# CONSTRUCT @Browser: Best Practices & 8-Tick Feasibility

## Overview

Analysis of SPARQL CONSTRUCT queries in browser/web client contexts, current best practices, and what can be accomplished within the 8-tick budget using CONSTRUCT8.

## 1. Browser-Based CONSTRUCT: Current State

### 1.1. Traditional Browser SPARQL Client Patterns

**Common Approaches:**

1. **Fetch API + SPARQL Endpoint**
   ```javascript
   // Standard browser SPARQL query
   async function constructQuery(endpoint, query) {
     const response = await fetch(endpoint, {
       method: 'POST',
       headers: {
         'Content-Type': 'application/sparql-query',
         'Accept': 'application/n-triples'
       },
       body: query
     });
     return await response.text();
   }
   
   const query = `
     CONSTRUCT { ?s ?p ?o }
     WHERE { ?s ?p ?o . FILTER(?p = <http://example.org/name>) }
   `;
   const graph = await constructQuery('https://sparql.example.org/query', query);
   ```

2. **SPARQL.js Client Libraries**
   ```javascript
   import { SparqlClient } from 'sparql-http-client';
   
   const client = new SparqlClient({ endpointUrl: 'https://sparql.example.org/query' });
   const result = await client.query.construct(`
     CONSTRUCT { ?s ?p ?o }
     WHERE { ?s ?p ?o }
   `);
   ```

3. **RDF.js / Comunica (Linked Data Fragments)**
   ```javascript
   import { newEngine } from '@comunica/actor-init-sparql';
   
   const engine = newEngine();
   const result = await engine.query(`
     CONSTRUCT { ?s ?p ?o }
     WHERE { ?s ?p ?o }
   `, {
     sources: ['https://example.org/data.ttl']
   });
   ```

### 1.2. Current Limitations

**Network Latency:**
- Browser→Server round-trip: 50-500ms (typical)
- **Cannot achieve 8-tick budget** with network I/O
- Network overhead dominates: ~100,000x slower than 8 ticks (2ns)

**Client-Side Processing:**
- JavaScript execution: ~1-10ms per query (typical)
- **Cannot achieve 8-tick budget** with JavaScript execution
- JS overhead: ~500,000x slower than 8 ticks (2ns)

**Memory Constraints:**
- Browser memory limits: ~2-8GB (typical)
- Cannot hold entire knowledge graph in browser memory
- Requires streaming/chunked processing

## 2. What CAN Be Done in 8 Ticks (Browser Context)

### 2.1. Prerequisites for 8-Tick CONSTRUCT in Browser

**Key Insight:** 8-tick budget applies to **server-side hot path**, not browser client.

**Architecture Pattern:**
```
Browser Client                    Server (KNHK Hot Path)
─────────────────────────────────────────────────────────
1. Prepare Query              →   1. Receive Query (Rust warm path)
2. Send Query (HTTP)          →   2. Validate & Route (Rust warm path)
3. Wait for Response          →   3. Execute CONSTRUCT8 (C hot path: ≤8 ticks)
4. Receive Results            →   4. Return Results (Rust warm path)
5. Render UI (async)          →   5. Stream Results (if large)
```

### 2.2. Browser → Server CONSTRUCT8 Flow

**Step 1: Browser Prepares Query**
```javascript
// Browser: Prepare CONSTRUCT8 query
const construct8Query = {
  op: 'CONSTRUCT8',
  template: {
    p: 'http://example.org/hasAccess',  // Fixed predicate
    o: 'http://example.org/Allowed'      // Fixed object (or variable)
  },
  where: {
    s: userId,                            // User ID
    p: 'http://example.org/role',        // Role predicate
    len: 4                               // Max 8 triples
  }
};

// Send to server
const response = await fetch('/api/knhk/construct8', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify(construct8Query)
});
```

**Step 2: Server Executes CONSTRUCT8 (Hot Path)**
```c
// Server: C hot path (≤8 ticks)
knhk_hook_ir_t ir = {
  .op = KNHK_OP_CONSTRUCT8,
  .p = hash_iri("http://example.org/hasAccess"),
  .o = hash_iri("http://example.org/Allowed"),
  .out_S = out_S,  // Preallocated
  .out_P = out_P,
  .out_O = out_O
};

knhk_receipt_t rcpt = {0};
int written = knhk_eval_construct8(&ctx, &ir, &rcpt);
// Executes in ≤8 ticks (2ns) on server
```

