The `/api/organizations` endpoint now supports a `since=` parameter to filter results by date. This enables efficient retrieval of organizations added to the database on or after a specific date.

## Usage

**Endpoint:** `GET /api/organizations?since=YYYY-MM-DD`

**Example:**
```bash
curl "https://api.charityapi.org/api/organizations?since=2025-01-15" \
  -H "apikey: YOUR_API_KEY"
```

## Behavior

- **Date Format:** ISO 8601 (YYYY-MM-DD)
- **Filter Logic:** Returns organizations where `first_seen_date >= specified_date`
- **Date Matching:** Organizations added on the specified date are included in results

## Implementation Details

The parameter filters to when an organization first appeared in our IRS data imports. This is not the same as the organization's IRS ruling date or formation date.

## Error Handling

Missing the `since=` parameter returns:

```json
{
  "error": {
    "message": "Missing required 'since' param. Please provide in the format YYYY-MM-DD e.g. 2023-09-15",
    "code": "MISSING_REQUIRED_PARAMETER",
    "details": {
      "parameter": "since",
      "expected_format": "YYYY-MM-DD"
    }
  }
}
```

## Use Cases

- **Incremental Sync:** Pull only new organizations since last sync
- **Change Detection:** Monitor database additions over time
- **Data Freshness:** Verify recent IRS data imports
- **Audit Trails:** Track when organizations entered the database

## Notes

- The `since=` filter operates on database insertion time, not IRS ruling dates
- Date comparison is inclusive (organizations added exactly on the specified date are included)
- Test API keys return mock data