User story: Export usage data as CSV

**As an** enterprise administrator, **I want** to download my organisation's usage data as a CSV, **so that** I can import it into our internal reporting tool.

User story: Export usage data as CSV

As an enterprise administrator,
I want to download my organisation’s usage data as a CSV,
so that I can import it into our internal reporting tool.

Priority

Must

Acceptance criteria

1. Given I am an authenticated enterprise admin, when I open Data → Export, then I can choose CSV, JSON, or XLSX.
2. Given I submit an export for a valid date range ≤ 24 months, when the job completes, then I receive an email with a download link within 5 minutes for datasets ≤ 1M rows.
3. Given I open the download link within its validity window, when I download the file, then the file is complete and opens without corruption errors.

Notes / constraints

• v1 excludes custom SQL and streaming export (see charter scope).

Traceability

• Requirement IDs: FR-EXPORT-1
• NFRs: NFR-PERF-1, NFR-REL-1
• Feature docs: docs/user/getting-started/quickstart.md