# Plant 3D 2026 DwgQuery / ModelFiles API contract

## Scope and method

This report is based on metadata-only inspection of the installed Plant 3D 2026
assemblies. The assemblies were read from `<PLANT3D_2026_INSTALL>` and were not
copied into the repository. Metadata-only inspection was necessary because the
normal PowerShell host cannot load the product's .NET 8 dependencies safely.

Legacy source at the documented local path was not present on this machine, so
there is no legacy API claim in this report.

## Confirmed assemblies

| Assembly | Version | Relevant type |
| --- | --- | --- |
| `PnPDwg2dDef` | `0.0.0.0` | `Autodesk.ProcessPower.Drawings2d.DwgQuery`, `IDwgQuery`, `DwgViewDef`, `IDwgViewDef`, `DwgSheetDef`, `IDwgSheetDef` |
| `PnPDwg2dUtil` | `0.0.0.0` | `Autodesk.ProcessPower.Drawings2d.ModelFile` |
| `PnP3dOrthoProjectPart` | `17.0.60.1` | Ortho project-part integration assembly; the metadata scan found no public DwgQuery declaration there |

`PnPDwg2dDef` and `PnPDwg2dUtil` use `0.0.0.0` assembly versions in the
installed metadata. The supported runtime contract is therefore identified by
the exact public type names below, not by an invented product-version number.

## Confirmed contract

```text
Autodesk.ProcessPower.Drawings2d.IDwgViewDef.DwgQuery
  : Autodesk.ProcessPower.Drawings2d.IDwgQuery

Autodesk.ProcessPower.Drawings2d.IDwgQuery.ModelFiles
  : Autodesk.ProcessPower.Drawings2d.ModelFile[]

Autodesk.ProcessPower.Drawings2d.ModelFile.ModelFileName
  : System.String

Autodesk.ProcessPower.Drawings2d.ModelFile.ModelFileGuid
  : System.String
```

`DwgViewDef` implements `IDwgViewDef`; `DwgQuery` implements `IDwgQuery` and
`IDisposable`; `ModelFile` implements `IComparable<ModelFile>`.

`ModelFiles` is an array, not an untyped enumerable. `ModelFileName` is the
only confirmed string field representing the model-file reference. `ModelFileGuid`
is a separate identity field. `IsReferencedDwg` and `Xform` describe reference
state and transform, not a substitute path.

## Public members relevant to source resolution

`IDwgViewDef` exposes `DwgQuery`, `ViewName`, layout/orientation properties,
and `SetClippingPlanes`, `SetLayout`, `SetOrientation`, `Erase`, and `New`.

`IDwgQuery` exposes `ModelFiles`, `Execute`, and `Erase`.

`ModelFile` exposes `ModelFileName`, `ModelFileGuid`, `IsReferencedDwg`, and
`Xform`; its constructors accept a file-name string and optional transform,
reference flag, and GUID.

`IDwgSheetDef.DwgViewDefs` exposes the view-definition collection. Sheet
`DwgName`/`DwgPath` identify the Ortho sheet and must not be used as the source
of Piping DataLinks.

## Current and legacy usage

The original adapter used reflection and tried several possible names
(`ModelFileName`, `Value`, and arbitrary string values). That was not a valid
Plant 3D 2026 contract.

The production read path now uses the confirmed typed chain only:

```text
IDwgViewDef.DwgQuery.ModelFiles[].ModelFileName
```

The legacy source path was unavailable locally, so no legacy source-model or
DataLinks workaround has been imported.

## Runtime evidence

Static metadata cannot prove whether `ModelFileName` is project-relative or
absolute in a concrete Ortho fixture, or whether a particular view has zero,
one, or multiple model files. In DryRun only, setting
`P_REC_ANNOT_DIAGNOSTICS=OrthoStructure` enables a sanitized structure probe.
It records type names, collection counts, null state, string length, and a
one-way value hash; it does not emit paths or engineering data.

On the local DryRun fixture, the runtime probe recorded one view with one
`ModelFile`. The concrete types were `DwgViewDef`, `DwgQueryByBox`, and
`ModelFile[]`; `ModelFileName` was non-null and an absolute fixture-model
reference. The path itself was not retained in repository evidence.

The resolver resolves that reference to exactly one
`PipingProject.GetPnPDrawingFiles()` entry by normalized full-path equality,
then uses the confirmed `DataLinksManager.SelectAcPpRowIds(int dwgid)` overload
with the resolved `PnPProjectDrawing.Id`. It does not open or query the active
Ortho database for Piping rows.

The production resolver has no fallback property-name search. If the exact
contract is unavailable at runtime it reports
`ORTHO_MODEL_FILES_API_UNSUPPORTED` rather than guessing.