# OpenNest Engines

Independent nesting engine plugins for [OpenNest](https://git.thecozycat.net/aj/OpenNest).
Each engine is a standalone class library that OpenNest discovers at runtime via
`NestingEngineRegistry.LoadPlugins()` — drop the DLL into an `Engines/` folder next to
the OpenNest app or `OpenNest.Benchmark` build output.

| Engine | Approach |
|--------|----------|
| [Gpt6Astra](OpenNest.Engine.Gpt6Astra/) | Contact-based placement |
| [Opus55](OpenNest.Engine.Opus55/) | Frontier-advance no-fit-polygon packing |
| [Qwen38FlashNext](OpenNest.Engine.Qwen38FlashNext/) | Bottom-left greedy insertion over convex NFPs with an exact clearance gate |

## Building

Engines compile against an OpenNest checkout, expected as a sibling clone:

```
src/
  OpenNest/           git clone https://git.thecozycat.net/aj/OpenNest.git
  OpenNest-Engines/   this repo
```

Use a different location with `/p:OpenNestRoot=<path>` (or the `OpenNestRoot`
environment variable).

```powershell
./Build-Engines.ps1                    # build all engines + deploy to the benchmark
./Build-Engines.ps1 -Engines Opus55    # just one
dotnet test OpenNest.Engine.Opus55/tests/OpenNest.Engine.Opus55.Tests.csproj
```

Each engine's README covers its algorithm and benchmark results.

`Engine.Testing/` contains shared xUnit contract tests, shapes, job builders and layout
assertions backed by `NestLayoutCheck`. It is a test dependency, not a plugin;
`Build-Engines.ps1` only deploys projects in `OpenNest.Engine.*` directories. All engines
require the shared-services APIs in the sibling host checkout. See
[the PR 5 migration report](MIGRATION-PR5.md) for validation and benchmark results.

## Writing a new engine

```powershell
./New-Engine.ps1 -Name Nova
```

This copies `_Template/` to `OpenNest.Engine.Nova/`: an `INestingEngine` stub, a README
spelling out what counts as an independent engine, `BENCH-RULES.md` (how a model's run
works: workspace limits, git, the real-part archive, reporting), and starter acceptance tests checked by
the shared `NestLayoutCheck` (they fail until `Solve()` is implemented).

To work inside an OpenNest checkout instead, stamp it into an `Engines/` folder there and
bring the shared build files and test kit along; they detect that layout automatically:

```powershell
./New-Engine.ps1 -Name Nova -Destination <OpenNest>/Engines -IncludeBuildFiles
```

## Layout

Each engine lives in `OpenNest.Engine.<Name>/` with an optional `tests/` subproject.
`Directory.Build.props` supplies the target framework and the `OpenNest.Engine`
reference, so an engine's `.csproj` can be nearly empty.