoding requires expertise
- Performance varies by problem structure

### Neutral
- Complements classical solvers for specific problem classes

## Related ADRs

| ADR | Relationship |
|-----|--------------|
| ADR-004: Plugin Architecture | Foundation - Defines plugin structure |
| ADR-017: RuVector Integration | Dependency - Provides WASM packages |
| ADR-033: Financial Risk | Related - Portfolio optimization |
| ADR-036: Test Intelligence | Related - Test selection optimization |
| ADR-038: Neural Coordination | Related - Task scheduling |

## References

- Quantum Annealing: https://arxiv.org/abs/cond-mat/0701277
- QAOA: https://arxiv.org/abs/1411.4028
- Grover's Algorithm: https://arxiv.org/abs/quant-ph/9605043
- ADR-017: RuVector Integration
- ADR-004: Plugin Architecture

---

**Last Updated:** 2026-01-24
