Add LeanPrint: foundation for a driverless FinePrint alternative

[azitc-ac]

Summary

Starts LeanPrint — a modern, lightweight, open-source alternative to FinePrint that pools print jobs, imposes them N-up (2-on-1, 4-on-1, booklet), previews them WYSIWYG, and forwards to a real printer. It is designed from day one to run on Windows on ARM (ARM64) as well as x64.

The key design decision: no third-party print driver. Windows is retiring third-party v3/v4 drivers (Windows Protected Print), and on ARM64 x64 print drivers aren't emulated at all — so a FinePrint-style virtual driver is a dead end. LeanPrint instead captures jobs via a loopback IPP service driven by the Microsoft in-box IPP class driver (user-mode, driverless, ARM64-native). Rationale in docs/ARCHITECTURE.md.

This PR is the first increment: the platform-neutral, unit-tested core. Nothing here talks to a printer yet — the Windows capture/render/app layers are scaffolded on the roadmap.

What's included

• Domain model (LeanPrint.Core): SourcePage, PrintDocument, PrintJobPool — print-job pooling / "summarise print jobs".
• Imposition engine:
  • NUpImposer — N-up grids (arbitrary rows × columns), margins, gutters, cell order (row/column-major), scale modes (fit / fill / stretch / actual size), and auto-rotate to maximise each page within its cell.
  • BookletImposer — saddle-stitch page reordering, padded to multiples of 4.
• Geometry in PostScript points, top-left origin (documented; renderer converts to PDF's bottom-left later).
• Tests: 21 xUnit tests covering N-up placement, ordering, rotation, margins/gutters, blanks, booklet ordering, and the model. Cross-platform (no Windows deps).
• Docs: README, ARCHITECTURE (capture strategy + why driverless), ROADMAP (M0–M5).
• CI: GitHub Actions workflow building/testing the core on push.

Verification

dotnet test (Debug and Release) — 21/21 passing on Linux with the .NET 8 SDK. The core is intentionally OS-neutral so this runs anywhere.

Layout

Path	Description
leanprint/src/LeanPrint.Core	Domain model + imposition engine (net8.0, no Windows deps)
leanprint/tests/LeanPrint.Core.Tests	xUnit tests
leanprint/docs/	Architecture & roadmap
.github/workflows/leanprint-core.yml	CI for the core

Notes for reviewers

• Everything lives under leanprint/ and is fully separate from the existing unblock-Files.ps1 utility. It may make sense to eventually split LeanPrint into its own repository — happy to do that.
• Licensed MIT; PDF rendering will use PDFium (BSD). Ghostscript/MuPDF (AGPL) are intentionally avoided to keep the project permissively licensed.

Next steps (see ROADMAP)

• M1 — loopback IPP capture prototype (proves the only real technical risk).
• M2 — PDFium rendering + WYSIWYG preview.
• M3 — forward imposed sheets to a physical printer.

🤖 Generated with Claude Code

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Generated by Claude Code

[azitc-ac]

Closing: OpenLeanPrint now lives in its own dedicated repository at azitc-ac/OpenLeanPrint, where the same foundation has been pushed to main. This PR was only a temporary placement inside the unrelated ps-unblock-files repo and is superseded.

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