**Step 3: Browser Receives Results**
```javascript
// Browser: Receive constructed triples
const result = await response.json();
// {
//   triples: [
//     { s: 'user1', p: 'hasAccess', o: 'resource1' },
//     { s: 'user1', p: 'hasAccess', o: 'resource2' },
//     ...
//   ],
//   ticks: 6,  // Server-side execution time
//   lanes: 4   // Number of triples constructed
// }
```

### 2.3. Browser-Side Optimizations

**1. Query Caching**
```javascript
// Cache CONSTRUCT8 results in browser
const cache = new Map();

async function construct8WithCache(query) {
  const key = JSON.stringify(query);
  if (cache.has(key)) {
    return cache.get(key);  // Instant return (0 ticks, but not measurable)
  }
  
  const result = await fetch('/api/knhk/construct8', {
    method: 'POST',
    body: JSON.stringify(query)
  });
  
  const data = await result.json();
  cache.set(key, data);
  return data;
}
```

**2. Batch Requests**
```javascript
// Batch multiple CONSTRUCT8 queries
async function batchConstruct8(queries) {
  const response = await fetch('/api/knhk/batch', {
    method: 'POST',
    body: JSON.stringify({ queries })
  });
  return await response.json();
}
```

**3. Prefetching**
```javascript
// Prefetch CONSTRUCT8 results for likely-needed data
async function prefetchAuthorization(userId) {
  const query = {
    op: 'CONSTRUCT8',
    template: { p: 'hasAccess', o: 'Allowed' },
    where: { s: userId, p: 'role', len: 8 }
  };
  
  // Prefetch in background
  fetch('/api/knhk/construct8', {
    method: 'POST',
    body: JSON.stringify(query),
    priority: 'low'  // Browser hint
  });
}
```

## 3. Best Practices for Browser CONSTRUCT

### 3.1. Query Optimization

**✅ DO:**
- Use CONSTRUCT8 for fixed templates (predicate/object constants)
- Limit query size to ≤8 triples per request
- Cache results aggressively
- Use batch requests for multiple queries
- Prefetch likely-needed data

**❌ DON'T:**
- Use full CONSTRUCT for large result sets (>8 triples)
- Make synchronous CONSTRUCT requests (block UI)
- Re-query same data without caching
- Use CONSTRUCT for real-time streaming (use WebSockets instead)

### 3.2. Error Handling

```javascript
async function construct8Safe(query) {
  try {
    const response = await fetch('/api/knhk/construct8', {
      method: 'POST',
      body: JSON.stringify(query),
      signal: AbortSignal.timeout(5000)  // 5s timeout
    });
    
    if (!response.ok) {
      throw new Error(`HTTP ${response.status}: ${response.statusText}`);
    }
    
    const result = await response.json();
    
    // Validate server-side execution time
    if (result.ticks > 8) {
      console.warn(`CONSTRUCT8 exceeded 8-tick budget: ${result.ticks} ticks`);
      // Fallback to cold path or show warning
    }
    
    return result;
  } catch (error) {
    if (error.name === 'AbortError') {
      // Timeout: fallback to cached data or show error
      return getCachedResult(query);
    }
    throw error;
  }
}
```

### 3.3. Progressive Enhancement

```javascript
// Progressive enhancement: Use CONSTRUCT8 when available, fallback otherwise
async function constructWithFallback(query) {
  // Try CONSTRUCT8 first (fast path)
  if (isConstruct8Compatible(query)) {
    try {
      return await construct8Safe(query);
    } catch (error) {
      console.warn('CONSTRUCT8 failed, falling back to full CONSTRUCT');
    }
  }
  
  // Fallback to full CONSTRUCT (cold path)
  return await fullConstruct(query);
}

function isConstruct8Compatible(query) {
  return (
    query.template.p &&  // Fixed predicate
    query.where.len <= 8 &&  // ≤8 triples
    !query.where.join  // No joins
  );
}
```

## 4. 8-Tick CONSTRUCT Patterns for Browser

### 4.1. Authorization Reflex (Most Common)

**Browser Code:**
```javascript
async function getUserPermissions(userId) {
  const query = {
    op: 'CONSTRUCT8',
    template: {
      p: 'http://example.org/hasAccess',
      o: null  // Variable: from role grants
    },
    where: {
      s: userId,
      p: 'http://example.org/role',
      len: 4  // Typically 1-4 roles per user
    }
  };
  
  const result = await construct8Safe(query);
  return result.triples.map(t => t.o);  // Extract permissions
}
```

