feat: Add Document Processing packages (MEDI)

[luisquintanilla]

Status (updated 2026-06-25): Draft. This PR has been synced with main (conflicts resolved, now mergeable) and retargeted to the latest MEDI published on nuget.org (Microsoft.Extensions.DataIngestion(.Abstractions) 10.7.0-preview.1.26309.5). It is marked draft while the broader document-AI building-block direction settles — see the provider-neutral OCR abstraction proposal dotnet/extensions#7587 (IOcrClient), which these packages are designed to compose with. No API surface here depends on that proposal yet.

Summary

Adds two new CommunityToolkit.DocumentProcessing packages as a new MEDI (Microsoft.Extensions.DataIngestion) top-level feature area, following the established MEVD pattern.

New Packages

Package	Description
CommunityToolkit.DocumentProcessing.PdfPig.OnnxLayoutAnalysis	ONNX-based layout detection (RT-DETR, configurable models, image preprocessing, NMS) implementing PdfPig's IPageSegmenter
CommunityToolkit.DocumentProcessing.PdfPig.DataIngestion	MEDI bridge with vision LLM enrichers (OCR, table extraction, contextual chunking) for PDF document ingestion

Origin

Ported from luisquintanilla/PdfPig (feature/intelligent-pdf-ingestion branch, PRs #1 and #2). See the investigation proposal for design rationale.

Infrastructure

• MEDI/ directory structure mirroring MEVD/ pattern
• Directory.Build.props for src and test
• Central package management (Directory.Packages.props) updates
• MEDI.slnf solution filter
• medi.yml CI workflow
• nuget.config restoring from nuget.org only (the MEDI previews are published there; the earlier dotnet-public feed mapping has been removed)

Namespace Mapping

Original	Toolkit
UglyToad.PdfPig.DocumentLayoutAnalysis.Onnx	CommunityToolkit.DocumentProcessing.PdfPig.OnnxLayoutAnalysis
UglyToad.PdfPig.DataIngestion	CommunityToolkit.DocumentProcessing.PdfPig.DataIngestion

Test Results

• 216 total: 213 passed, 3 skipped (require ONNX model file)
• ONNX: 133 tests (130 passed, 3 skipped)
• DataIngestion: 83 tests (all passed)

[roji]

Hey @luisquintanilla, will wait until all the setup/release stuff is done for MEVD, and then will review/help get this merged!

[luisquintanilla]

Refreshed this branch:

• Synced with main — the Directory.Packages.props conflict is resolved; the PR is mergeable again.
• Retargeted MEDI to the latest on nuget.org: Microsoft.Extensions.DataIngestion(.Abstractions) 10.4.0-preview.1.26160.2 → 10.7.0-preview.1.26309.5. That bump pulls in Microsoft.Extensions.AI.Abstractions 10.7.0 and Microsoft.Extensions.DependencyInjection.Abstractions 10.0.9 (both required by MEDI 10.7), so those pins moved too.
• Removed the dotnet-public feed — MEDI 10.7 previews are on nuget.org, so nuget.config now restores from nuget.org only. Verified a clean restore + build of all four PdfPig projects (net10.0;net8.0) against nuget.org alone.
• Marked draft while the document-AI direction settles alongside the IOcrClient abstraction proposal ([API Proposal]: IOcrClient — an OCR / document-extraction capability for Microsoft.Extensions.AI dotnet/extensions#7587). No surface here depends on it yet; the packages are designed to compose with it.