# Migration plan

| Stage | Scope | Size | Exit criterion |
|---|---|---|---|
| 1 | Freeze commands, UI, golden DWG, telemetry semantics | L | repeatable 2019 baseline |
| 2 | Extract DTO/rules/positioning/duplicate detection | L | Core tests without AutoCAD |
| 3 | Implement Plant 3D 2026 adapter and transaction service | XL | compile/runtime on test project |
| 4 | Add one Ribbon command with project-aware enablement | M | explicit command scope, no duplicate registration |
| 5 | Compare DWG objects/text/coordinates/layers/styles/undo | XL | golden equivalence and performance |
| 6 | Replace telemetry with event + separate object counters | M | 1 command = 1 usage event |

First implementation slice: `PXP-AAV`/`PXP-OA` on one controlled Ortho viewport, then `PXP-ALC` line connections. Do not start with batch `PXP-IOD`.