docs(plan): Epic B1 design — multi-sheet XLSX as the first paid Pro feature

[thiagoluga]

Design / decision PR — no feature code yet. Epic A (dynamic path) is done; this opens Epic B.

Per your calls: start with multi-sheet XLSX (B1), shipped as a paid, separate "Pro" package (commercial license), with the OSS core staying MIT.

Because this introduces a commercial-license boundary and an architecture extension (multi-section output), I'm recording the design for your approval before writing any code or license file.

What's here (docs only)

• docs/epic-b1-multisheet-pro.md — the blueprint:
  • why multi-sheet doesn't fit the v1 "one schema, one filter, project once" model;
  • the single-pass multi-section architecture (source read once; per-sheet filter + columns);
  • the OSS/Pro split — a small generic multi-section hook in MIT Core; the XLSX workbook writer + fluent API in the commercial NeoReports.Xlsx.Pro;
  • a fluent API sketch (XlsxWorkbook(wb => wb.Sheet("Approved", ...).Sheet("Rejected", ...)));
  • the B1.1–B1.5 implementation breakdown.
• DECISIONS.md — D22 updated (multi-sheet = first paid feature) + D27 new (Pro package model: separate package, commercial license, no runtime enforcement in v1, excluded from the OSS NuGet release).
• PLAN.md — Epic B reshaped.

Open sub-decisions I need from you (in the doc)

1. Package name — NeoReports.Xlsx.Pro (proposed)?
2. License type — source-available (visible, paid to use) vs closed-source? The legal text is yours; I'll scaffold a placeholder marked commercial.
3. License enforcement — none for now (recommended) vs a license-key gate later?
4. OSS/Pro boundary — OK that the generic multi-section hook is MIT (makes a free hand-rolled multi-section possible; the polished XLSX writer is the Pro value)?
5. CSV behavior with sections — reject with a clear error in v1 (recommended)?

Once you approve the approach (and answer the above), I'll proceed with B1.1 (the OSS multi-section hook), then B1.2 (the Pro package).

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud