Epic 4 — Customizable export templates (CRUD + Excel/CSV/JSON engine)

[xt0n1-t3ch]

Let the company define exactly how it wants the data exported, save it as a reusable template, and apply it in one click.

Scope

• Template model: name, output format (Excel/CSV/JSON), ordered columns each mapping a canonical field to a custom label, optional fixed/computed columns.
• Persist templates (EF) + seed 2-3 sensible defaults.
• Export engine applies a template to a documents canonical data -> ClosedXML (.xlsx) / CSV / JSON.\n- [ ] UI: manage templates (create/edit/duplicate/delete), live output preview, apply at export step.\n\n## Gate\nCreate a custom template, preview it, export a real document with it, open the file and the columns/labels match.

[xt0n1-t3ch]

Research-grounded scope (docs/research/reinsurance-landscape.md): export templates should include a Lloyds Coverholder Reporting Standards v5.2 preset (risk/premium/claims) alongside a generic canonical CSV/JSON — naming a real market standard reads as serious to a reinsurance audience. Templates map canonical fields -> output columns/labels, reusable and customizable.

[xt0n1-t3ch]

Landed in #38: customizable export templates (Excel/CSV/JSON) with a live preview, full CRUD, built-ins including Lloyd's CRS 5.2, the review Export menu, and /api/templates. Built-ins are seeded idempotently and protected. 25 unit + 9 integration + 3 e2e green.