**Server Execution:** ≤8 ticks (typically 4-6 ticks)

**Use Cases:**
- RBAC permission checks
- Entitlement generation
- Access control decisions

### 4.2. Compliance Classification

**Browser Code:**
```javascript
async function getComplianceStatus(resourceId) {
  const query = {
    op: 'CONSTRUCT8',
    template: {
      p: 'http://www.w3.org/1999/02/22-rdf-syntax-ns#type',
      o: 'http://example.org/Compliant'  // Fixed object
    },
    where: {
      s: resourceId,
      p: 'http://example.org/passesPolicy',
      len: 1  // Single compliance check
    }
  };
  
  const result = await construct8Safe(query);
  return result.triples.length > 0;  // Is compliant?
}
```

**Server Execution:** ≤8 ticks (typically 4 ticks with all-nonzero optimization)

**Use Cases:**
- Regulatory compliance flags
- Policy compliance states
- Audit trail generation

### 4.3. Risk Flag Generation

**Browser Code:**
```javascript
async function getRiskLevel(assetId) {
  const query = {
    op: 'CONSTRUCT8',
    template: {
      p: 'http://example.org/riskLevel',
      o: null  // Variable: computed from risk score
    },
    where: {
      s: assetId,
      p: 'http://example.org/riskScore',
      len: 1  // Single risk score
    }
  };
  
  const result = await construct8Safe(query);
  return result.triples[0]?.o || 'Unknown';
}
```

**Server Execution:** ≤8 ticks (typically 6 ticks)

**Use Cases:**
- Financial risk assessment
- Security risk flags
- Operational risk indicators

## 5. Browser Implementation Strategies

### 5.1. WebAssembly (WASM) Option

**Potential:** Compile CONSTRUCT8 C code to WASM for browser execution

**Challenges:**
- WASM overhead: ~10-100x slower than native C
- Still cannot achieve 8-tick budget (browser JS overhead)
- Network I/O still required for data loading

**Recommendation:** Not viable for 8-tick budget. Better to use server-side hot path.

### 5.2. Service Worker Caching

**Strategy:** Cache CONSTRUCT8 results in Service Worker

```javascript
// Service Worker: Cache CONSTRUCT8 results
self.addEventListener('fetch', event => {
  if (event.request.url.includes('/api/knhk/construct8')) {
    event.respondWith(
      caches.match(event.request).then(response => {
        if (response) {
          return response;  // Serve from cache
        }
        
        return fetch(event.request).then(response => {
          // Cache successful responses
          if (response.ok) {
            const clone = response.clone();
            caches.open('construct8-cache').then(cache => {
              cache.put(event.request, clone);
            });
          }
          return response;
        });
      })
    );
  }
});
```

**Benefit:** Eliminates network latency for cached queries

**Limitation:** First request still requires network round-trip

### 5.3. HTTP/2 Server Push

**Strategy:** Pre-push CONSTRUCT8 results

```javascript
// Server: Push CONSTRUCT8 results before browser requests
// (Requires HTTP/2 server implementation)

// Browser: Receive pushed results
// (Automatic via HTTP/2 push)
```

**Benefit:** Zero-latency for pre-pushed data

**Limitation:** Requires server-side prediction of needed queries

## 6. Performance Characteristics

### 6.1. Latency Breakdown

**Browser → Server CONSTRUCT8:**

| Phase | Latency | Notes |
|-------|---------|-------|
| Browser query prep | ~0.1-1ms | JS execution |
| Network request | ~10-100ms | HTTP round-trip |
| Server routing | ~1-10μs | Rust warm path |
| **CONSTRUCT8 execution** | **≤8 ticks (2ns)** | **C hot path** |
| Server response | ~1-10μs | Rust warm path |
| Network response | ~10-100ms | HTTP round-trip |
| Browser processing | ~0.1-1ms | JS execution |
| **Total** | **~20-200ms** | **Network dominates** |

**Key Insight:** CONSTRUCT8 execution (≤8 ticks) is **negligible** compared to network latency.

### 6.2. Cached Query Performance

**Browser Cache Hit:**

| Phase | Latency | Notes |
|-------|---------|-------|
| Cache lookup | ~0.01-0.1ms | Map/IndexedDB access |
| **Total** | **~0.01-0.1ms** | **1000-2000x faster** |

**Recommendation:** Aggressive caching is critical for browser performance.

## 7. Limitations & Trade-offs

### 7.1. Cannot Achieve 8-Tick Budget in Browser

**Reasons:**
1. **Network Latency:** HTTP round-trip is 10-100ms (5,000,000-50,000,000x slower than 8 ticks)
2. **JavaScript Execution:** JS overhead is ~1ms (500,000x slower than 8 ticks)
3. **Memory Constraints:** Cannot hold entire knowledge graph in browser
4. **Security:** Browser sandbox prevents direct memory access

