feat: add DataSync plugin with adapter pattern

dist/plugins.ts

@@ -6,3 +6,9 @@ export { ChangeDataCapturePlugin } from '../plugins/cdc'
 export { QueryLogPlugin } from '../plugins/query-log'
 export { ResendPlugin } from '../plugins/resend'
 export { ClerkPlugin } from '../plugins/clerk'
+export {
+    DataSyncPlugin,
+    DataSyncAdapter,
+    PostgresSync,
+    MySQLSync,
+} from '../plugins/data-sync'

plugins/data-sync/README.md

@@ -0,0 +1,87 @@
+# DataSync Plugin
+
+Incrementally replicate rows from an external database into your StarbaseDB (SQLite) instance using an append-only cursor column. Each supported engine ships as a **DataSyncAdapter** subclass — so adding a new source means subclassing one interface, not touching the plugin core.
+
+## Supported Sources
+
+| Adapter | Import |
+|---------|--------|
+| PostgreSQL | `PostgresSync` |
+| MySQL / MariaDB | `MySQLSync` |
+
+## Installation
+
+```typescript
+import { DataSyncPlugin, PostgresSync } from '../plugins/data-sync'
+
+const plugins = [
+    // ... other plugins
+    new DataSyncPlugin({
+        source: new PostgresSync({
+            host: 'db.example.com',
+            port: 5432,
+            user: 'readonly',
+            password: process.env.PG_PASSWORD!,
+            database: 'production',
+        }),
+        tables: [
+            { tableName: 'public.users',   trackingColumn: 'id' },
+            { tableName: 'public.orders',  trackingColumn: 'created_at' },
+        ],
+        syncIntervalMs: 60_000, // poll every minute (default: 5 min)
+    }),
+] satisfies StarbasePlugin[]
+```
+
+## Configuration Options
+
+### `DataSyncPluginOptions`
+
+| Option | Type | Default | Description |
+|--------|------|---------|-------------|
+| `source` | `DataSyncAdapter` | — | Database adapter (PostgresSync, MySQLSync, …) |
+| `tables` | `TableSyncConfig[]` | — | List of tables to replicate |
+| `syncIntervalMs` | `number` | `300000` | Poll interval in milliseconds |
+
+### `TableSyncConfig`
+
+| Option | Type | Description |
+|--------|------|-------------|
+| `tableName` | `string` | Fully-qualified (`public.users`) or plain (`users`) table name |
+| `trackingColumn` | `string` | Monotonically increasing column used as the sync cursor (`id`, `created_at`, …) |
+
+### PostgresSync options
+
+| Option | Type | Default | Description |
+|--------|------|---------|-------------|
+| `host` | `string` | — | PostgreSQL host |
+| `port` | `number` | `5432` | PostgreSQL port |
+| `user` | `string` | — | Database username |
+| `password` | `string` | — | Database password |
+| `database` | `string` | — | Database name |
+| `ssl` | `boolean` | `false` | Enable SSL/TLS |
+
+### MySQLSync options
+
+Same as PostgresSync but defaults `port` to `3306`.
+
+## How It Works
+
+1. **Schema discovery** — on first sync the adapter calls `getColumns()` and the plugin creates a matching SQLite table (schema prefix stripped).
+2. **Cursor tracking** — progress is stored in `tmp_data_sync_metadata` so syncs resume where they left off after restarts.
+3. **Incremental fetch** — only rows where `trackingColumn > lastValue` are fetched, keeping payloads small.
+4. **Alarm-based scheduling** — Cloudflare Durable Object alarms reschedule the next sync automatically.
+
+## Custom Adapters
+
+Extend `DataSyncAdapter` and implement three methods:
+
+```typescript
+import { DataSyncAdapter, ColumnInfo } from '../plugins/data-sync'
+
+export class MyDBSync extends DataSyncAdapter {
+    async getColumns(tableName: string): Promise<ColumnInfo[]> { /* ... */ }
+    async fetchRows(opts: { tableName: string; trackingColumn: string; lastValue: string | null; limit?: number }): Promise<Record<string, unknown>[]> { /* ... */ }
+    mapType(nativeType: string): string { /* ... */ }
+}
+```