thrilltrack-explorer/docs/PHASE_2_RESILIENCE_IMPROVEMENTS_COMPLETE.md

# Phase 2: Resilience Improvements - COMPLETE ✅

**Deployment Date**: 2025-11-06  
**Status**: All resilience improvements deployed and active

---

## Overview

Phase 2 focused on hardening the submission pipeline against data integrity issues, providing better error messages, and protecting against abuse. All improvements are non-breaking and additive.

---

## 1. Slug Uniqueness Constraints ✅

**Migration**: `20251106220000_add_slug_uniqueness_constraints.sql`

### Changes Made:
- Added `UNIQUE` constraint on `companies.slug`
- Added `UNIQUE` constraint on `ride_models.slug`
- Added indexes for query performance
- Prevents duplicate slugs at database level

### Impact:
- **Data Integrity**: Impossible to create duplicate slugs (was previously possible)
- **Error Detection**: Immediate feedback on slug conflicts during submission
- **URL Safety**: Guarantees unique URLs for all entities

### Error Handling:
```typescript
// Before: Silent failure or 500 error
// After: Clear error message
{
  "error": "duplicate key value violates unique constraint \"companies_slug_unique\"",
  "code": "23505",
  "hint": "Key (slug)=(disneyland) already exists."
}
```

---

## 2. Foreign Key Validation ✅

**Migration**: `20251106220100_add_fk_validation_to_entity_creation.sql`

### Changes Made:
Updated `create_entity_from_submission()` function to validate foreign keys **before** INSERT:

#### Parks:
- ✅ Validates `location_id` exists in `locations` table
- ✅ Validates `operator_id` exists and is type `operator`
- ✅ Validates `property_owner_id` exists and is type `property_owner`

#### Rides:
- ✅ Validates `park_id` exists (REQUIRED)
- ✅ Validates `manufacturer_id` exists and is type `manufacturer`
- ✅ Validates `ride_model_id` exists

#### Ride Models:
- ✅ Validates `manufacturer_id` exists and is type `manufacturer` (REQUIRED)

### Impact:
- **User Experience**: Clear, actionable error messages instead of cryptic FK violations
- **Debugging**: Error hints include the problematic field name
- **Performance**: Early validation prevents wasted INSERT attempts

### Error Messages:
```sql
-- Before:
ERROR: insert or update on table "rides" violates foreign key constraint "rides_park_id_fkey"

-- After:
ERROR: Invalid park_id: Park does not exist
HINT: park_id
```

---

## 3. Rate Limiting ✅

**File**: `supabase/functions/process-selective-approval/index.ts`

### Changes Made:
- Integrated `rateLimiters.standard` (10 req/min per IP)
- Applied via `withRateLimit()` middleware wrapper
- CORS-compliant rate limit headers added to all responses

### Protection Against:
- ❌ Spam submissions
- ❌ Accidental automation loops
- ❌ DoS attacks on approval endpoint
- ❌ Resource exhaustion

### Rate Limit Headers:
```http
HTTP/1.1 200 OK
X-RateLimit-Limit: 10
X-RateLimit-Remaining: 7

HTTP/1.1 429 Too Many Requests
Retry-After: 42
X-RateLimit-Limit: 10
X-RateLimit-Remaining: 0
```

### Client Handling:
```typescript
if (response.status === 429) {
  const retryAfter = response.headers.get('Retry-After');
  console.log(`Rate limited. Retry in ${retryAfter} seconds`);
}
```

---

## Combined Impact

| Metric | Before Phase 2 | After Phase 2 |
|--------|----------------|---------------|
| Duplicate Slug Risk | 🔴 HIGH | 🟢 NONE |
| FK Violation User Experience | 🔴 POOR | 🟢 EXCELLENT |
| Abuse Protection | 🟡 BASIC | 🟢 ROBUST |
| Error Message Clarity | 🟡 CRYPTIC | 🟢 ACTIONABLE |
| Database Constraint Coverage | 🟡 PARTIAL | 🟢 COMPREHENSIVE |

---

## Testing Checklist

### Slug Uniqueness:
- [x] Attempt to create company with duplicate slug → blocked with clear error
- [x] Attempt to create ride_model with duplicate slug → blocked with clear error
- [x] Verify existing slugs remain unchanged
- [x] Performance test: slug lookups remain fast (<10ms)

### Foreign Key Validation:
- [x] Create ride with invalid park_id → clear error message
- [x] Create ride_model with invalid manufacturer_id → clear error message
- [x] Create park with invalid operator_id → clear error message
- [x] Valid references still work correctly
- [x] Error hints match the problematic field

### Rate Limiting:
- [x] 11th request within 1 minute → 429 response
- [x] Rate limit headers present on all responses
- [x] CORS headers present on rate limit responses
- [x] Different IPs have independent rate limits
- [x] Rate limit resets after 1 minute

---

## Deployment Notes

### Zero Downtime:
- All migrations are additive (no DROP or ALTER of existing data)
- UNIQUE constraints applied to tables that should already have unique slugs
- FK validation adds checks but doesn't change success cases
- Rate limiting is transparent to compliant clients

### Rollback Plan:
If critical issues arise:

```sql
-- Remove UNIQUE constraints
ALTER TABLE companies DROP CONSTRAINT IF EXISTS companies_slug_unique;
ALTER TABLE ride_models DROP CONSTRAINT IF EXISTS ride_models_slug_unique;

-- Revert function (restore original from migration 20251106201129)
-- (Function changes are non-breaking, so rollback not required)
```

For rate limiting, simply remove the `withRateLimit()` wrapper and redeploy edge function.

---

## Monitoring & Alerts

### Key Metrics to Watch:

1. **Slug Constraint Violations**:
   ```sql
   SELECT COUNT(*) FROM approval_transaction_metrics
   WHERE success = false
   AND error_message LIKE '%slug_unique%'
   AND created_at > NOW() - INTERVAL '24 hours';
   ```

2. **FK Validation Errors**:
   ```sql
   SELECT COUNT(*) FROM approval_transaction_metrics
   WHERE success = false
   AND error_code = '23503'
   AND created_at > NOW() - INTERVAL '24 hours';
   ```

3. **Rate Limit Hits**:
   - Monitor 429 response rate in edge function logs
   - Alert if >5% of requests are rate limited

### Success Thresholds:
- Slug violations: <1% of submissions
- FK validation errors: <2% of submissions
- Rate limit hits: <3% of requests

---

## Next Steps: Phase 3

With Phase 2 complete, the pipeline now has:
- ✅ CORS protection (Phase 1)
- ✅ Transaction atomicity (Phase 1)
- ✅ Idempotency protection (Phase 1)
- ✅ Deadlock retry logic (Phase 1)
- ✅ Timeout protection (Phase 1)
- ✅ Slug uniqueness enforcement (Phase 2)
- ✅ FK validation with clear errors (Phase 2)
- ✅ Rate limiting protection (Phase 2)

**Ready for Phase 3**: Monitoring & observability improvements