# Clay Migration Deep Dive — Implementation Guide

## Pre-Migration Assessment

```bash
# Document current implementation
find . -name "*.ts" -o -name "*.py" | xargs grep -l "clay" > clay-files.txt
wc -l clay-files.txt
npm list | grep clay
pip freeze | grep clay
```

```typescript
interface MigrationInventory {
  dataTypes: string[];
  recordCounts: Record<string, number>;
  dependencies: string[];
  integrationPoints: string[];
  customizations: string[];
}

async function assessClayMigration(): Promise<MigrationInventory> {
  return {
    dataTypes: await getDataTypes(),
    recordCounts: await getRecordCounts(),
    dependencies: await analyzeDependencies(),
    integrationPoints: await findIntegrationPoints(),
    customizations: await documentCustomizations(),
  };
}
```

## Strangler Fig Pattern

```
Phase 1: Parallel Run      Old (100%) -> New (0%)
Phase 2: Gradual Shift     Old (50%)  -> New (50%)
Phase 3: Complete           Old (0%)   -> New (100%)
```

## Phase 1: Setup (Week 1-2)

```bash
npm install @clay/sdk
cp .env.example .env.clay
node -e "require('@clay/sdk').ping()"
```

## Phase 2: Adapter Layer (Week 3-4)

```typescript
interface ServiceAdapter {
  create(data: CreateInput): Promise<Resource>;
  read(id: string): Promise<Resource>;
  update(id: string, data: UpdateInput): Promise<Resource>;
  delete(id: string): Promise<void>;
}

class ClayAdapter implements ServiceAdapter {
  async create(data: CreateInput): Promise<Resource> {
    const clayData = this.transform(data);
    return clayClient.create(clayData);
  }

  private transform(data: CreateInput): ClayInput {
    // Map from old format to Clay format
  }
}
```

## Phase 3: Data Migration (Week 5-6)

```typescript
async function migrateClayData(): Promise<MigrationResult> {
  const batchSize = 100;
  let processed = 0;
  let errors: MigrationError[] = [];

  for await (const batch of oldSystem.iterateBatches(batchSize)) {
    try {
      const transformed = batch.map(transform);
      await clayClient.batchCreate(transformed);
      processed += batch.length;
    } catch (error) {
      errors.push({ batch, error });
    }
    console.log(`Migrated ${processed} records`);
  }

  return { processed, errors };
}
```

## Phase 4: Traffic Shift (Week 7-8)

```typescript
function getServiceAdapter(): ServiceAdapter {
  const clayPercentage = getFeatureFlag('clay_migration_percentage');

  if (Math.random() * 100 < clayPercentage) {
    return new ClayAdapter();
  }

  return new LegacyAdapter();
}
```

## Rollback Plan

```bash
# Immediate rollback
kubectl set env deployment/app CLAY_ENABLED=false
kubectl rollout restart deployment/app

# Data rollback (if needed)
./scripts/restore-from-backup.sh --date YYYY-MM-DD

# Verify rollback
curl https://app.yourcompany.com/health | jq '.services.clay'
```

## Post-Migration Validation

```typescript
async function validateClayMigration(): Promise<ValidationReport> {
  const checks = [
    { name: 'Data count match', fn: checkDataCounts },
    { name: 'API functionality', fn: checkApiFunctionality },
    { name: 'Performance baseline', fn: checkPerformance },
    { name: 'Error rates', fn: checkErrorRates },
  ];

  const results = await Promise.all(
    checks.map(async c => ({ name: c.name, result: await c.fn() }))
  );

  return { checks: results, passed: results.every(r => r.result.success) };
}
```