### 7.2. What CAN Be Optimized

**✅ Optimizable:**
- Query caching (eliminates network latency for cached queries)
- Batch requests (reduces network overhead)
- Prefetching (hides network latency)
- Progressive enhancement (fallback strategies)

**❌ Not Optimizable:**
- Network latency (fundamental limitation)
- JavaScript execution overhead (fundamental limitation)
- First-time query performance (no cache)

## 8. Recommendations

### 8.1. For Browser Developers

**✅ DO:**
1. Use CONSTRUCT8 for fixed templates (authorization, compliance, risk)
2. Cache results aggressively (IndexedDB, Service Worker)
3. Batch multiple CONSTRUCT8 queries
4. Prefetch likely-needed data
5. Use progressive enhancement (fallback to full CONSTRUCT)

**❌ DON'T:**
1. Expect 8-tick performance in browser (network latency dominates)
2. Make synchronous CONSTRUCT requests (block UI)
3. Re-query same data without caching
4. Use CONSTRUCT8 for large result sets (>8 triples)

### 8.2. For Server Developers

**✅ DO:**
1. Expose CONSTRUCT8 endpoint for browser clients
2. Return execution time (`ticks`) in response
3. Support batch CONSTRUCT8 requests
4. Implement query result caching
5. Stream large results (if >8 triples)

**❌ DON'T:**
1. Expose full CONSTRUCT endpoint for hot path (exceeds 8 ticks)
2. Skip validation (must enforce ≤8 triples)
3. Ignore receipt generation (provenance tracking)

## 9. Example: Complete Browser Implementation

```javascript
// Browser CONSTRUCT8 client library
class Construct8Client {
  constructor(endpoint) {
    this.endpoint = endpoint;
    this.cache = new Map();
    this.pending = new Map();
  }
  
  async construct8(query) {
    // Check cache first
    const cacheKey = JSON.stringify(query);
    if (this.cache.has(cacheKey)) {
      return this.cache.get(cacheKey);
    }
    
    // Avoid duplicate requests
    if (this.pending.has(cacheKey)) {
      return await this.pending.get(cacheKey);
    }
    
    // Make request
    const promise = fetch(`${this.endpoint}/construct8`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify(query),
      signal: AbortSignal.timeout(5000)
    })
    .then(response => {
      if (!response.ok) throw new Error(`HTTP ${response.status}`);
      return response.json();
    })
    .then(result => {
      // Validate server-side execution time
      if (result.ticks > 8) {
        console.warn(`CONSTRUCT8 exceeded budget: ${result.ticks} ticks`);
      }
      
      // Cache result
      this.cache.set(cacheKey, result);
      this.pending.delete(cacheKey);
      return result;
    })
    .catch(error => {
      this.pending.delete(cacheKey);
      throw error;
    });
    
    this.pending.set(cacheKey, promise);
    return await promise;
  }
  
  async batchConstruct8(queries) {
    return await fetch(`${this.endpoint}/batch`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ queries })
    }).then(r => r.json());
  }
}

// Usage
const client = new Construct8Client('https://api.example.org/knhk');

// Authorization reflex
const permissions = await client.construct8({
  op: 'CONSTRUCT8',
  template: { p: 'hasAccess', o: null },
  where: { s: userId, p: 'role', len: 4 }
});

// Compliance classification
const isCompliant = await client.construct8({
  op: 'CONSTRUCT8',
  template: { p: 'rdf:type', o: 'Compliant' },
  where: { s: resourceId, p: 'passesPolicy', len: 1 }
});
```

## 10. Conclusion

**Key Findings:**

1. **8-Tick Budget Applies to Server-Side Hot Path Only**
   - Browser cannot achieve 8-tick performance (network latency dominates)
   - CONSTRUCT8 execution (≤8 ticks) is negligible compared to network overhead

2. **Browser Best Practices:**
   - Use CONSTRUCT8 for fixed templates (authorization, compliance, risk)
   - Cache results aggressively (eliminates network latency)
   - Batch requests (reduces network overhead)
   - Prefetch likely-needed data (hides network latency)

3. **Architecture Pattern:**
   - Browser prepares query → Server executes CONSTRUCT8 (≤8 ticks) → Browser receives results
   - Total latency: ~20-200ms (network dominates)
   - Cached queries: ~0.01-0.1ms (1000-2000x faster)

4. **Limitations:**
   - Cannot achieve 8-tick budget in browser (fundamental network/JS limitations)
   - First-time queries require network round-trip
   - Limited to ≤8 triples per CONSTRUCT8 query

**Recommendation:** Focus on **server-side CONSTRUCT8 optimization** (≤8 ticks) and **browser-side caching** (eliminates network latency for cached queries).

