# Legacy compatibility and pilot contract

## Required user-facing behavior

| Legacy behavior | Preserve in Next | Pilot status |
|---|---|---|
| Product/project selection workflow | preserve after separate UX analysis | not implemented |
| Plant 3D version discovery | preserve through adapter/override | foundation adapter |
| Local corporate plugin availability | preserve through valid local cache | designed/tested locally |
| P_Rec commands and Ribbon | preserve through one managed entry assembly | plugin-owned, not launched here |
| Immediate legacy return | preserve `LauncherMode=Legacy` | designed |
| Other legacy plugins | retain existing chain until individually migrated | required |

## Can be removed only for migrated P_Rec_Annot

- OrthoLoader configuration fan-out and twenty sequential `NETLOAD` calls.
- Generated LISP/BAT as the package-loading mechanism, once explicit Next startup is runtime-proven.
- Per-file legacy copy replacing an active module directory.

They remain necessary for other legacy corporate plugins until those plugins have their own migration and acceptance evidence.

## Duplicated or avoidable work

The source shows installer recursive copy/delete, updater hash/copy work, generated LISP generation and twenty sequential module loads. The precise overlap and cost require measurement. Next reduces avoidable work by comparing manifests, reusing a valid local version, staging only a new version and loading one entry assembly. It must not claim that legacy runs these actions on every AutoCAD startup without runtime evidence.

## P_Rec_Annot pilot

The pilot is a dry-run contract only:

```text
discover Plant 3D 2026 -> validate fixture manifest -> local test-source staging
-> activate version pointer -> build one startup NETLOAD script
-> construct ProcessStartInfo -> do not start process
```

It uses a fixture manifest with a synthetic SHA-256 and a test-created placeholder file. No real bundle, Plant assembly, package cache or production catalog is included.